5.5. LAN speed maxed out

Without WAN optimization, the maximum bandwidth utilization between the WAN router and the LAN switch should not be more than the lowest bandwidth coming going through the WAN.

With WAN optimization, this balance doesn't exist anymore and the LAN interface can become a new bottleneck.

If your WAN bandwidth is 2 Mbps and LAN bandwidth is set to 10 Mbps, then there is a high probability that the post-optimized traffic will fill that 10 Mbps link.

If your WAN bandwidth is 10 Mbps and the LAN bandwidth is set to 100 Mbps, then there is a reasonable probability that the post-optimized traffic will fill that 100 Mbps link.

Figure 5.35. LAN bandwidth is more than 10 Mbps

LAN bandwidth is more than 10 Mbps

If the reason for this 100 Mbps limit is a limitation of the switch, then the switch should be replaced.

If the reason for the 10 Mbps or 100 Mbps is because the interface on the WAN router owned by the service provider is set a fixed speed and duplex, then the service provider should be urged to reconfigure the interface on the WAN router from a fixed speed and duplex configuration to an auto-negotiation configuration. This way the LAN interface on the Steelhead appliance can negotiate a gigabit Ethernet link to the LAN switch while it can negotiate a lower speed on the Ethernet link between the WAN interface and the WAN router.

If the service provider cannot do this, a VLAN bridge can be implemented.