Cisco switch / router to DSL modem??

[Shockwave]

Lets say you want to set up a small, high quality LAN. Is it possible to connect a Cisco 1900 or 2900 series Catalyst switch to a, say, Linksys DSL modem. I'd like a 12 port 10/100 Catalyst with 2 1000 meg high speed interfaces, run my server on the high speed, run the workstations on the 10/100 then connect the uplink to a Linksys DSL router, then get a higher end DSL connection. But, I dont know if its possible to connect a 1900 / 2900 Catalyst to a DSL router or not. Does anyone have any info on this, or any ideas?
Thanks,
§hock

[mbossman2]

yes you can, however, to share the DSL link with just a single public IP address you will need a router (or other device) that support NAT (network address translation). The layer 2 catalyst switches do not support that feature. For a small network like that, you may want to look at the PIX-501 for your firewall, it supports NAT and can act as your DHCP server as well.

[specop_007]

I thought the DSL routers would support NAT? So, the order would be
DSL router --> Pix-501 --> Catalyst switch? Also, hadnt Cisco released a 2900 Catalyst that was a Layer 3 switch, supporting NAT? Jeez, this is getting more confusing rather then easier!!

[mbossman2]

Originally posted by specop_007
I thought the DSL routers would support NAT? So, the order would be
DSL router --> Pix-501 --> Catalyst switch? Also, hadnt Cisco released a 2900 Catalyst that was a Layer 3 switch, supporting NAT? Jeez, this is getting more confusing rather then easier!!

The DSL router might support NAT (if it is a router), however many ISP's only provide to their customers DSL modems which generally have no services (like NAT or PAT) on them.

Yes, Cisco does have a layer 3 2900 (specifically the 2948G-L3), but according to the documentation that I reviewed, NAT is not one of the features that is currently supported on that switch. Generally NAT is not a requirement on the internal (private side) of a network. It is generally a feature used in routers and the internet to conserve public IP addresses and share that 1 (or more addresses) amongst a larger pool of users.

Additionally, for a small network like yours, I don't think (without further information) that you would really see a return on your investment in the above layer 3 switch (it lists for approximately $9995US)

The reason that I recommended the PIX was in your original post you did not indicate that you had any kind of firewall protection and that really is stronglt recommended (strike that - an absolute must have) with any connection to the internet. Check this page www.cisco.com/go/safe for more details on that (specifically the blue print for the small to medium size business, it is a big document but VERY worthwhile).

[glc]

The Linksys router is a NAT router - and the DSL modem plugs into it. For a small network, just use the Linksys - it will run at 100mbs full duplex, gigabit will do nothing for you because you can't get hard drive throughput anywhere near gigabit speeds. Gigabit is for large networks that have to share bandwidth among a LOT of workstations.