query: where is routing information stored in most routers

pos: Routing table forwarding provides uninterrupted performance. Routing table In computer networking a routing table, or routing information base (RIB), is a data table stored in a router or a networked computer that lists the routes to particular network destinations, and in some cases, metrics (distances) associated with those routes. The routing table contains information about the topology of the network immediately around it. The construction of routing tables is the primary goal of routing protocols. Static routes are entries made in a routing table by non-automatic means and which are fixed rather than being the result of some network topology "discovery" procedure.

pos: Route server Route server A route server is a computer server that was originally developed by the Routing Arbiter project, with funding from the National Science Foundation. This routing process directs information among Border Gateway Protocol (BGP) routers. These servers are placed at Network Access Points (NAP), where centralized computers organize and match routing data. Route servers are important because they help manage BGP sessions. BGP sessions have difficulties with overhead when managing sessions where routers with single and multiple domains are connected ("also known as full mesh routing connectivity)". Route servers reduce overhead by referencing the IP routing table of an

pos: Interior gateway protocol routing information "between" autonomous systems and rely on IGPs to resolve routes within an autonomous system. Distance-vector routing protocols use the Bellman–Ford algorithm. In these protocols, each router does not possess information about the full network topology. It advertises its distance value (DV) calculated to other routers and receives similar advertisements from other routers unless changes are done in local network or by neighbours (routers). Using these routing advertisements each router populates its routing table. In the next advertisement cycle, a router advertises updated information from its routing table. This process continues until the routing tables of each router converge

pos: Distance-vector routing protocol are configured to use the same distance-vector routing protocol. Once a router has this information it is able to amend its own routing table to reflect the changes and then inform its neighbours of the changes. This process has been described as ‘routing by rumour’ because routers are relying on the information they receive from other routers and cannot determine if the information is actually valid and true. There are a number of features which can be used to help with instability and inaccurate routing information. The oldest routing protocol, and the oldest distance-vector protocol, is version 1 of the

pos: Router (computing) packet to determine the ultimate destination. Then, using information in its routing table or routing policy, it directs the packet to the next network on its journey. The most familiar type of routers are home and small office routers that simply forward IP packets between the home computers and the Internet. An example of a router would be the owner's cable or DSL router, which connects to the Internet through an Internet service provider (ISP). More sophisticated routers, such as enterprise routers, connect large business or ISP networks up to the powerful core routers that forward data at high speed

pos: Routing Information Protocol network is reachable with the same hop count but via two different routes, the network will be entered into the routing table two times with different next hop routers. The RIPv1 enabled router will then perform what is known as equal-cost load balancing for IP packets. RIPv1 enabled routers not only request the routing tables of other routers every 30 seconds, they also listen to incoming requests from neighbouring routers and send their own routing table in turn. RIPv1 routing tables are therefore updated every 25 to 35 seconds. The RIPv1 protocol adds a small random time variable to the

pos: Distance-vector routing protocol protocol determine the distance between themselves and a destination. The best route for Internet Protocol packets that carry data across a data network is measured in terms of the numbers of routers (hops) a packet has to pass to reach its destination network. Additionally some distance-vector protocols take into account other traffic information, such as network latency. To establish the best route, routers regularly exchange information with neighbouring routers, usually their routing table, hop count for a destination network and possibly other traffic related information. Routers that implement distance-vector protocol rely purely on the information provided to them by other

pos: Distance Vector Multicast Routing Protocol Distance Vector Multicast Routing Protocol The Distance Vector Multicast Routing Protocol (DVMRP), defined in RFC 1075, is a routing protocol used to share information between routers to facilitate the transportation of IP multicast packets among networks. It formed the basis of the Internet's historic multicast backbone, Mbone. The protocol is based on the Routing Information Protocol (RIP). The router generates a routing table with the multicast group of which it has knowledge with corresponding distances (i.e. number of devices/routers between the router and the destination). When a multicast packet is received by a router, it is forwarded by the router's

pos: Network topology include devices such as routers and bridges, as well as devices that may distribute traffic based on load or based on application content (e.g., a Web URL identifier). A router is an internetworking device that forwards packets between networks by processing the routing information included in the packet or datagram (Internet protocol information from layer 3). The routing information is often processed in conjunction with the routing table (or forwarding table). A router uses its routing table to determine where to forward packets. A destination in a routing table can include a "null" interface, also known as the "black hole"

pos: Routing Information Protocol IP address from which the RIPv1 response was sent. As the requesting router receives updates from different neighbouring routers it will only update the reachable networks in its routing table, if it receives information about a reachable network it has not yet in its routing table or information that a network it has in its routing table is reachable with a lower hop count. Therefore a RIPv1 router will in most cases only have one entry for a reachable network, the one with the lowest hop count. If a router receives information from two different neighbouring router that the same

pos: Router (computing) example, quality of service (QoS). For pure IP forwarding, a router is designed to minimize the state information associated with individual packets. Once a packet is forwarded, the router does not retain any historical information about the packet. The routing table itself can contain information derived from a variety of sources, such as a default or static routes that are configured manually, or dynamic routing protocols where the router learns routes from other routers. A default route is one that is used to route all traffic whose destination does not otherwise appear in the routing table; this is common –

pos: Enhanced Interior Gateway Routing Protocol most distance vector routing protocols, EIGRP does not transmit all the data in the router's routing table when a change is made, but will only transmit the changes that have been made since the routing table was last updated. EIGRP does not send its routing table periodically, but will only send routing table data when an actual change has occurred. This behavior is more inline with link-state routing protocols, thus EIGRP is mostly considered a hybrid protocol. When a router running EIGRP is connected to another router also running EIGRP, information is exchanged between the two routers. They form a

pos: Routing Information Protocol Routing Information Protocol The Routing Information Protocol ('RIP') is one of the oldest distance-vector routing protocols which employ the hop count as a routing metric. RIP prevents routing loops by implementing a limit on the number of hops allowed in a path from source to destination. The largest number of hops allowed for RIP is 15, which limits the size of networks that RIP can support. RIP implements the split horizon, route poisoning and holddown mechanisms to prevent incorrect routing information from being propagated. In RIPv1 routers broadcast updates with their routing table every 30 seconds. In the early deployments,

pos: Administrative distance network administrator. On Cisco routers, routes issued by OSPF have a lower default administrative distance than routes issued by the Routing Information Protocol. By default, OSPF has a default administrative distance of 110 and RIP has a default administrative distance of 120. The administrative distance (AD) value is assigned by the router on a per-protocol basis. Routers, by design, should not install multiple routes into the routing table as this has the potential to cause routing loops. While a router may run multiple routing protocols on the same device, it is necessary for the router to implement a process to

pos: Network forensics the network (e.g., the Internet) by adding source and destination information which can be interpreted by routers all over the network. Cellular digital packet networks, like GPRS, use similar protocols like IP, so the methods described for IP work with them as well. For the correct routing, every intermediate router must have a routing table to know where to send the packet next. These routing tables are one of the best sources of information if investigating a digital crime and trying to track down an attacker. To do this, it is necessary to follow the packets of the attacker, reverse

pos: Enhanced Interior Gateway Routing Protocol workload on the router and the amount of data that needs to be transmitted. EIGRP replaced the Interior Gateway Routing Protocol (IGRP) in 1993. One of the major reasons for this was the change to classless IPv4 addresses in the Internet Protocol, which IGRP could not support. Almost all routers contain a routing table that contains rules by which traffic is forwarded in a network. If the router does not contain a valid path to the destination, the traffic is discarded. EIGRP is a dynamic routing protocol by which routers automatically share route information. This eases the workload on a

pos: Router (computing) along the optical fiber lines of the Internet backbone. Though routers are typically dedicated hardware devices, software-based routers also exist. When multiple routers are used in interconnected networks, the routers can exchange information about destination addresses using a routing protocol. Each router builds up a routing table listing the preferred routes between any two systems on the interconnected networks. A router has two types of network element components organized onto separate "planes": A router may have interfaces for different types of physical layer connections, such as copper cables, fiber optic, or wireless transmission. It can also support different network layer

pos: Routing routing table (sorted by priority): Because a routing metric is specific to a given routing protocol, multi-protocol routers must use some external heuristic to select between routes learned from different routing protocols. Cisco routers, for example, attribute a value known as the administrative distance to each route, where smaller administrative distances indicate routes learned from a supposedly more reliable protocol. A local network administrator, in special cases, can set up host-specific routes to a particular device that provides more control over network usage, permits testing, and better overall security. This is useful for debugging network connections or routing tables. In

pos: Routing Information Protocol to the RIP hop limit. There are three standardised versions of the Routing Information Protocol: "RIPv1" and "RIPv2" for IPv4, and "RIPng" for IPv6. The original specification of RIP, defined in RFC 1058, was published in 1988. When starting up, and every 30 seconds thereafter, a router with RIPv1 implementation broadcasts to 255.255.255.255 a request message through every RIPv1 enabled interface. Neighbouring routers receiving the request message respond with a RIPv1 segment, containing their routing table. The requesting router updates its own routing table, with the reachable IP network address, hop count and next hop, that is the router interface

pos: Control plane internal databases of candidate routes which are promoted when a route fails or when a routing policy is changed. Several different information sources may provide information about a route to a given destination, but the router must select the "best" route to install into the routing table. In some cases, there may be multiple routes of equal "quality", and the router may install all of them and load-share across them. There are three general sources of routing information: Routers forward traffic that enters on an input interface and leaves on an output interface, subject to filtering and other local rules.

pos: Routing Information Protocol subnet information, thus supporting Classless Inter-Domain Routing (CIDR). To maintain backward compatibility, the hop count limit of 15 remained. RIPv2 has facilities to fully interoperate with the earlier specification if all "Must Be Zero" protocol fields in the RIPv1 messages are properly specified. In addition, a "compatibility switch" feature allows fine-grained interoperability adjustments. In an effort to avoid unnecessary load on hosts that do not participate in routing, RIPv2 "multicasts" the entire routing table to all adjacent routers at the address 224.0.0.9, as opposed to RIPv1 which uses broadcast. Unicast addressing is still allowed for special applications. (MD5) authentication for

pos: Virtual routing and forwarding Virtual routing and forwarding In IP-based computer networks, virtual routing and forwarding (VRF) is a technology that allows multiple instances of a routing table to co-exist within the same router at the same time. Because the routing instances are independent, the same or overlapping IP addresses can be used without conflicting with each other. Network functionality is improved because network paths can be segmented without requiring multiple routers. VRF may be implemented in a network device by distinct routing tables known as forwarding information bases (FIBs), one per routing instance. Alternatively, a network device may have the ability to configure

pos: Border Gateway Protocol quadratically with the number of routers involved. To alleviate the problem, BGP implements two options: route reflectors (RFC 4456) and BGP confederations (RFC 5065). The following discussion of basic UPDATE processing assumes a full iBGP mesh. A given BGP router may accept Network Layer Reachability Information (NLRI) UPDATEs from multiple neighbors and advertise NLRI to the same, or a different set, of neighbors. Conceptually, BGP maintains its own "master" routing table, called the Local Routing Information Base ("Loc-RIB"), separate from the main routing table of the router. For each neighbor, the BGP process maintains a conceptual Adjacent Routing Information Base,

pos: Virtual routing and forwarding MPLS environment. , the key element in the Cisco MPLS VPN technology. Virtual routing and forwarding In IP-based computer networks, virtual routing and forwarding (VRF) is a technology that allows multiple instances of a routing table to co-exist within the same router at the same time. Because the routing instances are independent, the same or overlapping IP addresses can be used without conflicting with each other. Network functionality is improved because network paths can be segmented without requiring multiple routers. VRF may be implemented in a network device by distinct routing tables known as forwarding information bases (FIBs), one per

pos: Protocol-dependent module Protocol-dependent module Protocol-dependent modules (PDMs) are used by the routing protocol EIGRP to make decisions about adding routes learned from other sources; for example other routers or routing protocols to the routing table. In fact EIGRP has the capability for routing several different protocols including IPv4 and IPv6 using protocol-dependent modules (PDMs). The PDM is also capable of carrying information from the routing table to the topology table. EIGRP offers support for various routed protocols (e.g. Internet Protocol Version 6 (IPv6), IP, IPX, AppleTalk), and has added support for Service Routing (SAF) PDMs. The only other routing protocol that comes

pos: Cisco Express Forwarding routing table in order to get the next-hop information. Instead, fast switching will be performed on the line card itself. CEF currently supports Ethernet, Frame Relay, ATM, PPP, FDDI, tunnels, and Cisco HDLC. Cisco Express Forwarding Cisco Express Forwarding (CEF) is an advanced layer 3 switching technology used mainly in large core networks or the Internet to enhance the overall network performance. Although CEF is a Cisco proprietary protocol other vendors of multi-layer switches or high-capacity routers offer a similar functionality where layer-3 switching or routing is done in hardware (in an ASIC) instead of by software and the (central)

pos: SQL Slammer it slowed down systems worldwide. The slowdown was caused by the collapse of numerous routers under the burden of extremely high bombardment traffic from infected servers. Normally, when traffic is too high for routers to handle, the routers are supposed to delay or temporarily stop network traffic. Instead, some routers "crashed" (became unusable), and the "neighbour" routers would notice that these routers had stopped and should not be contacted (aka "removed from the routing table"). Routers started sending notices to this effect to other routers they knew about. The flood of routing table update notices caused some additional routers to

pos: Distance-vector routing protocol routers, and do not assess the network topology. Distance-vector protocols update the routing tables of routers and determine the route on which a packet will be sent by the "next hop" which is the exit interface of the router and the IP address of the interface of the receiving router. Distance is a measure of the cost to reach a certain node. The least cost route between any two nodes is the route with minimum distance. Updates are performed periodically in a distance-vector protocol where all or part of a router's routing table is sent to all its neighbours that

pos: Zone Routing Protocol path saved in the route reply packet to send data packets to the destination. Zone Routing Protocol Zone Routing Protocol, or ZRP is a hybrid Wireless Networking routing protocol that uses both proactive and reactive routing protocols when sending information over the network. ZRP was designed to speed up delivery and reduce processing overhead by selecting the most efficient type of protocol to use throughout the route. If a packet's destination is in the same zone as the origin, the proactive protocol using an already stored routing table is used to deliver the packet immediately. If the route extends outside

pos: Zone Routing Protocol Zone Routing Protocol Zone Routing Protocol, or ZRP is a hybrid Wireless Networking routing protocol that uses both proactive and reactive routing protocols when sending information over the network. ZRP was designed to speed up delivery and reduce processing overhead by selecting the most efficient type of protocol to use throughout the route. If a packet's destination is in the same zone as the origin, the proactive protocol using an already stored routing table is used to deliver the packet immediately. If the route extends outside the packet's originating zone, a reactive protocol takes over to check each successive zone

pos: Routing table Routing table In computer networking a routing table, or routing information base (RIB), is a data table stored in a router or a networked computer that lists the routes to particular network destinations, and in some cases, metrics (distances) associated with those routes. The routing table contains information about the topology of the network immediately around it. The construction of routing tables is the primary goal of routing protocols. Static routes are entries made in a routing table by non-automatic means and which are fixed rather than being the result of some network topology "discovery" procedure. A routing table uses

pos: Border Gateway Protocol that directly connected route's interface is active, the BGP route to the destination will not be put into the routing table. Once the interface goes down, and there are no more preferred routes, the Loc-RIB route would be installed in the main routing table. Until recently, it was a common mistake to say "BGP carries policies". BGP actually carried the information with which rules inside BGP-speaking routers could make policy decisions. Some of the information carried that is explicitly intended to be used in policy decisions are communities and multi-exit discriminators (MED). The BGP standard specifies a number of decision

neg: Convergence (routing) Convergence (routing) Convergence is the state of a set of routers that have the same topological information about the internetwork in which they operate. For a set of routers to have "converged", they must have collected all available topology information from each other via the implemented routing protocol, the information they gathered must not contradict any other router's topology information in the set, and it must reflect the real state of the network. In other words: In a converged network all routers "agree" on what the network topology looks like. Convergence is an important notion for a set of routers

neg: Route server autonomous system where the server is located. Route server A route server is a computer server that was originally developed by the Routing Arbiter project, with funding from the National Science Foundation. This routing process directs information among Border Gateway Protocol (BGP) routers. These servers are placed at Network Access Points (NAP), where centralized computers organize and match routing data. Route servers are important because they help manage BGP sessions. BGP sessions have difficulties with overhead when managing sessions where routers with single and multiple domains are connected ("also known as full mesh routing connectivity)". Route servers reduce overhead by

neg: Open Shortest Path First known to neighbouring routers. The information about the cost of a link, that is the speed of a point to point connection between two routers, is then cascaded through the network because OSPF routers advertise the information they receive from one neighbouring router to all other neighbouring routers. This process of flooding link state information through the network is known as "synchronisation". Based on this information, all routers with OSPF implementation continuously update their link state databases with information about the network topology and adjust their routing tables. An OSPF network can be structured, or subdivided, into routing "areas" to

neg: Convergence (routing) in a matter of seconds. Certain configuration and hardware conditions will prevent a network from ever converging. For instance, a "flapping" interface (an interface that frequently changes its state between "up" and "down") might cause conflicting information to propagate throughout the network so the routers never agree on its current state. Under certain circumstances it might be desirable to withhold detailed routing information from parts of the network via route aggregation, thereby speeding up convergence of the topological information shared by all routers. Convergence (routing) Convergence is the state of a set of routers that have the same topological information

neg: Convergence (routing) e.g. RIP, OSPF, BGP4. A state of convergence is achieved once all routing protocol-specific information has been distributed to all routers participating in the routing protocol process. Any change in the network that affects routing tables will break the convergence temporarily until this change has been successfully communicated to all other routers. Convergence time is a measure of how fast a group of routers reach the state of convergence. It is one of the main design goals and an important performance indicator for routing protocols, which should implement a mechanism that allows all routers running the protocol to quickly and

neg: Routing to reach those destinations. A route is defined as a pairing between a destination and the attributes of the path to that destination, thus the name, path vector routing, where the routers receive a vector that contains paths to a set of destinations. The path, expressed in terms of the domains (or confederations) traversed so far, is carried in a special path attribute that records the sequence of routing domains through which the reachability information has passed. Path selection involves applying a routing metric to multiple routes to select (or predict) the best route. Most routing algorithms use only one

neg: Route analytics Information is exchanged between network routers using different routing protocols to dynamically determine the best route for packets to take – the most widely deployed protocols include OSPF, IS-IS, EIGRP and BGP. Route analytics systems function by establishing a relationship (adjacency) with a single router in a Layer 3 network followed by passive listening of the control plane messages being exchanged by the routers. By becoming part of the control plane, route analytics systems effectively act as a passive router, having the same routing knowledge of other network routers but without the ability to forward actual data packets. Though the

neg: Routing protocol Routing protocol A routing protocol specifies how routers communicate with each other, distributing information that enables them to select routes between any two nodes on a computer network. Routing algorithms determine the specific choice of route. Each router has a prior knowledge only of networks attached to it directly. A routing protocol shares this information first among immediate neighbors, and then throughout the network. This way, routers gain knowledge of the topology of the network. The specific characteristics of routing protocols include the manner in which they avoid routing loops, the manner in which they select preferred routes, using information

neg: Routing bridge Routing bridge A routing bridge or RBridge, also known as a TRILL Switch, is a network device that implements the TRILL protocol, as specified by the IETF and should not be confused with BRouters (Bridging Routers). RBridges are compatible with previous IEEE 802.1 customer bridges as well as IPv4 and IPv6 routers and end nodes. They are invisible to current IP routers and, like routers, RBridges terminate the bridge spanning tree protocol. The RBridges in a campus share connectivity information amongst themselves using the IS-IS link state protocol. A link state protocol is one in which connectivity is broadcast to

neg: Distance-vector routing protocol Distance-vector routing protocol A distance-vector routing protocol in data networks determines the best route for data packets based on distance. Distance-vector routing protocols measure the distance by the number of routers a packet has to pass, one router counts as one hop. Some distance-vector protocols also take into account network latency and other factors that influence traffic on a given route. To determine the best route across a network routers on which a distance-vector protocol is implemented exchange information with one another, usually routing tables plus hop counts for destination networks and possibly other traffic information. Distance-vector routing protocols also

neg: Route redistribution public Internet. But in medium-sized and large networks, routers use dynamic routing protocols to determine the best paths to various network destinations. Sometimes, a network may use more than one dynamic routing protocol, for example, if two different companies merge or if networking devices from multiple vendors are used. In such networks, it is often useful to redistribute information from one routing protocol into another. Route redistribution In a router, route redistribution allows a network that uses one routing protocol to route traffic dynamically based on information learned from another routing protocol. On the Internet, routers forward data packets between

neg: Distance-vector routing protocol Routing Information Protocol (RIPv1). RIPv1 was formally standardised in 1988. It establishes the shortest path across a network purely on the basis of the hops, that is numbers of routers that need to be passed to reach the destination network. RIP is a interior gateway protocol, so it can be used in local area networks (LANs) on interior or border routers. Routers with RIPv1 implementation exchange their routing tables with neighbouring routers by broadcasting a RIPv1 packet every 30 second into all connected networks. RIPv1 is not suitable for large networks as it limits the number of hops to 15.

neg: Hierarchical routing if every router was connected to 2 routers, shows the convenience of hierarchical routing. It decreases the complexity of network topology, increases routing efficiency, and causes much less congestion because of fewer routing advertisements. With hierarchical routing, only core routers connected to the backbone are aware of all routes. Routers that lie within a LAN only know about routes in the LAN. Unrecognized destinations are passed to the default route. Hierarchical routing Hierarchical routing is a method of routing in networks that is based on hierarchical addressing. Most Transmission Control Protocol/Internet Protocol (TCP/IP) routing is based on a two-level hierarchical

neg: Internet Routing Registry Internet Routing Registry An Internet Routing Registry (IRR) is a database of Internet route objects for determining, and sharing route and related information used for configuring routers, with a view to avoiding problematic issues between Internet service providers. The Internet routing registry works by providing an interlinked hierarchy of objects designed to facilitate the organization of IP routing between organizations, and also to provide data in an appropriate format for automatic programming of routers. Network engineers from participating organizations are authorized to modify the Routing Policy Specification Language (RPSL) objects, in the registry, for their own networks. Then, any network

neg: Heuristic routing for transmitting data back to the sources. The IP routing protocols in use today are based on one of two algorithms: "distance vector" or "link state". Distance vector algorithms broadcast routing information to all neighboring routers. Link state routing protocols build a topographical map of the entire network based on updates from neighbor routers, and then use the Dijkstra algorithm to compute the shortest path to each destination. Metrics used are based on the number of hops, delay, throughput, traffic, and reliability. Heuristic routing Heuristic routing is a system used to describe how deliveries are made when problems in a

neg: Routing loop problem B, and B believes that C is reachable through A. In a simple reachability protocol, such as EGP, the routing loop will persist forever. In a naive distance vector protocol, such as the routing information protocol, the loop will persist until the metrics for C reach "infinity" (the maximum number of routers that a packet can traverse in RIP is 15. The value 16 is considered infinity and the packet is discarded). In a link-state routing protocol, such as OSPF or IS-IS, a routing loop disappears as soon as the new network topology is flooded to all the routers within

neg: Forwarding information base Routers used for accessing the entire Internet, however, experienced severe performance degradation in refreshing a small cache, and various implementations moved to having FIBs in one-to-one correspondence with the routing information base (RIB). RIBs are optimized for efficient updating by routing protocols and other control plane methods, and contain the full set of routes learned by the router. FIBs may also be implemented with fast hardware lookup mechanisms, such as ternary content addressable memory (TCAM). TCAM, however, is quite expensive, and tends to be used more in edge routers with relatively small numbers of routes than in routers that must

neg: Distance-vector routing protocol This hop limit was introduced to avoid routing loops, but also means that networks that are connected through more than 15 routers are unreachable. The distance-vector protocol designed for use in wide area networks (WANs) is the Border Gateway Protocol (BGP). BGP is a exterior gateway protocol and therefore implemented on border and exterior routers on the Internet. It exchanges information between routers through a Transmission Control Protocol (TCP) session. Routers with BGP implementation determine the shortest path across a network based on a range of factors other than hops. BGP can also be configured by administrators so that certain

neg: Routing Information Protocol multiple metrics for each route, including bandwidth, delay, load, MTU, and reliability. Routing Information Protocol The Routing Information Protocol ('RIP') is one of the oldest distance-vector routing protocols which employ the hop count as a routing metric. RIP prevents routing loops by implementing a limit on the number of hops allowed in a path from source to destination. The largest number of hops allowed for RIP is 15, which limits the size of networks that RIP can support. RIP implements the split horizon, route poisoning and holddown mechanisms to prevent incorrect routing information from being propagated. In RIPv1 routers broadcast

neg: Reverse path forwarding scan. uRPF extends this idea by utilizing the knowledge all routers must have to do their jobs using their routing information base (RIB) or forwarding information base (FIB) to help further restrict the possible sources addresses that should be seen on an interface. Packets are only forwarded if they come from a router's best route to the source of a packet, ensuring that: In cases of symmetric routing, routing where packets flow forward and reverse down the same path, and terminal networks with only one link, this is a safe assumption and uRPF can be implemented without many anticipated problems.

neg: Open Shortest Path First which developed its own proprietary DECnet protocols. Routing protocols like OSPF calculate the "shortest" route to a destination through the network based on an algorithm. The first routing protocol that was widely implemented, the Routing Information Protocol (RIP), calculated the shortest route based on hops, that is the number of routers that an IP packet had to traverse to reach the destination host. RIP successfully implemented dynamic routing, where routing tables change if the network topology changes. But RIP did not adapt its routing according to changing network conditions, such as data-transfer rate. Demand grew for a dynamic routing protocol

neg: Wireless grid such as routers and/or servers for facilitating the throughput of information from one node to the other. These 'routing nodes' have the ability to determine where information is coming from and where it is supposed to go. They give out names and addresses (IP addresses) to each connected node and regulate the traffic between them. In wireless grids, such dedicated routing devices are not (always) available and the bandwidth that is permanently available to traditional networks has to be either 'borrowed' from an already existing network or publicly accessible bandwidth (open spectrum) has to be used. A group addressing this

neg: Geocast by a single closed polygon. Geo Routers exchange service area polygons to build routing tables. The routers are organized in a hierarchy. Geographic addressing and routing has many potential applications in geographic messaging, geographic advertising, delivery of geographically restricted services, and presence discovery of a service or mobile network participant in a limited geographic area (see Navas, Imieliński, 'GeoCast - Geographic Addressing and Routing'.) Geocast Geocast refers to the delivery of information to a group of destinations in a network identified by their geographical locations. It is a specialized form of multicast addressing used by some routing protocols for mobile

neg: Interior gateway protocol Interior gateway protocol An interior gateway protocol (IGP) is a type of protocol used for exchanging routing information between gateways (commonly routers) "within" an autonomous system (for example, a system of corporate local area networks). This routing information can then be used to route network-layer protocols like IP. Interior gateway protocols can be divided into two categories: distance-vector routing protocols and link-state routing protocols. Specific examples of IGPs include Open Shortest Path First (OSPF), Routing Information Protocol (RIP), Intermediate System to Intermediate System (IS-IS) and Enhanced Interior Gateway Routing Protocol (EIGRP). By contrast, exterior gateway protocols are used to exchange

neg: Border Gateway Protocol addresses (known as address families) to be distributed in parallel. Whereas standard BGP supports only IPv4 unicast addresses, Multiprotocol BGP supports IPv4 and IPv6 addresses and it supports unicast and multicast variants of each. Multiprotocol BGP allows information about the topology of IP multicast-capable routers to be exchanged separately from the topology of normal IPv4 unicast routers. Thus, it allows a multicast routing topology different from the unicast routing topology. Although MBGP enables the exchange of inter-domain multicast routing information, other protocols such as the Protocol Independent Multicast family are needed to build trees and forward multicast traffic. Multiprotocol BGP

neg: Route poisoning an infinite (∞) route metric. This makes all nodes on the invalid route seem infinitely distant, preventing any of the routers from sending packets over the invalid route. Some distance-vector routing protocols, such as RIP, use a maximum hop count to determine how many routers the traffic must go through to reach the destination. Each route has a hop count number assigned to it which is incremented as the routing information is passed from router to router. A route is considered unreachable if the hop count exceeds the maximum allowed. Route poisoning is a method of quickly forgetting outdated routing

neg: Interior gateway protocol maps. Examples of link-state routing protocols: Hybrid routing protocols have both the features of distance vector routing protocols and linked state routing protocols. One example is Enhanced Interior Gateway Routing Protocol (EIGRP). Interior gateway protocol An interior gateway protocol (IGP) is a type of protocol used for exchanging routing information between gateways (commonly routers) "within" an autonomous system (for example, a system of corporate local area networks). This routing information can then be used to route network-layer protocols like IP. Interior gateway protocols can be divided into two categories: distance-vector routing protocols and link-state routing protocols. Specific examples of IGPs

neg: Virtual routing and forwarding appropriate in the large enterprise, multi-tenant and shared data center environments. In a typical deployment, customer edge (CE) routers handle local routing in a traditional fashion and disseminate routing information into Provider Edge (PE) where the routing tables are virtualized. The PE router then encapsulates the traffic, marks it to identify the VRF instance, and transmits it across the provider backbone network to the destination PE router. The destination PE router then decapsulates the traffic and forwards it to the CE router at the destination. The backbone network is completely transparent to the customer equipment, allowing multiple customers or user

neg: Distance Vector Multicast Routing Protocol This was more prevalent in early versions of the protocol, prior to the implementation of pruning. DVMRP's flat unicast routing mechanism, which is used to determine the source interface of a data stream, also affects its ability to scale. Distance Vector Multicast Routing Protocol The Distance Vector Multicast Routing Protocol (DVMRP), defined in RFC 1075, is a routing protocol used to share information between routers to facilitate the transportation of IP multicast packets among networks. It formed the basis of the Internet's historic multicast backbone, Mbone. The protocol is based on the Routing Information Protocol (RIP). The router generates a

neg: Open Shortest Path First but nothing more. OSPF neighbors do not exchange any routing information – the only packets they exchange are Hello packets. OSPF adjacencies are formed between selected neighbors and allow them to exchange routing information. Two routers must first be neighbors and only then, can they become adjacent. Two routers become adjacent if at least one of them is Designated Router or Backup Designated Router (on multiaccess type networks), or they are interconnected by a point-to-point or point-to-multipoint network type. For forming a neighbor relationship between, the interfaces used to form the relationship must be in the same OSPF area. While

neg: Routing protocol routing protocols. Examples of open-source applications are Bird Internet routing daemon, Quagga, GNU Zebra, OpenBGPD, OpenOSPFD, and XORP. Some network certification courses distinguish between routing protocols and "routed" protocols. A routed protocol is used to deliver application traffic. It provides appropriate addressing information in its Internet layer (network layer) to allow a packet to be forwarded from one network to another. Examples of routed protocols are the Internet Protocol (IP) and Internetwork Packet Exchange (IPX). Routing protocol A routing protocol specifies how routers communicate with each other, distributing information that enables them to select routes between any two nodes on

neg: Routing Information Protocol routing tables were small enough that the traffic was not significant. As networks grew in size, however, it became evident there could be a massive traffic burst every 30 seconds, even if the routers had been initialized at random times. In most networking environments, RIP is not the preferred choice for routing as its time to converge and scalability are poor compared to EIGRP, OSPF, or IS-IS. However, it is easy to configure, because RIP does not require any parameters unlike other protocols. RIP uses the User Datagram Protocol (UDP) as its transport protocol, and is assigned the reserved port

neg: Router (computing) found and corrected. Routers are also often distinguished on the basis of the network in which they operate. A router in a local area network (LAN) of a single organisation is called an interior router. An exterior router directs packets between hosts in one LAN and hosts in another LAN. A router that is operated in the Internet backbone is described as exterior router. While routers that connect a LAN with the wide area network (WAN) are called border routers, or gateway routers. Routers intended for ISP and major enterprise connectivity usually exchange routing information using the Border Gateway Protocol

neg: Internet Control Message Protocol 1995 by RFC 1812. Furthermore, forwarding of and any kind of reaction to (flow control actions) source quench messages was deprecated from 2012 by RFC 6633. Where: "Redirect" requests data packets be sent on an alternative route. ICMP Redirect is a mechanism for routers to convey routing information to hosts. The message informs a host to update its routing information (to send packets on an alternative route). If a host tries to send data through a router (R1) and R1 sends the data on another router (R2) and a direct path from the host to R2 is available (that is,

neg: Border Gateway Protocol "Interior Border Gateway Protocol"). When it runs between different autonomous systems, it is called "External BGP" ("eBGP" or "Exterior Border Gateway Protocol"). Routers on the boundary of one AS exchanging information with another AS are called "border" or "edge routers" or simply "eBGP peers" and are typically connected directly, while "iBGP peers" can be interconnected through other intermediate routers. Other deployment topologies are also possible, such as running eBGP peering inside a VPN tunnel, allowing two remote sites to exchange routing information in a secure and isolated manner. The main difference between iBGP and eBGP peering is in the way

neg: Routing and wavelength assignment the number of edges and formula_15 is the number of routers. The running time is just a constant if a predetermined path is used. This definition of SP-1 uses the hop count as the cost function. The SP-1 algorithm could be extended to use different cost functions, such as the number of EDFAs. Fixed alternate routing is an extension of fixed path routing. Instead of having just one fixed route for a given source and destination pair, several routes are stored. The probes can be sent in a serial or parallel fashion. For each connection request, the source node attempts

neg: Routing (electronic design automation) path as possible without violating design rule checking (DRC). Some more advanced interactive routers have "push and shove" (aka "shove-aside" or "automoving") features in an interactive router; the EDA tool pushes other nets out of the way, if possible, in order to place a new wire where the drafter wants it and still avoid violating DRC. Modern PCB design software also typically provides "autorouters" that route all remaining unrouted connections without human intervention. The main types of autorouters are: Many routers execute the following overall algorithm: For detailed routing, the most common technique is rip-up and reroute aka rip-up and

neg: Internetwork Packet Exchange in IP routing tables. There are 3 routing protocols available for IPX networks: In early IPX networks a version of Routing Information Protocol (RIP) was the only available protocol to exchange routing information. Unlike RIP for IP, it uses delay time as the main metric, retaining the hop count as a secondary metric. Since NetWare 3, the NetWare Link Services Protocol (NSLP) based on IS-IS is available which is more suitable for larger networks. Cisco routers implement an IPX version of EIGRP protocol as well. IPX can be transmitted over Ethernet using one of the following 4 frame formats or

neg: Forwarding information base route to the source address. For the routers near the edge of the Internet, packet filters can provide a simpler and more effective solution than methods which employ routing information lookup, though this approach can be challenging when managing routers which are reconfigured often. Ingress filtering for multihomed routers will accept the packet if there is a route back to its source address from "any" interface on the router. For this type of filtering, the router may also maintain an "adjacency table", also organized for fast lookup, that keeps track of the router interface addresses that are on all directly

neg: IS-IS operate with IPv6 networks, the OSPF protocol was rewritten in OSPF v3 (as specified in RFC 2740). Both OSPF and IS-IS routers build a topological representation of the network. This map indicates the subnets which each IS-IS router can reach, and the lowest-cost (shortest) path to a subnet is used to forward traffic. IS-IS differs from OSPF in the way that "areas" are defined and routed between. IS-IS routers are designated as being: Level 1 (intra-area); Level 2 (inter area); or Level 1–2 (both). Routing information is exchanged between Level 1 routers and other Level 1 routers of the same

neg: Turn restriction routing to destination router D. Implementing Turn restriction routing means that some of the turns from any of the feeder routers to the congested router S may now be restricted. Those feeder routers may have to use a longer path to get to destination D, thereby decongesting the link from S to D to an extend. Turn restriction routing A routing algorithm decides the path followed by a packet from the source to destination routers in a network. An important aspect to be considered while designing a routing algorithm is avoiding a deadlock. Turn restriction routing is a routing algorithm for

neg: Volatile memory in voltage. Every single bit in a static RAM chip needs a cell of six transistors, whereas dynamic RAM requires only one capacitor and one transistor. As a result, SRAM is unable to accomplish the storage capabilities of the DRAM family. SRAM is most commonly used in networking devices, like switches, routers, cable modems, etc., for buffering the transmitted information. Volatile memory Volatile memory, in contrast to non-volatile memory, is computer memory that requires power to maintain the stored information; it retains its contents while powered on but when the power is interrupted, the stored data is quickly lost. Volatile

neg: Cisco Express Forwarding Cisco Express Forwarding Cisco Express Forwarding (CEF) is an advanced layer 3 switching technology used mainly in large core networks or the Internet to enhance the overall network performance. Although CEF is a Cisco proprietary protocol other vendors of multi-layer switches or high-capacity routers offer a similar functionality where layer-3 switching or routing is done in hardware (in an ASIC) instead of by software and the (central) CPU. CEF is mainly used to increase packet switching speed by reducing the overhead and delays introduced by other routing techniques. CEF consists of two key components: The Forwarding Information Base (FIB) and

neg: Enhanced Interior Gateway Routing Protocol routers when the protocol is used. Juniper EX switch works with Cisco EIGRP via the limited mode in transit configuration only. Enhanced Interior Gateway Routing Protocol Enhanced Interior Gateway Routing Protocol (EIGRP) is an advanced distance-vector routing protocol that is used on a computer network for automating routing decisions and configuration. The protocol was designed by Cisco Systems as a proprietary protocol, available only on Cisco routers. Partial functionality of EIGRP was converted to an open standard in 2013 and was published with informational status as in 2016. EIGRP is used on a router to share routes with other routers

neg: Route redistribution Route redistribution In a router, route redistribution allows a network that uses one routing protocol to route traffic dynamically based on information learned from another routing protocol. On the Internet, routers forward data packets between computer networks. In order for a router to determine where to forward each packet, it may use: In a small network such as a home or home office, a default route is often used to send all traffic to the user's Internet service provider. Likewise, medium-sized networks such as branch offices or small Internet service providers may use default routes for traffic intended for the

neg: Internet the Internet IP routing structure and hypertext links of the World Wide Web are examples of scale-free networks. Computers and routers use routing tables in their operating system to direct IP packets to the next-hop router or destination. Routing tables are maintained by manual configuration or automatically by routing protocols. End-nodes typically use a default route that points toward an ISP providing transit, while ISP routers use the Border Gateway Protocol to establish the most efficient routing across the complex connections of the global Internet. An estimated 70 percent of the world's Internet traffic passes through Ashburn, Virginia. Common methods

neg: IP routing path algorithm. However, other routing protocols may use other metrics for determining the best path. Based on the metrics required and present for each link, each path has an associated "cost". The routing algorithm attempts to minimize the cost when choosing the next hop. A routing protocol is a software mechanism by which routers communicate and share information about the topology of the network, and the capabilities of each routing node. It thus implements the network-global rules by which traffic is directed within a network and across multiple networks. Different protocols are often used for different topologies or different application

neg: Prefix WhoIs Prefix WhoIs Prefix WhoIs is an open source project that develops and operates a free whois-compatible framework for stockpiling and querying various routing and registry information. Prefix WhoIs uses global BGP routing data learned from many ISP backbone routers. Other information sources are also supported, such as imported data from every Regional Internet Registry (AFRINIC, APNIC, ARIN, LACNIC and RIPE) and geocoding information. The project has been mentioned in a number of popular network security and network engineering books and articles. Many public servers around the world operate mirrors of Prefix WhoIs, making the information generally available worldwide. The service

neg: Network switch ports. A common layer-3 capability is awareness of IP multicast through IGMP snooping. With this awareness, a layer-3 switch can increase efficiency by delivering the traffic of a multicast group only to ports where the attached device has signalled that it wants to listen to that group. Layer-3 switches typically support IP routing between VLANs configured on the switch. Some layer-3 switches support the routing protocols that routers use to exchange information about routes between networks. While the exact meaning of the term "layer-4 switch" is vendor-dependent, it almost always starts with a capability for network address translation, and may

neg: Distance-vector routing protocol require that a router informs its neighbours of network topology changes periodically. Distance-vector routing protocols use the Bellman–Ford algorithm and Ford–Fulkerson algorithm to calculate the best route. Another way of calculating the best route across a network is based on link cost, and is implemented through link-state routing protocols. The term "distance vector" refers to the fact that the protocol manipulates "vectors" (arrays) of distances to other nodes in the network. The distance vector algorithm was the original ARPANET routing algorithm and was implemented more widely in local area networks with the Routing Information Protocol (RIP). Routers that use distance-vector

neg: Hierarchical routing Hierarchical routing Hierarchical routing is a method of routing in networks that is based on hierarchical addressing. Most Transmission Control Protocol/Internet Protocol (TCP/IP) routing is based on a two-level hierarchical routing in which an IP address is divided into a network portion and a host portion. Gateways use only the network portion until an IP datagram reaches a gateway that can deliver it directly. Additional levels of hierarchical routing are introduced by the addition of subnetworks. Hierarchical routing is the procedure of arranging routers in a hierarchical manner. A good example would be to consider a corporate [internet]. Most corporate

neg: Routing bridge during a temporary loop. A Reverse Path Forwarding Check and other checks are performed on multi-destination frames to further control potentially looping traffic. Routing bridge A routing bridge or RBridge, also known as a TRILL Switch, is a network device that implements the TRILL protocol, as specified by the IETF and should not be confused with BRouters (Bridging Routers). RBridges are compatible with previous IEEE 802.1 customer bridges as well as IPv4 and IPv6 routers and end nodes. They are invisible to current IP routers and, like routers, RBridges terminate the bridge spanning tree protocol. The RBridges in a campus

neg: Multiprotocol Label Switching domain, an LER uses routing information to determine the appropriate label to be affixed, labels the packet accordingly, and then forwards the labeled packet into the MPLS domain. Likewise, upon receiving a labeled packet which is destined to exit the MPLS domain, the LER strips off the label and forwards the resulting IP packet using normal IP forwarding rules. In the specific context of an MPLS-based virtual private network (VPN), LERs that function as ingress and/or egress routers to the VPN are often called PE (Provider Edge) routers. Devices that function only as transit routers are similarly called P (Provider)

neg: IS-IS ISO standard, causing confusion. IS-IS has been called "the "de facto" standard for large service provider network backbones." IS-IS is an interior gateway protocol, designed for use within an administrative domain or network. This is in contrast to exterior gateway protocols, primarily Border Gateway Protocol (BGP), which is used for routing between autonomous systems (RFC 1930). IS-IS is a link-state routing protocol, operating by reliably flooding link state information throughout a network of routers. Each IS-IS router independently builds a database of the network's topology, aggregating the flooded network information. Like the OSPF protocol, IS-IS uses Dijkstra's algorithm for computing

neg: Enhanced Interior Gateway Routing Protocol Enhanced Interior Gateway Routing Protocol Enhanced Interior Gateway Routing Protocol (EIGRP) is an advanced distance-vector routing protocol that is used on a computer network for automating routing decisions and configuration. The protocol was designed by Cisco Systems as a proprietary protocol, available only on Cisco routers. Partial functionality of EIGRP was converted to an open standard in 2013 and was published with informational status as in 2016. EIGRP is used on a router to share routes with other routers within the same autonomous system. Unlike other well known routing protocols, such as RIP, EIGRP only sends incremental updates, reducing the

neg: Open Shortest Path First Routing Protocol (IGRP) by Cisco. OSPF supports complex networks with multiple routers, including backup routers, to balance traffic load on multiple links to other subnets. Neighboring routers in the same broadcast domain or at each end of a point-to-point link communicate with each other via the OSPF protocol. Routers form "adjacencies" when they have detected each other. This detection is initiated when a router identifies itself in a "Hello" protocol packet. Upon acknowledgment, this establishes a "two-way state" and the most basic relationship. The routers in an Ethernet or Frame Relay network select a "Designated Router" (DR) and a "Backup

neg: Router (computing) may be found inside enterprises. The most powerful routers are usually found in ISPs, academic and research facilities. Large businesses may also need more powerful routers to cope with ever-increasing demands of intranet data traffic. A hierarchical internetworking model for interconnecting routers in large networks is in common use. Access routers, including small office/home office (SOHO) models, are located at home and customer sites such as branch offices that do not need hierarchical routing of their own. Typically, they are optimized for low cost. Some SOHO routers are capable of running alternative free Linux-based firmware like Tomato, OpenWrt or DD-WRT.

neg: Link-state advertisement Link-state advertisement The link-state advertisement (LSA) is a basic communication means of the OSPF routing protocol for the Internet Protocol (IP). It communicates the router's local routing topology to all other local routers in the same OSPF area. OSPF is designed for scalability, so some LSAs are not flooded out on all interfaces, but only on those that belong to the appropriate area. In this way detailed information can be kept localized, while summary information is flooded to the rest of the network. The original IPv4-only OSPFv2 and the newer IPv6-compatible OSPFv3 have broadly similar LSA types. The LSA types

neg: Dell Networking Operating System Tree Protocol and RSTP, VLAN and the IEEE 802.1Q standards, QinQ or IEEE 802.1ad, Link Layer Discovery Protocol and LLDP MED. The S-series switches ending with a V and some of the E-series line-cards support Power over Ethernet or PoE with the standards for this protocol. As mentioned above, by default an interface on a switch running DNOS 9.x are configured as a layer3 port. All these switches are thus routers with many interfaces that can (and most often are) reconfigured into a layer2 ethernet switch. All DNOS 9 switches run at least the following routing protocols: Routing Information Protocol

neg: Routing and wavelength assignment to find a connection on each of the paths. If all of the paths fail, then the connection is blocked. If multiple paths are available, only one of them would be utilized. The SP-formula_19 (Shortest Path, formula_19 Probes, formula_21) algorithm is an example of Fixed Alternate Routing. This algorithm calculates the formula_19 shortest paths using the number of optical routers as the cost function. The running time using Yen's algorithm is formula_23 where formula_17 is the number of edges, formula_15 is the number of routers, and formula_19 is the number of paths. The running time is a constant factor if

neg: TRILL (computing) TRILL (computing) TRILL ("TRansparent Interconnection of Lots of Links") is an IETF Standard implemented by devices called RBridges (routing bridges) or TRILL Switches. TRILL combines techniques from bridging and routing and is the application of link state routing to the VLAN-aware customer-bridging problem. RBridges are compatible with and can incrementally replace previous IEEE 802.1 customer bridges. They are also compatible with IPv4 and IPv6 routers and end nodes. They are invisible to current IP routers and, like routers, RBridges terminate the bridge spanning tree protocol. TRILL switches (RBridges) run a link state protocol amongst themselves. A link state protocol is

neg: Virtual routing and forwarding different virtual routers, where each one has its own FIB that is not accessible to any other virtual router instance on the same device. The simplest form of VRF implementation is VRF Lite . In this implementation, each router within the network participates in the virtual routing environment in a peer-based fashion. While simple to deploy and appropriate for small to medium enterprises and shared data centers, VRF Lite does not scale to the size required by global enterprises or large carriers, as there is the need to implement each VRF instance on every router, including intermediate routers. VRFs were

neg: Cisco IOS at the time, presented information about a vulnerability in IOS. Cisco had already issued a patch, but asked that the flaw not be disclosed. Cisco filed a lawsuit, but settled after an injunction was issued to prevent further disclosures. Cisco IOS Cisco IOS (originally Internetwork Operating System) is a family of software used on most Cisco Systems routers and current Cisco network switches. "(Earlier switches ran CatOS.)" IOS is a package of routing, switching, internetworking and telecommunications functions integrated into a multitasking operating system. Although the IOS code base includes a cooperative multitasking kernel, most IOS features have been ported

neg: Routing (electronic design automation) retry: This process repeats until all nets are routed or the program (or user) gives up. An alternative approach is to treat shorts, design rule violations, obstructions, etc. on a similar footing as excess wire length—that is, as finite costs to be reduced (at first) rather than as absolutes to be avoided. This multi-pass "iterative-improvement" routing method is described by the following algorithm: Most routers assign wiring layers to carry predominantly "x" or "y" directional wiring, though there have been routers which avoid or reduce the need for such assignment. There are advantages and disadvantages to each approach. Restricted directions

neg: 6to4 any number of 6to4 relay routers, so that IPv4 routing would take care of routing the encapsulated IPv6 packets to the one closest-by for forwarding onto IPv6 Internet. Due to unsolvable operational problems, this use has been deprecated. Packets from the IPv6 Internet to 6to4 systems must be sent to a 6to4 relay router by normal IPv6 routing methods. The specification states that such relay routers must only advertise and not subdivisions of it to prevent IPv4 routes polluting the routing tables of IPv6 routers. From here they can then be sent over the IPv4 Internet to the destination. For

neg: Connection-oriented communication data packet reordering on the receiver side. The sequence numbering requires two-way synchronization of segment counters during a three-step connection establishment phase . In a connection-oriented packet switched data link layer or network layer protocol, all data is sent over the same path during a communication session. The protocol identifies traffic flows only by a channel/data stream number, often denoted virtual circuit identifier (VCI), rather than by complete routing information for each packet (source and destination addresses) used in connectionless datagram switching such as conventional IP routers. In connection-oriented communication, routing information may be provided to the network nodes during

neg: Control plane are not standardized among IP routers. It is fair to say that subnets on directly connected active interfaces are always preferred. Beyond that, however, there will be differences. Implementers generally have a numerical preference, which Cisco calls an "administrative distance", for route selection. The lower the preference, the more desirable the route. Cisco's IOS implementation makes exterior BGP the most preferred source of dynamic routing information, while Nortel RS makes intra-area OSPF most preferred. The general order of selecting routes to install is: See forwarding plane for more detail, but each implementation has its own means of updating the forwarding

neg: Virtual Router Redundancy Protocol Virtual Router Redundancy Protocol The Virtual Router Redundancy Protocol (VRRP) is a computer networking protocol that provides for automatic assignment of available Internet Protocol (IP) routers to participating hosts. This increases the availability and reliability of routing paths via automatic default gateway selections on an IP subnetwork. The protocol achieves this by creation of virtual routers, which are an abstract representation of multiple routers, i.e. master and backup routers, acting as a group. The default gateway of a participating host is assigned to the virtual router instead of a physical router. If the physical router that is routing packets on