Gateway Address

I think I uderstand that a gateway is only needed to join two
incompatible networks but am wondering.

On the TCP/IP settings there always appears to be a gateway setting
that defaults to 0.0.0.0

For a simple home network that is all TCP/IP but with shared internet
as well as wired and wireless should the gateway be set to anything or
left blank?

Geoff Lane

In article <(E-Mail Removed)>, Geoff Lane
<(E-Mail Removed)> wrote:
>I think I uderstand that a gateway is only needed to join two
>incompatible networks but am wondering.
>
>On the TCP/IP settings there always appears to be a gateway setting
>that defaults to 0.0.0.0
>
>For a simple home network that is all TCP/IP but with shared internet
>as well as wired and wireless should the gateway be set to anything or
>left blank?
>
>Geoff Lane

I wouldn't say "incompatible networks", Geoff.

The default gateway is the IP address used to communicate with IP
addresses that aren't on any of a computer's local area network
interfaces. That typically includes all Internet web servers, E-mail
servers, news servers, etc. The default gateway address usually
belongs to your Internet service provider.

0.0.0.0 isn't a valid IP address, and it can't be the address of a
default gateway. Are you thinking of a route table entry that looks
like this?

0.0.0.0 0.0.0.0 a.b.c.d w.x.y.z

That's a default route, as indicated by values of 0.0.0.0 for the
destination IP address and the subnet mask. The default gateway's IP
address is "a.b.c.d", and TCP/IP uses the LAN interface with address
"w.x.y.z" to communicate with the default gateway.

Here's why TCP/IP uses the default gateway to access a non-LAN IP
address:

1. No local IP address or subnet matches a non-LAN IP address, and:

2. The logical "and" of any IP address with the subnet mask 0.0.0.0 is
0.0.0.0, which matches the destination IP address of the default
route.
--
Best Wishes,
Steve Winograd, MS-MVP (Windows Networking)

Please post any reply as a follow-up message in the news group
for everyone to see. I'm sorry, but I don't answer questions
addressed directly to me in E-mail or news groups.

Microsoft Most Valuable Professional - Windows Networking
http://mvp.support.microsoft.com

Steve Winograd's Networking FAQ
http://www.bcmaven.com/networking/faq.htm

On Mon, 22 Sep 2003 03:41:12 -0600, "Steve Winograd [MVP]"
<(E-Mail Removed)> wrote:


>>On the TCP/IP settings there always appears to be a gateway setting
>>that defaults to 0.0.0.0
>>
>>For a simple home network that is all TCP/IP but with shared internet
>>as well as wired and wireless should the gateway be set to anything or
>>left blank?

>The default gateway is the IP address used to communicate with IP
>addresses that aren't on any of a computer's local area network
>interfaces.

>0.0.0.0 isn't a valid IP address, and it can't be the address of a
>default gateway. Are you thinking of a route table entry that looks
>like this?
>
> 0.0.0.0 0.0.0.0 a.b.c.d w.x.y.z

Might be the explanation...

>That's a default route, as indicated by values of 0.0.0.0 for the
>destination IP address and the subnet mask. The default gateway's IP
>address is "a.b.c.d", and TCP/IP uses the LAN interface with address
>"w.x.y.z" to communicate with the default gateway.
>
>Here's why TCP/IP uses the default gateway to access a non-LAN IP
>address:
>
>1. No local IP address or subnet matches a non-LAN IP address, and:
>
>2. The logical "and" of any IP address with the subnet mask 0.0.0.0 is
>0.0.0.0, which matches the destination IP address of the default
>route.

Kinda follow, if I read it a few times I'm sure it'll make more sense.

Thanks for the explanation.

Geoff Lane

In article <(E-Mail Removed)>, Geoff Lane
<(E-Mail Removed)> wrote:
>On Mon, 22 Sep 2003 03:41:12 -0600, "Steve Winograd [MVP]"
><(E-Mail Removed)> wrote:
>>>On the TCP/IP settings there always appears to be a gateway setting
>>>that defaults to 0.0.0.0
>>>
>>>For a simple home network that is all TCP/IP but with shared internet
>>>as well as wired and wireless should the gateway be set to anything or
>>>left blank?
>
>>The default gateway is the IP address used to communicate with IP
>>addresses that aren't on any of a computer's local area network
>>interfaces.
>
>>0.0.0.0 isn't a valid IP address, and it can't be the address of a
>>default gateway. Are you thinking of a route table entry that looks
>>like this?
>>
>> 0.0.0.0 0.0.0.0 a.b.c.d w.x.y.z
>
>Might be the explanation...
>
>>That's a default route, as indicated by values of 0.0.0.0 for the
>>destination IP address and the subnet mask. The default gateway's IP
>>address is "a.b.c.d", and TCP/IP uses the LAN interface with address
>>"w.x.y.z" to communicate with the default gateway.
>>
>>Here's why TCP/IP uses the default gateway to access a non-LAN IP
>>address:
>>
>>1. No local IP address or subnet matches a non-LAN IP address, and:
>>
>>2. The logical "and" of any IP address with the subnet mask 0.0.0.0 is
>>0.0.0.0, which matches the destination IP address of the default
>>route.
>
>Kinda follow, if I read it a few times I'm sure it'll make more sense.
>
>Thanks for the explanation.
>
>Geoff Lane

You're welcome, Geoff.

There's an explanation of routes and routing tables in the Windows 98
Second Edition Resource Kit. You can install the Resource Kit from
the W98SE CD-ROM by running the file setup\tools\reskit\setup.exe.

To see the Resource Kit, go to Start | Programs | Windows 98 Resource
Kit | Resource Kit Online Book. In the table of contents, click
"Network Adapters and Protocols" and then click ""Microsoft TCP/IP
Protocol".
--
Best Wishes,
Steve Winograd, MS-MVP (Windows Networking)

Please post any reply as a follow-up message in the news group
for everyone to see. I'm sorry, but I don't answer questions
addressed directly to me in E-mail or news groups.

Microsoft Most Valuable Professional - Windows Networking
http://mvp.support.microsoft.com

Steve Winograd's Networking FAQ
http://www.bcmaven.com/networking/faq.htm

On Mon, 22 Sep 2003 23:25:49 -0600, "Steve Winograd [MVP]"
<(E-Mail Removed)> wrote:


>>>Here's why TCP/IP uses the default gateway to access a non-LAN IP
>>>address:
>>>
>>>1. No local IP address or subnet matches a non-LAN IP address, and:
>>>
>>>2. The logical "and" of any IP address with the subnet mask 0.0.0.0 is
>>>0.0.0.0, which matches the destination IP address of the default
>>>route.
>>
>>Kinda follow, if I read it a few times I'm sure it'll make more sense.

>There's an explanation of routes and routing tables in the Windows 98
>Second Edition Resource Kit. You can install the Resource Kit from
>the W98SE CD-ROM by running the file setup\tools\reskit\setup.exe.
>
>To see the Resource Kit, go to Start | Programs | Windows 98 Resource
>Kit | Resource Kit Online Book. In the table of contents, click
>"Network Adapters and Protocols" and then click ""Microsoft TCP/IP
>Protocol".

I'm having a problem at the moment setting up my daughter's laptop
with XP home installed to act as a server for Internet Sharing at the
moment so I might dig out my CD and give that a try.

Network's been going fine but due to an extension my main 'server'
computer needs to be put away for a while so settings need to be
altered :-(((

Geoff Lane