[afnog] BGP /AS filtering

[Mark Tinka]

On Friday, June 28, 2013 02:30:37 PM Saul Stein wrote:

> Hi
> Thanks for all the replies.
> I thought it strange that entities like Seacom and then
> MWeb allow that to transit through them....

Well, in this particular case, if any of the transit 
networks were running code that didn't support explicit 
removal of the private ASN because of the presence of a 
public ASN in the path, then presence of such a command in 
the transit networks would be useless.

Assuming the origin of the path is unable to remove the 
private ASN from their end (which is not an unreasonable 
request), then the transit providers would need to support 
code (and I'm speaking for Cisco and Juniper, vendors I know 
and understand) that allows for the removal of private ASN's 
in paths that also contain public ASN's. Of course, it is 
presumptuous to expect transit providers to run vendor 
equipment that support this, and moreover, code from vendors 
that support this on their supported boxes. If the transit 
providers are really picky about what features they want to 
support, some might find it hard to even support this 
without significant operator feedback over time.

Mark.
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