Multiple Paths EIGRP

[Tigerjoe]

I have two routers connected B2B (R1 and R2) using both serial interfaces on each router. S0 clock rate is 148000 and S1 clock rate is 4000000. Routing protocol is EIGRP.

R1=DCE
R2=DTE

Because of cabling issues I cannot increase the clock rate on S0. The problem that I have is that R2 sends packets via S0. These are not even close to equal cost routes, so why doesnt R2 use the faster route? I can post the configs if needed.



T J

To PING or not to PING?

 

[svermill]

Bandwidth statements are used to develop routing metrics in some protocols but are not used directly as metrics. Furthermore, bandwidth statements and clock rates are totally separate. You need to look at your config and your routing table. If there is no bandwidth statement under your interfaces, EIGRP will use the default value and treat them as equal.

 

[dnels]

Tigerjoe,

Do a sho interface and check the bandwidth, it's probably the same for both int's (Cisco Default). You will need to add bandwidth statements on the int's. This will aloow the routing metric to be different on these lines.


Dave

 

[Tigerjoe]

DCE#sho run

Current configuration : 1635 bytes
!
! Last configuration change at 18:16:16 UTC Thu Dec 19 2002
!
version 12.2
service timestamps debug datetime msec
service timestamps log datetime msec
no service password-encryption
!
hostname DCE
!
enable secret 15 $1$hC945rtyGHF\Q$B/Fv16duK5yhP3jP7D2wch9.
!
ip subnet-zero
ip name-server 41.1.1.1
!
!
!
!
interface Ethernet0
ip address dhcp
ip nat outside
no cdp enable
!
interface Serial0
bandwidth 148000
ip address 10.2.2.1 255.255.255.252
clockrate 148000
!
interface Serial1
bandwidth 4000000
ip address 10.0.0.1 255.255.255.252
ip nat inside
clockrate 4000000
!
router eigrp 2
network 10.0.0.0
network 172.16.0.0
auto-summary
no eigrp log-neighbor-changes
!
router rip
version 2
network 192.168.0.0
!
ip nat inside source list 1 interface Ethernet0 overload
ip classless
ip route 0.0.0.0 0.0.0.0 10.50.24.1
no ip http server
!
!
access-list 1 permit 10.0.0.0 0.0.0.255
access-list 1 permit 172.16.0.0 0.0.255.255
access-list 1 permit 192.168.0.0 0.0.255.255
access-list 1 permit 10.1.1.0 0.0.0.255
!
!
!
end

DTE#sho run
!
!
interface Serial0
bandwidth 148000
ip address 10.2.2.2 255.255.255.252
no fair-queue
!
interface Serial1
bandwidth 4000000
ip address 10.0.0.2 255.255.255.252
no ip route-cache
no ip mroute-cache
!
!
router eigrp 2
network 10.0.0.0
network 172.16.0.0
no auto-summary
no eigrp log-neighbor-changes
!
end




T J

To PING or not to PING?

 

[dnels]

Try a sho ip route to an address on the other side. This looks OK as the administrative distance of eigrp should override the RIP. Although it's acting like a RIP route is getting into the routing table. If I remember correctly RIP doesn't support multiple equal cost paths.

Dave

 

[Tigerjoe]

I change the routing protocol back to RIP v2 and its still the same.
DTE#sho ip rout
Codes: C - connected, S - static, I - IGRP, R - RIP, M - mobile, B - BGP
D - EIGRP, EX - EIGRP external, O - OSPF, IA - OSPF inter area
N1 - OSPF NSSA external type 1, N2 - OSPF NSSA external type 2
E1 - OSPF external type 1, E2 - OSPF external type 2, E - EGP
i - IS-IS, L1 - IS-IS level-1, L2 - IS-IS level-2, ia - IS-IS inter area
* - candidate default, U - per-user static route, o - ODR
P - periodic downloaded static route

Gateway of last resort is 10.0.0.0 to network 0.0.0.0

R 64.0.0.0/8 [120/2] via 10.0.0.1, 00:00:05, Serial1
[120/2] via 10.2.2.1, 00:00:05, Serial0
C 172.16.0.0/16 is directly connected, Ethernet1
* 10.0.0.0/30 is subnetted, 2 subnets
C 10.2.2.0 is directly connected, Serial0
C* 10.0.0.0 is directly connected, Serial1
R 192.168.0.0/24 [120/1] via 10.0.0.1, 00:00:05, Serial1
[120/1] via 10.2.2.1, 00:00:05, Serial0
S* 0.0.0.0/0 [1/0] via 10.0.0.0


T J

To PING or not to PING?

 

[svermill]

What was the

! Last configuration change at 18:16:16 UTC Thu Dec 19 2002

?

Bandwidth statements? Is your routing table now looking like you expect it to?

 

[Tigerjoe]

Actually that was for something else, but the routing table is not looking like it should. <-- Iam not really sure what that is but I think it would be easiest to shut down s0 since iam not getting too much bandwidth from it anyway.


T J

To PING or not to PING?

 

[svermill]

T J,

You're learning about the 64.0.0.0 and the 192.168.0.0 networks via RIP - not EIGRP. Thus, the equal hop-count places both interfaces in the routing table. If you turn off RIP and turn EIGRP back on, I can't see how you would have any problems? Unless something was really just broken...

 

[dnels]

tj

Something funny here. Your 'sho ip route' prompt is DTE and I don't see RIP running in that router's configuration. Rip is running on the router with the prompt DCE. Are you running RIP on both of the routers? If so you could add an offset list to add a hop to the routes coming in ser0:

router rip
offset-list 1 in 1 ser0

access-list 1 permit any

This would add 1 hop to any route coming in ser0 and make the rip metric better on ser1.

If you don't need to advertise RIP between the routers you could add a passive-interface in rip for ser0 and ser1. this would not advertise any RIP routes across the serial lines and force the eigrp metrics to work.

Dave