Route Loop Labs

Daniel333

Hey guys,

I really feel like I am lacking in the area of preventing and troubleshooting routing loops. I think I get the concepts, I just need to work though more scenarios to find the "gotchas". Anyone know where I can get some legit Q&A or scenarios to work though?

Heero

in my experience, troubleshooting route loops has just been:
1. ping
2. TTL expired in transit message
3. traceroute to see the loop
4. Look at routing table in devices, identify issue.

Identifying the issue once you know what the loop is is generally not too hard in my experience.

Routing loops are hard to create unless you are purposefully doing it, and they are normally caused by static routes or by tinkering with settings that you dont understand in a routing protocol, at least in my experience.

I don't know of anywhere that has awesome routing loop labs.

networker050184

Heero wrote: »

in my experience, troubleshooting route loops has just been:
1. ping
2. TTL expired in transit message
3. traceroute to see the loop
4. Look at routing table in devices, identify issue.

Thats how I go about looking for it also. I actually just fixed one that was caused by static routes being redistributed into OSPF inadvertently. A traceroute will usually showing you where the loop is as you can see it bouncing between the two.

APA

networker050184 wrote: »

Thats how I go about looking for it also. I actually just fixed one that was caused by static routes being redistributed into OSPF inadvertently. A traceroute will usually showing you where the loop is as you can see it bouncing between the two.

+1

mtr or something equivalent will show the loop...easy to identify what's wrong from there