Advertising BGP-4 from two islands

Patrick W. Gilmore patrick at
Sun Sep 13 10:39:30 UTC 2009

On Sep 13, 2009, at 2:22 AM, William Herrin wrote:
> On Sat, Sep 12, 2009 at 9:35 PM, Francois  
> Menard<francois at> wrote:
>> I have an opportunity to launch services in a remote marke, where I  
>> cannot
>> extend my backbone to.
>> However, this market is big enough that I can afford to put a Cisco  
>> 7201
>> over there and peer in BGP-4.
>> Do you have any advice as to what may happen if I advertise  
>> different blocks
>> from the same AS number, from two different locations, one of which  
>> I do not
>> have my own transport facilities to...
> This probably qualifies as a "unique routing policy" under ARIN NRPM
> section 5. That allows you to get another AS number.

Why burn an ASN?  There is no need.  With "neighbor $FOO allowas-in",  
you can even see your own prefixes.

> You could also get a small block of staticly-routed IPs from your ISPs
> in each location and use them to anchor a VPN (e.g. a GRE tunnel).
> That'd have the effect of extending your backbone.

Another useful suggestion.  Hell, don't even need GRE tunnels - who  
said all your IP space had to be in your personal ASN?


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