I am using one Cisco 2821 router with built in 2 GB interface. I have add one HWIC 4ESW and it works fine. But when I add another HWIC 4ESW than it is not working. The interface is detected and it show 8 FastEthernet. But when I configure them as switch port and define the vlan I can't access the connected devices on the HWIC 4ESW. I have checked cisco manual and it says cisco 2821 router will support 2 HWIC 4ESW. I have try with swapping the card and slot. But same result.
Prerequisites for Installing Two Ethernet Switch Network Modules in a Single Chassis
A maximum of two Ethernet switch network modules can be installed in a single chassis. If two Ethernet switch network modules of any type are installed in the same chassis, the following configuration requirements must be met:
â¢Both Ethernet switch network modules must have an optional Gigabit Ethernet expansion board installed.
â¢An Ethernet crossover cable must be connected to the two Ethernet switch network modules using the optional Gigabit Ethernet expansion board ports.
â¢Intrachassis stacking for the optional Gigabit Ethernet expansion board ports must be configured. For information about intrachassis stacking configuration, see the 16- and 36-Port Ethernet Switch Module for Cisco 2600 Series, Cisco 3600 Series, and Cisco 3700 series feature document.
Note Without this configuration and connection, duplications will occur in the VLAN databases, and unexpected packet handling may occur.
I think when you have more than 1 installed you have to "stack" them , search on stacking the hwics together .