Can't configure FastEthernet interface

I have a router Cisco 837, if I type 'sh version' command, I see following information about that:
Cisco Internetwork Operating System Software
IOS (tm) C837 Software (C837-K9O3SY6-M), Version 12.2(13)ZH4, EARLY DEPLOYMENT RELEASE SOFTWARE (fc1)
Synched to technology version 12.2(14.5)T
Technical Support:
Copyright (c) 1986-2004 by cisco Systems, Inc.
Compiled Wed 24-Mar-04 18:51 by ealyon
Image text-base: 0x800131E8, data-base: 0x80B51594

ROM: System Bootstrap, Version 12.2(8r)YN, RELEASE SOFTWARE (fc1)
ROM: C837 Software (C837-K9O3SY6-M), Version 12.2(13)ZH4, EARLY DEPLOYMENT RELEASE SOFTWARE (fc1)

Router uptime is 10 minutes
System returned to ROM by power-on
System image file is "flash:c837-k9o3sy6-mz.122-13.ZH4.bin"

CISCO C837 (MPC857DSL) processor (revision 0x400) with 29492K/3276K bytes of memory.
Processor board ID AMB07270RNW (3866833918), with hardware revision 0000
CPU rev number 7
Bridging software.
1 Ethernet/IEEE 802.3 interface(s)
1 ATM network interface(s)
128K bytes of non-volatile configuration memory.
8192K bytes of processor board System flash (Read/Write)
2048K bytes of processor board Web flash (Read/Write)

Configuration register is 0x2142
The router can't configure the 4 FastEthernet switch embedded (Managed LAN Switch functionality), because it doesn't accept any command:
Router(conf-t)#interface FastEthernetx (where x is the number 1,2,3,4).
Reading on, I have noted that:
Supported platforms: Cisco 831, 836 and 837; supported in all images (all k9o3y6 images).

Many thanks for your collaboration.

Antonio Morrocchesi

Who is Participating?

[Product update] Infrastructure Analysis Tool is now available with Business Accounts.Learn More

I wear a lot of hats...

"The solutions and answers provided on Experts Exchange have been extremely helpful to me over the last few years. I wear a lot of hats - Developer, Database Administrator, Help Desk, etc., so I know a lot of things but not a lot about one thing. Experts Exchange gives me answers from people who do know a lot about one thing, in a easy to use platform." -Todd S.

It is not Fastethernet, it's ethernet.

Try "interface EthernetX"

The 4 Fastethernet  switch ports are L2,  it's unlikely that you will be able to do anything on them, they are provided to do switch/hub functionality since this is SOHO router from cisco.......

If you give command "interface ?", this will show you the list of configurable interfaces and Fastethernets will not be there.

what do you mean they dont work?

how do you know this - is the user getting pop ups telling them that services cant start?  or are you just seeing the event viewer entries?

Its not exactly clear what your trying to do.

If I remember correctly the ports are named
FastEthernet0-3 which are all L2 ports and don't support much on the 837. So there is no 5th (FastEthernet4) port

Ethernet 0 is a layer 3 port connected to the switch.

there are some firmwares avilable for the 837 which will turn FE3 into a vlan'ed port and create a Ethernet 2 which it is then bound too and cannot be used as a 4 port switch anymore. Its a 3 Port + 1 Port switch :) But i can tell you don't have one of these firmwares installed.

Big Business Goals? Which KPIs Will Help You

The most successful MSPs rely on metrics – known as key performance indicators (KPIs) – for making informed decisions that help their businesses thrive, rather than just survive. This eBook provides an overview of the most important KPIs used by top MSPs.

amorrocchesiAuthor Commented:
I'll try to explain better the situation.
I have a Router Cisco 837 with 4 ethernet interfaces, like this: 
As you can see above, the router's requirements are:
1. ROM: C837 Software (C837-K9O3SY6-M), Version 12.2(13)ZH4, EARLY DEPLOYMENT RELEASE SOFTWARE (fc1)  
2. System image file is "flash:c837-k9o3sy6-mz.122-13.ZH4.bin"
3. 32 MByte DRAM
4. 12 Mbyte Flash memory
In this paper:
Cisco declares that the function 'Managed LAN Switch': Supported platforms: Cisco 831, 836 and 837; supported in all images (all k9o3y6 images).
My router Cisco 837 has loaded  k9o3sy6-mz.122-13.ZH4 image, so the function 'Managed LAN Switch' should be integrated, but if I type 'show interfaces' I see only ATM0 and Ethernet0 interfaces.
The same error appears when I typed:

Configuring from terminal, memory, or network [terminal]?
Enter configuration commands, one per line.  End with CNTL/Z.
Router(config)#interface Ethernet1
% Invalid input detected at '^' marker.


Configuring from terminal, memory, or network [terminal]?
Enter configuration commands, one per line.  End with CNTL/Z.
Router(config)#interface FastEthernet1
% Invalid input detected at '^' marker.

On Internet there are too many examples of Cisco 837 configurations, where there are 4 FastEthernet interfaces, I found an example here: 

Now the questions are:
1. Does anyone know why the router Cisco 837 has this behavior?
2. Does anyone know what is the Cisco IOS version where the function 'Managed LAN Switch' really is implemented.
3. Must I reloaded a new image of 'c837-k9o3sy6-mz.122-13.ZH4.bin' and where do I find that.

Kindly regards.
Antonio Morrocchesi



The 837 wont do what your wanting. It doesn't really have the hardware power to do it.
The next set of router that will do it is the 87x series. The 85x series also might do it.

With a standard ios you get 2 vlan's of your choice.
With the advanced ip ios you get 4 vlan's

The 83x series only offers 1 Ethernet Layer 3 Port and 4 Fast Ethernet Layer 2 ports (partially)
So it isn't really a managed switch but you can tell what state the interface is in.

FastEthernet0-3 are all Layer 2 ports , meaning that you cant assign a separate IP to each one. You can assign vlans (if you use specific IOS)

You will assign IP to "Ethernet 0" ; its similar to "vlan 1" in newer cisco models , like cisco 87x series.

amprant: the 837 does not support vlan's

It supports with specific IOS , from Y series
amorrocchesiAuthor Commented:
The router gets 32 MByte of DRAM and 12 MByte of Flash memory.
Does IOS Y series support this requirements?
I know that Cisco doesn't support the 837 series, Where do I find Y series IOS on Internet?
Kindly Regards.

Antonio Morrocchesi
I assume it is the same issue as with the PIX501. The built in switch is not realy configurable. Just couldn't find a note from cisco explaining that.


I will tell you again. The 837 will NOT support vlan's there is some very specific images that will create an ethernet 2 interface and bind Fe4 to it (in a vlan). Its call the DMZ port feature in the cisco ios compare. However it is not configurable and to turn it off again requires a change of ios.

It "managed" switch will not support stp / vlan's / trunk or anything else that you would want to do with a managed switch that is half decent.

Experts Exchange Solution brought to you by

Your issues matter to us.

Facing a tech roadblock? Get the help and guidance you need from experienced professionals who care. Ask your question anytime, anywhere, with no hassle.

Start your 7-day free trial
It's more than this solution.Get answers and train to solve all your tech problems - anytime, anywhere.Try it for free Edge Out The Competitionfor your dream job with proven skills and certifications.Get started today Stand Outas the employee with proven skills.Start learning today for free Move Your Career Forwardwith certification training in the latest technologies.Start your trial today

From novice to tech pro — start learning today.