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Multicast question

Mohammed Faiz
Honored Contributor

Multicast question

Hi,

I'm slightly confused about a multicast issue that I'm trying to diagnose and hoped someone could help.

In brief, I have a 5406zl (Router A) that is the default gateway to a number of networks where the multicast receivers live.

Connected to this 5406zl are two other routers; a firewall which is the default route, and another 5406zl (Router B).

The idea is that we don't want the multicast streams passing through the firewall so PIM-SM is only enabled on the interace/VLAN between Router A and Router B.

However the multicast streams only work when I add a static route to Router A to route traffic for the Rendezvous Point via the Router B link.

This implies that without the static route it is attempting to send the joins down the default route (to the firewall). When reading about how RPF/SPF works this does make sense but surely it shouldn't be using the firewall interface as PIM-SM isn't enabled on it?

Thanks,

Mo
7 REPLIES
Pieter 't Hart
Honored Contributor

Re: Multicast question

I've no real experience on this but..
- the firewall is the default-gateway for router-A.
so all trafic not on a local interface is sent to this firewall.

>>> PIM-SM is only enabled on the interace/VLAN between Router A and Router B <<<
I think you are mistaken when thinking this causes routing to be different then described above.
Pieter 't Hart
Honored Contributor

Re: Multicast question

according to the Multicast and Routing Guide Page 4-20+, you also need to configure a routing protocol.
RIP or OSPF per-router, or IGMP per-vlan.

Per-Router Global Configuration Context
Use these steps to enable routing and PIM operation in the global configuration
context of each PIM-SM router (ProCurve(config)#_)
1. Enable routing. (Use ip routing.)
2. Enable multicast routing. (Use ip multicast-routing.)
3. Enable PIM. (Use router pim.)
4. Configure the routing method(s) needed to reach the interfaces (VLANs)
on which you want multicast traffic available for multicast receivers in
your network:
4-21
PIM-SM (Sparse Mode)
Configuration Steps for PIM-SM
â ¢ Enable RIP or OSPF (Use router < rip | ospf >.)
â ¢ If desired, configure static routes to the destination subnets.
(Use ip route < dest-ip-address >/< mask-bits > < next-hop-ip-addr >.)

Mohammed Faiz
Honored Contributor

Re: Multicast question


> so all trafic not on a local interface is
> sent to this firewall.

Yes, sorry, I meant "default route" not "default gateway"

> >>> PIM-SM is only enabled on the
> interace/VLAN between Router A and Router B <
> I think you are mistaken when thinking this
> causes routing to be different then
> described above.

I'm beginning to think that myself, but the manual says:

"3. Enable PIM-SM on the VLAN interfaces where you want to allow routed
multicast traffic. (Default: disabled)"

I've got static routes on Router A so that's all fine.
Just to clarify, the multicast stream are working however I'm having serious performance issues once I start routing the multicast traffic which is why I'm trying to understand the routing process a bit more.

Thanks.

Mo
Pieter 't Hart
Honored Contributor

Re: Multicast question

>>> I'm having serious performance issues <<<
did you enable IGMP?

If you don't enable IGMP the switch will send multicast traffic to all ports in the vlan/subnet where this originates from.
this happens before it reaches the router (RP) for traffic to other subnets.
If there are many ports in this vlan, then the switch will get busy multiplying each packet.
also all workstations in this vlan will receive and process the multicasts, but eventually discard these packets, when no program listens to this.
Mohammed Faiz
Honored Contributor

Re: Multicast question

Yes, IGMP is enabled. I've tried to make it as simple as possible for the testing I'm doing.
Performance is perfect when connected to an interface on the border firewall (which is running PIM-SM, the RP is external to our network and is configured statically on all routers).
When I connect my laptop to a 5406zl ("Router B" in the previous posts) which is connected directly to that firewall and also running PIM-SM (and IGMP on the vlan to my laptop) performance is worse.
I then connect to "Router A" (discussed above) which is another hop away and performance is awful.
Mohammed Faiz
Honored Contributor

Re: Multicast question

Just to finish this thread the issue was firmware related. The answer is do not go near the K14 code if you are running multicast routing (Layer 2 multicast is fine).
The streams run perfectly on K.13.68 (and .71).
10 points for me :)
Pieter 't Hart
Honored Contributor

Re: Multicast question

thanks for reporting back.
Have seen more posts regading this FW.
points for you :)

Pieter