[c-nsp] Interdomain Multicast Routing

[Phil Mayers]

Gert Doering wrote:
> Hi,
> 
> On Mon, Sep 01, 2008 at 11:45:06AM -0400, Mike Louis wrote:
>> Do most sp these days support mc in their networks for customers?
> 
> Do you know *any* SPs these days that support multicast?
> 
> Yes, there are a few that have it still turned on, but does that mean
> it's a first grade, fully supported, product?
> 
> We disabled external multicasting in our SP network last week - because
> there was only minimal customer demand in the last 6 or 7 years, and
> on those few occasions, I usually spent ages diagnosing black hole 
> issues at one of our upstreams (turned up a new line, forgot to enable
> PIM on it, and such things).
> 
> IPv4 multicast is extremely painful to debug.  The whole MSDP/MBGP/PIM
> model is too complicated to maintain and too brittle for stable operations
> (SSM might be better - we never tried).

SSM is certainly *easier* to troubleshoot as is IPv6 embedded RP.

I wouldn't say they're "good" though; a large portion of the issues I've 
run into are much more general e.g. firewalls, lack of IGMP forwarding, 
lack of layer2 support, TTL problems, MTU problems, etc.