EIGRP topology "all-links" keyword and the feasibility condition

[MapleMagician]

My understanding is that the point of the 'all-links' keyword is to show even the routes that do not meet the feasibility condition. However, in this lab scenario I am not seeing the route at all and I am wondering why.

The route I am concerned with is 10.22.22.16/29 on CSR2. The scenario is that the bandwidth on R4's interface G0/1 has been set to 10,000. So on R4 both routes (through g0/4 and g0/1) satisfy the feasibility condition and are both in the routing table. On R3 the route through R4 clearly does not satisfy the feasibility condition and the route does not show up anywhere, not even using the 'all-links' command as shown below. As stated above, I'm trying to understand why its not showing up under all-links when I thought that was the point of the command is to show even routes that don't satisfy the condition.

R4#show run int g0/1

Building configuration...

Current configuration : 133 bytes

!

interface GigabitEthernet0/1

 bandwidth 10000

 ip address 20.20.224.4 255.255.255.0

 duplex auto

 speed auto

 media-type rj45

end

R4#show ip route 10.22.22.16

Routing entry for 10.22.22.16/29

  Known via "eigrp 100", distance 170, metric 40480, type external

  Redistributing via eigrp 100

  Last update from 20.20.34.3 on GigabitEthernet0/4, 00:45:31 ago

  Routing Descriptor Blocks:

  * 20.20.224.22, from 20.20.224.22, 00:45:31 ago, via GigabitEthernet0/1

      Route metric is 44095, traffic share count is 11

      Total delay is 5010 microseconds, minimum bandwidth is 10000 Kbit

      Reliability 255/255, minimum MTU 1500 bytes

      Loading 1/255, Hops 1

    20.20.34.3, from 20.20.34.3, 00:45:31 ago, via GigabitEthernet0/4

      Route metric is 40480, traffic share count is 12

      Total delay is 5050 microseconds, minimum bandwidth is 500000 Kbit

      Reliability 255/255, minimum MTU 1500 bytes

      Loading 1/255, Hops 5

R3#show ip eigrp topology all-links

EIGRP-IPv4 Topology Table for AS(100)/ID(20.20.113.3)

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

       r - reply Status, s - sia Status

…..omitted for brevity

P 10.22.22.16/29, 1 successors, FD is 2056, serno 17

        via 20.20.113.11 (2056/2052), GigabitEthernet0/5

[MHM Cisco World]

MHM

[MHM Cisco World]

MHM

[David Ruess]

Hello,

I have actually done this exact lab from INE if I remember correctly. The reason it doesn't show up is because its not being learned from R4. R4's BW is so high that its also using R3 to get to that route. R3 is not showing both links with the all-links command.

Remember from EIGRP that it will not advertise a route it learned from its successor (the path its using to get to that route) back to that successor. So since R4 is using R3 to get to that network it wont advertise that network to R3 and as a result R3 only shows one path to that network while it in turn advertises it "downstream" to R4 because of the high metric.

Hope that helps

-David

[MHM Cisco World]

this lab for you 
you want to see the effect of this command but you select the wrong router to see it 
in my Lab 
R1 recieve 6.6.6.6/32 via two path R2 and R3
I make R3 BW 1000000 so R1 now always use path via R3 for 6.6.6.6/32
you can see the path via R2 appear only when I run command with all-link keyword

in your case I thing it same you need to check in R4 the command not in R3 after you make sure that the  cost of path is more higher that other path 

MHM

[paul driver]

Hello

---

@MapleMagician wrote:

My understanding is that the point of the 'all-links' keyword is to show even the routes that do not meet the feasibility condition. However, in this lab scenario I am not seeing the route at all and I am wondering why.

On R3 the route through R4 clearly does not satisfy the feasibility condition and the route does not show up anywhere

---

R3#show ip eigrp topology all-links

EIGRP-IPv4 Topology Table for AS(100)/ID(20.20.113.3)

P 10.22.22.16/29, 1 successors, FD is 2056, serno 17

        via 20.20.113.11 (2056/2052), GigabitEthernet0/5

???


sh eigrp top 10.22.22.16/29
sh eigrp top zero