Re: [16NG] DAD in IEEE802.16

[Alexandru Petrescu <[e-mail]>]

Tjandra Paula-CPT015 wrote:
> Is it a requirement to assign unique prefix per MS in WiMAX? 
> <draft-ietf-16ng-ipv6-over-ipv6cs> seems to imply that it is. 
> Assuming that the MS/host has a unique prefix, why would the MS/host
>  need to perform DAD?

In case prefix-per-MN is used, and IPv6 CS is used, I think the only
collision that needs to be avoided by DAD on a point-to-point link is
with the IPv6 address the Base Station configures on its connection end
(because both "points" MS and BS need to use the same prefix, even if
it's called prefix-per-MN).

But, avoiding that collision can happen in three other than DAD ways:
(1) relying on uniqueness of IEEE assigned MAC addresses, (2)
negotiation during 802.16 network-entry of the MAC address potential
collision and (3) negotiation of the ID during a potential IPv6 ppp phase.

Alex

> 
> Regards, Paula. 
> ------------------------------------------------------------------------
>  *From:* Behcet Sarikaya [mailto:[e-mail]] *Sent:*
> Thursday, May 03, 2007 4:48 PM *To:* gabriel montenegro *Cc:*
> [e-mail] *Subject:* Re: [16NG] DAD in IEEE802.16
> 
> Gabriel, Let's take RFC3314. It says:
> 
> DAD is not performed, as the GGSN will not assign the same address to
> multiple nodes.
> 
> 
> So the context is important. Of course I agree with the above
> sentence, but in other contexts, DAD is needed.
> 
> Regards,
> 
> Behcet ----- Original Message ---- From: gabriel montenegro
> <[e-mail]> To: Behcet Sarikaya
> <[e-mail]> Cc: [e-mail] Sent: Thursday, May 3, 2007
> 4:17:37 PM Subject: Re: [16NG] DAD in IEEE802.16
> 
> Behcet said: "I don't think we can say that DAD is not needed."
> 
> This is what the documents I refer to below *already* say is fine
> under certain conditions. I believe those same conditions are likely
> to be generally satisfied in networks beyond those being explicitly
> mentioned in those documents (e.g., wimax).
> 
> If you want those documents to not say it may be ok to forgo DAD,
> then it's too late for the RFCs, but perhaps you can still argue it
> for the "IP Version 6 over PPP", but better hurry as it is in IESG
> right now. I happen to think that what it says is correct.
> 
> -gabriel
> 
> ----- Original Message ---- From: Behcet Sarikaya
> <[e-mail]> To: gabriel montenegro
> <[e-mail]> Cc: [e-mail] Sent: Thursday,
> May 3, 2007 11:45:33 AM Subject: Re: [16NG] DAD in IEEE802.16
> 
> Isn't DAD recommended even on p2p links? You are generating an
> address from either your MAC address or using some random numbers,
> you can not avoid a collision 100%. I heard that Vista generates a
> new IPv6 address every hour. I don't think we can say that DAD is not
> needed.
> 
> --behcet
> 
> ----- Original Message ---- From: gabriel montenegro
> <[e-mail]> To: Syam Madanapalli
> <[e-mail]>om>; Frank Xia <[e-mail]> Cc:
> [e-mail] Sent: Thursday, May 3, 2007 12:00:04 PM Subject: Re:
> [16NG] DAD in IEEE802.16
> 
> I really don't think it makes sense to consider END, a non-standard,
> for such a minor issue, which might actually be a non-issue. DAD
> itself may not be even needed, as mentioned by Syam already. This 
> point is mentioned informationally in the DAD discussions in:
> 
> Recommendations for IPv6 in Third Generation Partnership Project 
> (3GPP) Standards http://tools.ietf.org/html/rfc3314
> 
> Internet Protocol Version 6 (IPv6) for Some Second and Third 
> Generation Cellular Hosts http://tools.ietf.org/html/rfc3316
> 
> and normatively in section 5 of:
> 
> IP Version 6 over PPP 
> http://tools.ietf.org/html/draft-ietf-ipv6-over-ppp-v2-02
> 
> which is currently in IESG processing. Even though the above docs
> don't spell out w-i-m-a-x, the link characteristics from the point of
>  addressing are similar enough that the same considerations can
> apply.
> 
> -gabriel
> 
> ----- Original Message ---- From: Syam Madanapalli
> <[e-mail]> To: Frank Xia <[e-mail]> Cc:
> [e-mail] Sent: Thursday, May 3, 2007 8:38:59 AM Subject: Re:
> [16NG] DAD in IEEE802.16
> 
> Hi Frank,
> 
> 
> On 5/3/07, *Frank Xia* <[e-mail] 
> <mailto:[e-mail]>> wrote:
> 
>  Hi Syam
> 
> Even in ODAD, there is a normal DAD procedure in parallel. END is to
> improve normal DAD, not ODAD. END can co-work with ODAD well.
> 
> 
> 
> I see no reason to use ODAD along with END. END might have had better
> position if it were proposed before ODAD :-)
> 
> 
> 
> Any way, just as you said, is it useful enough to modify the router?
> 
> 
> 
> Yep, if we can answer this, then we will be in better position to 
> support this proposal.
> 
> 
> I don't know, but I think that any feasible improvement can be 
> considered.
> 
> 
> 
> I agree.
> 
> Thanks, Syam
> 
> 
> BR Frank
> 
> ----- Original Message ----- *From:* Syam Madanapalli
> <mailto:[e-mail]> *To:* Behcet Sarikaya
> <mailto:[e-mail]> *Cc:* [e-mail] <mailto:[e-mail]>
>  *Sent:* Thursday, May 03, 2007 2:18 AM *Subject:* Re: [16NG] DAD in
> IEEE802.16
> 
> 
> Hi Bachet,
> 
> Doing things deterministically is always good. But here I am
> wondering if it is worth the implementation changes on the routers as
> well as on hosts, especially on p2p links where the chance of
> collission is very very remote as the p2p link will be using just two
> addresses out of 2 ^64.
> 
> Assign unique prefix using prefix delegation for each host or
> configuring the router not to construct the IPv6 address using the
> advertised prefix in case the router advertises the prefix along with
> the ODAD may solve the problem completely, I think.
> 
> 
> Thanks, Syam
> 
> 
> On 5/3/07, *Behcet Sarikaya* <[e-mail] 
> <mailto:[e-mail]>> wrote:
> 
> Syam, isn't it better to make it deterministic in p2p links where you
> have an authoritative address cache?
> 
> --behcet
> 
> 
> ----- Original Message ---- From: Syam Madanapalli <
> [e-mail] <mailto:[e-mail]>> To: Frank Xia
> <[e-mail] <mailto:[e-mail]>> Cc: 김상언 <
> [e-mail] <mailto:[e-mail]>>; [e-mail] 
> <mailto:[e-mail]> Sent: Wednesday, May 2, 2007 1:02:35 PM 
> Subject: Re: [16NG] DAD in IEEE802.16
> 
> Hi Frank,
> 
> I understand the proposed END mechanism is more deterministic,
> however it comes at a cost: router modification and availability of 
> authoritative address cache.
> 
> And personally I do not like the RA as a response to DAD NS to tell
> the host that the address is unique, and at NA cannot be used as it
> will not be interoperable with unmodified hosts which will treat that
> the address is duplicate.
> 
> IEEE 802.16 based hosts would have the unique MAC address, so ODAD
> would work well I think.
> 
> Thanks, Syam
> 
> 
> On 5/2/07, *Frank Xia* <[e-mail] 
> <mailto:[e-mail]>> wrote:
> 
> Hi Syam
> 
> END can work together with  Optimistic DAD, and some of the
> description in our draft is " If END and [OPTDAD] are enabled, the SS
> will benefit from both the reliability and time advantages. "
> 
> Any way , there are some constraints for Optimistic DAD, please refer
> to the words form RFC4429: * Optimistic DAD SHOULD only be used when
> the implementation is aware that the address is based on a most
> likely unique interface identifier (such as in [RFC2464]), generated 
> randomly [RFC3041], or by a well-distributed hash function [RFC3972] 
> or assigned by Dynamic Host Configuration Protocol for IPv6 (DHCPv6)
> [RFC3315]. Optimistic DAD SHOULD NOT be used for manually entered 
> addresses."
> 
> BR Frank
> 
> ----- Original Message ----- *From:* Syam Madanapalli 
> <mailto:[e-mail]> *To:* Frank Xia
> <mailto:[e-mail]> *Cc:* Daniel Park
> <mailto:[e-mail]> ; 김상언
> <mailto:[e-mail]> ; [e-mail] <mailto:[e-mail]>
>  *Sent:* Wednesday, May 02, 2007 12:22 PM *Subject:* Re: [16NG] DAD
> in IEEE802.16
> 
> 
> 
> Hi Frank and Sangeon,
> 
> How about using Optimistic DAD (RFC 4429) to minimize the delay?
> 
> Thanks, Syam
> 
> 
> On 5/2/07, *Frank Xia* < [e-mail] 
> <mailto:[e-mail]>> wrote:
> 
> Hi Deniel and Sangeon
> 
> A  solution is proposed in the END draft and it applies to p2p link
> model as well.
> 
> http://tools.ietf.org/wg/16ng/draft-xia-16ng-end-01.txt 
> <http://tools.ietf.org/wg/16ng/draft-xia-16ng-end-01.txt+>
> 
> Comments are welcomed.
> 
> BR Frank
> 
> 
> 
> 
> 
> ----- Original Message ----- *From:* Daniel Park 
> <mailto:[e-mail]> *To:* '源�?곸뼵' 
> <mailto:[e-mail]> ; [e-mail] <mailto:[e-mail]>
>  *Sent:* Tuesday, May 01, 2007 6:39 PM *Subject:* [16NG] DAD in
> IEEE802.16
> 
> 
> [Trimming the list and subject]
> 
> Sangeon,
> 
> IPv6 subnet model document was gone. Its status is in RFC Queue. If
> you have any concern regarding IPv6 DAD, it may take place in IPv6CS
> or EthernetCS document in my sense. Can you elaborate on your concern
> more specific ?
> 
> -- Daniel Park
> 
> 
> 
> *From:* 源�?곸뼵 [mailto:[e-mail] 
> <mailto:[e-mail]>]
> 
> *Sent:* Monday, April 30, 2007 11:14 PM *To:* [e-mail]
> <mailto:[e-mail]> *Cc: *[e-mail] <mailto:[e-mail]>; 
> [e-mail] <mailto:[e-mail]> 
> *Subject:* Re: 16NG Digest, Vol 5, Issue 22
> 
> 
> Hi all,
> 
> The one of the important thing in IEEE802.16 is missed. RFC 2462
> specifies autoconfiguration in wired-based IPv6 Internet. It did not 
> specify configuration time. To use RFC 2462 specfication in 
> IEEE802.16e network, it is required faster procedure than current DAD
> procedure. Has anyone can tell the DAD processing time?
> 
> If the IEEE 802.16 network will consume more than one seconds to
> handover at IP layer, Does it practical?
> 
> So, I would like to propose to add some technical resolution for
> section 3.1.3 and 3.3.3.
> 
> regards,
> 
> 
> 2007/4/28, [e-mail] <mailto:[e-mail]> < 
> [e-mail] <mailto:[e-mail]>>:
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> Today's Topics:
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> 1.  Document Action: 'Analysis of IPv6 Link Models for   802.16 based
> Networks' to Informational RFC  (The IESG)
> 
> 
> ----------------------------------------------------------------------
> 
> 
> Message: 1 Date: Fri, 27 Apr 2007 11:30:34 -0400 From: The IESG < 
> [e-mail] <mailto:[e-mail]>> Subject:
> [16NG] Document Action: 'Analysis of IPv6 Link Models for 802.16
> based Networks' to Informational RFC To: IETF-Announce < 
> [e-mail] <mailto:[e-mail]>> Cc: Internet
> Architecture Board <[e-mail] <mailto:[e-mail]>>,  16ng mailing 
> list < [e-mail] <mailto:[e-mail]>>, 16ng chair <
> [e-mail] <mailto:[e-mail]>>,
>  RFC Editor <[e-mail] 
> <mailto:[e-mail]>> Message-ID: < 
> [e-mail] 
> <mailto:[e-mail]>>
> 
> The IESG has approved the following document:
> 
> - 'Analysis of IPv6 Link Models for 802.16 based Networks ' 
> <draft-ietf-16ng-ipv6-link-model-analysis-03.txt
>> as an Informational RFC
> 
> This document is the product of the IP over IEEE 802.16 Networks
> Working Group.
> 
> The IESG contact persons are Jari Arkko and Mark Townsley.
> 
> A URL of this Internet-Draft is: 
> http://www.ietf.org/internet-drafts/draft-ietf-16ng-ipv6-link-model-analysis-03.txt
>  
> <http://www.ietf.org/internet-drafts/draft-ietf-16ng-ipv6-link-model-analysis-03.txt>
> 
> 
> Technical Summary
> 
> This document provides different IPv6 link models that are suitable 
> for 802.16 based networks and provides analysis of various 
> considerations for each link model and the applicability of each link
>  model under different deployment scenarios.
> 
> Working Group Summary
> 
> This document is result of a Design Team that was formed to analyze
> the IPv6 link models for 802.16 based networks. Based on the
> recommendations of the design team and this document, the working
> group has chosen the unique-prefix-per- link/mn model over the
> previously assumed shared prefix model. The new model is in use in 
> the IPv6 over 802.16 IPCS document 
> (draft-ietf-16ng-ipv6-over-ipv6cs), and has also been adopted by the
> Wimax Forum.
> 
> Protocol Quality
> 
> Jari Arkko has revied this document for the IESG.
> 
> Note to RFC Editor
> 
> Please insert "IEEE" in front of references to 802.16 or other IEEE
> specification numbers throughout the document, including the title.
> 
> Please expand "MS" to "MS (Mobile Station)" on first occurence in
> Section 1. Similarly, expand "BS" to "BS (Base Station)". And later
> in the document, "CS" to "CS (Convergence Sublayer)".
> 
> Please expand "MLD" to "MLD (Multicast Listener Discovery)" in
> Section 3.1.3.
> 
> Please add the following informative reference:
> 
> [WiMAXArch] "WiMAX End-to-End Network Systems Architecture
> 
> http://www.wimaxforum.org/technology/documents"quot;, August 2006.
> 
> and refer to that from Section 1, 2nd paragraph, 1st sentence.
> 
> In Section 3.1, change "on per MS basis" to "on a per MS basis".
> 
> Also in Section 3.1, paragraph 1: change "does not any multicast" to
> "does not provide any multicast". And change "illustrates high" to
> "illustrate a". Finally, change "one more" to "one or more".
> 
> Change the section titles (3 instances) that say "Reuse of Existing
> Standards" to "Reuse of Existing Specifications".
> 
> Replace the text in the Security Considerations section with the
> following:
> 
> This document provides the analysis of various IPv6 link models for 
> IEEE 802.16 based networks and this document as such does not 
> introduce any new security threats. No matter what the link model is,
> the networks employ the same link-layer security mechanisms defined
> in [5]. However, the chosen link model affects the scope of link
> local communication, and this may have security implications for
> protocols that are designed to work within the link scope. This is
> the concern for shared link model compared other models wherein 
> private resources e.g. personal printer cannot be put onto a public 
> WiMAX network. This may restrict the usage of shared prefix model to
> enterprise environments.
> 
> The Neighbor Discovery related security issues are document in [RFC
> 
> 2461] [RFC 2462] and these are applicable for all the models 
> described in this documents. The model specific security 
> considerations are documented in their respective protocol 
> specifications.
> 
> Place a new top-level section between Sections 5 and 6:
> 
> X. Effect on Routing
> 
> The model used for in a 802.16 network may have a significant impact
> on how routing protocols are run over such a network. The deployment
> model presented in this document discusses the least impacting model
> on routing as connectivity on the provider edge is intentionally
> limited to point to point connectivity from one BS to any one of 
> multiple MSs. Any other deployment model may cause a significant 
> impact on routing protocols, however, but they are outside the scope
> of this document.
> 
> 
> 
> 
> 
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> 
> 
> 
> -- ------------------------------------------------
> 
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> Woomyeon-dong, Seocho-gu, Seoul, Korea
> 
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