BGP Optimizers (Was: Validating possible BGP MITM attack)

Thu May 17 10:14:19 UTC 2018

Hi Job,

I believe your disclaimer makes a lot of sense. From our perspective using more specifics is one of the options to make BGP follow the optimized path instead of the « natural » path. We used to be doing more specifics because with the same prefix being announced, we were simply not getting a best route announced back to the optimiser. Since the adoption of BGP ADD-PATH, our solution does not need to use more specifics to maintain a full collection of the routers BGP table. (In addition, it has actually never been a strong a requirement due to the use of other SNMP collection processes.)
Therefore LOCAL_PREF is the option we advise and implement.

The examples you mention confirm the issues are mainly due to poorly configured networks where routes are leaked out although they shouldn’t be. Adequate routers are able to filter out prefixes based on attributes like communities, which we set by default.
We’ve had an instance of such an issue with one of our customers a few years ago; it turned out to be mistaken CLI commands that the engineer gave to the router.
Our XCA software service and platform has hundreds of ASs running for years and none are making any noise.

Another point of discussion is the fact that transit and large content providers actually accept thousands of routes coming from anywhere, there is a lot of room for optimization. And I know how much you personally try to contribute to enhance this.

There actually is a reason for operating BGP optimizers. The BGP protocol, while robust and scalable, doesn't know anything about link capacity, doesn’t apply performance analytics and can easily drive links into saturation, introducing packet loss. Also, it is not aware of commercial agreements like CDR, generating costs that could be prevented. It also, of course, ignores the performance of available paths.
All of the above actually impacts customer traffic and business performance.
Since a few years we see our Customers take more care of quality and capacity management… and stop relying on BGP « blindly ».

Most transit providers like to explain that their service are premium and that’s the reason why their prices are premium. But when you look at actual performance measurements, some premium providers are actually just behind the cheaper ones.

I’m in RIPE 76 tomorrow, I’ll be more than happy to discuss this topic further with you.

Kind regards,
François

(I’m a product engineer at Border 6 - Expereo, a BGP optimization software company.)

François DEVIENNE
Mobile: +33.651.937.927
E-mail: francois.devienne at expereo.com<mailto:francois.devienne at expereo.com>
BORDER 6 S.A.S. - EXPEREO

On Aug 31, 2017 (35), at 22:06, Job Snijders <job at ntt.net<mailto:job at ntt.net>> wrote:

Dear all,

disclaimer:

   [ The following is targetted at the context where a BGP optimizer
   generates BGP announcement that are ordinarily not seen in the
   Default-Free Zone. The OP indicated they announce a /23, and were
   unpleasantly surprised to see two unauthorized announcements for /24
   more-specifics pop up in their alerting system. No permission was
   granted to create and announce these more-specifics. The AS_PATH
   for those /24 announcements was entirely fabricated. Original thread
   https://mailman.nanog.org/pipermail/nanog/2017-August/092124.html ]

On Thu, Aug 31, 2017 at 11:13:18AM -0700, Andy Litzinger wrote:
Presuming it was a route optimizer and the issue was ongoing, what
would be the suggested course of action?

I strongly recommend to turn off those BGP optimizers, glue the ports
shut, burn the hardware, and salt the grounds on which the BGP optimizer
sales people walked.

It is extremely irresponsible behavior to use software that generates
_fake_ BGP more-specifics for the purpose of traffic engineering. You
simply cannot expect that those more-specifics will never escape into
the global DFZ! Relying on NO_EXPORT is not sufficient: we regularly see
software bugs related to NO_EXPORT, and community-squashing
configuration mistakes happen all the time.

Consider the following: if you leak your own internal more-specifics, at
least you are the legitimate destination. (You may suffer from
suboptimal routing, but it isn't guaranteed downtime.) However if you
generate fake more-specifics for prefixes belonging to OTHER
organisations, you essentially are complicit in BGP hijacking. If those
fake more-specifics accidentally leak into the DFZ, you are bringing
down the actual owner of such prefixes, and depriving people from access
to the Internet. Example case:
https://mailman.nanog.org/pipermail/nanog/2013-January/054846.html

reach out to those 2 AS owners and see if they could stop it?

Yes, absolutely! And if everyone of the affected parties of this
localized hijack leak (or should we say 'victims') reaches out to the
wrongdoers, they contribute peer pressure to rectify the situation. Just
make sure you assign blame to the correct party. :)

Or is it something I just have to live with as a traffic engineering
solution they are using and mark the alerts as false positives?

No, this is not something we should just accept. The Default-Free Zone
is a shared resource. Anyone using "BGP optimizers" is not only risking
their own online presence, but also everyone else's. Using a BGP
optimizer is essentially trading a degree of risk to society for the
purpose of saving a few bucks or milliseconds. It is basically saying:
"The optimizer helps me, but may hurt others, and I am fine with that".

An analogy: We don't want transporters of radioactive material to cut
corners by using non-existant roads to bring the spent nuclear fuels
from A to B faster, nor do we want them to rely on non-robust shielding
that works "most of the time".

We share the BGP DFZ environment, 'BGP optimizers' are downright
pollution contributors.

Kind regards,

Job

ps. If you want to do BGP optimization: don't have the BGP optimizer
generate fake BGP announcements, but focus only on manipulating
non-transitive attributes (like LOCAL_PREF) on real announcements you
actually received from others. Or Perhaps BGP optimizers shouldn't even
talk BGP but rather push freshly generated TE-optimized routing-policy
to your edge boxes. Or perhaps the 'BGP optimizer' vendors should come
to IETF to figure out a safe way (maybe a new AFI/SAFI to manipulate
real announcements)... there are ways to do this, without risk to others!

p.s. providing a publicly available BGP looking glasses will contribute
to proving your innocence in cases like these. Since in many cases the
AS_PATH is a complete fabrication, we need to manually check every AS in
the AS_PATH to see whether the AS carries the fake more-specific. A
public looking glass speeds up this fault-finding process. If you don't
want to host a webinterface yourself, please consider sending a BGP feed
to the Route Views Project or RIPE RIS, or for something queryable in a
real-time fashion the NLNOG RING Looking Glass http://lg.ring.nlnog.net/