Large IPv6 Multicast Domains

[Stig Venaas]

Hi

On 6/20/2014 5:08 AM, David Barak wrote:
>
>> On Jun 20, 2014, at 5:09 AM, Phil Mayers <p.mayers at imperial.ac.uk> wrote:
>>
>>> On 20/06/14 07:11, Mark Tinka wrote:
>>>> On Thursday, June 19, 2014 08:17:07 PM Stig Venaas wrote:
>>>>
>>>> I'm
>>>> hoping SSM will be the way to go for interdomain in
>>>> general.
>>>
>>> Agree - prefer SSM also.
>>
>> Who doesn't - app coders AFAICT? ;o)
>
> There are specific use cases for ASM (in IPv4) in distributed monitoring (many->few traffic flows)  It sure would be a shame for that to go away...

But do you need that across multiple domains?

ASM is pretty much the only solution when it comes to autoconfig
and discovery where you don't want to hard code source addresses
and some device has no knowledge. But that is typically relevant
on a single link, or in a site. I can't think of any interdomain
cases.

Applications that need to discover remote sources for SSM would
need to have their own discovery mechanism. There are various
possible schemes. A device with no info might need to use DHCP
or something to learn how to reach a server, or maybe have some
fixed multicast group to discover some kind of local server that
has more info.

But yes, it is easier for application developers to assume ASM
works inter-domain. Embedded-RP works though, but you would
probably not want to hardcode a group addresses with an embedded
RP address in a device.

Stig


> David
>