Soliciting your opinions on Internet routing: A survey on BGP convergence

joel jaeggli joelja at
Tue Jan 10 05:51:40 UTC 2017

On 1/9/17 2:56 PM, Laurent Vanbever wrote:
> We often read that the Internet (i.e. BGP) is "slow to converge". But how slow
> is it really? Do you care anyway? And can we (researchers) do anything about it?
> Please help us out to find out by answering our short anonymous survey 
> (<10 minutes).
> Survey URL: <>
> ** Background:
> While existing fast-reroute mechanisms enable sub-second convergence upon 
> local outages (planned or not), they do not apply to remote outages happening 
> further away from your AS as their detection and protection mechanisms only 
> work locally.
> Remote outages therefore mandate a "BGP-only" convergence which tends to be
> slow, as long streams of BGP UPDATEs (containing up to 100,000s of them) must
> be propagated router-by-router. Our initial measurements indicate that it can
> take state-of-the-art BGP routers dozens of seconds to process and propagate
> these large streams of BGP UPDATEs. During this time, traffic for important
> destinations can be lost.

One of the phenomena that is relatively easy to observe by withdrawing a
prefix entirely is the convergence towards longer and longer AS paths
until the route disappears entirely. that is providers that are further
away will remain advertising the route and in the interim their
neighbors  will ingest the available path will  until they too process
the withdraw. it can take a comically long time (like 5 minutes)  to see
the prefix ultimately disappear from the internet. When withdrawing a
prefix from a peer with which you have a single adjacency this can
easily happens in miniature.

> ** This survey:
> This survey aims at evaluating the impact of slow BGP convergence on
> operational practices. We expect the findings to increase the understanding of
> the perceived BGP convergence in the Internet, which could then help
> researchers to design better fast-reroute mechanisms.
> We expect the questionnaire to be filled out by network operators whose job relates
> to BGP operations. It has a total of 17 questions and should take less 10 minutes
> to answer. The survey and the collected data are anonymous (so please do *not*
> include information that may help to identify you or your organization). 
> All questions are optional, so if you don't like a question or don't know the answer,
> please skip it.
> A summary of the aggregate results will be published as a part of a scientific
> article later this year.
> Thank you so much in advance, and we look forward to read your responses!
> Laurent Vanbever (ETH Zürich, Switzerland)
> PS: It goes without saying that we would be also extremely grateful if you could
> forward this email to any operator you might know who may not read NANOG.

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