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Users Fail to Request a Multicast Channel Because the Multicast Forwarding Entry Count on NE5000E Exceeds the Maximum

Publication Date:  2013-09-30 Views:  14 Downloads:  0
Issue Description

Networking:

                Multicast source

           /                   \

NE5000E-1     NE5000E-2

            \                  /

                  BRAS

Version: V200R003C02B609

Symptom: Users connected to the BRAS could not request a multicast channel, but could request other multicast channels. Users connected to other BRASs could request this multicast channel.
Handling Process

In normal cases, if the Loopback interface of a BRAS connected to an NE5000E was added to a multicast group in static mode, the multicast forwarding table on the NE5000E should contain the outbound interface connected to the BRAS. Information queried on NE5000E-1 was as follows:

<NE5000E-MASTER>display multicast routing-table 239.252.150.10

Multicast routing table of VPN-Instance: public net

 Total 775 entries ,33 matched

 00001. (58.223.148.6, 239.252.150.10)

       Uptime: 6w:1d

       Upstream Interface: GigabitEthernet21/1/0

       List of 33 downstream interfaces

           1:  GigabitEthernet11/1/1

           .

           .

           31:  GigabitEthernet10/0/1

           32:  GigabitEthernet17/0/1

           33:  GigabitEthernet10/0/0

<NE5000E-MASTER>display multicast forwarding-table 239.252.150.10

Multicast Forwarding Table of VPN-Instance: public net

Total 775 entries, 32 matched

00001. (58.223.148.6, 239.252.150.10)

     MID: 608, Flags: 0x0:0

     Uptime: 6w:1d, Timeout in: 00:03:29

     Incoming interface: GigabitEthernet21/1/0

     List of 32 outgoing interfaces:

           1:  GigabitEthernet11/1/1

           .

           .

           30:  GigabitEthernet17/0/0

           31:  GigabitEthernet10/0/1

           32:  GigabitEthernet10/0/0                                           

     Matched 416429493 packets(573363349404 bytes), Wrong If 3694894 packets

     Forwarded 412734599 packets(572875622160 bytes)

According to the preceding information, the multicast routing table contained 33 outbound interface, but the multicast forwarding table contained 32 outbound interface. The outbound interface that was missing in the multicast forwarding table was the one connected to the faulty BRAS. Therefore, it could be concluded that this issue was related to multicast forwarding on this NE5000E.
Root Cause

The output of the following command indicated that each multicast group in the current NE5000E version supported a maximum of 32 outbound interfaces:

<NE5000E-MASTER>display multicast forwarding-table statistics

775 entries are calculated in statistics

Max 32 OIFs can be supported in each entry

Max 8000 entries can be supported in the table
Solution

Huawei viewed information on the other NE5000E and found that the multicast routing table on NE5000E-2 had less than 20 outbound interfaces. This issue could be resolved by performing either of the following operations on the BRAS to move the configuration of the extra outbound interface in the multicast routing table on NE5000E-1 to the multicast forwarding table on NE5000E-2:

1. Add the BRAS interface connected to NE5000E-2 into the multicast group in static mode, and delete the Loopback interface from the multicast group.

2. Add the following static route on the BRAS:

ip rpf-route-static 58.223.157.9 32  GE0/0/2

                          |             |

                      Multicast source IP address      Interface connected to the NE5000E
Suggestions
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