Hi Woj,

Comments in line.

Cheers,
Ian

________________________________
From: Wojciech Dec [mailto:[email protected]]
Sent: Dienstag, 26. Juni 2012 09:55
To: Farrer, Ian
Cc: [email protected]; [email protected]
Subject: Re: [Softwires] [Softwire] draft-ietf-softwire-map-00 does NOT reflect 
the consensus from the WG



On 26 June 2012 09:13, <[email protected]<mailto:[email protected]>> 
wrote:
Hi Satoru,

Comment in line below.

Best regards,
Ian

Date: Mon, 25 Jun 2012 18:46:18 +0900
From: Satoru Matsushima 
<[email protected]<mailto:[email protected]>>
To: Peng Wu <[email protected]<mailto:[email protected]>>
Cc: [email protected]<mailto:[email protected]>, Yong Cui 
<[email protected]<mailto:[email protected]>>
Subject: Re: [Softwires] [Softwire] draft-ietf-softwire-map-00 does
NOTreflect the consensus from the WG
Message-ID: 
<[email protected]<mailto:[email protected]>>
Content-Type: text/plain; charset=iso-8859-1

Hi Peng,

On 2012/06/25, at 18:34, Peng Wu wrote:

Let's think that a CE provisioned with following BMR comes from MAP DHCPv6 
options.
BMR:
  o Rule-ipv6-prefix  : {exact matched with CE's delegated prefix}
  o Rule-ipv4-prefix  : x.x.x.x/32
  o EA-length         : 0
  o Port-param option : {PSID/length}
This BMR could be a LW46 provisioning means.
Again, all the information needed is the IPv4 address and port set.
1) The item like rule-ipv6-prefix is not needed at all.
2) Port set or PSID still needs extra provisioning (while in regular
MAP it's embedded in IPv6 address)
So why make it so difficult and obscure

Not difficult, easy business for CE which implemented MAP. Other difficulty in 
operator side in particular provisioning complex, that should be same with 
LW46. It also makes to complete MAP spec in the ea-len zero case.

[IF] Additional complexity in the operator side is where I see the problem with 
MAP in our case. The strength that MAP offers is for the mesh model and the 
complexity that it brings is a neat way of achieving this. But if hub-and-spoke 
is the only deployment scenario that you need, then the complexity for mesh is 
an unnecessary addition that results in operational complexity, which is 
something we're trying to engineer out wherever we can.
E.g. In the case above, for a shared IP address, the source port range is 
encoded in the port-param option. To troubleshoot user connectivity, ops need 
to have a good understanding of how this is being calculated so that they can 
trace the user. Not the end of the world, but with millions of customers and a 
hundred support staff, it's just better avoided if possible. This logic also 
then needs to be built into other business support systems that rely on the 
customers IP/port range as an identifier.
LW46 solves this with a simple (though long) lookup table. This does mean that 
it's very easy to extract how a user is configured or identified with a minimum 
of additional knowledge and calculating tools.

Well, a couple of observations:
A) MAP allows you to optimize complexity in not having to deal with per 
subscriber rules in cases where this is feasible.

But this re-introduces v4 and v6 addressing dependency which we're trying to 
avoid.

B) You're referring to data representation as an operational problem, which if 
so, actually applies to any solution incl LW46 that transmits port-range info 
to a client. I.e. "Whatever support staff" needs to be schooled to use some 
logic to glean useful port information from the data sent to a client

"Don't worry about unnecessary complexity, we'll just do more training!" isn't 
a very powerful argument in our business.

C) It is very easy to represent MAP data as port range info on routers, tools, 
etc.

On routers, I'm sure that it is. However, the fact that you need a tool to work 
out the mapping again points to complexity. On internally developed and 3rd 
party BSS systems then it's more work that offers no benefit.

-Woj.


cheers,
--satoru

------------------------------



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