The following figure shows an example of split horizon groups used to prevent communication between two access SAPs and between two network ports.
Using 7210 SAS-1 as an example:
Split horizon group ‟access” is created to prevent any communication between the SAP part of port 1/1/4 and port 1/1/5 (configured as access port) within the same VPLS.
Split horizon group ‟network” is created to prevent any communication between port 1/1/1 and port 1/1/3 (configured as a network port) within the same VPLS.
VPLS 100 is created on 7210 SAS-1 with spoke-SDPs on network port 1/1/1 and 1/1/3, and SAPs on 1/1/4 and 1/1/5 as part of this VPLS. CE1, CE2 and CE3 are the customer sites.
With this configuration, any communication between ports 1/1/4 and 1/1/5 gets blocked, similarly communication between ports 1/1/1 and 1/1/3 gets blocked but any traffic received on ports (for example, spoke-SDPs on these ports) that belong to split horizon group ‟network” will be switched to ports (for example, SAPs on these ports) that belong to split horizon group ‟access” and vice versa based on the FDB entries for VPLS 100.