Cisco Systems 3750E Configuring Basic Eigrp Parameters, Router eigrp autonomous-system, 38-39

Chapter 38 Configuring IP Unicast Routing

Configuring EIGRP

EIGRP NSF Capability

The Catalyst 3750-E IP-services feature set also supports EIGRP NSF-capable routing for IPv4 for better convergence and lower traffic loss following a stack master change. When an EIGRP NSF-capable stack master restarts or a new stack master starts up and NSF restarts, the switch has no neighbors, and the topology table is empty. The switch must bring up the interfaces, reacquire neighbors, and rebuild the topology and routing tables without interrupting the traffic directed toward the switch stack. EIGRP peer routers maintain the routes learned from the new stack master and continue forwarding traffic through the NSF restart process.

To prevent an adjacency reset by the neighbors, the new stack master uses a new Restart (RS) bit in the EIGRP packet header to show the restart. When the neighbor receives this, it synchronizes the stack in its peer list and maintains the adjacency with the stack. The neighbor then sends its topology table to the stack master with the RS bit set to show that it is NSF-aware and is aiding the new stack master.

If at least one of the stack peer neighbors is NSF-aware, the stack master receives updates and rebuilds its database. Each NSF-aware neighbor sends an end of table (EOT) marker in the last update packet to mark the end of the table content. The stack master recognizes the convergence when it receives the EOT marker, and it then begins sending updates. When the stack master has received all EOT markers from its neighbors or when the NSF converge timer expires, EIGRP notifies the routing information database (RIB) of convergence and floods its topology table to all NSF-aware peers.

Note NSF is not supported on interfaces configured for Hot Standby Router Protocol (HSRP).

Use the nsf EIGRP routing configuration command to enable EIGRP NSF routing. Use the show ip protocols privileged EXEC command to verify that NSF is enabled on the device. See the command reference for this release for information about the nsf command.

Configuring Basic EIGRP Parameters

Beginning in privileged EXEC mode, follow these steps to configure EIGRP. Configuring the routing process is required; other steps are optional:

	Command	Purpose
Step 1
	configure terminal	Enter global configuration mode.
Step 2
	router eigrp autonomous-system	Enable an EIGRP routing process, and enter router configuration
		mode. The AS number identifies the routes to other EIGRP routers
		and is used to tag routing information.
Step 3
	nsf	(Optional) Enable EIGRP NSF on a Catalyst 3750-E switch. Enter
		this command on the stack master and on all of its peers.
Step 4
	network network-number	Associate networks with an EIGRP routing process. EIGRP sends
		updates to the interfaces in the specified networks.
Step 5
	eigrp log-neighbor-changes	(Optional) Enable logging of EIGRP neighbor changes to monitor
		routing system stability.

	Catalyst 3750-E and 3560-E Switch Software Configuration Guide
OL-9775-02		38-39