4 mld troubleshooting help, 7 mld snooping, 1 introduction to mld snooping – PLANET XGS3-24040 User Manual

Page 430: Nooping

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Chapter 44 IPv6 Multicast Protocol

44-28

(3) Configure SwitchB:

Switch (config) #ipv6 pim multicast-routing

Switch (config) #ipv6 pim rp-address 3FFE::1

Switch (config) #interface vlan1

Switch (Config-if-Vlan1) #ipv6 address 3FFE::2/64

Switch (Config-if-Vlan1) #ipv6 pim sparse-mode

Switch (Config-if-Vlan1) #exit

Switch (config) #interface vlan2

Switch (Config-if-Vlan2) #ipv6 address 3FFA::1/64

Switch (Config-if-Vlan2) #ipv6 pim sparse-mode

Switch (Config-if-Vlan2) #ipv6 mld query-timeout 150

44.6.4 MLD Troubleshooting Help

When configuring and using MLD protocol, MLD protocol may fail to work normally due to physical

connections, incorrect configuration and so on. So, users shall note the following points:

Assure the physical connection is correct.

Assure the protocol of interface and link is UP (use show interface command)

Assure to start one kind of multicast protocol on the interface

Assure the time of the timers of each router on the same network segment is consistent; usually we

recommend the default setting.

Unicast route shall be used to carry out RPF examination for multicast protocol. So the correctness of

unicast route shall be guaranteed above all.

If all attempts fail to solve the problems on MLD, please use debug commands such as debug ipv6 MLD

event/packet, and copy DEBUG information in 3 minutes and send to Technology Service Center.

44.7 MLD Snooping

44.7.1 Introduction to MLD Snooping

MLD, the Multicast Listener Discovery Protocol, is used to realize multicasting in the IPv6. MLD is used by the

network equipments such as routers which supports multicast for multicast listener discovery, also used by

listeners looking forward to join certain multicast group informing the router to receive data packets from

certain multicast address, all of which are done through MLD message exchange. First the router send an

MLD Multicast listener Query message through a multicast address which can address all the listeners

(namely ff02::1). Once there is a listener who wishes to join the multicast address, it will send a MLD Multicast

listener Report back through the multicast address.

MLD Snooping is namely the MLD listening. The switch restricts the multicast traffic from flooding through

MLD Snooping, and forward the multicast traffic to ports associated to multicast devices only. The switch

listens to the MLD messages between multicast routers and listeners, and maintains the multicast group

forwarding list based on the listening result. The switches forwards multicast packets according to the

multicast forwarding list

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