On 4/2/08 1:50 AM, Lixia Zhang allegedly wrote:
On Apr 1, 2008, at 8:53 AM, Scott Brim wrote:The more we take these ideas and try to apply them to real life operations, the more we realize how helpful coordination among xTRs is. In order for a site to be able to coordinate behavior of its xTRs, to any degree and in any way it chooses, it is good to have them under the site's direct control.I completely agree with the above.(although I suspect, maybe only slightly, that what we have in mind about "site" in the above statement could be different, i.e. a customer site vs an ISP AS)I don't believe we can predict or should control how a site's xTRs will need to work together -- they might do something surprising. So I don't think a site should depend on inter-provider cooperation.again I strongly agree that one AS should not depend on others cooperation.and following all the above I had expected the next sentence to say that it's better to place xTRs in PE, but it said the opposite! :-)That means I believe that it's better to place xTR functionality in CEs.
this makes a perfect example to illustrate my concern in the earlier reply Robin: even when people may make the same statement, that does not necessarily mean we all understand each other. So gaining a real understanding, rather than critique based on incomplete understand, is a first important thing.
OK. As it turns out, the confusion seems to be with the term "cooperation" (or coordination). I didn't expect that.
To deploy encapsulation requires two points coordination, the encap point (ITR) and decap point (ETR) (I tried to avoid the word "tunneling" here, as Scott pointed out that tunneling is often used to refer to configured tunnels)Scott considered CE the right place, based on the assumption that CE can decides whether to perform encap, based on its understanding of whether the other end know the new game to do decap.
I was talking about cooperation betwen xTRs of the *same* site, for example to deal with operational up/down changes and policy-based mapping, coordinating on control of incoming traffic. I wasn't talking about cooperation between an ITR and an ETR (in order to encapsulate) at all.
My thinking was: If a site (i.e. an area of the network addressed only by EIDs and surrounded by xTRs) is connected to more than one ISP/AS, and the how can you
- have the xTRs in PEs, under control of the ISPs - have good cooperation between the xTRs, and - not depend on cooperation between the ISPsI can see how if you are using encapsulation to cross a single ISP, to relieve the burden on internal routers, it would be useful to have both ITR and ETR under the same administration.
Sorry for the confusion. Scott -- 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