Hi, Ian and All,
Thanks for your mail. I believe the DMR should contain the prefix and
prefix-length (the CIDR style), then the encapsulation mode MAP-E, lw4o6
and DS-lite will have /128; the translation mode MAP-T will have /64,
the 464xlat will have /96. This is also fully compatible with RFC6052
with prefix lengths of /32, /40,/48, /56, /64 and /96. The MAP-DHCP
specification is using this method and it works in our testing environment.
Regards,
xing
[email protected] 写道:
Hi,
Sorry to dig this one up again, but although there has been a fair bit
of discussion around the topic, I don't think that we have so far
reached an agreement on how to provision sw CPEs with the address of
the concentrator for MAP-E and lw4o6. We need to get a final answer on
this as there's a few drafts (softwire-unified-cpe, softwire-map-dhcp,
softwire-lw4over6) that are relying on it.
To try and summarise what's already out there:
The Unified CPE & lw4o6 drafts propose the use of DHCPv6 Option 64
(the DS-Lite AFTR FQDN option)
Map-dhcp describes the use of the default mapping rule (DMR) to
provide the /128 of the BR
I think that it's reasonable to say that both work – I.e. They contain
enough information to provision the client with the /128 of the
concentrator so that it can send traffic.
Here are the arguments for/against each that I've seen. I've tried to
list all the ones that I've seen, so if I've missed any, then please
add them:
DHCPv6 Option 64
Pros
FQDN means that DNS round-robin load balancing could be used
Reuse of an existing option
Cons
Can not be extended with additional sub-options
map-dhcp DMR
Pros
Option has an 'encapsulated options' field, so could be extended with
additional functionality (although no additional functionality has
currently been proposed at this stage)
Cons
Only one DMR /128 can be provisioned to a client, so round robin load
balancing can't be used
May conflict with the MAP-T (</128 prefix) DMR – Could be considered
to be out of scope for this discussion, but if we are following the
mechanisms described in Unified CPE so that a CPE can work out which
SW mode to configure, then a dedicated MAP-T sub-option (not shared by
any other mode) is needed. This is related to conversations that I've
had around extending the Unified CPE model for other softwire approaches.
My view: If there is additional functionality required in this option,
over an above the provisioning of a /128 prefix for the concentrator,
then the MAP DMR (limited to MAP-E) is the clear choice. However, if
no such functionality is needed, then we should re-use Option 64.
Cheers,
Ian
------------------------------------------------------------------------
_______________________________________________
Softwires mailing list
[email protected]
https://www.ietf.org/mailman/listinfo/softwires
_______________________________________________
Softwires mailing list
[email protected]
https://www.ietf.org/mailman/listinfo/softwires
