Re: What Multicast ICP?

Mr Martin Hamilton <martin@mrrl.lut.ac.uk> wrote:

> OK, well I kind of wrote it... :-)

Thank you!

> Personally I see this primarily as an experimental thing, which is
> probably only going to be useful at the moment for people who have
> native multicast routing deployed (or are running several caches on
> the same bit of wire) and who want to cut down on the number of ICP
> packets being bounced around. This matches the situation in ac.uk
> quite nicely, so I'm hoping that we can get interest from enough
> people with MBONE connectivity that we can do meaningful trials over a
> wide area. T

Personally I think so, too. In .jp (or tohoku.ac.jp), there are many
cache servers which sending ICP packets to some parent caches. I think
it is usefull for the many "child" caches and parents to join a
suitable multicast groups. And each cache configures own cache
hierarchy at the mulicast group with 'multicast-responder'.

I am now want to create multicast group at TOHOKU University Backbone
Network. There are one parent cache and several caches. I hope that
all cache servers in TOHOKU University get a multicast connectivity.

...
I have one question with using multicast ICP.
I tried to create a multicast group in our lab's subnet with two
caches. The configuration is below.
---------------------------------------------------------------------
host A: mcast_groups 239.133.**.**
        cache_host 239.133.**.** multicast 3128 3130 ttl=1
        cache_host AAA.our-lab.tohoku.ac.jp sibling 3128 3130 multicast-responder
host B: mcast_groups 239.133.**.**
        cache_host 239.133.**.** multicast 3128 3130 ttl=1
        cache_host BBB.our-lab.tohoku.ac.jp sibling 3128 3130 multicast-responder
---------------------------------------------------------------------
I send a request to host A, then host B's access.log says,

856049957.581 1 hostA.our-lab.tohoku.ac.jp UDP_HIT/000 78 ICP_QUERY http://foo.bar.bazz/ - NONE/- -

but host A's access.log says,

856049723.280 1 hostA.our-lab.tohoku.ac.jp UDP_MISS/000 78 ICP_QUERY http://foo.bar.bazz/ - NONE/- -
856049723.780 1198 hostA.our-lab.tohoku.ac.jp TCP_MISS/200 5921 GET
http://foo.bar.bazz/ - DIRECT/foo.bar.bazz text/html

It seems that host A don't receive ICP replies from host B.

What's wrong ?

---
Kenichi Matsui
Graduate Student at TOHOKU Univ. JAPAN
mailto:matsui@nemoto.ecei.tohoku.ac.jp      
http://www.nemoto.ecei.tohoku.ac.jp/~matsui/
I am a member at TAINS Cache Group
http://www.nemoto.ecei.tohoku.ac.jp/cache-tains/index-e.html