Multicast routing

Unanswered Question
Aug 1st, 2007

I'm testing QoS strategy on test network and I'm using wireshark to get result on my test scenario. I'm testing video broadcast across a network made with three 2600 router and 2 BPS2000 (Nortel switch) at the boundary.

PC1----BPS2000(switch)-----router1-----router2-----router3----BPS2000(switch)-----PC2.

I'm using VLC to do unicast video streaming across my network, and I use Wireshark at each end of my network to have measure.

I absolutly need measure such as max_bw, max_burst... provide by Wireshark. Unfortunatly Wireshark provide its statistic in the only case where I do multicast streaming and not unicast streaming.

Having absolutly no knowledge about multicast, I've tried to do multicast streaming instead of unicast streaming.

I've read cisco document about multicast streaming, but I don't succeed to do my musticast streaming.

I did this on each interface of my routers :

Router(config)# ip multicast-routing

Router(config-if)# ip pim dense-mode

On router1, where I want to create my multicast group I did this

Router1(config-if)# ip igmp join-group 224.1.1.1

The configuration I have made don't work. Do you know how can I do to do my multicast streaming from PC2 to PC1.

How can I do to create my multicast group?

Is something to do on the switch?

Thanks

I have this problem too.
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cjnwodo Wed, 08/01/2007 - 01:16

Hi,

Before we go into the bowels of multicast routing the first thing we have to ascertain is that your source PC2 is actually using VLC to stream the video content to a multicast address. If it is then running wireshark on PC2 should show that it is sending information to 1 or more multicast groups [224.x.x.x - 239.x.x.x]. Can you confirm this?

Secondly, you need to confirm that the 3 2600 routers are PIM neighbours of each other. I'm assuming that the link between the routers are WAN links. In that case running show ip pim nei on router1 should show that router2 is its PIM neighbour, running show ip pim nei on router2 should show that router1 & router3 are its PIM neighbours and finally running show ip pim nei on router3 should show that router2 is its PIM neighbour. can you confirm this?

In order to force router1 to send the traffic to PC1 [your receiver] use ip igmp static-group . But apply this on the interface that is connected to the BPS2000(switch)that is connected to PC1. Then to confirm that it is correctly applied issue the following command show ip igmp group. This should show that the interface you applied the command to is a receiver/member of the multicast group. Make sure that you have no ACLs that may be blocking PIM on the routers.

You can then run show ip mroute on router1, router2 & router3 to show that multicast state is created. Unfortunately, trying to go into the interpretation of the output will make this post even lengthier. But suffice to say that on each of the routers you should see the source as PC2 and the OIL [out going interface list] as the interface towards PC2.

Sorry this is a bit lengthy but it should get you on your way.

cjnwodo Wed, 08/01/2007 - 01:24

Hi,

One other thing, make sure that all routers have routers to the LAN subnet the PC2 resides on, if not the RPF check will fail

Djule2804 Wed, 08/01/2007 - 06:16

Hi cjnwodo

thank you for your response.

First, I confirm that VLC stream the video content to a multicast address.

Secondly ip pim nei give the good result on all the router.

Unfortunaltly when I start video streaming from PC2, transmission doesn't work. I can see activity on router1 (led blinks) but only on this one. I deduct that this router can't succeed to find out where it must route packets with 224.1.1.1 destination address.

You can find in attachment my network scheme and addressing and the running config of my three routers

Here is the result from

ip igmp group show :

router1#show ip igmp group

IGMP Connected Group Membership

Group Address Interface Uptime Expires Last Reporter

224.0.1.40 FastEthernet0/0 18:44:43 00:02:34 192.168.1.1

239.255.255.250 FastEthernet0/0 18:46:51 00:02:26 192.168.1.3

router2#show ip igmp group

IGMP Connected Group Membership

Group Address Interface Uptime Expires Last Reporter

224.0.1.40 FastEthernet0/1 00:22:44 00:02:32 192.168.3.2

router3#show ip igmp group

IGMP Connected Group Membership

Group Address Interface Uptime Expires Last Reporter

224.1.1.1 FastEthernet0/1 19:21:54 00:02:03 192.168.4.1

224.0.1.40 FastEthernet0/0 00:20:48 00:02:30 192.168.3.2

and here is the result from the following command show ip mroute

:

/////////////router1////////////////////////

(*, 224.0.1.40), 20:58:47/00:02:35, RP 192.168.1.1, flags: SJCL

Incoming interface: Null, RPF nbr 0.0.0.0

Outgoing interface list:

FastEthernet0/0, Forward/Dense, 20:56:38/00:00:00

(*, 239.255.255.250), 20:58:46/00:02:39, RP 192.168.1.1, flags: SJC

Incoming interface: Null, RPF nbr 0.0.0.0

Outgoing interface list:

FastEthernet0/1, Forward/Dense, 02:29:41/00:00:00

FastEthernet0/0, Forward/Dense, 20:56:37/00:00:00

/////////////router2(core)////////////////////////

(*, 224.0.1.40), 04:30:53/00:02:34, RP 0.0.0.0, flags: DCL

Incoming interface: Null, RPF nbr 0.0.0.0

Outgoing interface list:

FastEthernet0/0, Forward/Dense, 02:30:42/00:00:00

FastEthernet0/1, Forward/Dense, 04:30:01/00:00:00

/////////////router3////////////////////////

(*, 224.1.1.1), 21:36:56/stopped, RP 0.0.0.0, flags: DC

Incoming interface: Null, RPF nbr 0.0.0.0

Outgoing interface list:

FastEthernet0/1, Forward/Dense, 02:28:00/00:00:00

FastEthernet0/0, Forward/Dense, 04:31:37/00:00:00

(*, 224.0.1.40), 21:37:52/00:02:28, RP 0.0.0.0, flags: DCL

Incoming interface: Null, RPF nbr 0.0.0.0

Outgoing interface list:

FastEthernet0/0, Forward/Dense, 04:31:37/00:00:00

Jon Marshall Wed, 08/01/2007 - 06:41

Hi

Could you check if there is ttl setting for the video stream with the VLC software. You will need to make sure it has a ttl of at least 3 to reach PC1.

You should not need the "ip igmp join..." on R1 as this is pim dense mode so you should see the 224.1.1.1 group on all your routers anyway regardless of whether anything wants to receive the video stream.

Also could you confirm whether or not you have turned IGMP snooping on on the switches.

HTH

Jon

Djule2804 Wed, 08/01/2007 - 06:56

thank you very much, for your suggestion, I put the ttl to 4 and video stream has worked.

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