01-19-2009 05:30 PM - edited 03-06-2019 03:31 AM
Dynamic routing EIGRP running on all router and L3 switches on both sites.
Two ISP circuits between sites. 10MB lease line and 2MB Serial circuit.
Problem:
On switch (Sw-SideA), when I run 'shop ip eigrp topology I only see one route to 10.60.0.0/24 network, I was expecting to see two routes over both routers (R1-SideA & R1-SideB)
Please advise
R1-SideA
router eigrp 1
network 10.0.0.0
no auto-summary
R2-SideA
router eigrp 1
network 10.0.0.0
no auto-summary
Sw-SideA
router eigrp 1
network 10.0.0.0
no auto-summary
R1-SideB
router eigrp 1
network 10.0.0.0
no auto-summary
R2-SideB
router eigrp 1
network 10.0.0.0
no auto-summary
Sw-SideB
router eigrp 1
network 10.0.0.0
no auto-summary
01-19-2009 05:55 PM
Hi Colm,
Is Sw-SideA to R2-SideA and Sw-SideB to R2-SideB a routed port or a switchport?
Lejoe
01-20-2009 01:29 AM
Hello Colm,
first of all I would verify that EIGRP neighborship is built on vlan 61 between SW-sideA and R2-SideB.
The second note is that it is possible that in normal conditions R2-SideB uses vlan61 to reach the route and so it is seen as a downstream router:
to be listed in the eigrp topology table as a feasible successor the route advertised by R2-SideB must pass the feasibility test:
metric or R2-SideB < best metric to the route
if R2 uses the path via SW-SideA it is seen as more far from the destination route and so it is not installed in the EIGRP table.
Actually R2-Side B itself once decides that the path via vlan 61 is better applies split horizon and removes its advertisement of the route out vlan 61
(doesn't advertise out an inteface what it learns on the same link)
So what yo see is correct behaviour because the EIGRP metric is proportional to sums of delay and to the inverse of lowest bandwidth in path.
To check just do
sh ip route network
on R2-Sideb and see if the outgoing inteface is vlan61 to SW-SideA
Hope to help
Giuseppe
01-20-2009 07:18 AM
You only see that route because it is the better route and the route via the 10.254.0.0 network does not pass the feasible successor test; if the Reported Distance (RD) for 10.254.0.0 is larger than the Feasible Distance (FD) via 10.255.0.0 then this route is NOT entered into the Topology Table as a Feasible Successor. You could tweak this by manipulating the bandwidth and delay values along the path to insure the route was installed.
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