When you have 2+ NIC in one computer, how do you determine which is used?
09 January 2008, 09:19 PM
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When you have 2+ NIC in one computer, how do you determine which is used?
I'm just messing around (queue imminent failure of the machine 
)
I have a PCI Gigabit card, and also a 100MBit card on the mobo. For a laugh I decided to enable them both. They both have different IPs, and both point at the same gateway.
Looking at the router the Gigabit NIC is the one the PC chose to send connections through as it was the only one that was flashing. Unplugging the gigabit cable resulted in the computer being unhappy for about 3 seconds, and then all the traffic went down the 100MBit card. When I plugged the gigabit NIC cable back in, the traffic all switched to use that card again.
Surprisingly, Windows has actually done what you would want. Use the fastest card by default. Just out of interest, how would you change which card the PC uses (when both are enabled...no cheating by turning one off).
Also, is it possible for Windows (without add in programs) to use both cards at the same time splitting the workload.
All the above is just for a little fun. I feel like having a little play
)I have a PCI Gigabit card, and also a 100MBit card on the mobo. For a laugh I decided to enable them both. They both have different IPs, and both point at the same gateway.
Looking at the router the Gigabit NIC is the one the PC chose to send connections through as it was the only one that was flashing. Unplugging the gigabit cable resulted in the computer being unhappy for about 3 seconds, and then all the traffic went down the 100MBit card. When I plugged the gigabit NIC cable back in, the traffic all switched to use that card again.
Surprisingly, Windows has actually done what you would want. Use the fastest card by default. Just out of interest, how would you change which card the PC uses (when both are enabled...no cheating by turning one off).
Also, is it possible for Windows (without add in programs) to use both cards at the same time splitting the workload.
All the above is just for a little fun. I feel like having a little play
Last edited by Luminous; 09 January 2008 at 09:22 PM.
09 January 2008, 11:11 PM
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If the cards are the same some manufacturers have teaming software so you can bond the two together to either work as failover or as a team doubling the network speed
only one MAC address is used in the above instance
Your not supposed to have a gateway on multiple NIC's only on the primary NIC
They have a binding order under advanced settings should tell you which NIC is the primary (bascially the one higher in the list)
When you say they both have different IP's do you mean they have different IP's on the same subnet
IE card 1 192.168.10.2
card 2 192.168.10.3
default gateway on both NIC's 192.168.10.1
if so that will work regardless, however in the above configuration, you would normally have two different subnets
ie
Card 1 192.168.10.1
Card 2 10.10.10.1
one will have a default gateway, the other routes by using static routes, but Windows isnt the best device for routing IP
only one MAC address is used in the above instance
Your not supposed to have a gateway on multiple NIC's only on the primary NIC
They have a binding order under advanced settings should tell you which NIC is the primary (bascially the one higher in the list)
When you say they both have different IP's do you mean they have different IP's on the same subnet
IE card 1 192.168.10.2
card 2 192.168.10.3
default gateway on both NIC's 192.168.10.1
if so that will work regardless, however in the above configuration, you would normally have two different subnets
ie
Card 1 192.168.10.1
Card 2 10.10.10.1
one will have a default gateway, the other routes by using static routes, but Windows isnt the best device for routing IP
10 January 2008, 10:03 AM
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Bindings are just used to assign a NIC to a piece of software when it requests network access.
"When you have 2+ NIC in one computer, how do you determine which is used?"
Route metrics
start->run->cmd <enter>
Type route print
In the last column you'll see metrics.
Basically every route on every bit of routing hardware had a number associated with it. Imagine it as the length of a piece of string connecting your hardware. If two routes are going to the same destination, the one with the lower metric will be used as that is a "shorter" virtual distance.
In windows, you can change these with the route change command but I'd advise against doing it unless you really know what you're doing
Changing the binding order will change the metrics behind the scenes, but it is only a by product of changing the binding order to make sure that the general populous dont have networking issues every time they change the binding.
Jules
"When you have 2+ NIC in one computer, how do you determine which is used?"
Route metrics
start->run->cmd <enter>
Type route print
In the last column you'll see metrics.
Basically every route on every bit of routing hardware had a number associated with it. Imagine it as the length of a piece of string connecting your hardware. If two routes are going to the same destination, the one with the lower metric will be used as that is a "shorter" virtual distance.
In windows, you can change these with the route change command but I'd advise against doing it unless you really know what you're doing
Changing the binding order will change the metrics behind the scenes, but it is only a by product of changing the binding order to make sure that the general populous dont have networking issues every time they change the binding.
Jules
Last edited by judgejules; 10 January 2008 at 10:08 AM. Reason: typos
10 January 2008, 11:05 AM
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The two different IPs are on the same subnet mask. ie 192.168.0.5 and 102.168.0.6 as an example (not the real addresses)
The cards are from different manufacturers, so no easy options there
Route print is really cool. It shows the gigabit card with a metric of 10, while the 100MBit card has a metric of 20. Hence while the gigabit card is capable of working its used
Mind you, that route print output is full of other stuff. Just goes to show, when it comes to computers you never really learn more. You just realise how much more there is out there to learn
The cards are from different manufacturers, so no easy options there
Route print is really cool. It shows the gigabit card with a metric of 10, while the 100MBit card has a metric of 20. Hence while the gigabit card is capable of working its used
Mind you, that route print output is full of other stuff. Just goes to show, when it comes to computers you never really learn more. You just realise how much more there is out there to learn
10 January 2008, 12:09 PM
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Go in to network connections.
Select both of the active connections then right click one and select "bridge connections".
Et voila, a single IP using both connections.
Don't ask me about the throughput and whether the 100mb will be holding the 1gb back (I doubt it) as its been many years since I've done bridging for real and that was at the hardware level using two similar cards (as sonic mentioned above).
Give it a whirl
J
Select both of the active connections then right click one and select "bridge connections".
Et voila, a single IP using both connections.
Don't ask me about the throughput and whether the 100mb will be holding the 1gb back (I doubt it) as its been many years since I've done bridging for real and that was at the hardware level using two similar cards (as sonic mentioned above).
Give it a whirl
J
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10 January 2008, 04:04 PM
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Today is a day for trying things...
earlier I decided it would be a great idea if I knocked over about 1/2 pint of hot tea
It went over my AV amp, both externall HDDs, calculator, keyboard, mouse, sub, network hub, subwoofer, new computer, spare computer, power socket and mobile.
Fully understanding the water and electricity don't mix I stood back and waited for the electrical blast of doom. And waited... None came. For the last couple of hours I have been turning things upside down watching tea run out of them. Its amazing how much tea fits inside a keyboard
Amazingly, I suffered no damage...and all items were on at the time!
earlier I decided it would be a great idea if I knocked over about 1/2 pint of hot tea
It went over my AV amp, both externall HDDs, calculator, keyboard, mouse, sub, network hub, subwoofer, new computer, spare computer, power socket and mobile.Fully understanding the water and electricity don't mix I stood back and waited for the electrical blast of doom. And waited...
None came. For the last couple of hours I have been turning things upside down watching tea run out of them. Its amazing how much tea fits inside a keyboard Amazingly, I suffered no damage...and all items were on at the time!
Last edited by Luminous; 10 January 2008 at 04:08 PM.
10 January 2008, 04:12 PM
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Go in to network connections.
Select both of the active connections then right click one and select "bridge connections".
Et voila, a single IP using both connections.
Don't ask me about the throughput and whether the 100mb will be holding the 1gb back (I doubt it) as its been many years since I've done bridging for real and that was at the hardware level using two similar cards (as sonic mentioned above).
Give it a whirl
J
Select both of the active connections then right click one and select "bridge connections".
Et voila, a single IP using both connections.
Don't ask me about the throughput and whether the 100mb will be holding the 1gb back (I doubt it) as its been many years since I've done bridging for real and that was at the hardware level using two similar cards (as sonic mentioned above).
Give it a whirl
J
This should be useful for helping to diagnose my network fault. The hub often refuses to recognise the Gigabit card unless it is rebooted. Now that the 100MBit is also connected, it should tell me if its an issue with the card or the hub.
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