Problem about "show ip eigrp topology"

[xianglingzj]

From Cisco document, the output of command

show ip eigrp topology A.B.C.D W.X.Y.Z

and

show ip eigrp topology

should give me the same information of the known peers which informed the router about the network. The difference is merely the previous one got more details.

But today I got some output like this:

R2#sh ip eig top 172.16.8.0 255.255.255.0

IP-EIGRP topology entry for 172.16.8.0/24

State is Passive, Query origin flag is 1, 1 Successor(s), FD is 2195456

Routing Descriptor Blocks:

172.16.3.1 (Ethernet0), from 172.16.3.1, Send flag is 0x0

Composite metric is (2195456/2169856), Route is Internal

Vector metric:

Minimum bandwidth is 1544 Kbit

Total delay is 21000 microseconds

Reliability is 255/255

Load is 1/255

Minimum MTU is 1500

Hop count is 1

10.2.2.1 (Serial1), from 10.2.2.1, Send flag is 0x0

Composite metric is (23284736/22772736), Route is Internal

Vector metric:

Minimum bandwidth is 115 Kbit

Total delay is 40000 microseconds

Reliability is 255/255

Load is 1/255

Minimum MTU is 1500

Hop count is 1

R2#sh ip eig top

IP-EIGRP Topology Table for process 100

Codes: P - Passive, A - Active, U - Update, Q - Query, R - Reply,

r - Reply status

P 10.2.1.0/24, 1 successors, FD is 23284736

via 10.2.2.1 (23284736/22772736), Serial1

P 10.1.1.0/24, 1 successors, FD is 2195456

via 10.2.2.1 (2195456/281600), Serial1

P 10.2.2.0/24, 1 successors, FD is 2169856

via Connected, Serial1

P 172.16.227.0/24, 1 successors, FD is 2681856

via 10.2.2.1 (2681856/1761792), Serial1

P 172.16.23.0/24, 1 successors, FD is 2809856

via 10.2.2.1 (2809856/1889792), Serial1

P 172.16.8.0/24, 1 successors, FD is 2195456

via 172.16.3.1 (2195456/2169856), Ethernet0 <=================

P 172.16.10.0/24, 1 successors, FD is 409600

via 172.16.3.1 (409600/128256), Ethernet0

P 172.16.5.0/24, 1 successors, FD is 2809856

via 10.2.2.1 (2809856/1889792), Serial1

P 172.16.1.0/24, 1 successors, FD is 2681856

via 10.2.2.1 (2681856/1761792), Serial1

P 172.16.3.0/24, 1 successors, FD is 281600

via Connected, Ethernet0

R2#

Can somebody help me on understanding why the latter one gives me only 1 peer but the former one gives me 2? TIA.

[Harold Ritter]

The output of the first command reports all paths whether they are successors, feasible successors or not.

The output of the second command only shows the successor and feasible successor paths.

A feasible successor is a path that is not selected as the best path but that has a reported distance smaller than the feasible distance (FD).

In your scenario the second path is not a feasible successor since its reported distance (22772736) is greater than the FD (2195456). It is therefore not reported in the output of the second command.

Let me know if I answered your question,

[Harold Ritter]

You can use the command "sh ip eigrp topology all-links" if you want to see all paths (not only succesors and FS).

Hope this helps,

[xianglingzj]

Sorry but I can not agree with you.

From Cisco Document:

http://www.cisco.com/univercd/cc/td/doc/product/software/ios120/12cgcr/np1_r/1rprt1/1reigrp.htm#wp1021350

via :IP address of the peer that told the software about this destination

Obviously it is showing not only the feasible successor.

[Harold Ritter]

Quote from the URL that you sent:

"Usage Guidelines

The show ip eigrp topology command can be used without any keywords or arguments. If this command is used without any keywords or arguments, then only routes that are feasible successors are displayed."

Hope this helps,

[xianglingzj]

That's great. Thanks a lot. And apologize for this careless question. Thanks again.