HP 6125G HP 6125G & 6125G/XG Blade Switches IP Multicast Configuration - Page 227

Enabling fast-leave processing, Disabling a port from becoming a dynamic router port

Page 227 highlights

NOTE: Unlike a static member port, a port that you configure as a simulated member host ages out like a dynamic member port. Enabling fast-leave processing The fast-leave processing feature enables the switch to process MLD done messages quickly. After the fast-leave processing feature is enabled, when the switch receives an MLD done message on a port, it immediately removes that port from the forwarding entry for the multicast group specified in the message. Then, when the switch receives MLD multicast-address-specific queries for that multicast group, it does not forward them to that port. On a port that has only one host attached, you can enable fast-leave processing to save bandwidth and resources. However, on a port that has multiple hosts attached, you should not enable fast-leave processing if you have enabled dropping unknown IPv6 multicast data globally or for the port. Otherwise, if a host on the port leaves an IPv6 multicast group, the other hosts attached to the port in the same IPv6 multicast group cannot receive the IPv6 multicast data for the group. Enabling fast-leave processing globally Step 1. Enter system view. 2. Enter MLD-snooping view. 3. Enable fast-leave processing. Command system-view mld-snooping fast-leave [ vlan vlan-list ] Enabling fast-leave processing on a port Remarks N/A N/A Disabled by default Step 1. Enter system view. 2. Enter Layer 2 Ethernet interface view or Layer 2 aggregate interface view. Command system-view interface interface-type interface-number 3. Enable fast-leave processing. mld-snooping fast-leave [ vlan vlan-list ] Remarks N/A Use either command. Disabled by default. Disabling a port from becoming a dynamic router port The following problems exist in a multicast access network: • After receiving an MLD general query or IPv6 PIM hello message from a connected host, a router port becomes a dynamic router port. Before its timer expires, this dynamic router port receives all multicast packets within the VLAN where the port belongs, and forwards them to the host, affecting normal multicast reception of the host. • In addition, the MLD general query and IPv6 PIM hello message that the host sends affects the multicast routing protocol state on Layer 3 devices, such as the MLD querier or DR election, and might further cause network interruption. 216

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216
NOTE:
Unlike a static member port, a port that you configure as a simulated member host ages out like a dynamic
member port.
Enabling fast-leave processing
The fast-leave processing feature enables the switch to process MLD done messages quickly. After the
fast-leave processing feature is enabled, when the switch receives an MLD done message on a port, it
immediately removes that port from the forwarding entry for the multicast group specified in the message.
Then, when the switch receives MLD multicast-address-specific queries for that multicast group, it does not
forward them to that port.
On a port that has only one host attached, you can enable fast-leave processing to save bandwidth and
resources. However, on a port that has multiple hosts attached, you should not enable fast-leave
processing if you have enabled dropping unknown IPv6 multicast data globally or for the port.
Otherwise, if a host on the port leaves an IPv6 multicast group, the other hosts attached to the port in the
same IPv6 multicast group cannot receive the IPv6 multicast data for the group.
Enabling fast-leave processing globally
Step
Command
Remarks
1.
Enter system view.
system-view
N/A
2.
Enter MLD-snooping view.
mld-snooping
N/A
3.
Enable fast-leave processing.
fast-leave
[
vlan
vlan-list
]
Disabled by default
Enabling fast-leave processing on a port
Step
Command
Remarks
1.
Enter system view.
system-view
N/A
2.
Enter Layer 2 Ethernet
interface view or Layer 2
aggregate interface view.
interface
interface-type
interface-number
Use either command.
3.
Enable fast-leave processing.
mld-snooping fast-leave
[
vlan
vlan-list
]
Disabled by default.
Disabling a port from becoming a dynamic router port
The following problems exist in a multicast access network:
After receiving an MLD general query or IPv6 PIM hello message from a connected host, a router
port becomes a dynamic router port. Before its timer expires, this dynamic router port receives all
multicast packets within the VLAN where the port belongs, and forwards them to the host, affecting
normal multicast reception of the host.
In addition, the MLD general query and IPv6 PIM hello message that the host sends affects the
multicast routing protocol state on Layer 3 devices, such as the MLD querier or DR election, and
might further cause network interruption.