nanog mailing list archives
Re: Odd router brokenness
From: Mark Radabaugh <mark () amplex net>
Date: Wed, 23 Nov 2011 12:01:32 -0500
On 11/23/11 11:41 AM, Keegan Holley wrote:
It's fixed at this point. You are correct in that it was quite painful getting this escalated far enough to get it fixed. The tools that are available (at least that I know of) to try to prove the issue to level 1 and 2 support just doesn't get the job done.2011/11/23 Saku Ytti<saku () ytti fi>On (2011-11-23 09:41 -0500), Mark Radabaugh wrote:The question is: How does a router break in this manner? It appears to unintentionally be doing something different with traffic based on the source address, not the destination address. I realize this can be done intentionally - but that is not the case here (unless somebody isn't telling me something).I don't think we can determine that it has anything to do with source address based on data shown. 38.104.148.5 could very well be 6500 and somehow broken adjacency to 74.125.226.6, perhaps hardware adjacency having MTU of 0B, causing punt which is rate-limited by different policer than TTL exceeded policer. Agree. I've seen similar effects with a different ISP who had one side ofan ether-channel go south without the port showing down. Stuff hashed over the good like was fine, stuff hashed over the bad like wasn't. Led to some painful support calls from customers. I agree this list is a haven of speculation and OT comments. In order to avoid making a bad problem worse you should probably contact cogent.
It's the eternal problem of convincing L1/2 support that you really have a problem not of your own making.
Mark
Current thread:
- Odd router brokenness Mark Radabaugh (Nov 23)
- Re: Odd router brokenness Saku Ytti (Nov 23)
- Re: Odd router brokenness Keegan Holley (Nov 23)
- Re: Odd router brokenness Mark Radabaugh (Nov 23)
- Re: Odd router brokenness Mark Radabaugh (Nov 23)
- RE: Odd router brokenness Leigh Porter (Nov 23)
- Re: Odd router brokenness Saku Ytti (Nov 23)
- Re: Odd router brokenness Keegan Holley (Nov 23)
- Re: Odd router brokenness Saku Ytti (Nov 23)