Re: Multicast routing between subnets

MahirHrustic · ‎05-25-2012

Hey there folks,

My hardware:

Router: Cisco 2811 running ver 12.3 T7

Switches: Cisco 2950 running 12.1 EA1

I've been working on this for days, without much success. I've searched online, and can't really tell what it is that I'm doing wrong. I hate asking for help (especially in writing) but have hit a brick wall.

I'm trying to get a multicast video stream to broadcast between VLANs/subnets (via PIM, although the method really doesn't matter). The end goal is to send a multicast stream via an IPSEC tunnel (between ASAs) to a customer's site. But, to get there, first I need to get multicast between subnets working.

I have multicast routing enabled on the router, and PIM in dense mode enabled on the interfaces. I did this by doing:

conf t

ip multicast-routing

ip bim bidir-enable

int fa0/0

ip pim dense-mode

int fa0/1

ip pim dense-mode

end

When I do sh ip multicast int, I get:

FastEthernet0/0 is up, line protocol is up

Internet address is 10.0.110.3/24

Multicast routing: enabled

Multicast switching: fast

Multicast packets in/out: 760/0

Multicast TTL threshold: 0

Multicast Tagswitching: inactive

FastEthernet0/1 is up, line protocol is up

Internet address is 10.0.0.2/24

Multicast routing: enabled

Multicast switching: fast

Multicast packets in/out: 301/30

Multicast TTL threshold: 0

Multicast Tagswitching: inactive

When I do sh ip pim int fa0/0, I get:

10.0.110.3 FastEthernet0/0 v2/D 1 30 1 10.0.110.3

and sh ip pim int fa0/1

10.0.0.2 FastEthernet0/1 v2/D 2 30 1 10.0.0.5

When I do sh ip mroute, I get:

(*, 229.55.150.208), 17:26:24/stopped, RP 0.0.0.0, flags: D

Incoming interface: Null, RPF nbr 0.0.0.0

Outgoing interface list:

FastEthernet0/1, Forward/Dense, 17:25:21/00:00:00

FastEthernet0/0, Forward/Dense, 17:25:55/00:00:00

(10.0.110.72, 229.55.150.208), 17:26:24/00:02:39, flags: PT

Incoming interface: FastEthernet0/0, RPF nbr 0.0.0.0, Udlr

Outgoing interface list:

FastEthernet0/1, Prune/Dense, 17:24:19/00:02:39, A

(*, 224.0.1.40), 17:26:24/stopped, RP 0.0.0.0, flags: DCL

Incoming interface: Null, RPF nbr 0.0.0.0

Outgoing interface list:

FastEthernet0/1, Forward/Dense, 17:25:21/00:00:00

FastEthernet0/0, Forward/Dense, 17:26:24/00:00:00

My multicast stream is being sent from 10.0.120.104 (on the 120 vlan) on the 232.0.0.254 multicast address. I have one box at 10.0.120.106 which gets the stream fine, but a box on 10.0.110.106 (on my 110 vlan) which does not.

When I run wireshark on the non-working box, I get the following IGMP packets:

[code]

source destination protocol info

10.0.110.106 232.0.0.254 IGMP V2 membership report / join group 232.0.0.254

[/code]

On the working box (on the same subnet as the server) I get:

[code]

source destination protocol info

10.0.120.106 224.0.0.22 IGMP V3 membership report / join group 232.0.0.254 for any sources

[/code]

Like I said, I'm really not sure what I'm doing wrong, and any help would be greatly appreciated.

Reza Sharifi · ‎05-25-2012

Are you using VLC to send multicast?

If yes, when configuring the source raise the TTL to 2 or 3 and than try again.

don't be afraied of asking for help.

HTH

AJ Cruz · ‎05-25-2012

Looks to me like your app is source specific multicast (232).

Try this:

Int f0/0

Ip igmp ver 3

Int f0/1

Ip igmp ver 3

Ip PIM SSM default

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MahirHrustic · ‎05-25-2012

Thanks for the response. The stream is in the SSM range (and I tried your fix above) with no luck.

The app I'm using is Adobe Flash Streaming Server. I can assign any multicast IP/port combination I want -- I havent been able to get it working on 232.0.0.254 or on 224.0.2.245.

The odd thing (to me) is, in the Wireshark captures, on the non-working vlan, the info for the IGMP packets shows "V2 membership report / join group 232.0.0.254" -- where as on the working vlan, it shows "V3 membership report / join group 232.0.0.254 for any sources." Could this have anything to do with it?

I'm open to any and all ideas! Thanks again for the quick response.

AJ Cruz · ‎05-26-2012

Where does 10.0.120.0 fit in? I only see 10.0.0.0 & 10.0.110.0 on your interfaces. Can you post a topology?

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Giuseppe Larosa · ‎05-26-2012

Hello Mahir,

the test receiver in vlan 110 as showed in the wireshark captures is running IGMPv2 instead of IGMPv3, as a result of this it sends out IGMPv2 joins that don't fit with the Source specific Mode that requires IGMPv3.

Or you fix the receiver box or you need additional commands to have IGMPv2 joins converted to IGMPv3 at the multicast router device.

Edit:

you can use SSM mapping to achieve this see

http://www.cisco.com/en/US/docs/ios-xml/ios/ipmulti_igmp/configuration/12-4t/imc_ssm_map.html#GUID-749FCA08-725A-40F8-A14A-67415721CE99

Hope to help

Giuseppe

MahirHrustic · ‎05-26-2012

Hey guys,

Thanks for all the responses. I really appriciate it.

Just to get it working on a simpler level. I'll change the multicast range to a non-ssm one (though SSM is the end goal).

For now, I'll use 224.0.2.245

On the 120 vlan (which, as before, the receiver shares with the server) in wireshark I get:

source destination protocol info

10.0.120.106 224.0.0.22 IGMP V3 Membership Report / Join group 224.0.2.245

My receiver box is 10.0.120.106. I'm not really sure what 224.0.0.22 is.

On the not working box (10.0.110.106), I now get:

source destination protocol info

10.0.110.106 224.0.0.22 IGMP V3 Membership Report / Join group 224.0.2.245 for any sources

Still no video, or multicast packets, though.

The IGMP packets being sent from the not working and thw working box are the same, yet I never see any multicast packets on the 110 vlan.

Is there anything specific I need to do on the router to allow it to rebroadcast the multicast to another vlan? As I said earlier, multicast and PIM (in bidirectional and dense-mode) are both enabled -- do I need to manualy configure anything else to get it to translate the igmp request into PIM and to rebroadcast it?

Giuseppe Larosa · ‎05-28-2012

Hello Mahir,

first of all, as suggested by Reza you have to check the IP TTL of the multicast stream you can do this using wireshark on the receiver box that is on the same subnet as the sender. IP TTL has to be greater then 1 to have a routable multicast stream.

Now your second receiver box is speaking IGMPv3, 224.0.0.22 is the well-known multicast address used by IGMPv3.

After having checked TTL on sender vlan, the next step could be that of using again an SSM group as the receiver in the other vlan is now IGMPv3 capable.

Feel free to post the multicast configuration of the router to get better help.

Hope to help

Giuseppe

AJ Cruz · ‎05-28-2012

Can you post the topology. I'm still a bit confused. I see PIM on interfaces for 10.0.0.0/24 & 10.0.110.0/24 but not 10.0.120.0. Is the 120 network on the same router?

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rizwanr74 · ‎05-28-2012

Hi Mahir,

Please try this.

Interface FastEthernet0/0

ip address 10.0.110.3 255.255.255.0

ip multicast helper-map 232.0.0.254 10.0.110.255

Please let me know, if this helps.

thanks

Rizwan Rafeek