Hello, Everyone!
Many SFP agreements include terms that the peering link will not be used as
an upstream with static defaults. A few examples are provided below.
*h. must agree not to abuse the peering relationship by engaging in
activities such as but not limited to: pointing a default route at the
other or otherwise forwarding traffic for destinations not explicitly
advertised, resetting next-hop, selling or giving next-hop to others;*
Source: http://www.level3.com/en/legal/ip-traffic-exchange-policy/
*2.6. Neither Network shall point default into or transit the other Network
where that network has*
*not advertised a route for the destination in question.*
Source: http://www.zayo.com/wp-content/uploads/2017/02/ZayoPeeringPolicy.pdf
How is this monitored and tracked? Are ACLs applied to help enforce this
(seems to be limited at scale)? Flow export and alarming? Analytics and
anomalous behavior detection? Common professional courtesy?
Thanks so much for any insight you may have. I'd like to ensure I'm
following all best practices when in IX and peer situations.
-Raymond Beaudoin
Dear Raymond,
How is this monitored and tracked? Are ACLs applied to help enforce this
(seems to be limited at scale)? Flow export and alarming? Analytics and
anomalous behavior detection? Common professional courtesy?
This RFC RFC 7789 - Impact of BGP Filtering on Inter-Domain Routing Policies covers the topic of
“unexpected traffic flows” which is essentially the same as having default
being pointed at you without you permission. May be worth reading!
A most scalable option is to use a flow collection / monitoring program
like pmacct (http://pmacct.net/) to inspect flows and flag the ones that
shouldn’t exist according to your policy. Paolo Lucente has done excellent
work to make this problem space manageable:
http://wiki.pmacct.net/DetectingRoutingViolations
Also, if you are at an internet exchange, make sure to enable MAC
accounting (if available) on the IX facing interface, so you can easily
monitor for traffic coming from MAC addresses with which you don’t have a
BGP session.
Kind regards,
Job
Job,
Thanks so much for the helpful information, especially the RFC. This is
exactly what I was looking for. Have a fantastic week!
Warm Regards,
Raymond Beaudoin