Xiaohu –

RFC 5316 already has defined this – see sub-TLVs 11 and 12.

If the concern is that these are defined as TE specific it would be better to 
make an explicit statement to allow these to be used for purposes other than TE 
as has been done in RFC 5305 and RFC 6119 than to define a duplicate sub-TLV.

   Les


From: OSPF [mailto:[email protected]] On Behalf Of Xuxiaohu
Sent: Sunday, May 04, 2014 1:29 AM
To: George, Wes
Cc: [email protected]; [email protected]; [email protected]; [email protected]; 
[email protected]
Subject: Re: [OSPF] [sunset4] IPv6 router IDs

Hi Wes,

Thanks for pointing out these two drafts.

The motivation for these two drafts 
(http://tools.ietf.org/html/draft-xu-isis-ipv6-router-id-00 and 
http://tools.ietf.org/html/draft-xu-ospf-ipv6-router-id-00) is very simple: the 
IPv6 ISIS|OSPF capability TLV/RI-LSA which are used for advertising router 
capabilities can be flooded across areas, however, only a 4-octect router ID is 
carried in them. As a result, it’s hard for routers in one area to establish 
correlations between IPv6 addresses and capabilities of routers in another 
area. For example, assume IS-IS router A in one area has established a L3VPN 
session with IS-IS router B in another area over their own IPv6 addresses. When 
router A needs to send L3VPN traffic to router B via a MPLS-SR tunnel, router A 
wants to know whether router B has the ELC 
(http://tools.ietf.org/html/draft-xu-isis-mpls-elc-00) 
before<http://tools.ietf.org/html/draft-xu-isis-mpls-elc-00)%20before> 
inserting an EL into the MPLS-SR packet . However, the Capability TLV 
originated by router B doesn’t carried an IPv6 address of its own. As a result, 
it’s hard for router A to know the ELC of router B.

Best regards,
Xiaohu

发件人: George, Wes [mailto:[email protected]]
发送时间: 2014年5月2日 1:51
收件人: Xuxiaohu
抄送: [email protected]<mailto:[email protected]>; 
[email protected]<mailto:[email protected]>; 
[email protected]<mailto:[email protected]>
主题: Re: [sunset4] IPv6 router IDs

I got a bounce-back on all 3 draft aliases, trying again with the authors’s 
email addresses directly.

From: <George>, "George, Wes" 
<[email protected]<mailto:[email protected]>>
Date: Thursday, May 1, 2014 at 1:42 PM
To: 
"[email protected]<mailto:[email protected]>"
 
<[email protected]<mailto:[email protected]>>,
 
"[email protected]<mailto:[email protected]>"
 
<[email protected]<mailto:[email protected]>>
Cc: 
"[email protected]<mailto:[email protected]>"
 
<[email protected]<mailto:[email protected]>>,
 "[email protected]<mailto:[email protected]>" 
<[email protected]<mailto:[email protected]>>
Subject: [sunset4] IPv6 router IDs

I see that you have submitted two drafts for IPv6 router IDs in ISIS and OSPF, 
noting that the existing router ID is only 4 octets. This has also come up in 
IDR for BGP. The authors of that draft are copied. I’ll give you a similar set 
of feedback to what I gave them -

It is important to distinguish between places where a unique identifier is 
needed, and by convention an IPv4 address assigned to the device has been used 
to provide that unique ID, vs. places where the actual IP address has some sort 
of importance to the protocol (I.e. That information must be available to take 
action on).
In other words, is the protocol requirement that the ID be unique across some 
domain, but that the actual value does not matter, or is the protocol 
requirement that the value must correspond to something on the router? In many 
of the former cases, the fact that the value isn’t relevant has been used to 
make recommendations that are easier for humans to deal with (I.e. Tying the 
router ID to an IP address) but that value as a human-readable set of info does 
not necessarily justify  changes to the protocol to support that convention as 
we move to IPv6.
I would argue that the router ID used in routing protocols must merely be 
unique, but it doesn’t have to be an IP address at all. Thus it is not strictly 
necessary to create a new field to carry IPv6 addresses when operating without 
IPv4 addresses on a network. If you believe otherwise, the justification needs 
to be documented in the draft.

There are many places in IETF protocols where a 32 bit unique identifier is 
needed, and by convention an IPv4 address has been used. It would be far more 
useful to write a general draft identifying this problem and discussing several 
solutions, including simply generating unique IDs manually, systematically 
generating a random ID, etc.  the place for such a draft may be in Sunset4, 
either as a part of the existing gap analysis draft or as another standalone 
draft.

There was rather a long discussion about this on IDR, thread here: 
https://mailarchive.ietf.org/arch/search/?qdr=a&email_list=idr&q=%22%5Bidr%5D+%5Bv6ops%5D+BGP+Identifier%22&as=1&gbt=1

And in the IDR meeting, minutes:
http://www.ietf.org/proceedings/89/minutes/minutes-89-idr (see page 11)

I’d encourage the authors of these drafts to work together on this.

Thanks,

Wes George

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