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1.1       misho       1: > $Id: README.debug,v 1.4 2002/11/17 20:01:31 pavlin Exp $
                      2: 
                      3: This file contains some hints how to debug your multicast routing.
                      4: 
                      5: **NOTE:** currently, it is very incomplete.  If something is missing
                      6:              and/or unclear, email to the current maintainer of pimd or
                      7:              file an issue in the GitHub issue tracker.
                      8: 
                      9: 1. Make sure that the TTL of the sender is large enough to reach the
                     10:    receiver. E.g., if the sender and the receiver are separated by a
                     11:    two routers in the middle, the TTL of the data packets transmitted
                     12:    by the sender must be at least 3.
                     13: 
                     14: 2. Make sure the receiver sends IGMP join (membership report) for the
                     15:    group(s) it wants to receive.  Use tcpdump on the router closest to
                     16:    the receiver to make sure.  Sometimes buggy IGMP snooping switches,
                     17:    or cloud provider networks, filter out multicast in general, or all
                     18:    control traffic (IGMP/PIM) in particular.
                     19: 
                     20: 3. Before you start the multicast routing daemon, verify the kernel
                     21:    config, the following settings should be activated:
                     22: 
                     23:    - On Linux:
                     24: 
                     25:                 CONFIG_IP_MROUTE=y
                     26:                 CONFIG_IP_PIMSM_V1=y
                     27:                 CONFIG_IP_PIMSM_V2=y
                     28:                 CONFIG_IP_MROUTE_MULTIPLE_TABLES=y    # Optional
                     29: 
                     30:      Check the list of multicast capable interfaces:
                     31: 
                     32:                 cat /proc/net/dev_mcast
                     33: 
                     34:    - On *BSD:
                     35: 
                     36:                 options    MROUTING         # Multicast routing
                     37:                 options    PIM              # Enable for pimd
                     38: 
                     39:    - Start the multicast routing daemon in debug mode.  E.g., `pimd -dall`
                     40:         or if you just want to see some subystems: `pimd -drpf,mrt -s7`
                     41: 
                     42: 4. After you start the multicast routing daemon
                     43: 
                     44:    - Are the multicast vifs correctly installed in the kernel:
                     45: 
                     46:         - On Linux:
                     47: 
                     48:                 cat /proc/net/ip_mr_vif
                     49: 
                     50:         - On *BSD:
                     51: 
                     52:                 netstat -gn
                     53: 
                     54:  - Is multicast forwarding enabled on those vifs:
                     55: 
                     56:         - On Linux:
                     57: 
                     58:                 sysctl net.ipv4.conf.eth0.mc_forwarding
                     59: 
                     60:           For each of the enabled interfaces.  If it returns zero, the
                     61:           multicast forwarding on that interface is not working.
                     62: 
                     63:         - On *BSD:
                     64: 
                     65:                 sysctl net.inet.ip.forwarding
                     66:                 sysctl net.inet.ip.mforwarding      # Only OpenBSD
                     67: 
                     68:  - Is the PIM multicast routing daemon exchanging `PIM_HELLO` messages
                     69:    with its neighbors?  Look into the debug messages output; if
                     70:    necessary, use `tcpdump` as well.
                     71: 
                     72:  - Are the Bootpstrap messages received by all PIM-SM daemons?
                     73: 
                     74:  - If a Bootstrap message is received, is it accepted, or is it
                     75:    rejected because of a wrong iif?
                     76: 
                     77:  - After a while, does the Cand-RP set contain the set of RPs?
                     78: 
                     79:  - After the first multicast packets are received, is there `CACHE_MISS`
                     80:    signal from the kernel to the user-level daemon?
                     81: 
                     82:  - After the `CACHE_MISS` signal, are the MFC (Multicast Forwarding Cache)
                     83:    entries installed in the kernel?
                     84:  
                     85:         - On Linux:
                     86: 
                     87:                 cat /proc/net/ip_mr_cache
                     88: 
                     89:         - On *BSD:
                     90: 
                     91:                 netstat -gn
                     92: 
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