Solved: Eigrp Problem

arjunsawant · ‎08-29-2009

Hi....

I have location DC and DR which are connected with two lease line running eigrp.

DC ------------------------------ DR

------------------------------

10.5.0.162 10.5.0.161

10.5.0.150 10.5.0.149

On DC Router

router eigrp 111

redistribute static

network 10.0.0.0

no auto-summary

On DC Router

router eigrp 111

redistribute connected

redistribute static

network 10.1.0.0 0.0.255.255

no auto-summary

My issue is,when I trace...why it like

149--161---141

DC#trace 10.1.0.3

Type escape sequence to abort.

Tracing the route to 10.1.0.3

1 10.5.0.149 0 msec

10.5.0.161 4 msec

10.5.0.149 0 msec

2 10.1.0.3 0 msec 4 msec 0 msec

Same thing from DR..

DR#trace 10.0.0.100

Type escape sequence to abort.

Tracing the route to 10.0.0.100

1 10.5.0.150 4 msec

10.5.0.162 0 msec

10.5.0.150 4 msec

2 192.168.3.1 0 msec 4 msec 0 msec

3 10.0.0.100 4 msec 0 msec 4 msec

I don't have any problem but i don't understand why it's like loop.

Thanx......

Giuseppe Larosa · ‎08-30-2009

Hello Arjun,

Edison has explained what you thought was an issue.

It is wise to rate useful posts as the Edison's one. This can help other people undestand this thread has an happy end.

About traceroute:

traceroute works in the following manner

UDP packets with an high UDP port like 34xyz are sent.

First round:

TTL=1 in sent packets

send 3 packets using multiple paths if present:

first path uses path1

second path used path2

in your case third packet is sent out path1 because there is no a third path.

So what you see is the result of this activity.

Round2:

increase TTL to 2 sends out 3 packets

devices receiving packet with TTL=1 sends an icmp message telling TTL is expired.

in this way traceroute originating node finds the next-hops in the path to destination from the source ip addresses of icmp error messages received back

Hope to help

Giuseppe

View solution in original post

Edison Ortiz · ‎08-29-2009

It's not a loop but an expected behavior when having a route installed in the RIB with multiple paths - it's called load balancing the traffic.

When you traceroute, you send 3 packets - per the output one packet was sent via one path and the other packet was sent via the other path.

Issue show ip route 10.0.0.100 from the DR and you will see 2 identical paths to the destination.

HTH,

__

Edison.

arjunsawant · ‎08-30-2009

Hi..

Thanx fir ur reply....

I tried sh ip route from DR for 10.0.0.100, it shows two path.

Can u bit explain "When you traceroute, you send 3 packets - per the output one packet was sent via one path and the other packet was sent via the other path".

I know traceroute is basic question but ur precious reply is helpful for me.

thanx....

Giuseppe Larosa · ‎08-30-2009