Cisco 831, confusing interfaces

Answered Question
Jan 3rd, 2008

Hi everyone,

I got a Cisco 831 router running IOS 12.4. Physically there are 5 ports which are 1 WAN (E1) and 4 LAN (FE1, FE2, FE3, FE4).

When I "sh run", it shows up 7 interfaces. Besides the above 5 ports, there are E0 and E2. And my understanding is E0, E1, E2 are Layer 3 interfaces. FE1-FE4 are Layer 2 interfaces. And FE1-FE3 access E0, FE4 accesses E2.

My need is like this, in my LAN subnet(192.168.1.0/24), I want FE1-FE4 are in the same subnet. Say FE1 is connected a PC(192.168.1.1), FE2=192.168.1.2, FE3=192.168.1.3, FE4=192.168.1.4. E0 interface is configured as 192.168.1.5 for the router itself.

How can I make FE4 in the same LAN? I didn't find VLAN commands so I'm assuming 831 doesn't support VLAN, otherwise I would config VLAN for FE1-FE4.

Any suggestion is appreciated!

I have this problem too.
0 votes
Correct Answer by chschroe about 8 years 11 months ago

Just issue a shutdown in the e2 interface and don't supply it with any configuration.

Fas4 will work as normal.

NS

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j-marenda Fri, 01/04/2008 - 14:51

e2 with fe4 as physic is the "DMZ" Interface

which can have it's own IP-configuration but

shares the ~10MBit/s FDX channel to the CPU with the other 3 FE Ports.

Try to shutdown e2 or to say "no int e2"

and view the logging messages on console

or by show log (hopefully logging buffered

enabled)

Get a 871 or better 1812 :-)

panweicisco Fri, 01/04/2008 - 17:06

It doesn't allow me to remove it.

Any way to remove this DMZ port and restore F4 as equal to F1-F3?

Thanks.

--- router output ---

R831(config)#no int e2

% Removal of physical interfaces is not permitted

Correct Answer
chschroe Fri, 01/04/2008 - 21:30

Just issue a shutdown in the e2 interface and don't supply it with any configuration.

Fas4 will work as normal.

NS

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