[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

Re: [RRG] What do we have consensus on?




On May 28, 2008, at 12:57 AM, Tony Li wrote:

|Tony suggested 3 branches:
|
|- Transport:   this falls with #1 in the above
|- Map-n-encap: this is #2 in the above
|- Translation: I did not get exactly what this one is, if it is
|                not the GSE rewrite.
|
|there was a debate between Tony and Brian at the time about whether
|SHIM6 is translation. I dont think I fully understood Tony's argument
|on why SHIM6 is a translation; may be Tony could try one more
|time here.

The way that I look at it, Shim6 establishes a set of 'identifiers' that the transport protocols will use and then plays some games to determine the set of 'locators' for network layer operations. Since it is doing wholesale swapping of the locators for the identifiers, I'd claim that it's mostly a
translation approach.

I think that it's clear that it's not actually changing transport. Further, it's pretty clear that while it is piggybacking some information, it really
isn't going to the full-scale extent of a real encapsulation.

That said, I recall thinking that there was some validity to Brian's
position and at the same time thinking that it wasn't yet worth worrying about the specific details. I am, of course, very happy to revisit this if
it becomes productive.

Tony

through a phone chat with Tony, I finally got what's the above tried to say.
It's all due to from which angle one looks at the picture.

I take the view of scaling routing by provider-aggregatable prefixes: for a multihomed site, both SHIM6 and Handley proposal take the multiple provider-based addresses all the way *into* each host. As far as routing scalability is concerned, it makes no difference whether these multiple PA addresses stop at a shim layer, or go to transport layer (of course it can make a big difference as far as transport functions are concerned).
This is top-level branch#1 in my earlier msg http://psg.com/lists/rrg/2008/msg01220.html

Tony's above msg took the view from transport layer and *looking downward*: SHIM6 has this notion of EID, and the actual IP packets *may* be sent using IP addresses that are different from EID, hence "this is a translation" view, i.e. a translation from an "EID" to an "IP address". (to be more precise, SHIM6's notion, as I understand it, is really a binding of a set of IP addresses to one transport session, so anyone in the set can be used. But lets not argue this semantic detail).

Lixia


--
to unsubscribe send a message to rrg-request@psg.com with the
word 'unsubscribe' in a single line as the message text body.
archive: <http://psg.com/lists/rrg/> & ftp://psg.com/pub/lists/rrg