CISCO891 : Difference between Ethernet LAN and Ethernet WAN Port

Unanswered Question
May 20th, 2010


i have maybe some simple questions regardings the ports called ethernet-lan / ethernet-wan.?

1. what is the technical difference between these ports ?
2. does a ethernet-wan port also work as a normal ethernet-port ?

i want to use a cisco891 as a "normal" ethernet router with 2 ethernet ports and v92 as backup. i think, that NAT is the default
configuration between the WAN Port and the LAN Ports - is that right ?

And is it possible to disable NAT between LAN and WAN-Port ?  -  i want to use the ports as standard ethernet routing ports !

thanks a lot

I have this problem too.
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spremkumar Thu, 05/20/2010 - 05:59

Hi Thomas

With ethernet as as a wan port can be assigned with ip address and other L3 parameters and as a simple lan(switch)port you can only assign an vlan or configure the lan port to be a member of particular vlan. you wont be able to configure ip address or any L3 related parameters on the switch port as you do with normal wan port.

Most of the Cisco 800 series routers comes with ethernet wan connection for your service provider link termination and the lan port for your lan termination.

You can change the nat relate configs as per the requirement but you need to be more specific on what you want to do with the box here.


tstauffer Thu, 05/20/2010 - 06:14


all i need is routing between two ethernet subnets and a backup by a serial line (v92) in case that one connection is broken.

                   |--------|      ethernet      |--------|
subnet_A |---------| Router |--------------------| Router |-------|subnet_B

                   |--------|       noISP!       |--------|

                        |                            |

                        |                            |

                        |                            |

                        |-------backup: telecom------|


as you can see - it is very simple. i want to use the WAN-Port for the noISP site, and the switchports

for the subnet_A and B.

The Router should be a cisco891 !


spremkumar Fri, 05/21/2010 - 03:43


are the routers kept in different location? how many users are there in each subnet? whats the application or the nature of the traffic flow between these subnets?



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