<[email protected] <mailto:[email protected]>>
Subject: Re: [Isis-wg] [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
%5
Bidr%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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