Subject: Re: [savi] Links with both SAVI-capable and legacy switches

From: Christian Vogt <[email-masked]>
Date: Fri, 13 Feb 2009 19:43:51 -0800

[Forked from thread "Binding establishment based on data or control  
packets?"]

On Feb 3, 2009, Guang Yao wrote:

> Maybe you are considering the partial deployment, and there can be
> spoofing from local nodes. This is a problem. If we specify that the
> mechanism should work when partially deployed, many things should be
> re-considered.

Guang -

If I understand you correctly, then what you mean by "partial  
deployment"
is a link with multiple switches, some of which are SAVI-capable, some  
of
which are legacy.

Why do you think such a scenario would be problematic?  Assuming that
SAVI devices allow multiple source addresses per port, then it should be
possible for a port to extent to a link segment with legacy switches and
multiple hosts.

Am I missing something?

- Christian

---

From: Christian Vogt <[email-masked]>
Date: Fri, 13 Feb 2009 20:25:24 -0800

Guang Yao wrote:

> Many kinds of attacks can be designed in this situation. For instance,
> send spoofing NA to prevent other hosts behind SAVI devices to get
> stateless addresses.

I don't agree.  The attack you mention is impossible if SAVI devices
drop NA packets for which the target address has no corresponding
binding -- as I described in an earlier email.  It is irrelevant whether
the attacker is the only node on its SAVI switch port, or whether the
attacker is on a link segment that connects to a SAVI switch port via
legacy switches.

- Christian