Snooping IGMP and VLAN in the hardware switch


#1

Hello!

# swconfig list
Found: switch0 - ag71xx-mdio.0
# swconfig dev switch0 get igmp_snooping
0

When igmp_snooping disabled I see IGMP packet in the all vlan:
vlan 1:

# tcpdump -n -i eth0.1 'igmp'
tcpdump: verbose output suppressed, use -v or -vv for full protocol decode
listening on eth0.1, link-type EN10MB (Ethernet), capture size 262144 bytes
14:37:57.887185 IP 192.168.1.35 > 232.35.246.37: igmp v2 report 232.35.246.37
14:37:58.376251 IP 192.168.1.35 > 232.35.246.37: igmp v2 report 232.35.246.37
14:38:04.591387 IP 192.168.1.35 > 224.0.0.2: igmp leave 232.35.246.37
14:38:04.592926 IP 192.168.1.1 > 232.35.246.37: igmp query v2 [gaddr 232.35.246.37]

the same in the vlan 0:

# tcpdump -n -i eth0 'igmp'
tcpdump: verbose output suppressed, use -v or -vv for full protocol decode
listening on eth0, link-type EN10MB (Ethernet), capture size 262144 bytes
14:37:57.887185 IP 192.168.1.35 > 232.35.246.37: igmp v2 report 232.35.246.37
14:37:58.376251 IP 192.168.1.35 > 232.35.246.37: igmp v2 report 232.35.246.37
14:38:04.591387 IP 192.168.1.35 > 224.0.0.2: igmp leave 232.35.246.37

After enable igmp_snooping:

# swconfig dev switch0 set igmp_snooping 1
# swconfig dev switch0 get igmp_snooping
1

I don't see the igmp packets on the vlan 1:

# tcpdump -n -i eth0.1 'igmp'
tcpdump: verbose output suppressed, use -v or -vv for full protocol decode
listening on eth0.1, link-type EN10MB (Ethernet), capture size 262144 bytes

But packets are in the vlan 0:

# tcpdump -n -i eth0 'igmp'
tcpdump: verbose output suppressed, use -v or -vv for full protocol decode
listening on eth0, link-type EN10MB (Ethernet), capture size 262144 bytes
14:46:58.219388 IP 192.168.1.35 > 232.35.246.37: igmp v2 report 232.35.246.37
14:46:58.385012 IP 192.168.1.35 > 232.35.246.37: igmp v2 report 232.35.246.37
14:47:01.525315 IP 192.168.1.35 > 224.0.0.2: igmp leave 232.35.246.37

Why igmp packets do not get into vlan 1 when switch igmp_snooping enabled?


Multicast/switch/snooping/vlan problem. Bug?