Comprehensive community Guideline and Policies for an AS

Joe Maimon jmaimon at
Sun Feb 22 21:34:08 UTC 2009

Kevin Blackham wrote:
> See nLayer. That should be the gold standard. :)

A gold standard is precisely what I am looking for.

nLayer's does look fairly comprehensive.

A few nitpick that lead me to hesitate to adopt it.

The informational tags comprised of


T   The type of relationship that the route was learned through
C   The continent where the route was learned
R   The region where the route was learned
PP  The POP location (city code)


Type of routes have a maximum of 6 possible types. That could be 
limiting. nLayer lists 1-5 types already, granted those are the typical 
relationships and should cover most needs.


Pop location code has a maximum of 99. nLayer is already up to 30.

What are they going to do when they reach 100? Suppose instead of cities 
you wanted to number pops? Quite conceivable to have multiple pops in 
the same city.

Import/Export Action Communities

These communities define specific import/export behaviors, and contain
location codes to specify which BGP sessions the actions should be applied
to. The second half of the Community will always be 4 digits long, and
will have the following structure:


ASN  The Autonomous System Number to affect
A      The export action to perform
C      Continental code (or 0 for all continents)
R      Regional code (or 0 for all regions)
PP     POP Location code (city code)

Using other ASN's as part of your communities policy raises two issues:

- Is it a good idea without drawback (sprint does this also but only 
with private ASNs)?

- How will this scale to 4byte ASN's?

Anyways, the point I am working from is that there are too many 
divergent approaches and all networks cant be that different and there 
should be one general approach that will work for all.



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