[AusNOG] AARNET and Aggregates

[Tomas Paseka]

Advertise the /20 to Equinix too and that'll fix your problem.

-----Original Message-----
From: ausnog-bounces at lists.ausnog.net
[mailto:ausnog-bounces at lists.ausnog.net] On Behalf Of Sean K. Finn
Sent: Wednesday, 11 November 2009 12:20 PM
To: 'Jonathan Thorpe'; 'AusNOG at ausnog.net'
Subject: Re: [AusNOG] AARNET and Aggregates

Do you mean that if you advertise a /20 and a /24 that the route that is
preferenced is the /24 ?

I.e. the more-specific route (/24) takes precedence over the aggregated
route (/20) ?

-Sean.

-----Original Message-----
From: ausnog-bounces at lists.ausnog.net
[mailto:ausnog-bounces at lists.ausnog.net] On Behalf Of Jonathan Thorpe
Sent: Wednesday, 11 November 2009 10:12 AM
To: AusNOG at ausnog.net
Subject: [AusNOG] AARNET and Aggregates

Hi All,

I've been trying to track down an odd problem that I've noticed over the

past few days and hope someone can shed some light on this.

Looking at AARNet's looking glass (http://lg.aarnet.edu.au/cgi-bin/lg), 
it seems that routes that are flagged as aggregated are ignored when 
there are routes available that are not aggregated, despite having 
longer AS paths.

This results in inbound traffic that we would prefer to come in over 
peering networks (e.g. Equinix) entering our network over transit 
instead. This is not ideal because it results in using more expensive 
bandwidth and is a bit more asymmetrical than we'd like.

At first, I thought it was just us (we advertise two /20s as a series of

/24s - e.g. 122.202.64.0/24 and 203.124.176.0/24 under AS37996 which are

aggregates of smaller prefixes), but looking at other peers that show up

over our Equinix link, others that also have aggregated routes seem to 
experience the same phenomenon.

I've written to the AARNET NOC already, however I'm wondering if this 
could be by design or simply a side effect?


Thoughts anyone?

Kind Regards,
Jonathan
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