Re: [trill] Suresh Krishnan's Discuss on draft-ietf-trill-arp-optimization-06: (with DISCUSS and COMMENT)

[Suresh Krishnan <[e-mail]>]

Hi Donald,
   Your proposed changes look good to me. I will clear once the new version 
gets posted with the changes,

Thanks
Suresh

On 07/07/2016 10:04 AM, Donald Eastlake wrote:
> Hi Suresh,
>
> Thanks for your insightful comments. See below.
>
> On Wed, Jul 6, 2016 at 12:36 AM, Suresh Krishnan
> <[e-mail]> wrote:
>> Suresh Krishnan has entered the following ballot position for
>> draft-ietf-trill-arp-optimization-06: Discuss
>>
>> ...
>>
>> ----------------------------------------------------------------------
>> DISCUSS:
>> ----------------------------------------------------------------------
>>
>> * After the ingress RBridge learns the mapping between an IPv6 address
>> and a MAC address how is the liveness being tested/maintained? i.e. If a
>> "learnt" target IP goes off link and the Rbridge keeps responding to NS
>> messages wouldn't it make troubleshooting a nightmare?
>
> There needs to be appropriate liveness determination. There are a lot
> of ways this could be done but rather than going into this here, I
> think that a section should be added to the document on this topic.
> (Exactly what would happen if and IPv6 end station crashed or got
> disconnected would depend on many factors. In some cases the edge
> RBridge would know right away if it was a point-to-point link that
> went down. But optimized ARP/NS responses should stop not long after
> the end station becomes non-responsive to ARP/NS messages it receives
> directly.)
>
>> * Section 3.2 case a): There is no guidance as to why or when an Rbridge
>> would pick cases a1..a5. e.g. When a SEND NS is received only option a2
>> can work and all others will fail.
>
> Yes, the restrictions on SEND should be noted. Otherwise, the choice
> is a matter of local policy.
>
>> * Section 3.2 case a.1): What should be the source IPv6 address of the NA
>> generated by the ingress RBridge? Will this be an address of the target
>> of the NS or one of the ingress Rbridge that responds?
>
> There is no requirement in the TRILL protocol that an RBridge have
> either an IPv4 or IPv6 address (although as a practical matter, they
> probably almost always do). So the source IPv6 address should be that
> of the target.
>
>> * Section 3.2: How is an ND message where the target IP is not known
>> handled? This case seems to be left out.
>
> If the target IP is "unknown", then generally you would flood based on
> the destination MAC within the VLAN/Label of the traffic but if you
> were in an environment with complete directory information and you
> know that IP did not exist, I think you could just discard the message.
>
>> ----------------------------------------------------------------------
>> COMMENT:
>> ----------------------------------------------------------------------
>>
>> * The draft contains no discussion of SEND (RFC3971) in the Security
>> considerations section when talking about forged ND messages.
>
> Yes, I think that should be mentioned.
>
> Thanks,
> Donald
> ===============================
>   Donald E. Eastlake 3rd   [phone] (cell)
>   155 Beaver Street, Milford, MA 01757 USA
>   [e-mail]
>