forward multicast between 2 interfaces on a cisco router

Apr 20, 2013 5 Replies

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programmer.phillip 13 years ago

Hi, I want to forward multicast packets:

Src 192.168.2.12 multicast dst 225.2.1.14 And Src 192.168.2.22 multicast dst 225.2.1.24

They are going to an address 10.100.1.8

So basically I want to forward from eth0 to eth1 I have played with pim and access lists but nothing seems to work. Unicast and icmp all work fine just not multicast.

Any ideas?

Thanks in advance.

Router# Router# Router#write term Building configuration... Current configuration : 557 bytes ! version 12.2 service timestamps debug uptime service timestamps log uptime no service password-encryption ! hostname Router ! enable secret 5 redacted enable password redacted ! ip subnet-zero ! ! ! ip multicast-routing ! ! ! interface FastEthernet0/0 ip address 192.168.2.254 255.255.255.0 duplex auto speed auto ! interface FastEthernet0/1 ip address 10.100.1.254 255.255.255.0 duplex auto speed auto ! ip classless no ip http server ip pim bidir-enable ! ! ! line con 0 line aux 0 line vty 0 4 password redacted login ! ! end Router#

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Martin Gallagher 13 years ago

Does 10.100.1.8 know the multicast is coming, i.e. does it send IGMP joins for 225.2.1.14 and 225.2.1.24?

You do need to at least enable multicast on the interfaces

ip pim sparse-dense mode

That might just work.

"show ip mroute" and "show ip mroute count" would be helpful.

Or slightly more sophisticated:

ip pim rp-address 1.1.1.1

interface loopback0 ip address 1.1.1.1 255.255.255.255 ip pim sparse-dense-mode

ip pim sparse-dense mode

REF: ==== Multicast Quick-Start Configuration Guide

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Phillip Programmer 13 years ago

it does work if they are configured for the same subnet I do see the join going to 224.0.0.22 for the 225 groups.

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Martin Gallagher 13 years ago

So that's IGMPv3, in which case you also need to add "ip igmp version 3" to F0/0 and F0/1.

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Phillip Programmer 13 years ago

Hi, Figured it out.

All that was needed was the igmp on the interfaces and ip multicast routing The traffic I was trying to route had a ttl of 1 so once the traffic was fixed it worked

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Nick B. 13 years ago

it worked

ip multicast ttl-threshold?

I can recommend Cisco's IP Multicast Troubleshooting Guide.

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