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How To Pass Multicast Traffic on an Extreme Switch

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TitleHow To Pass Multicast Traffic on an Extreme Switch
Objective
  • To pass multicast streams on Extreme switches
Environment
ExtremeXOS
Procedure
  • By default, IGMPv2 and IGMP Snooping are enabled on every VLAN in ExtremeXOS
  • If the sender and receiver of the multicast stream are within the same VLAN, no added configuration is required provided the receiver is attempting to JOIN the multicast stream
To verify the sender is sending the stream and it is arriving on the ingress port use the show mcast cache command:
# show mcast cache 
Snooping/MVR Cache Timeout: 300 sec 

 Type Group             Sender               Age  InVlan 

snoop 224.12.34.56       192.0.2.10          11   Sender_vl
      Vlan             Port        Vid  
      Sender_vl        10          4 
      Receiver_vl      20          9  
  • The above shows that the multicast stream 224.12.34.56 is arriving on port 10 in VLAN Sender_vl and there exists a receiver of the stream connected to port 20 in VLAN Receiver_vl
What multicast steams a VLAN is seeing can also be seen from the show igmp snooping <vlan-name> command output:

VLAN Sender_vl
# show igmp snooping "Sender_vl" 
Router Timeout                :    260 sec
Host Timeout                  :    260 sec
Igmp Snooping Fast Leave Time :   1000 ms

VLAN Sender_vl         (4) Snooping=Enabled  
    Group           Sender          Age  
    224.20.0.65     10.18.3.150     13   
    1 Incoming multicast streams
VLAN Receiver_vl
# show igmp snooping "Receiver_vl" 
Router Timeout                :    260 sec
Host Timeout                  :    260 sec
Igmp Snooping Fast Leave Time :   1000 ms

VLAN Receiver_vl       (9) Snooping=Enabled  
    Port   Host            Subscribed        Age    Group-Limit    
    21     192.0.2.10      224.12.34.56      0      0              
  • From the above we can deduce that on port 21 in VLAN Receiver_vl there is a client currently subscribed to a multicast stream being sent by a host 192.0.2.10


Usefull command to see if the right ports are seeing the multicast streams sender and receivers is:
show igmp snooping <vlan>

If the multicast traffic needs to routing between vlans you need a multicast routing protocol like for example pim or MVR.

MVR is very simple, you enable mvr on 1 vlan where the multicast streams are received, then any vlan that needs the multicast stream will forward it after it received a igmp join.
enable mvr
configure mvr add vlan <MULTICAST_SENDER_VLAN>

Pim can operate in dense mode or sparse mode.
In Dense mode multicast traffic is send to all vlans after which they are pruned if they are not needed.
Sparse mode works the other way, it only forwards multicast streams to the vlans/subnets that need these streams. 

Example pim dense mode (2 vlans, vlan vl1 and vl2)
enable ipmcforwarding vl1
enable ipmcforwarding vl2
configure pim add vlan vl1 dense
configure pim add vlan vl2 dense
enable pim

Example pim sparse mode (same vlans)

Create a policy file describing the multicast groups you want to forward.
(This is for the RP, in this simple example the switch will be RP and BSR).
vi rpset.pol
entry rp-set {
 if match any {
 }
 then {
  nlri 239.0.0.0/24
 }
}
enable ipmcforwarding vl1
enable ipmcforwarding vl2
configure pim add vlan vl1 sparse
configure pim add vlan vl2 sparse
configure pim crp vlan "vl1" "rpset"
configure pim cbsr vlan "vl1" 10
configure pim 
enable pim

Some examples are in these links:
How to configure PIM sparse mode on EXOS
How to Configure PIM-SSM in EXOS
How To Configure MVR
How To Configure an S-Series and Summit to Route Multicast Between Each Other using PIM Sparse
 
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