Subject: [16NG] Precedence of sl/sf indicator?

From: Alexandru Petrescu <[email-masked]>
Date: Sat, 16 Dec 2006 18:29:29 +0100

I think there may be a contention when deciding on the use of stateless
or stateful autoconfiguration mechanisms: sl/sf.

One indicator comes in the Reg-Resp (802.16 MAC message), IEEE 802.16:
"For SS using IPv6, they shall either invoke DHCPv6 [IETF RFC 3315] or
  IPv6 Stateless Address Autoconfiguration [IETF RFC 2462] based on the
  value of a TLV tuple in REG-RSP."

Another indicator is the bit 'M' in the RA itself.

Given that the M is set by a router (presumably AR) and the TLV tuple in
REG-RSP is set by the BS I think there's a risk of inconsistency.

So the question is what should the mobile do if it receives a M=1 in RA
and a TLV tuple (a value I can't find because table 110 doesn't exist,
or contains arq feedback payload format) telling it to do stateless
autoconf.  I think the precedence should be given to the RA contents.

In the two documents, IPv6-over-ETHCS and over IPCS, the precedence is
clearly given to the RA contents, by not talking at all about the
REG-RSP TLV indicator.  On one hand this is good, recommends the good
thing, but on the other hand, being silent about what the IEEE 802.16
MAC says is not good either - underspecification.

So I think this should be made explicit in both drafts, that the RA
contents takes precedence over the REG-RSP contents (with respect to
address autoconf mechanism to use).

What do you think?  Should the RA content take precedence?  Should the
802.16 MAC behaviour be mentioned?  Etc?

Alex

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From: Tim Enos <[email-masked]>
Date: Sun, 17 Dec 2006 02:20:44 -0600 (CST)

Hi Alex/all,

>From: Alexandru Petrescu <[email-masked]>
>Date: 2006/12/16 Sat AM 11:29:29 CST
>To: [email-masked]
>Subject: [16NG] Precedence of sl/sf indicator?

>REG-RSP is set by the BS I think there's a risk of inconsistency.

I can't envision from what other router (besides the AR) the SS would receive an RA, but do think there's a risk of inconsistency.

These I ask not knowing the answers:

Would there be any less risk of the aforementioned inconsistency if the BS and AR were on the same device?

Either way, how does the BS "decide" (sorry about the anthropomorphism) what to set in the Reg-Resp?

>802.16 MAC behaviour be mentioned?  Etc?

I also think the RA content should take precedence insofar as address autoconf is concerned.

>Alex

Best Regards,

Tim Enos
Rom 8:28