Objectives
The simulator ticks each one as soon as the network meets it.
On all four switches install and enable the FabricPath feature set (install feature-set fabricpath, feature-set fabricpath).
Give each switch a switch-id: S1 1, S2 2, L1 11, L2 12.
Put VLAN 10 in mode fabricpath on all four, and make Ethernet1/1-2 (the fabric links) switchport mode fabricpath.
show fabricpath route on L1: switch-id 12 is reached over two next hops.
Ping PC2 (192.168.10.20) from PC1.
Before you start
FabricPath runs IS-IS between switch-ids, so there is no spanning tree in the core and equal-cost paths are all used. A VLAN crosses the fabric only if it is in mode fabricpath, and a fabric port forms an adjacency only with another fabric port. The spines need VLAN 10 in mode fabricpath too.
Concept
FabricPath: routing Layer 2 frames between switch-ids
FabricPath replaces spanning tree inside the data-center core. Every switch has a switch-id, and FabricPath IS-IS computes shortest paths between switch-ids over all FabricPath links, so no core link is blocked and equal-cost paths are all used. Frames from classic Ethernet are encapsulated with the source and destination switch-id at the edge.
