Windows 2008 - mulitple nics, single subnet

Forums › LAN (ethernet/Wifi/routers/Bluetooth) › Windows 2008 - mulitple nics, single subnet - appear as "one"

davidcole

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#108682 3-Sep-2012 17:44

Basically I want to have some sort of balancing/tolerance on the machine. The NICs are differing brands (and not server ones, so I'm not able to team them.

They both currently get their own ip address from dhcp, which I dont have a problem with, but I wouldn't mind both being accessible via the same server name - is this possible?

Any one know how? I'd hope that if accessible they would automagically split traffic (on each new connection) across the two nics? So say if I was copying a large file on nic1, initiating a another file copy would use the 2nd nic?

I'd just prefer to not have to do the two file transfers using the servers 2 names (or ip addresses direcctly).

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Ragnor

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#681217 4-Sep-2012 10:50

Fairly sure Windows server 2008 doesn't have native link aggregation (Windows server 2012 does) and you need to use the NIC vendors software for this (Broadcom or Intel typically) which usually means you need two of the same vendor/model.

You should be able to pick up a cheap broadcom or intel two port NIC that supports link aggregation/teaming, try trademe.

davidcole

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#681222 4-Sep-2012 10:55

I was hoping I could just do something in DNS. This (2.3) seemed to imply I could...but didn't tell me how.

ubergeeknz

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#681226 4-Sep-2012 11:08

You could just have 2 A records for the box at each IP address. That will kind of work, for multiple clients at least. But you might have problems with firewalls etc. in the case that traffic takes a different return path from the server (which can happen if both have a default GW set)

davidcole

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#681228 4-Sep-2012 11:10

ubergeeknz: You could just have 2 A records for the box at each IP address. That will kind of work, for multiple clients at least. But you might have problems with firewalls etc. in the case that traffic takes a different return path from the server (which can happen if both have a default GW set)

This is only for internal lan stuff. I've no interest in exposing both ip addresses to the internet.

gehenna

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#681230 4-Sep-2012 11:12

What ubergeeknz said is probably your best bet for getting it working quickly, easily, and without buying any new NICs.

It might not prove to be a very agile solution over time though if you need to make alterations or changes.

Ragnor

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#681234 4-Sep-2012 11:28

davidcole: I was hoping I could just do something in DNS. This (2.3) seemed to imply I could...but didn't tell me how.

Is there a windows domain/active directory or is this just a windows workgroup setup?

Actually I think it should just work like 2.3 either way already for connections initiated by clients to the server. For connections initiated by the server I think it will always just use the NIC with the lowest metric/priority for the route.

You could test client to server by running pings on the clients to the server-name, see what ip address you get, then run another and another (individually) and you should get different ip addresses on different occasions (round robin).

To check the route table on the client or server open a cmd window (windows key + r > cmd) type: route print

Zeon

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#681237 4-Sep-2012 11:41

While you could use round robin DNS this won't work too well and is still limiting you to the same subnet. For the price of NICs I would strongly suggest you get the same vendor so you can use 802.3ad (teaming) which is designed for your usage case. Does your switch support it though?

I've recently upgraded our dual port NICs to quad ports (all Intel) so feel free to PM me if you are after a dual port Intel NIC (practically brand new).

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davidcole

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#681262 4-Sep-2012 12:03

Ragnor:
davidcole: I was hoping I could just do something in DNS. This (2.3) seemed to imply I could...but didn't tell me how.

Is there a windows domain/active directory or is this just a windows workgroup setup?

Actually I think it should just work like 2.3 either way already for connections initiated by clients to the server. For connections initiated by the server I think it will always just use the NIC with the lowest metric/priority for the route.

You could test client to server by running pings on the clients to the server-name, see what ip address you get, then run another and another (individually) and you should get different ip addresses on different occasions (round robin).

To check the route table on the client or server open a cmd window (windows key + r > cmd) type: route print

Just a workgroup with gargoyle as the router the machine is connected to (twice). But if I ping the server, surely gargoyle is going to give me the IP address - rather than the server.

Do I need to take this machine out of DHCP so that it's broadcasting it's name and ipaddres(s)?

If I was able to implement a pretty simple solution I would, failing that I'll just access it via both hostnames/ip addresses manually if I have to.

Ragnor

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#681284 4-Sep-2012 12:28

Every time you ping the server name from another PC you should have a 50% chance of getting ip #1 or ip #2

Gargoyle Router doesn't seem to have a WINS server so master browser (a computer holding a list of the names/ip addresses on the network) will default to one of the windows machines on your network.

davidcole

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#681288 4-Sep-2012 12:36

Ragnor: Every time you ping the server name from another PC you should have a 50% chance of getting ip #1 or ip #2

Gargoyle Router doesn't seem to have a WINS server so master browser (a computer holding a list of the names/ip addresses on the network) will default to one of the windows machines on your network.

I don';t think I've ever seen this behaviour. But if Gargoyle is listed as the gateway and dns for the subnet, wont that provide the static IP address it gives out for that host name?

Ragnor

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#681509 4-Sep-2012 21:32

davidcole: Gargoyle is listed as the gateway and dns for the subnet, wont that provide the static IP address it gives out for that host name?

Only if the DNS server and DHCP client are integrated would the routers dns server/cache know about local host/computer names.

At a cmd prompt what does nslookup server-name show?

Edit:

These articles cover name resolution on windows

Microsoft TCP/IP Host Name Resolution Order
NetBIOS over TCP/IP Name Resolution and WINS

So it does try DNS, but the question is does your router's DNS server know about local host/computer names.

wasabi2k

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#681942 5-Sep-2012 17:52

Short Version: Buy NICs that support Teaming.

Long Version: DNS Round Robin provides some level of load balancing but requires a large number of clients to be at all effective. Clients will cache name resolution in most cases - so it will resolve IP1 and continue to use IP1 until cache is cleared OR TTL expires. The times vary based on name resolution technology (WINS, Broadcast, DNS) and client.

Outbound, you will not achieve anything. Your PC will use the combination of routing metric and NIC binding order to send outbound traffic. First NIC will always be used until it fails.

Round Robin will NOT provide failover or HA, client will simply get directed to a failed IP/link.

2 NICs on the same subnets with different IPs is in short a waste of time. GLHF.

See Short Version.