All things related to multicast

[Havard Eidnes <>]

> >Sorry; must have forgotten to reply to that one.  I'm not sure
> >how the router can revert to dense-mode behaviour with each and
> >every interface configured for "ip pim sparse", though:
>
> Interface mode and group mode are not the same thing although
> they are related.  This is an often confused fact.
>
> The mode of a "group" depends on the existence of an RP for the
> group.  More specifically, the contents of the Group-to-RP
> mapping cache is the key here.
>
> Hence the need for you to send the output of the 'show ip pim
> rp mapping' command.

OK, here goes:

s-gw>show ip pim rp map
PIM Group-to-RP Mappings

Group(s) 224.0.1.39/32
  RP 193.10.252.1 (pim-rp.nordu.net), v1
    Info source: local, via Auto-RP
         Uptime: 7w0d, expires: never
Group(s) 224.0.1.40/32
  RP 193.10.252.1 (pim-rp.nordu.net), v1
    Info source: local, via Auto-RP
         Uptime: 7w0d, expires: never
Group(s): 224.0.0.0/4, Static
    RP: 193.10.252.1 (pim-rp.nordu.net)
s-gw>


sw-gw>show ip pim rp map
PIM Group-to-RP Mappings

Group(s) 224.0.1.39/32
  RP 193.10.252.1 (pim-rp.nordu.net), v1
    Info source: local, via Auto-RP
         Uptime: 00:30:00, expires: never
Group(s) 224.0.1.40/32
  RP 193.10.252.1 (pim-rp.nordu.net), v1
    Info source: local, via Auto-RP
         Uptime: 00:30:00, expires: never
Group(s): 224.0.0.0/4, Static
    RP: 193.10.252.1 (pim-rp.nordu.net)
sw-gw>


The 233.2.171.1 group falls within 224.0.0.0/4, and as you can
see we have a single statically configured RP address on our
routers.  (I always considered this auto-rp goop as too much
operational complexity; we have trouble enough making PIM-SM work
without also having to debug it!)


Regards,

- Håvard