Noob Subnet Mask Question

--amadeus--

I know I should be able to work this out and I did fix it once before but it's wrecking my head so all help greatly appreciated.

I have a test PC running Win XP connected to a LAN with a DC running Win Server 2000 (I like old tech, it's stable ). Desktop box also has a wireless card connecting to the router for 'net access.

But I can't get both to work at teh same time. I know why - it's attempting to route Internet traffic through the LAN. i also know that the solution is to use teh correct subnet masks (or at least I think I do).

Damned if I can get it to work though.

Setup on desktop is:

LAN (all static):
IP: 192.168.2.250
Subnet Mask: 255.255.255.0
Default gateway: 192.168.2.254
DNS: 192.168.2.254

Wireless (all dynamic)
IP: 192.168.1.1
Subnet Mask: 255.255.255.0
Default Gateway: 192.168.1.254
DNS: 192.168.1.254

Help, please. The tech gods will smile on you if you do!

Spear

--amadeus-- wrote: »

I know I should be able to work this out and I did fix it once before but it's wrecking my head so all help greatly appreciated.

I have a test PC running Win XP connected to a LAN with a DC running Win Server 2000 (I like old tech, it's stable ). Desktop box also has a wireless card connecting to the router for 'net access.

But I can't get both to work at teh same time. I know why - it's attempting to route Internet traffic through the LAN. i also know that the solution is to use teh correct subnet masks (or at least I think I do).

Damned if I can get it to work though.

Setup on desktop is:

LAN (all static):
IP: 192.168.2.250
Subnet Mask: 255.255.255.0
Default gateway: 192.168.2.254
DNS: 192.168.2.254

Wireless (all dynamic)
IP: 192.168.1.1
Subnet Mask: 255.255.255.0
Default Gateway: 192.168.1.254
DNS: 192.168.1.254

Help, please. The tech gods will smile on you if you do!

What's at the two gateway addresses?

Snaga

A multihomed host should only have one default gateway configured - otherwise windows will pick one of them to use and ignore the other.

The best way to do this is remove the default gateway from one of the lans (The one not connected to the internet usually) and add more specific static routes on the host pointing towards the second (and now non-default gateway) for each of the networks you want to access via this second router.

You can add the routes using the "route add" command via the windows command prompt... (Example using 10.0.0.0/24 as a remote network we want to reach via the second GW).

"route add 10.0.0.0 mask 255.255.255.0 192.168.2.1"

You can tack a '-p' on the end to make it a permanent route which survives a host reboot.

accensi0n

What caused the change?

--amadeus--

Spear wrote: »

What's at the two gateway addresses?

One is the wireless router the other is the Domain Controller

Snaga wrote: »

A multihomed host should only have one default gateway configured - otherwise windows will pick one of them to use and ignore the other.

The best way to do this is remove the default gateway from one of the lans (The one not connected to the internet usually) and add more specific static routes on the host pointing towards the second (and now non-default gateway) for each of the networks you want to access via this second router.

You can add the routes using the "route add" command via the windows command prompt... (Example using 10.0.0.0/24 as a remote network we want to reach via the second GW).

"route add 10.0.0.0 mask 255.255.255.0 192.168.2.1"

You can tack a '-p' on the end to make it a permanent route which survives a host reboot.

Hmmm, I think I'm following. Sounds like a sledgehammer to crack a nut though, isn't there an easier way?

accensi0n wrote: »

What caused the change?

The desktop PC is wiped down with a fresh install of Win XP fairly often and I don't think it's ever worked in it's current configuration but a similar setup was working in my other lab (if that makes sense)

Snaga

--amadeus-- wrote: »

Hmmm, I think I'm following. Sounds like a sledgehammer to crack a nut though, isn't there an easier way?

Well - a default gateway is a route of last resort - it doesn't really make sense to have more than one. Windows will choose the LAN interface GW over the WiFi GW as a matter of preference.

If you don't actually need to route outside of the 192.168.2.X network (i.e. your just trying to access a test box on that subnet) then just remove the default gateway from the LAN interface IP configuration (its not a required field) and leave the WiFi interface to get its details via DHCP as normal.

Your host will have connectivity to the 192.168.2.0/24 network but the host only has a single default gateway to use via the WiFi interface, et voila - internet access.

--amadeus--

Snaga wrote: »

Well - a default gateway is a route of last resort - it doesn't really make sense to have more than one. Windows will choose the LAN interface GW over the WiFi GW as a matter of preference.

If you don't actually need to route outside of the 192.168.2.X network (i.e. your just trying to access a test box on that subnet) then just remove the default gateway from the LAN interface IP configuration (its not a required field) and leave the WiFi interface to get its details via DHCP as normal.

Your host will have connectivity to the 192.168.2.0/24 network but the host only has a single default gateway to use via the WiFi interface, et voila - internet access.

I need to access file & print on the 192.168.2.X network but it sounds like your solution will sort that - I'm back in the office tomm afternoon & I'll give it a spin then.

Thanks!

--amadeus--

It worked, cheers