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Genart Telechat review: draft-ietf-pcp-anycast-07

2015-09-14 15:09:38
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Document: draft-ietf-pcp-anycast-07
Reviewer: Robert Sparks
Review Date: 14 Sep 2015
IETF LC End Date: past
IESG Telechat date: 17 Sep 2015

Summary: On the right track, but has issues that should be discussed

I can't find any response to the LC review provided below. Apologies if I'm just failing to find or remember a thread...

Reviewing the diff between -06 and -07, I see some text in the introduction that touches point 1. I think, however, it would be good to have something more strongly

There's also new text in 5.2 that looks like it's targeting point 4, and I think it's sufficient.

The other points do not appear to be addressed.


On 6/4/15 2:20 PM, Robert Sparks wrote:
I am the assigned Gen-ART reviewer for this draft. For background on
Gen-ART, please see the FAQ at


Please resolve these comments along with any other Last Call comments
you may receive.

Document: draft-ietf-pcp-anycast-06
Reviewer: Robert Sparks
Review Date: 04Jun15
IETF LC End Date: 11Jun15
IESG Telechat date: Not yet scheduled

Summary: On the right track, but has issues that should be discussed

This draft reads easily, but there are a few things that might need more attention. It could be that these have been beaten to death already, but if so, it would be better if the document gave pointers to places where others with the questions wouldn't be left wondering.


1) The document recommends hard-coding these addresses into applications. In the spirit (at least) of BCP 105 (RFC4085), shouldn't the recommendation be more "have their configuration set by default to this well known value"?

2) Section 3 punts on some really hard things that deserve more discussion in this document, or this document should point to a good discussion elsewhere. It's fine that the document doesn't solve the synchronization or coordination problems it hints at, but it should make it more clear that these problems will exist, and are important to consider when deploying a new node that joins this anycast address. In particular, without careful synchronization and coordination, applications like VoIP using PCP controlled resources will be disrupted. The current text really does not convey that message.

3) Aren't there some new security issues with just having the well-known address? At a minimum, it's an attractive target, and the guidance in 18.3.1 of RFC6887 may be particularly relevant. More subtly, would it make it easier to construct packets that look enough like PCP to be disruptive to send from compromised nodes participating in a DDos Attack from inside an administrative domain? Would it make it easier for an attacker that has partially compromised a host influence the firewall between him and that host, making finishing the compromise even easier? (Especially compared to a PCP server that was configured at the client that wasn't just the default router).

4) It would help to expand on the 3rd paragraph of section 5.2. In very simple scenarios (like having a home router start responding to this address), it's easy to see the tradeoffs between automatic configuration and securing the pcp commands. But it would help if the document talked through the consequences of not using pcp-authentication in more complex environments (using something like a departmentalized university, or several distinct administrative domains behind a common CGN as an example perhaps?)

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