[c-nsp] AS-set usage

[Tim Devries]

Hi, 

 

I wondering if this list can settle a friendly dispute a co-worker and I are
having regarding the usage of the BGP command 'as-set' when summarizing.

 

Assuming I am AS X, this is the scenario for simplicity (i.e. AS X also has
other upstreams):

 

AS X connects to AS Y, receives table and announces summary of x.x.x.x/20
upstream

 

AS X allocates /24 of x.x.x.x/20 to customer AS Z

 

AS Z then peers with us (AS X) as well as AS Y announcing /24 to both 

 

Z----Y

 |  /

 X

 

I am of the opinion here that since AS X is announcing the /20 summary for
that /24 it needs to also ensure it keeps the AS set intact in order to
prevent loops in BGP.  

 

According to
http://www.cisco.com/en/US/tech/tk365/technologies_tech_note09186a0080094826
.shtml
<http://www.cisco.com/en/US/tech/tk365/technologies_tech_note09186a008009482
6.shtml>  it sounds like the AS set information should be preserved but I'd
just like any thoughts from the list.

 

Thanks,

 

Tim Devries