mld access-limit

Function

The mld access-limit command sets the maximum number of MLD group memberships that can be created on an interface.

The undo mld access-limit command cancels the setting.

By default, the maximum number of MLD group memberships on an interface is not configured.

Format

mld access-limit number [ except { ExceptAclNumValue | acl6-name ExceptAclNameValue } ]

undo mld access-limit [ number [ except { ExceptAclNumValue | acl6-name ExceptAclNameValue } ] ]

Parameters

Parameter	Description	Value
number	Specifies the maximum number of MLD entries that can be created on an interface.	The value is an integer that ranges from 1 to 16384.
except ExceptAclNumValue	Specifies the number of a basic or an advanced ACL.	The number of a basic ACL is an integer that ranges from 2000 to 2999. A basic ACL filters only group addresses and does not distinguish (*, G) entries and (S, G) entries. The sequence number of an advanced ACL ranges from 3000 to 3999. Only (S, G) entries on the interface are filtered.
acl6-name ExceptAclNameValue	Specifies the name of a named ACL.	The value is a string of 1 to 64 case-sensitive characters, spaces not supported. The value must start with a letter (a to z or A to Z).

Parameter

Description

Value

number

Specifies the maximum number of MLD entries that can be created on an interface.

The value is an integer that ranges from 1 to 16384.

except ExceptAclNumValue

Specifies the number of a basic or an advanced ACL.

The number of a basic ACL is an integer that ranges from 2000 to 2999. A basic ACL filters only group addresses and does not distinguish (*, G) entries and (S, G) entries. The sequence number of an advanced ACL ranges from 3000 to 3999. Only (S, G) entries on the interface are filtered.

acl6-name ExceptAclNameValue

Specifies the name of a named ACL.

The value is a string of 1 to 64 case-sensitive characters, spaces not supported. The value must start with a letter (a to z or A to Z).

Views

100ge sub-interface view, 100GE interface view, 10GE sub-interface view, 10GE interface view, 200GE sub-interface view, 25GE sub-interface view, 25GE interface view, 400GE sub-interface view, 400GE interface view, 40GE sub-interface view, 40GE interface view, 50GE sub-interface view, 50GE interface view, Eth-Trunk sub-interface view, Eth-Trunk interface view, FlexE interface view, GE optical interface view, GE sub-interface view, GE interface view, GE electrical interface view, Global VE sub-interface view, PW-VE sub-interface view, VE sub-interface view, VLANIF interface view

Default Level

2: Configuration level

Task Name and Operations

Task Name	Operations
igmp	write

Usage Guidelines

Usage Scenario

When a large number of users watch multiple programs at the same time, a large amount of bandwidth of the router is occupied, which degrades the performance of the router. To prevent this problem, run the mld access-limit command on the router interface to limit the number of MLD entries. When receiving an MLD Join message, the router checks whether the number of entries exceeds the limit. If the number of entries does not exceed the limit, the router sets up a member relationship and forwards the data flow of the multicast group to the user. This improves the clarity and stability of programs for users who have joined multicast groups.

The methods of counting the number of MLD entries are as follows:

Each (*, G) entry and each (S, G) entry are counted separately as an interface entry.
The (*, G) entries used for SSM-Mapping are not counted. The (S, G) entries generated based on mapping are counted as one interface entry.

Prerequisites

The multicast ipv6 routing function has been enabled using the multicast routing-enable command.

Precautions

To use except, an ACL must be configured to filter MLD Join messages received by an interface. If except is specified, the maximum number of MLD entries is not effective for multicast groups that match the specified ACL. If except is not specified, the maximum number is effective for all multicast groups, including source-specific groups.

The mld access-limit command requires an ACL configured using the acl (basic ACL) or acl (advanced ACL) command. To use a numbered ACL, perform either of the following operations to configure an ACL rule:

In the basic ACL view, specify the source parameter in the rule command to set the range of multicast groups whose MLD entries are not limited.
In the advanced ACL view, specify the source parameter in the rule command to set the range of sources that are allowed to send multicast data to multicast groups. Specify the destination parameter in the rule command to set the range of multicast groups whose MLD entries are not limited.
If the mld access-limit command is run more than once, the latest configuration overrides the previous one.

Example

# Create a named ACL6 myacl, and configure a rule for the named ACL6 to allow hosts to receive messages sent by multicast source 100::1 to multicast group FF1E::/120. Specify 1024 as the maximum number of MLD entries that can be created on GE 0/1/0, and exclude MLD entries with the multicast group address FF1E::/120 from this maximum number limit.

<HUAWEI> system-view
[~HUAWEI] multicast ipv6 routing-enable
[*HUAWEI] acl ipv6 name myacl
[*HUAWEI-acl6-advance-myacl] rule permit ipv6 source 100::1 128 destination FF1E::1 120
[*HUAWEI-acl6-advance-myacl] quit
[*HUAWEI] interface GigabitEthernet 0/1/0
[*HUAWEI-GigabitEthernet0/1/0] ipv6 enable
[*HUAWEI-GigabitEthernet0/1/0] mld access-limit 1024 except acl-name myacl

# Specify 1024 as the maximum number of MLD entries that can be created on GE 0/1/0.

<HUAWEI> system-view
[~HUAWEI] multicast ipv6 routing-enable
[*HUAWEI] interface GigabitEthernet 0/1/0
[*HUAWEI-GigabitEthernet0/1/0] ipv6 enable
[*HUAWEI-GigabitEthernet0/1/0] mld access-limit 1024