Subnet Size for BGP peers.

Benjamin Billon bbillon-ml at splio.fr
Wed Jul 29 17:09:27 CDT 2009


Imagine two of your clients are competitors, they probably don't want to 
be on the same IP range. And yes, when you sell your service to several 
customers, you don't want one of them blowing up all the other's SLA.

IXs use /24, as far as I know, and peers connected there can usually use 
md5 password if they want to. But in that case, some troubles like arp 
broadcast storm could happen, coming from any of the connected network.

I guess it's not the same level of service, but I agree, many /30 or /29 
are a big loss of addresses.

It reminds me GLBP with two gateways: on 10.0.0.0/29, you got
10.0.0.0 : network
10.0.0.7 : broadcast
10.0.0.1 : gw1
10.0.0.2 : gw2
10.0.0.6 : virtual gw
only 3, 4 and 5 for other equipments.

Who knows any other good way to lose IP addresses?


Jim Wininger a écrit :
> I have a question about the subnet size for BGP peers. Typically when we
>
> turn up a new BGP customer we turn them up on a /29 or a /30. That seems to
>
> be the "norm".
>
>
> We connect to many of our BGP peers with ethernet. It would be a simple
>
> matter to allocate a /24 for connectivity to the customer on a shared link.
>
> This would help save on some address space.
>
>
> My question is, is this in general good or bad idea? Have others been down
>
> this path and found that it was a bad idea? I can see some of the pothols on
>
> this path (BGP session hijacking, incorrectly configured customer routers
>
> etc). These issues could be at least partially mitigated. Are there larger
>
> issues when doing something like this or is it a practical idea?
>
>   




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