BGP multihoming

Justin M. Streiner streiner at
Wed Jan 29 17:25:55 UTC 2014

On Wed, 29 Jan 2014, Baldur Norddahl wrote:

> I had a customer ask if we could provide him with BGP such that he could be
> multihomed. He already has 128 IP addresses from another ISP. Obviously a
> /25 is a non go for multihoming as everyone are going to ignore his route.

Not necessarily everyone, but a lot of providers will filter that.  More 
headaches than it's worth.

> I would then need to help him with acquiring a /24 PI. Which appears to be
> impossible as RIPE does no longer assign PI space and PI can not be
> reassigned and thus be bought.
> Is assigning a /24 from my own PA space for the purpose of BGP multihoming
> considered sufficient "need"?

I haven't looked at RIPE policies in a while, but I would imagine that 
assigning a customer a /24 of your space because they need to multihome is 
considered a justifiable use.

> Could he get some PI from another region, such as ARIN? How does others
> handle this situation?

Most likely no, for two reasons.  1. Most RIRs don't assign IPv4 /24s to 
end-users except in very special cases, 2. The smallest PI block they 
would assign is usually something like a /21 or /22, so your customer 
would need to be justifiably using that much space before they could apply 
for a PI block, and 3, if the customer is in an area outside of $RIR's 
service area, they would direct them to contact the appropriate RIR.

I also hope your customer is making plans for IPv6 deployment.


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