Re: Benjamin Kaduk's No Objection on draft-ietf-rtgwg-enterprise-pa-multihoming-08: (with COMMENT)

[Benjamin Kaduk <[e-mail]>]

On Thu, Jul 04, 2019 at 10:42:35AM +1000, Jen Linkova wrote:
> Hi Ben,
> 
> I've just submitted -10 version which has Chris's changes integrated
> as well as all suggestions you made.
> 
> The diff:
> https://www.ietf.org/rfcdiff?url2=draft-ietf-rtgwg-enterprise-pa-multihoming-10
> 
> Full text:
> https://tools.ietf.org/html/draft-ietf-rtgwg-enterprise-pa-multihoming-10
> 
> A few comments below:
> 
> On Thu, Jul 4, 2019 at 6:12 AM Benjamin Kaduk <[e-mail]> wrote:
> > > > >    To fully benefit from the RA-based solution, first-hop routers need
> > > > >    to implement SADR and be able to send dedicated RAs per scoped
> > > > >
> > > > > It's not just the first-hop routers, though -- won't all the first-hops
> > > > > need to be part of the same connected SADR domain?
> > > >
> > > > They are. By design/definition.
> >
> > Perhaps I'm still confused, but I thought other parts of this document
> > admitted the possibility of having multiple SADR-capable routers that are
> > not all in a connected domain, if only to say "don't do that".  For
> > example, all the  SERs need to be in the same domain.  But if I look at,
> > e.g., Figure 1's topology, R3 would be a first-hop router for H41, and if I
> > read the quoted text literally, having R3 and the SERs support SADR but not
> > R5 would seem to produce a disconnected domain and thus problems.
> 
> That's why we are saying:
> "Therefore all SADR-capable routers within the domain MUST be
> logically connected."
> Having R3 and SERs in the SADR domain with non-SADR capable R5 between
> them might lead to a routing loop.
> 
> The changes made in -10 to clarify this:
> 1) Replaced:
> "To fully benefit from the RA-based solution, first-hop routers need
> to implement SADR and be able to send dedicated RAs per scoped
> forwarding table as discussed above,"
> 
> with
> "To fully benefit from the RA-based solution, first-hop routers need
> to implement SADR, belong to the SADR domain and be able to send
> dedicated RAs per scoped forwarding table as discussed above.."
> 
> 2) Added another item to the Deployment Considerations section:
> https://tools.ietf.org/html/draft-ietf-rtgwg-enterprise-pa-multihoming-10#section-7.1
> "During the incremental SADR domain expansion from the SERs down
> towards first-hop routers it's important to ensure that at any
> moment of time all SADR-capable routers within the domain are
> logically connected (see Section 5)."
> 
> Is it less confusing now?

Greatly so; thank you!

> > That's one type of attack, yes.  I think there may be another one where the
> > attacker has some wiretap in ISP_A but not ISP_B, and they can use the
> > ICMPv6 message to tell the sender to use the source address from ISP_A when
> > traffic would otherwise go to ISP_B or elsewhere -- the forged message
> > causes the traffic to be routed where the attacker can do other things to
> > it.
> >
> > > > I think that if such messages are required to be sent from the
> > > > link-local address and the GTSM is enforced, then the attack vector is
> > > > limited to the same L2 domain which is a bit better..I'll add the text
> > > > to clarify it tomorrow.
> 
> After thinking about it I've realized that GTSM would not help here.
> Those messages could be sent from SERs (which are a few hops away).
> I've moved all security considerations from that section to Section 10:
> https://tools.ietf.org/html/draft-ietf-rtgwg-enterprise-pa-multihoming-10#section-10
> 
> Please let me know if you have any comments for -10 version.

It looks good here (just one typo "tra ffic" that may be my fault anyway).

Thanks again,

Ben