How to connect to two LANs?

[David Maynard]

An outlet on a wall is a port of a switch, router or hub. Therefore, I
should connect it to the Uplink port on the switch. And there will not
be another Uplink port for the other network outlet. How to connect the
other outlet on a wall to my switch?

You don't. It's a separate network.

 

[Dima]

Both networks require to get an IP address automatically, therefore, a
subnet mask is grayed out for the both networks, therefore, I cannot
say if they are on the same subnet or not.

 

[Dima]

Will not connecting our two networks to two NICs in one computer cause
a problem to any of the networks? Because our domain administrators
connected only one network to a computer and gave two computers to a
person who needed both networks.

 

[David Maynard]

Both networks require to get an IP address automatically, therefore, a
subnet mask is grayed out for the both networks, therefore, I cannot
say if they are on the same subnet or not.

They can't be on the same subnet or else they wouldn't be two networks.

 

[David Maynard]

Will not connecting our two networks to two NICs in one computer cause
a problem to any of the networks? Because our domain administrators
connected only one network to a computer and gave two computers to a
person who needed both networks.

Why don't you ask the domain administrators since they know the network and
what will, or will not, cause problems for them?

But if a multi-homed computer is going to create problems for them then
connecting the two networks together with a switch for dern sure is.

I'd think a dual homed machine would be okay as long as you tell one of the
network connections to not register the connection with DNS so there's not
a double entry for the one machine which, of course, is avoided by using
two computers and is, no doubt, why they did it that way.

 

[Dima]

They are physically separated, different networks, therefore, their
subnet IP addresses can be set the same. One of the networks is not
connected to internet at all.

 

[Dima]

Thanks for your reply.
The domain administrators are not here, I cannot ask them any more. How
to tell one of the network connections to not register the connection
with DNS so there's not a double entry for the one machine?

 

[Dima]

Should I uncheck 'Register addresses of this connection in DNS' on DNS
tab in 'Advanced TCP/IP parameters' window of one of the two NIC
properties?

 

[David Maynard]

They are physically separated, different networks, therefore, their
subnet IP addresses can be set the same. One of the networks is not
connected to internet at all.

I have no idea where those two networks go, what domain controller serves
them, where they get DNS, WINS, or anything else so there's no way to know
anything about them. And even if their subnet addresses 'could' be the same
that doesn't mean they are.

There's just nothing to go on.

 

[David Maynard]

Should I uncheck 'Register addresses of this connection in DNS' on DNS
tab in 'Advanced TCP/IP parameters' window of one of the two NIC
properties?

Yes, that's the one I meant but I'm assuming both subnets are in the same
domain.

 

[Dima]

How to know if both subnets are in the same domain? I do not change
anything in my computer to connect to both networks by connecting
cables interchangeably. My Windows 2000 is in a domain.

 

[David Maynard]

How to know if both subnets are in the same domain? I do not change
anything in my computer to connect to both networks by connecting
cables interchangeably. My Windows 2000 is in a domain.

If you're connecting to both of them with the same domain logon then both
subnets are in the same domain and they're probably not 'completely
separate' as you suggested since it would be almost certain they're on the
same domain controller. At least that would be the 'normal' way to do it.
That would also mean they're different subnets.

That one or the other may or may not have internet access is simply a
matter of routing and they might have done that if they wanted one to be
more 'secure' than the other, or if they simply didn't want people on that
subnet on the internet for whatever reason.

At any rate, I'd think that as long as your machine doesn't register in DNS
on both NICs and doesn't attempt to route between the two it should be okay
to dual home it as that's not much different than having a local LAN and a
DSL connection at the same time, like I'm doing right now.

On the other hand, if you can't see machines on one network from the other
then it strikes me that they don't *want* people to be on both, or else
they'd route them to each other, so they may not be real happy with you
doing that even if it technically works and I can think of at least one
reason why. If they've got the second subnet isolated to protect it from
internet infection then your dual homed machine would subvert that intent
by providing an infection path. I.E. You inadvertently get a
virus/worm/trojan, by whatever means, and, poof, your machine then pukes it
onto the second subnet.

 

[Dima]

How to make sure my machine doesn't attempt to route between the two
NICs?
Should not my machine register in DNS on both NICs or one NIC?

 

[Dima]

Windows Autoapdate is enabled, all updates are installed as soon as
they appear. Mcafee VirusScan 8.0.0 is updated and VirusScan 8.0.0
on-access scan is enabled.

 

[David Maynard]

How to make sure my machine doesn't attempt to route between the two
NICs?

It won't unless you gateway them or have a server version and configure
remote access and routing.

Should not my machine register in DNS on both NICs or one NIC?

Just one NIC or else the one machine name will be in DNS with two addresses.

 

[Dima]

ipconfig /all shows that DHCP is allowed, a default gateway is the same
172.31.144.1 and DHCP server is the same 172.31.0.10 for the both NICs,
IP-routing is turned off.
I successfully installed the second NIC - TRENDnet MEDIAnet USB To Fast
Ethernet Adapter TU-ET100C. First 10 minutes I could get access to
network
resources through it, but now any of the two networks, connected to it,
is
not accessible. Both networks are accessible through first NIC
interchangeably. I unchecked "Register addresses of this connection in
DNS"
in both NICs properties.
How to get access to a network through TU-ET100C NIC?

 

[David Maynard]

ipconfig /all shows that DHCP is allowed, a default gateway is the same
172.31.144.1 and DHCP server is the same 172.31.0.10 for the both NICs,
IP-routing is turned off.

If they both have the same gateway then the two networks are not isolated
from each other like you suggested.

I successfully installed the second NIC - TRENDnet MEDIAnet USB To Fast
Ethernet Adapter TU-ET100C. First 10 minutes I could get access to
network
resources through it, but now any of the two networks, connected to it,
is
not accessible.

Sounds like something is messed up in your configuration and the server
thinks the second NIC is some bogus unauthorized faker trying to use your
machine name.

Both networks are accessible through first NIC
interchangeably. I unchecked "Register addresses of this connection in
DNS"
in both NICs properties.

You have to be registered in DNS on SOMETHING, one or the other, just not
both at the same time.

How to get access to a network through TU-ET100C NIC?

I don't know because what you give doesn't match. Like I said above, if
they've got the same gateway then they're not separate networks and one NIC
on one wall port should provide access to all of it.

But if they *are* separate then the gateway should be different for each NIC.

 

[Dima]

Thank you, David, for your help.
Now, the NIC's have different default gateways and the third numbers in
the NIC's IP addresses, after disconnecting from USB and reconnecting
to another USB port. I have access to both networks now. However,
subnet masks are the same in both NIC's properties. How to prevent both
network cards from having the same gateway in the
future reconnections? IP addresses are got automatically in TCP/IP
properties of both network cards, therefore, default gateway is grayed
out.
Why have I to be registered in DNS on SOMETHING?
Is USB 1.1 speed a constraint for 100 mbit Ethernet? Should I change
"TRENDnet MEDIAnet USB 1.1 To Fast Ethernet Adapter TU-ET100C" to
"D-Link DUB-E100 USB 2.0 Fast Ethernet Adapter" to use 100 mbit
Ethernet full speed?

 

[David Maynard]

Thank you, David, for your help.
Now, the NIC's have different default gateways and the third numbers in
the NIC's IP addresses, after disconnecting from USB and reconnecting
to another USB port. I have access to both networks now.
Good.

However,
subnet masks are the same in both NIC's properties.

Doesn't matter. There's nothing wrong with having the same subnet mask as
that just defines which bits are used to distinguish between the subnets
and they probably use the same ones since that's the easy way to configure
a small to medium size network. I've got 4 subnets here and they all have
the same subnet mask.

How to prevent both
network cards from having the same gateway in the
future reconnections? IP addresses are got automatically in TCP/IP
properties of both network cards, therefore, default gateway is grayed
out.

DHCP does that and you probably had the same gateway by swapping the NIC
between networks so the server said "hell no you don't get a new address,
you're still on that one over there" so Windows just used what it 'had'
from the last DHCP request.

Why have I to be registered in DNS on SOMETHING?

How is anything going to find your machine by it's name if the name isn't
in DNS with an address assigned to it?

Is USB 1.1 speed a constraint for 100 mbit Ethernet?

Since USB 1.1 is 12Mbits/second max, yeah.

Should I change
"TRENDnet MEDIAnet USB 1.1 To Fast Ethernet Adapter TU-ET100C" to
"D-Link DUB-E100 USB 2.0 Fast Ethernet Adapter" to use 100 mbit
Ethernet full speed?

If by all that alphabet soup of names you mean plug the NIC into a USB 2
port then yes.

 

[Dima]

Why should anything find my machine by it's name in DNS with an address
assigned to it? I find everything in networks by myself.
I replaced "TRENDnet MEDIAnet USB 1.1 To Fast Ethernet Adapter
TU-ET100C" with "D-Link DUB-E100 USB 2.0 Fast Ethernet Adapter".