intermittent routing prob. eigrp

cfajardo1_2 · ‎05-03-2007

SCENARIO

core sw (vlanx, vlany,vlanz)---mainrouter-------remotes

NOTES;

CORE SWITCH

vlanz connected to main router

vlanz conected to firewall (def gateway)

vlanx 192.168.1.1/24

vlany 192.168.2.1/24

vlanz 10.1.1.1/24

MAIN ROUTER

f0/0 10.1.1.254/24

s0/0.1 ip unnumbered f0/0

s0/0.2 ip unnumbered f0/0

REMOTES

remote1 f0 10.2.2.254/24

remote2 f0 10.3.3.254/24

iam facing an intermittent problem reaching remotes only from machines on vlanz. Below are the relevant configurations.

CORE

router eigrp 100

network 192.168.1.0 0.0.0.255

network 192.168.2.0 0.0.0.255

network 10.0.0.0

no auto-summary

IP ROUTE 10.2.2.0 255.255.255.0 10.1.1.254

IP ROUTE 10.3.3.0 255.255.255.0 10.1.1.254

MAIN ROUTER

router eigrp 100

network 25.0.0.0

no auto-summary

REMOTE ROUTER1

router eigrp 100

network 10.0.0.0

no auto-summary

REMOTE ROUTER1

router eigrp 100

network 10.0.0.0

no auto-summary

IF I PUT THE ROUTE ADD ON THE PCs ON VLANZ AS FOLLOWS

ROUTE ADD 10.0.0.0 MASK 255.0.0.0 10.1.1.254, THEN EVERYTHIN WILL BE OK

ANY OBVIOUS PROBLEM ON MY CONFIGURATION?

THANKS A LOT.

Harold Ritter · ‎05-03-2007

You should not need to configure the two static routes on the core switch as these subnets (10.2.20.0/24 and 10.3.3.0/24) should be learnt via EIGRP.

Make sure your the PCs on vlanz have a default route pointing to 10.1.1.254.

Hope this helps,

Harold Ritter
Sr Technical Leader
CCIE 4168 (R&S, SP)
harold@cisco.com
México móvil: +52 1 55 8312 4915
Cisco México
Paseo de la Reforma 222
Piso 19
Cuauhtémoc, Juárez
Ciudad de México, 06600
México

sundar.palaniappan · ‎05-03-2007

The problem you are running into is due to IP redirects. IP redirects can be good or bad depending on how the PCs handle the redirect packets.

It appears the hosts on vlanZ might be using the gateway address of 10.1.1.1. The switch would be sending a ICMP redirect packet to the hosts to forward the traffic over to the core router. Sometimes it works and sometimes it doesn't.

Try adding this config to the switch and see if that resolves your problem.

int vlanz

no ip redirects

HTH

cfajardo1_2 · ‎05-04-2007

not 10.1.1.254....all the vlans default gateways are pointing to the vlan ip address on the core...incase of vlanz dg=10.1.1.1

sundar.palaniappan · ‎05-04-2007

Did you try configuring the 'no ip redirects' on int vlanz?

cfajardo1_2 · ‎05-04-2007

not yet...i will be having access to it again on sunday..

whaT will happen to the route to the remotes if ill do that.

sundar.palaniappan · ‎05-04-2007

It won't affect the route to the remote sites. All this command does is to force the switch to route the traffic to the remotes rather than send ICMP redirect packets to the host in vlanZ.

HTH

Sundar

cfajardo1_2 · ‎05-05-2007

ive tried and it works...since the problem is intermittent..lets observe it a day or 2.

thanks