Re: [secdir] Secdir review of draft-ietf-mpls-ldp-igp-sync-bcast-04

Sriganesh Kini <sriganesh.kini@ericsson.com> Fri, 01 October 2010 20:09 UTC

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From: Sriganesh Kini <sriganesh.kini@ericsson.com>
To: Tobias Gondrom <tobias.gondrom@gondrom.org>, "iesg@ietf.org" <iesg@ietf.org>, "secdir@ietf.org" <secdir@ietf.org>
Date: Fri, 1 Oct 2010 16:08:20 -0400
Thread-Topic: Secdir review of draft-ietf-mpls-ldp-igp-sync-bcast-04
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Cc: "swallow@cisco.com" <swallow@cisco.com>, Wenhu Lu <wenhu.lu@ericsson.com>, "draft-ietf-mpls-ldp-igp-sync-bcast.all@tools.ietf.org" <draft-ietf-mpls-ldp-igp-sync-bcast.all@tools.ietf.org>, "adrian.farrel@huawei.com" <adrian.farrel@huawei.com>, "martin.vigoureux@alcatel-lucent.com" <martin.vigoureux@alcatel-lucent.com>, "loa@pi.nu" <loa@pi.nu>
Subject: Re: [secdir] Secdir review of draft-ietf-mpls-ldp-igp-sync-bcast-04
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Hello Tobias,

Pls see inline at [Sri].

Thanks

> -----Original Message-----
> From: Tobias Gondrom [mailto:tobias.gondrom@gondrom.org]
> Sent: Monday, September 27, 2010 4:37 AM
> To: iesg@ietf.org; secdir@ietf.org
> Cc: draft-ietf-mpls-ldp-igp-sync-bcast.all@tools.ietf.org;
> Sriganesh Kini; Wenhu Lu; swallow@cisco.com; loa@pi.nu; 
> adrian.farrel@huawei.com; martin.vigoureux@alcatel-lucent.com
> Subject: Secdir review of draft-ietf-mpls-ldp-igp-sync-bcast-04
> 
> 
>  I have reviewed this document as part of the security directorate's 
> ongoing effort to review all IETF documents being processed by the 
> IESG.  These comments were written primarily for the benefit of the 
> security area directors.
> Document editors and WG chairs should treat these comments just like 
> any other last call comments.
> 
> 
> draft-ietf-mpls-ldp-igp-sync-bcast-04
> LDP IGP Synchronization for broadcast networks
> 
> the draft updates RFC 5443 (LDP IGP Synchronization) It basically 
> proposes the following mechanism: "If an interface is not a 'cut-edge'
> then the updating of the LSA with that link to the pseudo-node is 
> postponed until LDP is operational."
> 
> The document states that there would be no security considerations 
> beyond RFC5443.
> I am not certain of that. Although the idea behind bcast is good, it 
> adds a new mechanism beyond 5443.
> To make sure the security considerations are accurate, I'd like to 
> raise two questions for the authors/WG:
> 1. Which security implications does the WG see for removing a coming 
> up link from the LSDB?

[Sri] Since the link is only delayed from being added to the LSDB we don't believe there are any new/additional security implications.

> 2. Can there be a gap between the algorithm to determine "cut-edge" 
> and TTL (e.g. may not qualify for "cut-edge" and thus be removed from 
> LSDB, but have a large number of links and effectively not be 
> reachable)?

[Sri] This problem is not unique to this draft. Even in RFC 5443 when the link has high metric, an alternate path with num hops > 255 (but a lower path metric than the directly connected link's max metric) can result in unreachability.

> 
> and three minor editorial comments:
> - section 3, last paragraph:
> s/Since A's cost to reach B not high/Since A's cost to reach B is not 
> high

[Sri] Accepted

> - Appendix A: Computation of 'cut-edge'
> there should be an informative reference for mentioned "Dijkstra's 
> algorithm"

[Sri] Accepted. Will refer to RFC 2328 sec 16.1

> - abbreviation "SPF" should list the its expanded term (Shortest Path
> First) at first mentioning.

[Sri] Accepted.

> 
> Best regards, Tobias
> 
> 
> 
> 
>