Changes in version 8 resulting from comments in: Re: teardown of the ULID-pair context

[marcelo bagnulo braun <marcelo@it.uc3m.es>]

El 12/12/2006, a las 14:47, Matthijs Mekking escribió:

> Hi,
>
> I have a question about the teardown of the ULID-pair context. In
> chapter 9, the proto6 draft says "A reasonable approach would be not to
> tear down a context until at least 5 minutes have passed since the last
> message was sent or received using the context." Does this include
> messages that do not contain a shim6 extension header? My opinion is 
> yes:
>
> If there is a context on host A for host B, this means that both are
> multihomed. They should enjoy the goals of multihoming, such as
> failover. However, the communication between A and B initially uses the
> ULID address pair. Therefore, the IPv6 address fields do not need to be
> replaced by a different locator pair, and the message is not tagged 
> with
> a shim6 extension header. In other words, the context is not being used
> at the moment. This means that if after 5 minutes there was no context
> switch, the context states may be teared down again. If shortly after
> this the link corresponding to the ULID pair fails, the hosts are not
> able to do failover anymore.
>
> So, shim unaware payloads (traffic not using the context) should also 
> be
> observed. I suggest that the text 'using the context' in chapter 9 will
> be removed.

I have added the  following note on this section:

 (Note that
packets that use the ULID pair as locator pair and that do not require
address rewriting by the Shim6 layer are also considered as packets
using the associated Shim6 context)

> In order to observer shim unaware payloads, the shim6 layer should look
> up a context for these kind of messages. Chapter 11 already defines how
> this should be done for sending ULP payloads. For receiving packets
> (chapter 12), this information is missing. I suggest there should be a
> section before 12.1 receiving payload extension headers:
>
> 12.x Receiving payload without extension headers
>
> The receiver extracts the IPv6 source and destination fields, and uses
> this to find a ULID-pair context, such that the IPv6 address fields
> match the ULID(local) and ULID(peer). If such a context is found, the
> context appears not to be quiescent and this should be remembered. The
> host continues with proceeding the message.

I have added this section with some few changes

the final text is the following

<section title="Receiving payload without extension headers">

<t>The receiver extracts the IPv6 source and destination fields, and 
uses
this to find a ULID-pair context, such that the IPv6 address fields
match the ULID(local) and ULID(peer). If such a context is found, the
context appears not to be quiescent and this should be remembered in 
order to
avoid tearing down the context and for reachability detection porpuses 
as described in
<xref target="I-D.ietf-shim6-failure-detection"/>.
The host continues with the normal processing of the IP packet.
</t>
</section>


thanks for the comments
regards, marcelo


> With regards,
>
> Matthijs Mekking
> matthijs@NLnetLabs.nl
> NLnetLabs/Radboud University