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List:       inet-access
Subject:    Re: Classful address filtering?
From:       Herb Peyerl <hpeyerl () beer ! org>
Date:       2007-05-17 21:40:55
Message-ID: F865EFA8-501A-45EC-8001-5D692EE450DB () beer ! org
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On 17-May-07, at 12:21 PM, Kevin Kargel wrote:

> Most providers will not advertize any allocation smaller than a /24  
> and
> require ISP's to aggregate BGP announcements to at least this
> granularity.  This is ok because it means that if there is a  
> problem it
> is a routing issue at your provider.
>
> If you want to check and see who is announcing your IP block check at
> one of the many public Looking Glass servers that monitor BGP
> advertisements.
>
> This is suspect if you can query nameservers further away.  That would
> tend to prove routing.
>
> I would suspect other issues like nameserver policies, or ACL's at  
> your
> ISP.

The looking glass thing is not something I was familiar with before  
so thanks for that... So apparently to the outside world, the block  
in question is part of a larger /17... So the problem is clearly  
inside the aggregation somewhere which my experimentation seems to  
support... I've sent them output from lots of mtr/traceroute/dig  
tests and so forth but there's a layer-9 firewall in place... I was  
throwing the problem out to you fine folks in hopes that I had missed  
something....


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