Re: [secdir] review of draft-ietf-isis-bfd-tlv-02

[Sam Hartman <[e-mail]>]

>>>>> "Stephen" == Stephen Kent <[e-mail]> writes:

    Stephen> The Security Considerations section is just one paragraph,
    Stephen> which states that the addition of this feature does not
    Stephen> adversely affect the security mechanism (sic) of IS-IS. I'm
    Stephen> not questioning this assertion, based on reading this
    Stephen> document, but I think a couple of additional sentences are
    Stephen> needed here, to justify the assertion.


How about something like: This TLV does not adversely affect the
security of IS-Is. The primary consequence of using the BFD mechanism in
a case where it is not supported is incorrectly detecting a false
failure of bidirectional forwarding.  The primary consequence of not
using BFD when BFD is supported is failure to detect situations in which
bidirectional forwarding is not happening on a link. At worst, this
leads to a denial of service condition. However, a party who can
manipulate the contents of this TLV is already in a position to create
such a denial of service by disrupting IS-IS routing.

If the above paragraph is correct, I think it may go some distance to
addressing Stephen's concern.

However, I wonder how the authentication mechanisms of BFD interact with
the authentication mechanisms of IS-IS? Is it possible to get into a
situation where IS-IS is authenticated but BFD is not?  If so, that
should be discussed in the security considerations section.

--Sam