Subject: Re: [Softwires] I-D Action: draft-ietf-softwire-map-01.txt

From: Paco Cortes <[email-masked]>
Date: Thu, 5 Jul 2012 16:28:57 +0200

Hi Ole,

I've some comments on draft-ietf-softwire-map-01.txt:

1) Section 5, bullet 3 "Default Mapping Rule".
Is there a reason to preclude the usage of more than one Mapping Rule
for destinations outside the MAP domain?
I would consider desirable that a network provider is able to use
different BRs for routing optimization. Example:
- one/several BRs for legacy IPv4 services provided by the operator
(IPTV, ... using IPv4 prefixes owned by the operator)
- one/several towards transit ISPs

2) Section 5.1.1, last sentence
It says "For a=0, j MAY be 0 to allow...."
But if j would be different from 0, then the factor "R * M * j" in the
port number equation in section 5.1 bullet 1 would be a multiple from
65536.
As a result, the port number would be invalid if no "modulos 65536" is
used, or it would be fully equivalent to j=0 if modulos is used.
In the previous sentence you also say that "j larger than 0" ensures
excluding the system ports. This is not stricly true as it depends on
"a" being less than 7.
You should rethink the whole paragraph, and also if you want to
mandate that system ports are always excluded (implying a minimum
value for "a" and a minimum value for "A"), or if you want to allow
for them being also provisioning, what would require some other
"MAYs".

4) Section 5.1.2, first sentence.
I would recommend that yo put the PSID length k within parenthesis as
you do with the second example a few lines below. It would remark that
given R=1024 and a=4, then PSID length is derived from it (namely
log2(R)).

5) Section 5.2, 2nd last sentence above Figure 4.
It says "A MAP node MUST reserve the first IPv6 prefix in a End-user
IPv6 prefix for the purpose of MAP". I find confusing speaking about
"the first prefix in a prefix". Should it rather say "A MAP node MUST
reserve the prefix using this first subnet for the purpose of MAP"?
(or similar like "....using the MAP subnet ID...".

Best regards,
  Paco

2012/6/28  <[email-masked]>:
>
> A New Internet-Draft is available from the on-line Internet-Drafts directories.
>  This draft is a work item of the Softwires Working Group of the IETF.
>
>         Title           : Mapping of Address and Port (MAP)
>         Author(s)       : Ole Troan
>                           Wojciech Dec
>                           Xing Li
>                           Congxiao Bao
>                           Yu Zhai
>                           Satoru Matsushima
>                           Tetsuya Murakami
>         Filename        : draft-ietf-softwire-map-01.txt
>         Pages           : 33
>         Date            : 2012-06-28
>
> Abstract:
>    This document describes a mechanism for transporting IPv4 packets
>    across an IPv6 network, and a generic mechanism for mapping between
>    IPv6 addresses and IPv4 addresses and transport layer ports.
>
>
> The IETF datatracker status page for this draft is:
> https://datatracker.ietf.org/doc/draft-ietf-softwire-map
>
> There's also a htmlized version available at:
> http://tools.ietf.org/html/draft-ietf-softwire-map-01
>
> A diff from previous version is available at:
> http://tools.ietf.org/rfcdiff?url2=draft-ietf-softwire-map-01
>
>
> Internet-Drafts are also available by anonymous FTP at:
> ftp://ftp.ietf.org/internet-drafts/
>
> _______________________________________________
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