Using Ethernet2 as WAN Port on 836


I wanted to use the DMZ Ethernet2 port of a Cisco 836 to access the public network. I read that the Ethernet2 interface is restricted from being used as a WAN port. Does this means that I simply cannot use e2 interface to route ou nat internal traffic to the ouside.

My ideia was.. I have an 805 (Serial router in a leased line) router in brigded mode, the external IP is available on the LAN interface. I have this lan interface connected to the ethernet2 interface of the

836 which also provides the ADSL connectivity. The ideia was to concentrate both networks on the 836 so that I could use the 836 only to decide my routing.

Altough this WAN limitation on the Ethernet2 interface, does anyone believe that this setups is feasable?


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I actually use Eth2 on my 837 as the WAN port (NAT outside) facing towards my cable modem. This works fine except when everything gets powercycled, because the cable modem comes up, then the 837 rommon comes up and starts bridging everything, so that one of my client devices gets a DHCP address from the cable modem, so that when IOS comes up, it can't get an address from the cable modem.

As far as whether this is supported ... I guess if we say that it's not, then if it doesn't work too well, you don't have the right to whine.



Reply to
Aaron Leonard

Hi there, I am using a 836-Router at home - as far as I can see, the Ethernet2-Interface can be used both as a LAN or a WAN interface. Although Cisco mentions this restriction in the docs, I doubt that the info is correct for current IOS versions.

I used an external DSL modem, which I connected via Ethernet to the E2-port (using PPPoE).... later I changed my setup, now I´m using the built-in DSL-modem of the 836 and I´m using the E0-Ports (Fa1-3) and the E2-Port (Fa4) as router ports to decide my routing. Works fine.

Regards, Axel

HangaS schrieb:

Reply to
Axel Gärtner

HangaS schrieb:

This restriction was removed with IOS 12.3(8)YG and 12.3(14)T.

The major drawback is the permanent blinking of the ATM0/DSL moden LED ;-)

Don't expect good performance, since the physical bandwith between Eth0 and the CPU is shared with Eth2, so 5MBit/s is physical max. But the 836 maxes out earlier depending on config...

Reply to
Uli Link

Thank you all.

You're right Uli there is no restriction anymore.

I'm successfuly using the Ethernet2 port as a WAN port now. I tryed a few setups before without success, but not related with the "restriction".

Regarding the leds,, that is no issue to me, as I'm using both the ATM0 and Ethernet2 Ports :)

The only issue now it that I would like to use the Ethernet2 as a backup for the ATM0/Dialer combo but there is no dialer wacther group on Ethernets of couse. But no big issue cos this setup was temporary.

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