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Port Expander for Cisco 1841 router


We are using Cisco 1841 routers in our organisation. Presently we use first ethernet ports to transfer data from WAN to LAN side. Now we want to add another port so that we can take two input from WAN side and one at LAN side. Can we do it by using existing auxillary port or we need to purchase additional HWIC module?


Sandip K Sadhukhan

Joseph W. Doherty
Hall of Fame Expert


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Depending on you port needs, you might consider whether using a small switch, that supports VLANs, could be used to trunk to your 1841.

Collin Clark

You will need the HWIC-4ESW module to expand the physical ports.

Hi Collin,

Can we use the following product to take two more ethernet input?

As per our requirement we want 3 ethernet input from WAN side and take out the bobded output to the LAN side. Please suggest.




Yes, you could go for HWIC-1FE or HWIC-2FE. What really matters is what you are trying to do & how much it cost you to achieve the same.

HWIC-4ESW is the 4-port single-wide 10/100BaseT Ethernet switch HWIC. The 4ESW is a L2 switch and is cost effective. HWIC-4ESW has the capability to setup VLAN as well as SVI which is logically L3 but they are not the routed ports. This module has limited QOS support.

HWIC-1FE is 1-port Fast Ethernet HWIC. The HWIC-1FE is a true L3 interface and is expensive

It has feature parity with an onboard FE interface except for OAM support, which is delayed.

Whereas, HWIC-1FE has the same characteristics as Onboard FE ports.



Thank you Amit for your reply. Can you give me some suggestion?

At present  we are using two FE ports, one for taking WAN side input from external provider and other to connect to LAN side. Now we want to take two more WAN input. So we need two more ethernet ports may be of type FE and then bond all three WAN side inputs. Which cost effective model do you suggest to achieve this?



So we need two more ethernet ports may be of type FE and then bond all three WAN side inputs.

What is the bandwidth of your WAN link?

The existing one is of 68 Mbps and we want to put two 34 Mbps additional link.

The existing one is of 68 Mbps and we want to put two 34 Mbps additional link.

Putting additional FE ports is a waste of your money.  The 1841 router can push up to 38.40 Mbps of UN-ENCRYPTED and HALF DUPLEX worth of data.

So what you are doing will just overwhelm the router when you've got data barreling down at full speed.

Your situation is like this:  You are going to haul 20 tons worth of cargoes daily along Germany's autobahn (this signifies your bandwidth) and you are using a 1975 East German Trabant (this signifies what your router can do). 

You need a minimum of 2921 ISR G2 which will support your speed in full duplex.