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Community Member

SPAN possible on a 1811 router ?

Hi all,

1811 router lets me get as far as "monitor session 1 source interface fastethernet" but when I finish it with the interface number "fastethernet 0"

it gives me a "Invalid input detected at marker |^| pointing at the F in fastethernet.

The Cisco 1800 Series Integrated Services Routers (Fixed) Software Configuration Guide claims SPAN is possible. Page 5-9

Thanks,

Mike

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Bronze

Re: SPAN possible on a 1811 router ?

I believe this is because the Fa0 and Fa1 ports are technically router ports (that can never be used for switching) on the 1811, while the Fa2 through Fa9 ports are Layer 2 switch ports (which you can set up span sessions for).

SPAN is a switch technology, not a router technology (as far as I know). It's more a router with layer 2 switching ability, not a switch with routing capability (like the 6500 series Cats).

Just curious, but why do you want to SPAN a WAN port?

4 REPLIES
Bronze

Re: SPAN possible on a 1811 router ?

I believe this is because the Fa0 and Fa1 ports are technically router ports (that can never be used for switching) on the 1811, while the Fa2 through Fa9 ports are Layer 2 switch ports (which you can set up span sessions for).

SPAN is a switch technology, not a router technology (as far as I know). It's more a router with layer 2 switching ability, not a switch with routing capability (like the 6500 series Cats).

Just curious, but why do you want to SPAN a WAN port?

Community Member

Re: SPAN possible on a 1811 router ?

Thanks for the response.

It would have helped to monitor the traffic from our remote offices when trying to analyze network slowdowns using Wireshark.

In our situation, our WAN circuits are provided by another company, and they have agreed to SPAN ports on their switch and let me tap into it. Problem solved.

Thanks again for your response.

Mike

Bronze

Re: SPAN possible on a 1811 router ?

For future reference, you can simply get a hub, put it on the outside of your router, and hook a server into that. You might have to put the NIC into promiscuous mode.

Re: SPAN possible on a 1811 router ?

Some of the newer code has a packet capture feature. It is rather clunky to use though. A sniffer would probably be the best way to go.

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