Multicast issue across VLANs

imkazi
imkazi used Ask the Experts™
on
Hi,
On my internal network connecting Server's to the Core Switch, I have a problem wherein, multicast traffic is received by the receiver Server in the same VLAN as the sender server, but a receiver Server in a different VLAN does not receive it. I believe I have configured all the required commands at the core and server edge switch level. Below I have included the network details and configuration details pertaining to Multicast. As far as Unicast goes, all communication between the same servers works fine, even across VLANs.
Network Topology -->
Core switch  6506
Server Edge switch  Cisco 3750 (connected to Core via trunked Fiber link)
Server Connectivity -->
Sender Server 1  VLAN 30
Receiver Server 1  VLAN 30
Receiver Server 2  VLAN 69 (does not recieve multicast traffic)

I did a sniff on the switch-port connecting the "receiver server 2" and noticed that the port itself receives the Multicast traffic, but for some reason the Server application does not read that packet from the port. I do NOT doubt the Server application because the same application is running on "receiver server 1" in the same VLAN and receives the Multicast message.

Any help will be appreciated...
Core Switch -->
ip multicast-routing 
no ip igmp snooping
mls ip multicast flow-stat-timer 9
 
interface Vlan30
 description Server 1 and 2 VLAN
 ip address 192.168.30.2 255.255.255.0
 ip pim sparse-dense-mode
 ip pgm router
 no ip igmp snooping
 standby 1 ip 192.168.30.1
 standby 1 priority 105
 standby 1 preempt delay minimum 10
 
interface Vlan69
 description server 3 VLAN
 ip address 172.16.69.2 255.255.255.0
 ip pim sparse-dense-mode
 ip pgm router
 no ip igmp snooping
 standby 1 ip 172.16.69.1
 standby 1 priority 105
 standby 1 preempt delay minimum 10
 
ip pim rp-address core IP
ip pim sparse sg-expiry-timer 57600
 
Server Edge Switch Multicast Configuration -->
ip multicast-routing distributed
no ip igmp snooping
 
ip pim rp-address core IP

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Commented:
Why did you disable "igmp snooping" on the edge switch facing to "Receiver Server 2"?
IGMP Snooping (or CGMP) is needed to interface between the servers IGMP and the Routers PIM.

Which multicast addresses are you using? Could they be in 224.0.0.0/24 - this is link local and will not be routed thru L3.
Don JohnstonInstructor
Top Expert 2015

Commented:
>I did a sniff on the switch-port connecting the "receiver server 2" and noticed that the port itself receives the Multicast traffic, but for some reason the Server application does not read that packet from the port.

Then it's not a switching/routing issue. For whatever reason the client application (running on server 2) isn't registering the multicast address with the NIC. Check the application configuration on Server 2.

Author

Commented:
I was busy doing some tests and seem to have narrowed down the issue to the PGM protocol, or atleast I think so. I tried testing multicast messaging using another utility from Microsoft called "mcast" which uses UDP for communcation, unlike the application I need to work, which uses TCP over the PGM protocol. The mcast worked just fine across VLANs in the same environment. The "IP PGM router" command which I have mentioned in the core switch is not available in my Edge switc, so I guess it is this command that is needed on the Edge switch for the PGM protocol to work across VLAN.
Do let me know what you think?
Regards,
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Author

Commented:
Hi All, any advice, please.
Thanks,
Instructor
Top Expert 2015
Commented:
If all the layer 3 devices don't support PGM, then you won't be able to use that protocol.

Author

Commented:
Don,

The version on my edge switch is Cisco IOS Software, C3750 Software (C3750-IPSERVICES-M), Version 12.2(35)SE5
Do you know which IOS version will bring me the PGM protocol support?

Thanks,

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