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How to get a DSL modem to work with cisco router on a stick?

By geonetworks ·
I have a cisco 2620 router and a cisco 2924XL switch, both are running ver 12.2 I've configured management vlan 1, vlan 100 for the modem and vlan 200 for my LAN hosts. All works fine when I try pinging a PC on vlan 100 but the modem is not responding to pings. Any Ideas anyone?

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Look here

by Dumphrey In reply to How to get a DSL modem to ...

http://www.cisco.com/warp/public/794/dsl_ipsec.html#t1

you will need to set up a dialer (I think) for DSL and then configure ACLs to send all traffic that way.

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Router on a stick via DSL

by geonetworks In reply to Look here

A dialer is only needed if PPPoE is being used because authentication is required. This connection uses a dynamic configuration and provides IP addresses via DHCP, in other words... I can connect my SOHO Linksys router and get an IP and connect to the internet with no advanced config required, thanks for the suggestion though, I appreciate it.

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what's the route?

by CG IT In reply to How to get a DSL modem to ...

router on a stick is for inter-vlan routing where your ethernet interface has subinterfaces for each VLAN.

still need to tell the router what to do with packets that aren't destined for any Vlan [LAN]. Otherwise the router will drop the packets.

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Drop the packets

by geonetworks In reply to what's the route?

That's interesting CG IT, but what's confusing is that when I disconnect the ethernet cable from the DSL modem and connect a PC with the same IP and netmask as the DSL modem it pings fine. The sub-interfaces on the router are configured and everything works fine except that I can't reach the DSL modem.

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again what's the route out?

by CG IT In reply to Drop the packets

Nothing confusing about it.

If the router doesn't know what to do with the packets, it'll drop them. Since everything points to the router not knowing what to do with packets not destined for any LAN and dropping packets, then it doesn't know what to do with them.

So what's the route out?

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The route out

by geonetworks In reply to again what's the route ou ...

I have each of the sub-interfaces on the router set as the gateway for each VLAN. I did not think another route was needed since the DSL modem's IP address is part of the VLAN subnet that the switch port to which it is connected has been statically assigned. Of course the Modem's gateway is different than PCs in either VLAN and this is where I think the problem resides. If this is the problem, then the question is, how do I configure the router to allow the DSL modem to talk to devices in the VLANs?

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Route out

by CG IT In reply to The route out

Original Question:

I have a cisco 2620 router and a cisco 2924XL switch, both are running ver 12.2 I've configured management vlan 1, vlan 100 for the modem and vlan 200 for my LAN hosts. All works fine when I try pinging a PC on vlan 100 but the modem is not responding to pings. Any Ideas anyone?

So how does your ethernet modem connect to the 2620?

if you have 2 ethernet interfaces which one is the route out? If you have 1 ethernet interface, then see question above.

The router must perform PAT for the inside hosts as they have private addressing and the "modem" will have a global address. The router must also have a default gateway. What is the default gateway for the router?

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default gateway for the router

by geonetworks In reply to Route out

The modem connects to VLAN 100 via fa0/1 on the 2924, I have a PC connected to VLAN 200 via fa0/2 on the 2924. I have fa0/24 on the 2924 trunking to fa0/0 on the 2620. I also have fa0/0.100 configured as VLAN 100 and fa0/0.200 configured as VLAN 200 on the 2620, encapsulation is dot1q, VLAN 1 is the native/management vlan. I do not have a gateway set on the router.

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you have your DSL modem [not a DSL router]

by CG IT In reply to default gateway for the r ...

connected to the 2900 switch? so, without any layer 3 device performing NAT/PAT what host gets the public address, default gateway and DNS servers from your ISP?

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