Can I use old router as network hub/switch ?

[Ken Smith]

I want to attach some network storage to my existing network but I am
already using all the available LAN ports on my current router.

I have an old spare router.
Can I take a LAN connection from my current router into the WAN socket of my
old router and then use the 4 LAN sockets on the old router to expand my
network ?

Just wondering if this is viable before starting to waste time & effort.

[Bruce]

I would hook it into one of the LAN ports instead. Turn off DHCP in the
router and just use it as a 3 port switch.

Thanks,
Bruce
"Ken Smith" <kgsmith@blueyonder.co.uk> wrote in message
news:0chHj.117930$nw4.45261@fe1.news.blueyonder.co.uk...
>I want to attach some network storage to my existing network but I am
>already using all the available LAN ports on my current router.
>
> I have an old spare router.
> Can I take a LAN connection from my current router into the WAN socket of
> my old router and then use the 4 LAN sockets on the old router to expand
> my network ?
>
> Just wondering if this is viable before starting to waste time & effort.

[News Reader]

If you do that you will have two separate networks (each with their own
IP address space), separated by the newly implemented spare router
(downstream router).

You would need to configure the pre-existing router (upstream router)
with a static route so that it knows how to reach the new network on the
downstream side of the downstream router.

If a host on the upstream network needs to connect with a host on the
downstream network, it will forward the first packet to its default
gateway (upstream router). The upstream will check its route table and
determine that it is necessary to forward the packet to the downstream
router in order to reach the downstream host. It will then forward the
packet.

The upstream router then sends an ICMP message to the upstream host
saying "use the downstream router to reach the downstream host, it has a
better route than I do". The upstream host should then add a route to
its local routing table, modify its behavior, and send subsequent
packets directly to the downstream router to reach the downstream host.

Furthermore, you would need to configure the WAN interface on the
downstream router to permit communication from upstream hosts, to
downstream host.

It's a bit more involved than adding a switch isn't it?

If you were to connect the LAN interface of the spare router to the LAN
interface of the pre-existing router you would achieve what you are
after, but there are precautions that must be taken.

You need to ensure that the web management interfaces of the two routers
are not using the same IP address BEFORE connecting them together. You
would also want to disable the DHCP server on the spare router. You may
or may not need a crossover cable to connect the two routers via their
LAN interfaces depending on their capabilities.

Best Regards,
News Reader

Ken Smith wrote:
> I want to attach some network storage to my existing network but I am
> already using all the available LAN ports on my current router.
>
> I have an old spare router.
> Can I take a LAN connection from my current router into the WAN socket of my
> old router and then use the 4 LAN sockets on the old router to expand my
> network ?
>
> Just wondering if this is viable before starting to waste time & effort.
>

[News Reader]

Make sure the two routers are not using the same web administration IP
address BEFORE connecting the two devices.

Best Regards,
News Reader

Bruce wrote:
> I would hook it into one of the LAN ports instead. Turn off DHCP in the
> router and just use it as a 3 port switch.
>
> Thanks,
> Bruce
> "Ken Smith" <kgsmith@blueyonder.co.uk> wrote in message
> news:0chHj.117930$nw4.45261@fe1.news.blueyonder.co.uk...
>> I want to attach some network storage to my existing network but I am
>> already using all the available LAN ports on my current router.
>>
>> I have an old spare router.
>> Can I take a LAN connection from my current router into the WAN socket of
>> my old router and then use the 4 LAN sockets on the old router to expand
>> my network ?
>>
>> Just wondering if this is viable before starting to waste time & effort.
>
>

[David H. Lipman]

From: "News Reader" <user@domain.null>

| If you do that you will have two separate networks (each with their own
| IP address space), separated by the newly implemented spare router
| (downstream router).
|
| You would need to configure the pre-existing router (upstream router)
| with a static route so that it knows how to reach the new network on the
| downstream side of the downstream router.
|
| If a host on the upstream network needs to connect with a host on the
| downstream network, it will forward the first packet to its default
| gateway (upstream router). The upstream will check its route table and
| determine that it is necessary to forward the packet to the downstream
| router in order to reach the downstream host. It will then forward the
| packet.
|
| The upstream router then sends an ICMP message to the upstream host
| saying "use the downstream router to reach the downstream host, it has a
| better route than I do". The upstream host should then add a route to
| its local routing table, modify its behavior, and send subsequent
| packets directly to the downstream router to reach the downstream host.
|
| Furthermore, you would need to configure the WAN interface on the
| downstream router to permit communication from upstream hosts, to
| downstream host.
|
| It's a bit more involved than adding a switch isn't it?
|
| If you were to connect the LAN interface of the spare router to the LAN
| interface of the pre-existing router you would achieve what you are
| after, but there are precautions that must be taken.
|
| You need to ensure that the web management interfaces of the two routers
| are not using the same IP address BEFORE connecting them together. You
| would also want to disable the DHCP server on the spare router. You may
| or may not need a crossover cable to connect the two routers via their
| LAN interfaces depending on their capabilities.
|
| Best Regards,
| News Reader
|

Not needed if the WAN port isn't used and the DHCP server is disabled.

--
Dave
http://www.claymania.com/removal-trojan-adware.html
Multi-AV - http://www.pctipp.ch/downloads/dl/35905.asp

[CWatters]

"Bruce" <brucenospam@adelphia.net> wrote in message
news:LzhHj.103$p97.76@trnddc03...
> I would hook it into one of the LAN ports instead. Turn off DHCP in the
> router and just use it as a 3 port switch.

In other words the WAN port is left unconnected and everything is connected
to LAN ports including the wire to the existing router. The firewall in the
new router isn't used and everything appears on the same network. DHCP is
turned off in the second router as you only want one issuing IP addresses.

[Ken Smith]

Thanks to everybody for the information & suggestions.
Much appreciated.

Ken