Hi all, hi Randy and Alessandro, and thank you for sharing your experience with BGP data collection and ADD-PATH/BMP. I wanted to reopen this thread after a couple of years because we’ve just added BMP support to bgproutes.io <http://bgproutes.io/>. Everything is automated: operators can connect their routers to us via BMP, and the data will be available to the public—either in an MRT archive, through an API, or via a live WebSocket stream. We’ve written a blog post with more details if you’re interested: https://bgproutes.io/blog-bmp. Below is our experience with BMP and our feedback with respect to the points raised by Randy and Alessandro in the previous emails: BMP/ADD-PATH must be used carefully. Users need to know from which peer the data comes, and—if using BMP—at which stage in the router the data is exported (Adj-RIB-In pre/post, Loc-RIB, etc.). The good news is that with BMP we can obtain this information cleanly (it’s more difficult with ADD-PATH). In bgproutes.io <http://bgproutes.io/>, we updated our API to give users fine-grained control over the data they collect: for a BMP session, they can filter on specific peer IPs or the BMP stage (e.g., Adj-RIB-In pre, Loc-RIB, etc.). More generally, this is why we chose BMP over ADD-PATH: BMP provides precise, fine-grained context about what is being exported, whereas, afaik, with ADD-PATH you may see additional/backup paths, but it’s harder to map those paths back to the peer that actually sent them. Another advantage of BMP is access to the Loc-RIB—the output of the BGP decision process—which, afaik, ADD-PATH cannot provide precisely. This can be very helpful; however, operators should be aware that if they export both Adj-RIB-In and Loc-RIB, users may be able to infer routing policies. That may or may not be desirable. On data privacy: I’m not a legal expert, but I agree with Alessandro that what BMP/ADD-PATH export compared to a standard BGP session is essentially a superset; any updates in that superset can end up being the subset actually announced on the BGP session. From that perspective, it seems acceptable. That said, BMP can introduce a practical issue: some routers do not allow per-peer export selection (it’s “all peers or none”). That’s problematic if an operator only wants to share updates from a subset of peers. In bgproutes.io <http://bgproutes.io/>, when operators fill out the onboarding form, they can tell us which peers we should not collect. The data will still reach us, but we exclude and discard those peers immediately. Interoperability challenges: most routers support BMP, but not all—and even among commercial vendors, each tends to do BMP with its own flavor. We couldn’t just implement the RFC literally; we added checks to ensure compatibility across devices. We also observe that many routers cannot export every stage (Adj-RIB-In pre/post, Loc-RIB, Adj-RIB-Out pre/post). Fortunately, it’s usually Adj-RIB-Out pre/post that’s weakly supported—which is less useful for a data-collection platform like bgproutes.io <http://bgproutes.io/> (or RIS/RouteViews). What matters most—Adj-RIB-In pre/post and Loc-RIB—is generally well supported. Detecting feed changes: another challenge with BMP is knowing when an operator changes the exported stages after the session is established. For example, if an operator starts with Adj-RIB-In pre and later switches to Adj-RIB-In post, we’ll correctly receive the new stage, but we won’t automatically know that Adj-RIB-In pre was deactivated. We don’t have a solid solution for this yet; we’ll explore options as we gain more operational experience. Since we’ve just launched this feature, it’s too early to say how people will use the data and how many operators will connect via BMP. We’ll be happy to share a recap once we have more data points. To conclude: if some of you are interested, we’re going to present this at the NLNOG Day (Sept. 30). For now, we’re connected with Randy and Alarig Le Lay (thanks to both!), but if you like this approach and would like to connect with us via BMP, you’re very welcome—all data is publicly available and onboarding is super simple. Cheers, Thomas
On 17 Mar 2023, at 17:51, Alessandro Improta via mat-wg <mat-wg@ripe.net> wrote:
Let's see...
o once a collector commits to ADD-PATH, it's a promise to keep the data forever; well, it's been 26 years of RV and a few less for RIS. - Did operators find the ADD-PATH data sufficiently useful to be worth the cost? How did they use the ADD-PATH data and how often? - Did researchers find the ADD-PATH data sufficiently useful to be worth the cost? How did they use the ADD-PATH data and how often? - Did folk develop special tools to take advantage of ADD-PATH data?
This is hard to answer... I know for sure that a couple of research groups used Isolario data for their studies, in particular researchers at Max Planck Institute where studying ADD-PATH data we collected, but I'm not sure on the final outcome of their research. Also, data was used by Hurricane Electric for their bgp.he.net <http://bgp.he.net/> tool. Besides that, I am not aware of operators that used the data, but I never focused my attention on access logs back in the days.
o On the problem of stream/peer identification. You describe the divergence of BIRD and FRR. What about commercial router vendors?
This may be totally wrong, but I remember that Cisco was not allowing ADDPATH for eBGP. Not sure about other vendors though.
o You say data were often redundant, though not fully. Did you investigate mechanisms to reduce the storage, or did you see that as a path to complexity and fragility merely to save some spinning rust?
We did investigate that. Memory-wise, we studied methodologies to exploit compressing technique such as LZW (see Interactive Collector Engine (ripe.net) <https://ripe75.ripe.net/presentations/21-pres.pdf>). However, the routing engine we devised for route collecting + the amount of RAM we had in the collectors were enough and never required us to turn that feature on. Disk-wise, we found out that xz was a great candidate to replace bz2 and gz as the next compressing methodology for route collecting. I don't remember the results to be honest, but that should be easy to reproduce. However, we decided to not compress data in xz because only bgpscanner was able to read xz data - hence anyone that wanted to use other tools such as bgpdump would not have been able to read them.
o You mention the withdraw storm between your peer and their peer (and later an announcment storm, I presume). For peers with large out-degree, this could be likely. Were these data interesting in any way, or just more storage?
Yes, you presume correct. I honestly didn't find that really useful... A simple "Peer down" message would have been sufficient in those cases to replace the withdrawn storm, while the announcement storm caused by the RIB transfer of peers was inevitable.
again, thanks so much for real experience. gives me a bit more clue.
You're most welcome!
Best Regards,
Alessandro Improta Engineering manager p. +393488077654 e. aimprota@catchpoint.com <mailto:aimprota@catchpoint.com> a. Via Oberdan 53, Pietrasanta (LU) <Outlook-ajnjxisv.png> Learn more about Catchpoint → Watch this 2-minute video! <https://www.catchpoint.com/explainer> <https://www.linkedin.com/company/catchpoint-systems-inc> <https://twitter.com/Catchpoint> <https://www.facebook.com/catchpoint/> <https://www.youtube.com/c/Catchpoint/>
From: Randy Bush <randy@psg.com> Sent: Friday, March 17, 2023 5:15 PM To: Alessandro Improta <aimprota@catchpoint.com> Cc: Measurement Analysis and Tools Working Group <mat-wg@ripe.net> Subject: Re: [mat-wg] some thoughts on add-path and bmp at ripe/ris
alessandro,
real data and experience deeply appreciated. a few questions.
o once a collector commits to ADD-PATH, it's a promise to keep the data forever; well, it's been 26 years of RV and a few less for RIS.
- Did operators find the ADD-PATH data sufficiently useful to be worth the cost? How did they use the ADD-PATH data and how often?
- Did researchers find the ADD-PATH data sufficiently useful to be worth the cost? How did they use the ADD-PATH data and how often?
- Did folk develop special tools to take advantage of ADD-PATH data?
o On the problem of stream/peer identification. You describe the divergence of BIRD and FRR. What about commercial router vendors?
o You say data were often redundant, though not fully. Did you investigate mechanisms to reduce the storage, or did you see that as a path to complexity and fragility merely to save some spinning rust?
o You mention the withdraw storm between your peer and their peer (and later an announcment storm, I presume). For peers with large out-degree, this could be likely. Were these data interesting in any way, or just more storage?
again, thanks so much for real experience. gives me a bit more clue.
randy --
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