Re: BGP ORF in practice

[Rob Shakir <rjs () rob sh>]

On 31 May 2012, at 18:18, Wayne Tucker wrote:

> What's the general consensus (hah! ;) regarding the use of RFC5291 BGP
> outbound route filtering?  It's worked well for me in the lab, but I have
> yet to use it in a live environment (and I don't know that most service
> providers would know what I was talking about if I asked for it).  Does it
> work great or does it end up being more pain than it's worth?


Hi Wayne,

In my experience, ORF is not particularly widely deployed in live network deployments.

It has some potential to be difficult to manage where implementations begin to experience complexities in building 
UPDATE message replication groups (where peers have a dynamic advertisement (egress) policy due to ORF, then this may 
mean that the number of peers with common UPDATE policies reduces, and hence concepts like policy-driven UPDATE groups 
become less efficient). This may impact the scaling of your BGP speakers in ways that are not easy to model - and hence 
may be undesirable on PE/border devices where control-plane CPU is a concern.

Further to this, there is, or has been, some disconnect in the modes of ORF that are supported between various speakers 
- for instance, some vendors support only prefix-based ORF, where others support only RT-based, which causes some 
barriers to implementation.

In an inter-domain context, I have seen some discussion of ORF as a means by which an L3VPN customer may choose to 
receive only a subset of their routing information at particular "low feature" sites - but the inter-operability issues 
mentioned above resulted in this not being deployed. Do you have a similar deployment case?

Cheers,
r.