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

Robert Sparks <> Mon, 14 September 2015 20:09 UTC

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Subject: Genart Telechat review: draft-ietf-pcp-anycast-07
To: General Area Review Team <>,, "" <>,, Brian Haberman <>
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From: Robert Sparks <>
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Date: Mon, 14 Sep 2015 15:09:00 -0500
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I am the assigned Gen-ART reviewer for this draft. The General Area
Review Team (Gen-ART) reviews all IETF documents being processed
by the IESG for the IETF Chair. Please wait for direction from your
document shepherd or AD before posting a new version of the draft.

For more information, please see the FAQ at


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.
> Issues:
> 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?)