README.debug

  $Id: README.debug,v 1.4 2002/11/17 20:01:31 pavlin Exp $

This file contains some hints how to debug your multicast routing.

XXX: currently, it is very incomplete. If something is missing and/or
     is unclear, send email to the current maintainer of pimd.
     (see file AUTHORS for email address).

1. All systems
 - Make sure that the TTL of the sender is large enough to reach the
   receiver. E.g., if the sender and the receiver are separated by a
   two routers in the middle, the TTL of the data packets transmitted
   by the sender must be at least 3.

2. Linux

2.1 Before you start the multicast routing daemon
 - Check the kernel config, the following settings should be activated:
    * CONFIG_IP_MROUTE=y
    * CONFIG_IP_PIMSM_V1=y
    * CONFIG_IP_PIMSM_V2=y

 - Check the list of multicast capable interfaces:
	cat /proc/net/dev_mcast

 - Start the multicast routing daemon in debug mode (e.g., pimd -d all)

2.2 After you start the multicast routing daemon
 - Are the multicast vifs correctly installed in the kernel:
	cat /proc/net/ip_mr_vif

 - Is multicast forwarding enabled on those vifs:
	cat /proc/sys/net/ipv4/conf/eth0/mc_forwarding

    for each of the enabled interfaces. If it returns zero, the multicast
    forwarding on that interface is not working.

 - Is the PIM multicast routing daemon exchanging PIM_HELLO
   messages with its neighbors?
   (Look into the debug messages output; if necessary, use tcpdump as well).

 - Are the Bootpstrap messages received by all PIM-SM daemons?

 - If a Bootstrap message is received, is it accepted, or is it
   rejected because of a wrong iif?
 - After a while, does the Cand-RP set contain the set of RPs?

 - After the first multicast packets are received, is there CACHE_MISS
   signal from the kernel to the user-level daemon?

 - After the CACHE_MISS signal, are the MFC (Multicast Forwarding Cache)
   entries installed in the kernel?
	cat /proc/net/ip_mr_cache