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Switch support

The Cisco 3560-E, 3750-E, 4500 (with Sup 6-e), and 4900M support MLD v1 and v2 snooping in hardware. See this document for configuration instructions. The Cisco 6500 (running IOS 12.2(18)SXE and the Sup-720) and 7200 and 7600 (running IOS 12.2(33)SRA) also support MLDv2 snooping.

The Foundry FastIron LS claims to support MLD v1 and v2 snooping, but it's unclear if this is done in hardware.

The HP Procurve 3500, 3500yl, 5400zl, 6200yl, 6600, and 8200zl support MLDv1 and v2 snooping.

The 3com 4500G and 4800G supports MLDv1 and v2 snooping.

The D-Link DES-3528, DES-3800, DGS-3100, DGS-3200, DGS-3400, and DGS-3600 series switches support MLD snooping.

The Netgear GSM7328S and GSM7352S switches support MLDv1 and v2 snooping.

Address format

General

Defined in RFC 4291, section 2.7

|    8   |  4 |  4 |                     112                     |
+--------+----+----+---------------------------------------------+
|11111111|flgs|scop|                  group ID                   |
+--------+----+----+---------------------------------------------+

8-bit Multicast Prefix (FF)

4-bit flags:

    0: Reserved
    R: 1 = multicast address embeds the address of the Rendezvous Point (RFC 3956)
    P: 0 = multicast address is not based on unicast prefix; 1 = multicast address is based on prefix (RFC 3306)
    T: 0 = Permanent multicast address (registered with IANA); 1 = temporary multicast address

    Notes:
        If P=1, T must be set to 1.
        If R=1, P and T be set to 1.

4-bit scope:

    0 reserved
    1 Interface-Local scope
    2 Link-Local scope
    3 reserved
    4 Admin-Local scope
    5 Site-Local scope
    6 (unassigned)
    7 (unassigned)
    8 Organization-Local scope
    9 (unassigned)
    A (unassigned)
    B (unassigned)
    C (unassigned)
    D (unassigned)
    E Global scope
    F reserved

112-bit group ID

The format of the group ID varies depending on the nature of the multicast address.

Unicast-Prefix-based addressing

This format is defined in RFC 3306. It is a method of allocating multicast addresses based on an organization's unicast prefix. Penn State's IPv6 unicast prefix is 2610:8::/32

If using unicast-prefix-based multicast addressing, the P flag must be set.

The group id is formatted as:

		|   8    | 8  |       64       |    32    |
		+--------+----+----------------+----------+
		|reserved|plen| network prefix | group ID |
		+--------+----+----------------+----------+

8-bits of zero
8-bit prefix length (must not be greater than 64)
64-bit unicast prefix
32-bit group ID

The group ID should be allocated based on guidelines in RFC 3307.

Embedded RP-based addressing

This format is defined in RFC 3956.

If the R-bit is set, the group ID is defined as:

		|  4 |  4 | 8  |       64       |    32    |
		+----+----+----+----------------+----------+
		|rsvd|RIID|plen| network prefix | group ID |
		+----+----+----+----------------+----------+

4-bits of zero
4-bit Rendezvous Point Interface ID
8-bit prefix length (must not be 0 and must not be greater than 64)
64-bit prefix
32-bit group ID

The group ID should be allocated based on guidelines in RFC 3307.