Subject: [Roll] Question on Multi-Homing in RPL

From: "Don Sturek" <[email-masked]>
Date: Wed, 14 Oct 2009 22:40:14 -0700

A question on RPL -03:   Is Multi-Homing supported?  Here is the use case:

1)       In a Smart Energy setting, the Smart Meter is assumed to have one
prefix.   Some collection of devices join this network and can communicate
to the meter and via the meter to the utility headend

2)      The customer also owns a router connected to an ISP.  Let's suppose
the ISP is providing IPv6 service with a separate prefix.

Here are the questions:

1)       Within a DAG, could devices be Multi-Homed or are they required to
have a single prefix?

2)      Are there any limitations or suggestions on how address assignment
should be handled with respect to the two prefix address spaces.

3)      If we would like the same devices to be able to communicate to the
meter/headend and then also to the internet via the customers ISP, would:

a.       There need to be DAGs supporting separate prefix addresses?

b.      Can the devices in a single DAG support multihomed devices?  Would
all devices in a given DAG need to be multihomed the same way?

Don

---

From: Michael Richardson <[email-masked]>
Date: Thu, 15 Oct 2009 15:42:59 -0400

>>>>> "Don" == Don Sturek <[email-masked]> writes:
    Don> A question on RPL -03:   Is Multi-Homing supported?  Here is
    Don> the use case: 

(SmartMeter + ISP) situation described.
This is a scenario that I think is completely valid.

    Don> Here are the questions:

    Don> 1)       Within a DAG, could devices be Multi-Homed or are they
    Don> required to have a single prefix?

I think they have to have a single prefix.

    Don> 2)      Are there any limitations or suggestions on how address
    Don> assignment should be handled with respect to the two prefix
    Don> address spaces. 

I'm not sure if you asking about whether the prefixes have to be
coordinated, or if you asking if the assignments within each prefix
needs to be coordinated.

    Don> 3)      If we would like the same devices to be able to
    Don> communicate to the 
    Don> meter/headend and then also to the internet via the customers
    Don> ISP, would: 

    Don> a.       There need to be DAGs supporting separate prefix
    Don> addresses? 

I think the device needs to associate to two DAGs.

    Don> b.      Can the devices in a single DAG support multihomed
    Don> devices?  Would all devices in a given DAG need to be
    Don> multihomed the same way? 

I think all the devices involved would need to join multiple DAGs.
Some of them might not be able to, and would have to pick one or the
other.  If they are owned/controlled by utility, I imagine it likely
they would prefer the meter route.

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