Cisco 837 - Ethernet 2 interface issue

growse

growse

growse

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Hi all, just read about the fact that the cisco 837 has more than one useable ethernet interface. I know it lists 3 (0-2), but assumed that 0 was connected to the switch and the other two were unusable. Turns out that if you enable 2, the 4th port on the switch (fastethernet 4) becomes the physical interface for ethernet 2. Useful for setting up a DMZ.

So I go and configure the interface, just give it an ip of 10.1.0.1/24, and bring it up. Seems to come up ok. Then I plug something into the 4th port, and the internet stops working on ethernet0. It's rather strange, as soon as I plug something in, dns stops happening for ethernet0. Unplug it from ethernet2, and it starts working again.

Any ideas what the hell's going on?
 
Cisco router doesn't like ethernet 2. It seems to me you need to configure it in the router or perhaps its for something specialist like a hub?
 
Last edited:
You mean ethernet 2? Looking at the documentation for my IOS, ethernet 2 is there to provide another interface for use as a DMZ, so it should all be supported...
 
this is the config on mine, ethernet ports 1,2 & 3 i use for the dmz & port 4 to the switch for the lan.

interface Ethernet0
description DMZ
ip address x.x.x.x 255.255.255.248
no ip redirects
no ip proxy-arp
ip nat outside
ip virtual-reassembly
no cdp enable
hold-queue 100 out
!
interface Ethernet2
description LAN
ip address 192.168.0.254 255.255.255.0
no ip redirects
no ip proxy-arp
ip nat inside
ip virtual-reassembly
no cdp enable
hold-queue 100 out
 
growse said:
Hi all, just read about the fact that the cisco 837 has more than one useable ethernet interface. I know it lists 3 (0-2), but assumed that 0 was connected to the switch and the other two were unusable. Turns out that if you enable 2, the 4th port on the switch (fastethernet 4) becomes the physical interface for ethernet 2. Useful for setting up a DMZ.

So I go and configure the interface, just give it an ip of 10.1.0.1/24, and bring it up. Seems to come up ok. Then I plug something into the 4th port, and the internet stops working on ethernet0. It's rather strange, as soon as I plug something in, dns stops happening for ethernet0. Unplug it from ethernet2, and it starts working again.

Any ideas what the hell's going on?
Click to expand...


Post up the config minus any passwords or public IP addressing if you are still having problems!
 
Ive been trying to find the readme that came with the very first IOS that supported this (12.3(7) XR) but i cant find it!!
Im gunna have a look at work tommorow to see if we stored it anywhere.

One thing to bare in mind is that we had an 877 router once that would accept a connection in one interface. As soon as you plugged a second device in, it killed all network traffic across it! Might be worth a thought. We got that one replaced and the problem disapeared. Funnily enough, that was 2 seperately addressable interfaces too, although in the form of Vlans.

Your IOS may support it, but does the feature set? Thats also worth having a look at.
 
Code: 
nosey>sh ver
Cisco IOS Software, C837 Software (C837-K9O3Y6-M), Version 12.3(8)YG2, RELEASE SOFTWARE (fc1)
Synched to technology version 12.3(10.3)T2
Technical Support: [url]http://www.cisco.com/techsupport[/url]
Copyright (c) 1986-2005 by Cisco Systems, Inc.
Compiled Fri 06-May-05 05:19 by ealyon

ROM: System Bootstrap, Version 12.2(8r)YN, RELEASE SOFTWARE (fc1)
ROM: Cisco IOS Software, C837 Software (C837-K9O3Y6-M), Version 12.3(8)YG2, RELEASE SOFTWARE (fc1)

nosey uptime is 3 weeks, 2 hours, 10 minutes
System returned to ROM by reload at 08:34:54 BST Thu Feb 2 2006
System restarted at 08:37:31 GMT Thu Feb 2 2006
System image file is "flash:c837-k9o3y6-mz.123-8.YG2.bin"

I'm on 12.3(8) here, so it should support it. It's certainly in the 12.3(8)YG2 documentation...
 
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