VSX LAG

VSX LAGs span both aggregation switches. The two switches appear as one device to partner downstream or upstream devices or both when forming a LAG with the VSX pair. The two switches synchronize their databases and states over a user configured link referred to as an Inter-Switch Link (ISL).

VSX LAGs are preferable to VLANs because VSX LAGs greatly reduce the number of transit VLANs and associated SVIs, resulting in less latency. You can also greatly decrease the latency by also enabling active forwarding and active gateway. When active forwarding and active gateway is enabled, north-south and south-north traffic bypasses the ISL link.

A VSX LAG must be LACP-based. A non-LACP/static VSX LAG is not supported.