EIGRP and split-horizon

Do yuou think that split horizon has nothing to do with it? Today I'll try to filter a route from hub1 to switch1 and see what happens. Thanks again. Bye, Tosh.

What is the EIGRP router-id on hub1?

see via "show ip eigrp topo" command

#sh ip eigrp topo IP-EIGRP Topology Table for AS(10)/ID(201.64.0.201)

IP-EIGRP Topology Table for AS(10)/ID(11.22.33.44)

This address (purged) is a loopback configured on the router, does it have something to do with our issue? Tnx, Tosh.

Hi Merv, I tried to filter the announcements made by Hub1 to the local lan so that Hub1 dosn't announce anymore the network 192.168.45.0/24 learned from the outside. These are the topology details before the filtering:

Hub1#sh ip eigrp top 192.168.45.0/24 IP-EIGRP (AS 100): Topology entry for 192.168.45.0/24 State is Passive, Query origin flag is 1, 1 Successor(s), FD is 307200 Routing Descriptor Blocks: 172.17.3.1 (FastEthernet0/1), from 172.17.3.1, Send flag is 0x0 Composite metric is (307200/281600), Route is External Vector metric: Minimum bandwidth is 10000 Kbit Total delay is 2000 microseconds Reliability is 255/255 Load is 25/255 Minimum MTU is 1500 Hop count is 1 External data: Originating router is 172.17.3.1 AS number of route is 65535 External protocol is BGP, external metric is 0 Administrator tag is 1 (0x00000001)

Switch1#sh ip eigrp top 192.168.45.0/24 IP-EIGRP (AS 100): Topology entry for 192.168.45.0/24 State is Passive, Query origin flag is 1, 1 Successor(s), FD is 5427200 Routing Descriptor Blocks: 172.16.3.1 (Vlan3), from 172.16.3.1, Send flag is 0x0 Composite metric is (5427200/307200), Route is External Vector metric: Minimum bandwidth is 10000 Kbit Total delay is 202000 microseconds Reliability is 255/255 Load is 25/255 Minimum MTU is 1500 Hop count is 2 External data: Originating router is 172.17.3.1 AS number of route is 65535 External protocol is BGP, external metric is 0 Administrator tag is 1 (0x00000001) 172.16.5.4 (Vlan5), from 172.16.5.4, Send flag is 0x0 Composite metric is (7419392/2299392), Route is External Vector metric: Minimum bandwidth is 2048 Kbit Total delay is 241000 microseconds Reliability is 255/255 Load is 1/255 Minimum MTU is 1500 Hop count is 2 External data: Originating router is 172.17.5.1 AS number of route is 65522 External protocol is BGP, external metric is 0 Administrator tag is 1 (0x00000001

These are the same details after the filtering:

Switch1#sh ip eigrp top 192.168.45.0/24 IP-EIGRP (AS 100): Topology entry for 192.168.45.0/24 State is Passive, Query origin flag is 1, 1 Successor(s), FD is 5427200 Routing Descriptor Blocks: 172.16.5.4 (Vlan5), from 172.16.5.4, Send flag is 0x0 Composite metric is (7419392/2299392), Route is External Vector metric: Minimum bandwidth is 2048 Kbit Total delay is 241000 microseconds Reliability is 255/255 Load is 1/255 Minimum MTU is 1500 Hop count is 2 External data: Originating router is 172.17.5.1 AS number of route is 65522 External protocol is BGP, external metric is 0 Administrator tag is 1 (0x00000001)

Hub1#sh ip eigrp top 192.168.45.0/24 IP-EIGRP (AS 100): Topology entry for 192.168.45.0/24 State is Passive, Query origin flag is 1, 1 Successor(s), FD is 307200 Routing Descriptor Blocks: 172.17.3.1 (FastEthernet0/1), from 172.17.3.1, Send flag is 0x0 Composite metric is (307200/281600), Route is External Vector metric: Minimum bandwidth is 10000 Kbit Total delay is 2000 microseconds Reliability is 255/255 Load is 25/255 Minimum MTU is 1500 Hop count is 1 External data: Originating router is 172.17.3.1 AS number of route is 65535 External protocol is BGP, external metric is 0 Administrator tag is 1 (0x00000001) 172.16.3.51 (FastEthernet0/0), from 172.16.3.51, Send flag is 0x0 Composite metric is (7421952/7419392), Route is External Vector metric: Minimum bandwidth is 2048 Kbit Total delay is 241100 microseconds Reliability is 255/255 Load is 170/255 Minimum MTU is 1500 Hop count is 3 External data: Originating router is 172.17.5.1 AS number of route is 65522 External protocol is BGP, external metric is 0 Administrator tag is 1 (0x00000001)

As you can see Switch1 starts to announce that paticular network as soon as Hub1 stops to annonce the same network. All other routes doesn't change state on both devices and as soon as I negate the filter all comes back to the original state. It's looking like split horizon to me. Bye, Tosh.

Are you running multiple EIGRP processes on hub1 ?

Absolutely not, if you like I can send you some purged config and some outputs via private mail, but I don't want to abuse you. Tnx, Tosh.

Configs would probably be helpful at this point.

Also via private email the IP address of the links between hub1-switch1, switch1-switch2 and switch2 -hub2 as this is the only way to make sense of the next hop info.

The reason I asked about the multile EIGRP proceess is that the show ip eigrp topo you posted yesterday show AS as 10 and todays posting showed the AS as 100

Your problem is interesting. If I understand what has been going on, it appears across the radio link you are not working properly, which is why you are asking about the split horizon. You also mentioned you are using wireless bridges. Can you ping across the bridge, and does the bridge perform a proper link test. I have seen where you can ping across the bridge, but the link test fails. If you already have done the above, is it possible for you to find a time where you can disable split horizon on both sides of the bridge without causing any degradation to the network, IE after business hours.

That was the beacuse of the purge :-))

The radio link is working good, there are also some servers that syncrohize themselves correctly across the radio link. I think I've got any problem, simply I see routes from switch1 going to hub1 only if hub1 is not advertising the same routes back, this seems to me a perfectly legal split horizon situation, what I'm asking about is why this is happening on switch1 instead of any other device and if it can happen that this behaviour should migrate to hub1....this way I'll be in big troubles. I'm not going to disable split horizon since this is a round the clock service, what I've tried to do was to fliter the announce for 1 route from hub1 to switch1, at this time switch1 started to announce the same route back, and only that, to hub1. Bye, Tosh.