: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?
As of a year or two ago, Cisco started supporting "DMZ" on the 83x,
in which one of the 4 LAN ports could be severed from the switch
group into a different subnet.
I have no information as to whether the second LAN so formed is
equvilent to the others or is somewhat restricted.
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
in my eyes this is a rather bad idea.
The internals of the Cisco 83x-Routers are as follows:
----| 5 Port | | Router with |---- DSL etc...
----| Switch |-----| 10mbps Ethernet, |
----| 100mbps | | ADSL etc... |
----| | | |
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
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
It looks like you don't understand what I am trying to do, I am thinking
if it is possible to create something like this:
-1--| 4p switch | | Router |---- DSL (unused)
LAN -2--| 100Mbps || |
-3--| VLAN1 | | |
+-----------+ | |
WAN -4--| VLAN2 || |
So basically the questions are:
- is this even possible to do in IOS?
- is the 83x capable of routing from VLAN1 to VLAN2 at decent speeds?
ADSL2 can be up to 20/1Mbps I think. (routing over the ""
Cisco IOS Software, C837 Software (C837-K9O3SY6-M), Version 12.3(11)T,
RELEASE SOFTWARE (fc2)
Cisco C837 (MPC857DSL) processor (revision 0x500) with 44237K/4915K
bytes of memory.
Processor board ID AMB0833097L (1943130886), with hardware revision 0000
CPU rev number 7
1 Ethernet interface
4 FastEthernet interfaces
1 ATM interface
128K bytes of NVRAM.
12288K bytes of processor board System flash (Read/Write)
2048K bytes of processor board Web flash (Read/Write)
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
Ethernet FDX is limited to 10Mbps/10Mbps. For more, you'll need a
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.
Ah, too bad...
But, the LAN ethernet ports on the 83x are FastEthernet interfaces. (see
the previous post).
Or perhaps time to simply get a Linksys ethernet router :-(
Oh well, by selling the 837 I probably can buy four new Linksys routers
On 07.08.2005 20:11 Arnoud Helmantel wrote
yes, assign a 2ndary IP address on eth0 and route back to you new WAN
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 ...