Multi-homing with multiple ASNs

Curtis L. Parish Curtis.Parish at
Mon Nov 24 15:14:31 UTC 2014

Thanks to everyone for your input on our less than desirable BGP situation. 

I do want to make sure I add that the state network we are a part of serves everything from elementary schools, to universities.  to the traffic cameras on the interstate.    Many of these are in rural locations and in the past each state entity had created their own network including two separate state university networks.    The state vendor managed network was created to save money and provide higher level services than just an ISP.   Among other things it serves as the private WAN for some state agencies.    As our internet redundancy and bandwidth demands have increased we have outgrown the need for the high touch services offered by the state network but we must participate in order to maintain WAN access to other state universities.   

Thanks again for the feedback.


Curtis Parish
Senior Network Engineer
Middle Tennessee State University 

-----Original Message-----
From: NANOG [mailto:nanog-bounces at] On Behalf Of joel jaeggli
Sent: Sunday, November 23, 2014 1:21 PM
To: mark.tinka at; nanog at
Subject: Re: Multi-homing with multiple ASNs

On 11/21/14 1:07 AM, Mark Tinka wrote:
> On Friday, November 21, 2014 12:00:47 AM Curtis L. Parish
> wrote:
>> We have recently added a second ISP  (third if you count I2).  Our 
>> first "ISP" is actually a private state network that peers with two 
>> Tier 1 providers.  We own an AS number and our IP space but at the 
>> last minute learned our state network is advertising our network 
>> using two different ASNs (neither ours) so they can load
>> balance their connections.    If you hit the right
>> looking glass server you can see our network advertised
>> by three different ASNs.    We were told by the new ISP
>> that this is a problem but the state network says it is not.
>> Looking for opinions and words of wisdom on this split advertising 
>> issue.
> Why aren't you originating your own prefixes and ASN by yourselves, 
> since you own both?

The practical problem here is that the control of prefix origination is distributed. so if there is a need to withdraw it from the state network or advertise it no export for some reason (e.g. performance problem maintenance etc) you likely can't. Their grasp of load-balancing seems a bit shallow also.

> Mark.

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