Appendix: port-based split horizon

The port-based split horizon feature can be used to disable local switching on the 7210 SAS. A loop-free topology can be achieved using split horizon on 7210 SAS switches.

Traffic arriving on an access or an access-uplink port within a split horizon group will not be copied to other access and an access-uplink ports in the same split horizon group, but will be copied to an access-uplink ports in other split horizon groups.

Because split horizon is a per port feature in 7210 SAS, all SAPs associated with the port becomes part of split horizon group configured on that port.

The following configuration guidelines must be followed to configure a split horizon group:

1. Create a split horizon group in the config prompt. The group name must be unique across the system.

   7210-SAS1>config#info
   #--------------------------------------------------
   echo "Split-horizon-group Configuration"
   #--------------------------------------------------
       split-horizon-group access create 
           description ‟Block access between access Ports”
       split-horizon-group access-uplink create
           description "Block access between access-uplink Ports"
       exit 
   #-------------------------------------------------- 
   7210-SAS1>config#
   

2. Associate ports 1/1/4 and 1/1/5 with split horizon group ‟access” By default all ports are access ports. The default Ethernet encapsulation for access port is ‟null”.

   7210-SAS1>config#info
   #--------------------------------------------------
   echo "Port Configuration"
   #--------------------------------------------------
       port 1/1/4
           split-horizon-group access
           ethernet
           exit
           no shutdown
   exit 
       port 1/1/5
           split-horizon-group access
           ethernet
           exit
           no shutdown
     exit
   #--------------------------------------------------
   
   
   7210-SAS1>config#
   

3. Configure ports 1/1/1 and 1/1/3 as access uplink and associate these ports with split horizon group ‟access-uplink” default Ethernet encapsulation for access uplink port is ‟qinq”.

   7210-SAS1>config# info
   #--------------------------------------------------
   echo "Port Configuration"
   #--------------------------------------------------
       port 1/1/1
           split-horizon-group access-uplink
           ethernet
                  mode access uplink
           exit
           no shutdown
   exit 
       port 1/1/3
           split-horizon-group access-uplink
           ethernet
                  mode access uplink
           exit
           no shutdown
     exit
   #--------------------------------------------------
   
   
   7210-SAS1>config#
   

4. Create a VPLS instance 100.

   #--------------------------------------------------
   echo "Service Configuration"
   #--------------------------------------------------
       service
             customer 2 create
             exit
            vpls 100 customer 2 create
               stp
                   shutdown
               exit
               sap 1/1/1:100.* create
               exit
               sap 1/1/3:100.* create
               exit
               sap 1/1/4 create
               exit
               sap 1/1/5 create
               exit
               no shutdown
       exit
   ...
   #--------------------------------------------------
   

   Note:

   A split horizon on a port must be configured before creating any SAPs associated with that port.