At the moment (and the near future) I can keep using my 837 as my ADSL router, but in the more distant future (a few months from now) it is likely that my ISP will offer ADSL2/+ connections, which will render my
837 more or less useless. Is it possible to use the LAN ports of my router as an ethernet router and use another modem in bridge mode to connect to the Internet?
For example, can I use FastEthernet1 as a WAN port and the others as LAN ports?
The "router" itself has only one 10mbps ethernet-interface. Behind the router, but on the same circuit-board is a 5-port switch. Four of the switchports are connected to the RJ45-ports on the back of the router, however the fifth port is soldered to the "router" 10mbps interface. Therefore: as long as you use the switch as a "switch", no problem. But as soon as you want LAN traffic to be "routed", you run into serious performance issues because everything has to go in and out on the same 10mbps ethernet interface.
Apart from that: yes, there is a DMZ-Port-Feature (look for "DMZ-Port" in the Feature navigator), which is supported by recent IOS versions. In my eyes quite a nice feature, I use it at home to separate my WLAN-Segment from my LAN... as long as you dont need to much performance, no problem.
Walter Robers> > :Is it possible to use the LAN ports of my router as an ethernet router
No. VLAN feature is not available on 83x platform.
Depends on what decent means. I think 12.3(14)T introduced using the E2 port (switch port 4) as backup interface. You *can* connect your modem there.
Ethernet FDX is limited to 10Mbps/10Mbps. For more, you'll need a FastEthernet interface. Since all packets have to go in and out the max throughput is to low for datarates requiring ADSL2.
Bad luck: You have an old 83x with 48MB RAM max. For 12.3(14) or 12.4 you'll need 64MB, perhaps the small image (without PLUS) does work with 48MB and "memory-size iomem 5". Perhaps Cisco finds a way for adding a 32MB SIMM and get it recognized.
yes, assign a 2ndary IP address on eth0 and route back to you new WAN gateway.
Physically there is only one connection. Hence traffic from/to the FE ports to/from the WAN have to cross this 10Mbps connection twice. Calculate yourself which max thruput you get and if it is "decent" for you.
Buying a switch would imho make much more sense, but ymmv ...