[ih] The story of BGP?

Tony Li tony.li at tony.li
Mon Feb 11 09:38:54 PST 2013

Hi Guy,

> And, of course, key disadvantages:
> <> elevating local inter-AS routing decisions, which inevitably mixed technical, operational, and business aspects to being non-local / community / political decisions.
>  Instead, of course, we have very messy BGP configurations.
>  These stemmed, in part, from the early BGP implementations using the full AS path *length* as the de-facto "metric".
>  That was implementable, but obviously resulted in weak selections of inter-AS routes.  The patches to BGP to ameliorate this weakness are perhaps both regrettable and inevitable.

I'll agree with the inevitable portion.  As we found when working on IDPR, the need for interesting peering policies in a newly commercialized Internet was paramount.  Unlike the benign dictatorship of DARPA or the more cooperative but still segregationist NSFnet, the wild and wooly commercial Internet had many ISPs who were mutually hostile.  Sometimes openly so, but more frequently under the table. 

The ability to craft policy that optimized for local routing at the expense of one's neighbors (i.e., hot potato routing) was one expression of this.

So, this was indeed an inevitable outcome of commercialization.  However, I'm not sure that it was all that regrettable.  The result is far more expressive than a centralized (and politicized) routing authority or even link-state protocol could have ever supported.  As such, it has proven to be extremely flexible and allowed the Internet to grow freely.

If BGP complexity is the price of freedom, it's well worth paying.


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