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| executes operating system instructions, such as system initialization, routing functions, and switching functions |
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can be used to help verify and troubleshoot some of the basic hardware and software components of the router.
The command displays information about the Cisco IOS software currently running on the router, the bootstrap program, and information about the hardware configuration, including the amount of system memory. |
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| the quantitative value used to measure the distance to a given route |
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| require a clock signal to control the timing of the communications. In most environments, the service provider (a DCE device such as a CSU/DSU) will provide the clock. By default, Cisco routers are DTE devices. |
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| When the router has to perform multiple lookups in the routing table before forwarding a packet |
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| otherwise known as a routing domain - is a collection of routers under a common administration. |
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| routes are advertised as vectors of distance and direction. Distance is defined in terms of a metric such as hop count and direction is simply the next-hop router or exit interface. |
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| when all routers' routing tables are at a state of consistency. when all routers have complete and accurate information about the network. |
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| A value used by routing protocols to assign costs to reach remote networks. Used to determine which path is most preferable when there are multiple paths to the same remote network. |
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| A value determined either by the IOS or by the network administrator to indicate preference for a route. Can represent a metric, a combination of metrics or a policy. |
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| Assesses the probability of a link failure, calculated from the interface error count or previous link failures |
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| Considers the traffic utilization of a certain link |
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| used to mark the route as unreachable in a routing update that is sent to other routers. Unreachable is interpreted as a metric that is set to the maximum. For RIP, a poisoned route has a metric of 16. |
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| split horizon with poison reverse |
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Definition
when sending updates out a specific interface, designate any networks that were learned on that interface as unreachable
a specific circumstance that overrides split horizon. |
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Definition
| summarizes multiple network addresses with a mask less than the classful mask. |
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| involves taking the routes from one routing source and sending those routes to another routing source |
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| a route with a subnet mask equal to or less than the classful mask of the network address. |
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Definition
| a network address with a mask less than the classful mask. |
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Definition
| used by EIGRP to discover neighbors and to form adjacencies with those neighbors |
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| used by EIGRP to propagate routing information. Packets are sent only when necessary. Contain only the routing information needed and are sent only to those routers that require it. Use reliable delivery |
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Definition
| sent by EIGRP when reliable delivery is used |
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used by DUAL when searching for networks and other tasks.
Queries and replies use reliable delivery. Queries use multicast, whereas replies are always sent as unicast. |
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Definition
| tracks all routes, uses its metric to select efficient, loop-free paths, and selects the routes with the least cost path to insert into the routing table. |
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| a neighboring router that is used for packet forwarding and is the least-cost route to the destination network |
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Definition
the lowest calculated metric to reach the destination network.
it is the metric listed in the routing table entry as the second number inside the brackets. As with other routing protocols this is also known as the metric for the route. |
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Definition
| neighbor who has a loop-free backup path to the same network as the successor by satisfying the feasibility condition |
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Definition
| met when a neighbor's reported distance (RD) to a network is less than the local router's feasible distance to the same destination network. |
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Definition
an EIGRP neighbor's feasible distance to the same destination network
The metric that a router reports to a neighbor about its own cost to that network. |
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Definition
| EIGRP packet used to discover, verfiy, and rediscover neighboring routers |
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| the period, expressed in seconds, that the router will wait to receive a Hello packet before declaring the neighbor "down." |
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Definition
| responsible for updating all other OSPF router when a change occurs in the multiaccess network. |
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| locally significant, which means that it does not have to match other OSPF routers in order to establish adjacencies with those neighbors. |
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Definition
| a group of routers that share link-state information. All routers must have the same link-state information in their link-state databases. |
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Definition
| used to uniquely identify each router in the OSPF routing domain. it is simply an IP address. |
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Definition
| means that the router and its neighbor have identical OSPF link-state databases. |
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Term
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Definition
| A flapping link can cause OSPF routers in an area to constantly recalculate the SPF algorithm, preventing proper convergence. To minimize this problem, the router waits 5 seconds (5000 msecs) after receiving an LSU before running the SPF algorithm. |
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Definition
| network with more than two devices on the same shared media |
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Term
| Autonomous System Boundary Router (ASBR) |
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Definition
| This router is sometimes called the edge, entrance or gateway router. However, in OSPF terminology, the router located between an OSPF routing domain and a non-OSPF network |
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Term
| Router(config-if)#ip summary-address eigrp as-number network-address subnet-mask |
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Definition
| To establish EIGRP manual summarization on all interfaces that send EIGRP packets, use the following interface command |
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Term
network 10.1.1.1 0.0.0.0 area 0
(ospf) |
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Definition
| tells the router to enable the interface for the routing process |
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Term
| show ip ospf database command |
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Definition
| is used to verify the OSPF LSDB |
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