At Tue, 29 Nov 2016 20:23:55 -0500, "John G. Scudder" <j...@juniper.net> wrote: > > On Nov 13, 2016, at 1:40 AM, Alvaro Retana (aretana) > <aret...@cisco.com> wrote: > > C1. The reference to rfc7607 should be Informative. > > Done (in -10 candidate source). > > > C2. [Major] Security Considerations. I think that there is one > > consideration that should be mentioned in this section: Given that > > the largest value is preferred (2 = invalid), there is an attack > > vector where a router in the path (yes, even an internal router) can > > inject a community indicating that the route is invalid; the > > communities are not protected. This action could result in > > inconsistent routing or in even a DoS. I know the document is not > > explicit about what to do with the validation state (which is ok), > > but the clear intention (from rfc6811 and rfc7115) is that it will > > be used to make routing decisions. Please add some text about this > > potential issue. > > I started to write something about this and then realized I don't > understand what you mean. At first I thought you were saying that an > attacker that can forge an OV community can bias route > selection. While this is true of course, it's also not unique to OV > (Localpref has this property for example). It probably wouldn't be > hard to write a sentence to summarize this, if necessary. > > However, you specifically refer to the invalid state: "a router in the > path ... can inject a community indicating that the route is > invalid". This makes me think you think there's something special > about "invalid", and I don't know what it is. You also say something > about the sorting order, which I'm also not sure why that would > matter.
I read this with the implicit: "Of course 'invalid == drop'." So, if between an edge/core nodes you marked the edge -> core prefix stream (mid-stream) with 'invalid' the core may discard all routes seen and so marked. This COULD move traffic away from a single edge node (or nodes) and bias traffic across longer/other paths OR it could isolate folk behind the edge node(s). Of course, just wiping out the prefixes in flight and stitching back together the tcp session... same effect. -chris _______________________________________________ sidr mailing list sidr@ietf.org https://www.ietf.org/mailman/listinfo/sidr
