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Using IGMP but Multicast still Flooding

Occasional Visitor

Using IGMP but Multicast still Flooding

Hello everyone, Im new here.

I want to ask about the multicast, 

The first case is, I have switch HP 2530 24 port with 24 10/100 and 2 100/1000 NIC, And i have servers with bandwidth video multicast around 120-125Mbps. Servers plug into 2 gigabit NIC switch and the client into 10/100 NIC. Using IGMPv2 as the default.

The problem is,

1. When I set IGMP to mode AUTO the video is good and multicast not flooding to the client. But after 5-10 minutes the client stop receive multicast traffic.

2. And I set IGMP to mode FORWARD, Client receive multicast trafiic and video NOT stopping after 5-10 minutes. But the problem is the client only have 10/100 NIC but multicast traffic send bandwidth around 120mbps, so when i start playing video, The video is Lagging.


Any suggestion guys? maybe have a sollution for this problem?



Frequent Advisor

Re: Using IGMP but Multicast still Flooding


first of all, you will not be able to get a lag free 120Mb/s stream with a 100Mb/s NIC. When you subtract overhead, packet size, etc. you will probably get around 85-90Mb/s max. Which is around 1/4 dropped packets on the switch.

You can see the current IGMP config with "show ip igmp" on the switch. You can check if the correct clients are still in the multicast group after 5 minutes.

Does the switch have an IP address in this VLAN? If yes, it will be an IGMP querier by default. If you have multiple IGMP queriers one of them will be elected as dedicated querier. When the switch does not have an IP address, it will enable IGMP snooping in that VLAN by default (auto mode). It will then update the querier and only send the multicast traffic to the clients in the group and not on every port.


Occasional Visitor

Re: Using IGMP but Multicast still Flooding

First, Thanks for the reply.

Okay this is my configuration :

HP-2530-24(vlan-100)# sh ip igmp vlan 100

IGMP Service Protocol Info

Total VLANs with IGMP enabled : 1
Current count of multicast groups joined : 2

IGMP Filter Unknown Multicast: Enabled
IGMP Filter Unknown Multicast Status: Enabled

VLAN ID : 100
VLAN Name : iptv
IGMP version : 2
Querier Address : Querier initial wait

Active Group Addresses Type Expires Ports Reports Queries
---------------------- ---------- --------------- ---------- ------- ------- Filter 0h 3m 23s 23 2 0 Filter 0h 3m 30s 13-16,23 3101 0


Okay if i set NIC to forward it will flooding and lagging if i play the video because the bandwidth is 120mb/s.

Now if i set to Auto. What can i do or what configuration to do for client not stop after 5 minutes?


For now i not configuration the IP address and not plugin to the router just static IP servers and client.