Wired Intelligent Edge (Campus Switching and Routing)

How to configure Multicast MLD snooping on MAS switch?

Aruba Employee
Aruba Employee

Introduction :


This article is applied from MAS switch on code and above.


1. MAS supports MLD snooping. MLD snooping prevents multicast flooding on Layer 2 network.

2. Multicast traffic is treated as broadcast traffic at Layer 2 – so all streams could be flooded to all ports on that VLAN.

3. Without snooping ,End-hosts that happen to be in the same VLAN when multicast flooding occurs would be receiving all the streams - only to be discarded.

4. When MLD snooping is enabled, the MAS will become MLD-aware and will process the multicast frames as received.

            a) This needs to be done to correctly process all MLD membership reports and MLD done messages.

            b) MLD snooping table is maintained at hardware for line rate traffic forwarding

5. Multicast routers and multicast receivers associated with each IPv6 multicast group will be learned dynamically

6. Relays MLD report from all receiver per group to the multicast router port.

7. Query from multicast router will be relayed to all ports in the VLAN.

8. When MLD query message is seen, it becomes a mrouter port in MLD snooping table.

9. Mrouter port can be detected based on MLD query or PIMsmV6 hello message

10. Static mrouter port configuration is supported



Only MLDv1  is supported for snooping at FCS.
MAS does not behave properly for IPv6 multicast addresses with last 4 bytes same.
For example: FF15::1 and FF1E::1.

  • MLD snooping on un-trust port not supported.
  • MLD-snooping proxy not supported at FCS

Environment :


In a Typical Environment of client using Multicast services extensively.


Network Topology:




Configuration from CLI


(ArubaMAS) (config) #vlan-profile mld-snooping-profile MLD_SNOOP

(ArubaMAS) ((mld-snooping-profile "MLD_SNOOP“) #snooping


 Per VLAN basis

(ArubaMAS) (config) #vlan 444

(ArubaMAS) (VLAN “444") # mld-snooping-profile MLD_SNOOP


  • MLD snooping is enabled per-VLAN basis.
  • MLD snooping static mrouter configuration


(ArubaMAS) (config) #interface gigabitethernet 0/0/22

(ArubaMAS) (gigabitethernet "0/0/22") #mld-snooping mrouter-vlan ?

<vlan-list>             List of VLANs to associate the mrouter port

add                     Add VLANs to the current list

delete                  Remove VLANs from the current list

(ArubaMAS) (gigabitethernet "0/0/22") #mld-snooping mrouter-vlan 444


Answer :


From the above config; we could notice MLD snooping is configured on MAS switch.


Verification :


User-configurable timers for query and interval parameters can be configured in the MLD snooping profile. They can be viewed by following CLI command:


(ArubaMAS) # show vlan-profile mld-snooping-profile MLD_SNOOP


mld-snooping-profile "MLD_SNOOP"


Parameter                         Value

---------                         -----

robustness-variable               2

last-member-query-interval(secs)  1

query-interval(secs)              125

query-response-interval(secs)     10

Enable fast leave                 Disabled

Enable mld snooping               Enabled


ArubaMAS) # show  mld-snooping groups

MLD Snooping Multicast Route Table


VLAN  Group    Port List

----  -----    ---------

0444  ff15::1  GE1/0/46 GE1/0/37

0444  ff15::2  GE1/0/46 GE1/0/36


ArubaMAS) # show  mld-snooping membership

MLD Snooping Multicast Membership


VLAN  Group    Port       Expiry    UpTime

----  -----    ----       ------    ------

0444  ff15::1  GE1/0/37   00:04:30  17:44:19

               GE1/0/46   00:00:00  17:44:56



(ArubaMAS) # show  mld-snooping mrouter

Flags: D - Dynamic, S - Static, P - PIM, M - IGMP/MLD query

MLD Snooping Multicast Router Ports


VLAN  Elected-Querier           Ports (Flags)  Expiry    UpTime

----  ---------------           -------------  ------    ------

0444  fe80::226:88ff:fe71:b380  GE1/0/46 (DP)  00:06:22  17:45:50

                                GE1/0/46 (DM)  00:05:32  17:45:20



Verify Configuration is done and applied on the right VLAN.
Make sure L2/L3 connectivity is good from MAS switch to Multicast Router.
Port monitoring on MAS switch and uplink captures would provide more information to understand the MLD query message for request and response.

Version history
Revision #:
1 of 1
Last update:
‎11-11-2014 05:58 AM
Updated by:
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