2xNAT, 2xDHCP, Modem, Router "is this a messy network??"

Hi,

Below is my current network setup. It works! (read from top to
bottom).

¬¬ADSL>>>>>+-------------------------+
| ADSL MODEM (A) |
| SINGLE ETHERNET PORT |
| IP Address 192.168.1.1 |
| DHCP ON |
| NAT ON |
| |
| IP ASSIGNED RANGE |
| 192.168.1.2 to 10 |
| |
| ONLY CLIENT ASSIGNED |
| WIRELESS ROUTER (B) |
| 192.168.1.2 |
+-------------------------+
"
"
CAT 5
"
+-------------------------+
| WIRELESS ROUTER (B) |
| 4 WIRED PORTS |
| DHCP ON |
| IP Address 192.168.2.1 |
| |
| NAT ON |
| |
| IP ASSIGNED RANGE |
| 192.168.2.2 to 10 |
+-------------------------+

..all the client PC's (which includes a CENTOS Linux file and print
server) hang off the wireless router.

but....

I keep thinking that 2 NATS and 2 DHCP servers, is not right and
numerous Google searches seem to confirm this.

I suppose your next question is; "...if it works..leave it!" and this
would seem the right approach, but I do notice that if I plug a PC
directly into the ADSL MODEM (A), that the slight delay between a
website request and it being displayed (that seems to afflict the
setup shown), is not there. I speculate that this is because of the
unnecessary "doubling" of NAT and DHCP.

Now, the "Google" consensus seems to be; "switch NAT and DHCP off in
WIRELESS ROUTER (B) and let the ADSL MODEM (A) do the work, but this
does not seem to work. Therefore is the best best option;

1) Turn NAT and DHCP off on ADSL MODEM (A), but retain its IP address
of 192.168.1.1;
2) Create a static LAN client in ADSL MODEM (A) with IP of 192.168.1.2
which is for WIRELESS ROUTER (B);
3) Change the IP assigning range in WIRELESS ROUTER (B) to
192.168.1.3-11 (so all devices are on the same subnet, where the mask
is 255,255,255,0, but the internet gateway modem is outside the DHCP
range of WIRELESS ROUTER (B));
4) Assign or tick box (if available) for WAN port to LAN port(?) so
that WAN traffic is directly passed to 192.168.1.2;
5) Set a nice strong password on WIRELESS ROUTER (B), which doesn't
have one presently (bit obvious that one!).

What do you think?

ST

....if not, a messy post sorry about the odd character set usage!

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(E-Mail Removed) wrote:

[snipped]

> Now, the "Google" consensus seems to be; "switch NAT and DHCP off in
> WIRELESS ROUTER (B) and let the ADSL MODEM (A) do the work, but this
> does not seem to work. Therefore is the best best option;

It probably wouldn't because either you don't have any DHCP relay software
installed on your Wireless router. OR you've not connected ADSL modem to
the one of those 4 LAN ports of your wireless router, instead connected the
ADSL modem to the 'Internet' (or WAN) port of the wireless router.

>
> 1) Turn NAT and DHCP off on ADSL MODEM (A), but retain its IP address
> of 192.168.1.1;

If you turn off NAT on your ADSL modem, packets from your LAN with source
address set to an 192.168.1.0/24 (an RFC1918 address) will go out and get
dropped by the ISP's gateway.

> 2) Create a static LAN client in ADSL MODEM (A) with IP of 192.168.1.2
> which is for WIRELESS ROUTER (B);

okay

> 3) Change the IP assigning range in WIRELESS ROUTER (B) to
> 192.168.1.3-11 (so all devices are on the same subnet, where the mask
> is 255,255,255,0, but the internet gateway modem is outside the DHCP
> range of WIRELESS ROUTER (B));

okay

> 4) Assign or tick box (if available) for WAN port to LAN port(?) so
> that WAN traffic is directly passed to 192.168.1.2;

so 192.168.1.2 will act as gateway, and to whom it will forward the traffic.
to 192.168.1.1 ? okay, but I don't know what 192.168.1.1 will do to all
packets with SOURCE MAC set to MAC address of 192.168.1.2 but SOURCE IP of
other clients, hmm....

> 5) Set a nice strong password on WIRELESS ROUTER (B), which doesn't
> have one presently (bit obvious that one!).

thats obvious

> What do you think?

Posted above.

> ST

HTH
- --
Ashish Shukla आशीष श�क�ल http://wahjava.wordpress.com/
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> I keep thinking that 2 NATS and 2 DHCP servers, is not right and
> numerous Google searches seem to confirm this.

> I suppose your next question is; "...if it works..leave it!" and this
> would seem the right approach, but I do notice that if I plug a PC
> directly into the ADSL MODEM (A), that the slight delay between a
> website request and it being displayed (that seems to afflict the
> setup shown), is not there. I speculate that this is because of the
> unnecessary "doubling" of NAT and DHCP.

If the NAT&DHCP&DNS service offered by the modem is sufficient for your
needs, then change your router into a mere "switch + access point": turn
off the DHCP&DNS servers on the router; don't use the WAN port (or
change it into a 5th port on the LAN-swaitch if you can); set the
router's LAN IP to be within the modem's network (192.168.1.X), maybe by
letting it query its LAN address via DHCP.

Maybe another option is to put your modem in bridge mode (and change
the router to manage PPPoE connection).

Yet another is to put your router in DMZ zone, but this is likely to not
do what you want.


Stefan

On Dec 23, 1:32 am, Stefan Monnier <monn...@iro.umontreal.ca> wrote:
> If the NAT&DHCP&DNS service offered by the modem is sufficient for your
> needs, then change your router into a mere "switch + access point": turn
> off the DHCP&DNS servers on the router; don't use the WAN port (or
> change it into a 5th port on the LAN-swaitch if you can); set the
> router's LAN IP to be within the modem's network (192.168.1.X), maybe by
> letting it query its LAN address via DHCP.
>
Stefan,

After a bit of manual reading (should have done this firstly), I have
turned the Access Point feature "ON" (Belkin router) and now all the
NAT and DHCP address allocation is done by the ADSL modem. I gave the
Belkin router an address in the same sub net as the modem, but outside
the DHCP range. All works fine now.

Thanks.

ST