$Id: index.html,v 1.2 2005/07/18 04:55:37 suz Exp $
This troubleshooting guide classifies the tips for IPv6 multicast troubleshooting into three categories.
KAME transmits IPv6 multicast packets with hoplimit = 1, unless application explicitly specifies some hoplimit value. This fact means that IPv6 multicast packets don't go over a router by default due to a lack of hoplimit.
So if you cannot receive packets from a multicast packet sender, please check the hoplimit first!
Some router does not generate ICMPv6 Packet-Too-Big Error for multicast packets, to prevent ICMPv6 Error packet generation for multicast packets (Precisely speaking, it's against ICMPv6 Spec(draft-ietf-ipngwg-icmp-v6-04.txt section 2.4 (e)). Such systems, however, assumes that multicast senders transmit multicast packets less than 1280 Byte).
If your network has such a router, you should take a great care to see if the size of the transmitted packets shouldn't exceed more than 1280 bytes.
Sometimes people forget to start IPv6 multicast receiver application:-)
Especially when there's a MLD snooping switch between a host and its accomodating router, you should take care of the MLD version.
In case of pim6sd, you can check the mapping using "pim6stat" command.
# pim6stat .... ---------------------------RP-Set---------------------------- Current BSR address: 2001:200:0:8000::2000:1 Prio: 10 Timeout: 160 RP-address(Upstream)/Group prefix Prio Hold Age YOUR:RP:ROUTER::ADDR(fe80::UPST:REAM:RTR%IFNAME) ffxx:x:xxxx::/96 0 150 150
c.f.) the equivalent command on other implementations. (Other vendor info is welcome!)
- AlaxalA AX-series: show ipv6 pim rendezvous-point mapping
- Allied Telesys SB-series: show ipv6 pim rendezvous-point mapping
- Cisco IOS-series: show ipv6 pim group-map
- Cisco IOS XR-series: show pim ipv6 group-map
- Foundry: show ipv6 pim group(?)
- Hitachi GR/GS-series: show ipv6 pim rendezvous-point mapping
- Juniper JunOS: show pim rps inet6
- NEC IP8800-series: show ipv6 pim rp-mapping
If you cannot find out the right Group-RP mapping, you should check the following things: