MCasting blocked from VLAN to ETH 3Com NBX

Unanswered Question
Mar 12th, 2008
User Badges:

I have a new Cisco 871 with this config:

ip subnet-zero

ip cef



no ip domain lookup

ip domain name

ip multicast-routing

no ip igmp snooping




interface FastEthernet0


interface FastEthernet1


interface FastEthernet2


interface FastEthernet3


interface FastEthernet4

ip address

ip igmp version 3

duplex auto

speed auto


interface Vlan1

ip address

ip igmp static-group *

ip igmp version 3


router rip

version 2



ip classless

ip route permanent


ip http server

ip http authentication local

ip http secure-server

ip http timeout-policy idle 60 life 86400 requests 10000


no cdp run

I am trying to get a POE switch (plugged into F0) and phone (plugged into POE switch) to talk back over the F4 port to our NBX Phone system. F0 is a member of VLAN1.

I get power on the phone, and with my PC plugged into the phone tether port, I get an IP and can ping, etc. The only thing not working is the phone picking up a registration from multicasting from our NBX.

Thing is -- I know its something being blocked on this new 871 VLAN/Multi/Broad/Unicasting because if I bypass it the phone works fine.

Since this is an smaller 871 - PIM, Sparse, Dense, etc. all are not available to me.

I was hoping to get this router in our remote office this evening but I cannot for the life of me figure out how to get the router to just pass on all multicasting.

Can anyone make any recommendations?


  • 1
  • 2
  • 3
  • 4
  • 5
Overall Rating: 0 (0 ratings)
Edison Ortiz Wed, 03/12/2008 - 14:24
User Badges:
  • Super Bronze, 10000 points or more
  • Hall of Fame,

    Founding Member

F4 and F0 are on different subnets. In order to transport multicast packets between subnets, it must be routed.

You've already stated this router does not support PIM so you have 2 choices.

1) Have only one Vlan

2) Get a device that support multicast routing and enable it on both Vlans.





This Discussion