[c-nsp] Multicast Packet Loss over GRE

[Dav A]

Hi All, 

Was hoping someone can provide some advice with regards to troubleshooting a 
particularly painful multicast issue. 


The set up isnt particularly complex:

Servers <>Switch<>Tunnel router (RP) >>>>> GRE over WAN >>>> Tunnel router 
<>Switch<>Servers

The tunnel router interfaces have been configured with the TCP mss adjust mtu 
command and set to 1400. 


Everythings been up and working for a year but recently weve been experiencing 
issues with mcast and can see dropped packets when using a sniffer on the 
server. The suspicion lies with the WAN provider who has recently made changes 
but extended pings/sweeps over the WAN shows no drops.

Has anyone any ideas or experience on how to troubleshoot packet loss over GRE 
for multicast? 


Regards, David