Subject: Re: [multimob] IGMP/MLD on PtP Links

From: Behcet Sarikaya <[email-masked]>
Date: Thu, 6 Sep 2007 09:46:42 -0700 (PDT)

----- Original Message ----
From: Hitoshi Asaeda <[email-masked]>
To: [email-masked]
Cc: [email-masked]
Sent: Wednesday, September 5, 2007 9:34:34 PM
Subject: Re: [multimob] IGMP/MLD on PtP Links

> I think IGMPv3 was designed thinking how to save RAM in routers and
> this is the reason of the complexity when it mixes include and
> exclude sources in one record. 15 years ago the cost of 1MB of ram
> was around 40$ but now you have 4GB for this price.

The aim of LW-IGMPv3/MLDv2 is not only for contribution to reduce the
memory size in an end host. One of the big advantages is that
it highly reduces the processing cost on the upstream switch-side or
the router-side by eliminating the exclude mode operations. If both
include and exclude mode operations are supported in your multicast
services, your switches and routers need to maintain all source
addresses joined from your end hosts. Even if an SPT is well
coordinated by (S,G) joins given by SSM-capable receivers, the routers
need to refresh (and re-generate) some or all of the corresponding
routing paths whenever more than one of your downstream hosts requests
exclude mode join. This situation gives non scalable manner.

> PIM-SM, for example, has different state machines for Join(S,G) and
> Join(*,G) and those state machine are more simple than IGMPv3 state
> machine.

State change from (*,G) to (S,G) or vice versa takes much cost.

> Perhaps IGMPv3 can be modified exactly in the opposite way of the
> draft: with more filter modes, each one with its own state machine.

I cannot catch your point, but if it's "lightweight", then the
solution might be fine.

[behcet] I would like to add the following to the requirements of an MLD/ IGMP for Multimob:
- support PtP links. In this case the link is simple, i.e. there is only one mobile. However the complexity moves into the management of possibly large number of links.
- Dormant mode support. The protocol should not wake up the mobile for some unnecessary reporting. This is a requirement from SDOs that need to seriously consider the dormant mode operation for battery savings.

Regards,

Behcet

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---

From: Hitoshi Asaeda <[email-masked]>
Date: Fri, 07 Sep 2007 13:35:46 +0900 (JST)

> - support PtP links. In this case the link is simple, i.e. there is
> only one mobile. However the complexity moves into the management
> of possibly large number of links.

Why IGMP/MLD cannot support PtoP links? I think they can.

> - Dormant mode support. The protocol should not wake up the mobile
> for some unnecessary reporting. This is a requirement from SDOs
> that need to seriously consider the dormant mode operation for
> battery savings.

This would be the special requirement for mobile communications, where
the functions wouldn't be included in the common spec, I think.
But for me it's interesting to illustrate the addendum functions for
mobile nodes, and I may want to think about them.

Regards,
--
Hitoshi Asaeda

---

From: "Jong-Hyouk Lee" <[email-masked]>
Date: Fri, 7 Sep 2007 14:11:38 +0900

Dear Hitoshi Asaeda.

One of development issues for support mobility is a network-based mobility
model, Proxy Mobile IPv6. Might be, Behcet considers this. In Proxy Mobile
IPv6, PtoP link is assumed between the access router and the mobile
node. For scalability and flexibility of IGMP/MLD on such environments, I
agree with Behcet.

Cheers.

-- 
Internet Management Technology Lab, Sungkyunkwan University.
Jong-Hyouk Lee.

#email: jonghyouk (at) gmail (dot) com
#webpage: http://www.hurryon.org
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