Multicast Issues

If you are not able to get a DOUG client to talk with a comm server, try the following:

Test multicast

First, make sure that MultiCast is being passed properly. You can do this by using this handy dandy test program here.

Disable iptables

If iptables or other firewall stuff is running, it could be blocking multicast. If the test above fails, try turning off iptables and retesting with the utility above:

> service iptables stop

If the test passes now, disable iptables so it doesn't come on after rebooting, or figure out how to adjust your iptables rules to allow multicast:

> chkconfig iptables off

Examine and check comm parameters

If that test utility works, then double check that all of your comm paramters are the same on both sides. Particularly, look at the following:

• echo $MC_TAG
• echo $MC_GROUP
• echo $MC_PORT
• echo $TCP_PORT

Use a direct comm connection

If you can't get multicast to work (perhaps the config changes required are not under your control), you can use the direct comm capabilities introduced in EDGE_v1.1_DCOMM_071120. If you are using EDGE v2.3 or greater, see the article "Connecting Clients to Manager Without Multicast". If your version of EDGE is older than v2.3, you can read about the new capabilities in the release notes here.

Another thing to try from keith:

NOTE: Frankie will probably need to correct this.

# If you want to run with comm, even standalone, 
 # you need to have multicast setup
 #
 # Try this to see if multicast is working:
 % ping 224.0.0.1

 # If that fails you may try the following for the loopback device
 root> ip route add 224.0.0.0/4 dev lo
 root> echo 1 > /proc/sys/net/ipv4/ip_forward

  — [vetter][4] June 26, 2007, at 03:49 PM