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CLI-based Configuration Guide - IP Multicast

AR100, AR120, AR160, AR1200, AR2200, AR3200, and AR3600 V300R003

This document provides the basic concepts, configuration procedures, and configuration examples of the interfaces supported by the device.
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Multicast Routing and Forwarding

Multicast Routing and Forwarding

Devices performing different roles on an IPv6 multicast network maintain different multicast tables, including the Multicast Listener Discovery (MLD) group table, MLD routing table, multicast protocol routing table, multicast routing table, and multicast forwarding information base (MFIB). The following sections describe the functions of these tables in IPv6 multicast route management.

MLD Group and Routing Tables

A multicast router creates an MLD group entry when it receives an MLD Join message from a host. The router maintains group memberships of MLD group entries and instructs a multicast routing protocol, usually the Protocol Independent Multicast (PIM) protocol, to create corresponding (*, G) entries. The router maintains an MLD group entry for each interface provided that the interfaces have MLD enabled and have received MLD Join messages.

The following is an example of a group entry on an interface:

<Huawei> display mld group
Interface group report information
 GigabitEthernet1/0/0(FE80::4E1F:CCFF:FE44:FFF0):
  Total 1 MLD Group reported
   Group Address:FF1E::1
    Last Reporter:FE80::1
    Uptime:00:13:20
    Expires:00:04:00 

Table 8-2 explains the fields of this MLD group entry.

Table 8-2  Description of fields in the MLD group entry
Field Description
Group Address Indicates the address of the group that an interface has joined.
Last Reporter Indicates the IP address of the last user that sent an MLD Join message to the group.
Uptime Indicates the time elapsed since the group was created.
Expires Indicates the time remaining before the group will be aged out.

MLD also maintains an MLD routing table. An interface is included in an MLD routing entry only when PIM is not enabled on the interface. The MLD routing table increases the number of available outbound interfaces for multicast routing entries. The following is an example of an MLD routing entry:

<Huawei> display mld routing-table
Routing table
 Total 2 entries

 00001. (FC00:AA::123, FF44::)
       List of 1 downstream interface in include mode
        GigabitEthernet1/0/0 (FE80::EE:53),
                   Protocol: STATIC

 00002. (*, FF55::)
       List of 1 downstream interface
        GigabitEthernet1/0/0 (FE80::EE:53),
                   Protocol: MLD

Table 8-3 explains the fields in this MLD routing entry.

Table 8-3  Description of fields in the MLD routing entry
Field Description
00001. (FC00:AA::123, FF44::) 00001 is the entry number, and (FC00:AA::123, FF44::) is an (*, G) entry, where * indicates any source and G indicates a group address.
List of 1 downstream interface Lists the downstream interfaces in the routing entry.
Protocol: MLD Indicates the protocol that generates the downstream interfaces.

According to the preceding information, the downstream interface is generated by MLD, indicating that PIM is not enabled on the interface. If PIM is enabled on an interface, the routing entries of the interface are maintained by PIM.

Multicast Protocol Routing Table

Multicast routing protocols maintain their own routing tables to guide multicast routing and forwarding. PIM is the most widely used multicast routing protocol. The following is an example of a PIM routing table:

<Huawei> display pim ipv6 routing-table
VPN-Instance: public net
 Total 0 (*, G) entry; 1 (S, G) entry

 (FC00::2, FFE3::1)
     Protocol: pim-sm, Flag: SPT LOC ACT
     UpTime: 00:04:24
     Upstream interface: GigabitEthernet2/0/0
         Upstream neighbor: FE80::A01:100:1
         RPF prime neighbor: FE80::A01:100:1
     Downstream interface(s) information:
     Total number of downstreams: 1
         1: GigabitEthernet1/0/0
             Protocol: pim-sm, UpTime: 00:04:24, Expires: 00:02:47

Table 8-4 explains the fields in this PIM routing entry.

Table 8-4  Description of fields in the PIM routing entry
Field Description
(FC00::2, FFE3::1) Indicates an (S, G) entry, where FC00::2 is the source address and FFE3::1 is the group address.
Protocol: pim-sm The first Protocol field in an entry indicates the protocol that generates the entry, and the second Protocol field indicates the protocol that generates the downstream interfaces.
Flag: SPT LOC ACT Indicates the flag of the PIM routing entry.
UpTime: 00:04:24 The first UpTime field in an entry indicates how long the entry has existed, and the second UpTime field indicates how long a downstream interface has existed.
Upstream interface: GigabitEthernet2/0/0 Indicates the upstream interface pointing to the multicast source.
Upstream neighbor: FE80::A01:100:1 NULL indicates that no upstream neighbor is available.
RPF prime neighbor: FE80::A01:100:1 NULL indicates that no reverse path check (RPF) neighbor is available.
Downstream interface(s) information: Indicates information about downstream interfaces toward receivers.
Total number of downstreams: 1 Indicates the number of downstream interfaces.
Expires: 00:02:47 Indicates the aging time of a downstream interface.

For details about PIM routing entries, see Configuring IPv6 PIM-SM in the PIM feature description.

Multicast Routing Table

A multicast routing table is generated and maintained by the multicast route management module of a router. If a router supports multiple multicast protocols, its multicast routing table contains the optimal routes selected from the routing tables of these protocols.

In unicast routing, routing tables of various routing protocols, such as Open Shortest Path First version 3 (OSPFv3) and Routing Information Protocol next generation (RIPng), constitute an IP routing table. Similarly, routing tables of different multicast protocols constitute a multicast table. Routers deliver multicast routing entries to their MFIBs to guide multicast data forwarding. The following is an example of a multicast routing table:

<Huawei> display multicast ipv6 routing-table
IPv6 multicast routing table
 Total 1 entry

 00001. (FC00::2, FFE3::1)
       Uptime: 00:00:14
       Upstream Interface: GigabitEthernet1/0/0
       List of 1 downstream interface
           1:  GigabitEthernet2/0/0

Table 8-5 explains the fields in this multicast routing entry.

Table 8-5  Description of fields in the multicast routing entry
Field Description
00001. (FC00::2, FFE3::1) 00001 is the entry number, and (FC00::2, FFE3::1) is an (S, G) entry, where S indicates a source address and G indicates a group address.
Uptime: 00:00:14 Indicates the time elapsed since the multicast routing entry was updated.
Upstream Interface: GigabitEthernet1/0/0 Indicates the upstream interface pointing to the multicast source.
List of 1 downstream interface Indicates the downstream interfaces toward receivers.

MFIB

An MFIB is created and maintained by the route management module of a router according to multicast routing information. Routers forward multicast data according to their MFIBs. An MFIB has the same functions as a unicast FIB. The following is an example of an MFIB.

<Huawei> display multicast ipv6 forwarding-table
IPv6 Multicast Forwarding Table
Total 2 entries, 2 matched

00001. (FC00:1::3, FF1E::1)
     MID: 10, Flags: ACT
     Uptime: 02:54:43, Timeout in: 00:02:27
     Incoming interface: GigabitEthernet1/0/0
     List of 1 outgoing interfaces:
       1: LoopBack0
         Activetime: 00:23:15
     Matched 0 packets(0 bytes), Wrong If 0 packets
     Forwarded 0 packets(0 bytes)

00002. (FC00:1::3, FF1E::2)
     MID: 11, Flags: ACT
     Uptime: 00:00:03, Timeout in: 00:03:26
     Incoming interface: GigabitEthernet2/0/0
     List of 1 outgoing interfaces:
       1: LoopBack0
         Activetime: 00:23:15
     Matched 38264 packets(1071392 bytes), Wrong If 0 packets
     Forwarded 38264 packets(1071392 bytes)

Table 8-6 explains the fields in this multicast forwarding entry.

Table 8-6  Description of fields in the multicast forwarding entry
Field Description

00001. (FC00:1::3, FF1E::1)

00001 is the entry number, and (FC00:1::3, FF1E::1) is an (S, G) entry, where S indicates a source address and G indicates a group address.

MID: 10

Indicates the unique identifier of the multicast forwarding entry in the MFIB. It is used to rapidly search the MFIB.
Flags: ACT Indicates the flag of the multicast forwarding entry.
UpTime: 02:54:43 Indicates how long the multicast forwarding entry has existed.

Timeout in: 00:03:26

Indicates how soon the multicast forwarding entry will time out.
Incoming interface: GigabitEthernet2/0/0 Indicates the inbound interface in the multicast forwarding entry.

List of 1 outgoing interfaces

Lists the outbound interfaces toward receivers.
Activetime: 00:23:15 Indicates how long an outbound interface has existed.

Matched 38264 packets(1071392 bytes)

Indicates the number of packets that match the multicast forwarding entry.

Wrong If 0 packets

Indicates the number of packets that arrive on the incorrect inbound interfaces.

Forwarded 38264 packets(1071392 bytes)

Indicates the number of forwarded packets.

The preceding information shows that multicast data is forwarded according to the MFIB. Each multicast forwarding entry records statistics about packets that are forwarded according to the entry.

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Updated: 2019-03-06

Document ID: EDOC1100069332

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