question about eigrp lab

christianpho · ‎06-24-2009

Hi !

I'm currently working on my BSCI certification. Here attached in the zip file, a small schema of my EIGRP lab and configuration of my routers labs devices.

First question, if I was'nt used "no auto summurary" command on none of my router. And all of them are run EIGRP as the only routing protocol (and no static route was added to there configuration) All router are member as the same autonomous system. I remember in my reading by default EIGRP auto summaried at class-full boundary. I would like to know why this routing configuration working well with auto-summarisation enable at class-full boundary even if this configuration is contiguous....

Second question : I had used "offset-list" command on R1 to create 2 paths with differents costs to one network to be able to view result in topologie table and also routing table when mofidify variance parameter. Before modify metric to network 10.1.200.0/24, I see 2 equals paths to this network in topology table :

R1#sh ip eigrp topo

P 10.1.3.0/24, 1 successors, FD is 409600

via 10.1.100.3 (409600/128256), FastEthernet0/0

P 10.1.2.0/24, 2 successors, FD is 409600

via 10.1.200.2 (409600/128256), FastEthernet0/1

via 10.1.100.2 (409600/128256), FastEthernet0/0

P 10.1.1.0/24, 1 successors, FD is 128256

via Connected, Loopback1

P 192.168.100.0/24, 1 successors, FD is 409600

via 10.1.100.3 (409600/128256), FastEthernet0/0

P 10.1.100.0/24, 1 successors, FD is 281600

via Connected, FastEthernet0/0

P 10.1.200.0/24, 1 successors, FD is 281600

via Connected, FastEthernet0/1

P 192.16.0.0/24, 1 successors, FD is 409600

via 10.1.100.4 (409600/128256), FastEthernet0/0

P 192.17.0.0/24, 1 successors, FD is 409600

via 10.1.100.5 (409600/128256), FastEthernet0/0

like is was suppose !

after I had the follwing like in my EIGRP process :

"

variance 4

offset-list serial in 245 FastEthernet0/1

offset-list serial out 245 FastEthernet0/1

R1#sh ip eigrp topo

P 10.1.3.0/24, 1 successors, FD is 409600

via 10.1.100.3 (409600/128256), FastEthernet0/0

P 10.1.2.0/24, 1 successors, FD is 409600

via 10.1.100.2 (409600/128256), FastEthernet0/0

via 10.1.200.2 (409845/128501), FastEthernet0/1

P 10.1.1.0/24, 1 successors, FD is 128256

via Connected, Loopback1

P 192.168.100.0/24, 1 successors, FD is 409600

via 10.1.100.3 (409600/128256), FastEthernet0/0

P 10.1.100.0/24, 1 successors, FD is 281600

via Connected, FastEthernet0/0

P 10.1.200.0/24, 1 successors, FD is 281600

via Connected, FastEthernet0/1

P 192.16.0.0/24, 1 successors, FD is 409600

via 10.1.100.4 (409600/128256), FastEthernet0/0

P 192.17.0.0/24, 1 successors, FD is 409600

via 10.1.100.5 (409600/128256), FastEthernet0/0

"

10.1.2.0/24, have only 1 successors and 2 availables paths, but in routing table :

R1# sh ip route

Gateway of last resort is not set

10.0.0.0/24 is subnetted, 5 subnets

D 10.1.3.0 [90/409600] via 10.1.100.3, 16:04:57, FastEthernet0/0

D 10.1.2.0 [90/409600] via 10.1.100.2, 16:04:57, FastEthernet0/0

C 10.1.1.0 is directly connected, Loopback1

C 10.1.100.0 is directly connected, FastEthernet0/0

C 10.1.200.0 is directly connected, FastEthernet0/1

D 192.17.0.0/24 [90/409600] via 10.1.100.5, 16:04:57, FastEthernet0/0

D 192.16.0.0/24 [90/409600] via 10.1.100.4, 16:04:57, FastEthernet0/0

D 192.168.100.0/24 [90/409600] via 10.1.100.3, 16:04:57, FastEthernet0/0

we have only one path the 10.1.2.0/24 network.

I don't understand why the second path is not also add as available route to this destination. Could someone can help me !

jimmysands73_2 · ‎06-25-2009

Chris,

You could also try the Cisco Learning Network arena for a resolution to your question.

https://cisco.hosted.jivesoftware.com/index.jspa?ciscoHome=true

On the left they link to various levels (certs) with forums also for posting questions. I use both forums are resources depending on the my question.

Now let me look at your question....

:)

viyuan700 · ‎06-29-2009

I don't understand why the second path is not also add as available route to this destination. Could someone can help me !

Second path is not in routing in table because it is Feasible successor (FS)not successor.

P 10.1.2.0/24, 2 successors, FD is 409600

via 10.1.200.2 (409600/128256), FastEthernet0/1

via 10.1.100.2 (409600/128256), FastEthernet0/0

in this case u can find both routes in routing table as both are successor. check ur routing tablle.

christianpho · ‎06-29-2009

Hi !

I was understand it is not a successor only feasible successor... But, I was modify variance value to 4 to make both as a successor. It's the part of what I missed understanding !