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I have two routers:

Router A 192.168.X.X

Router B 192.168.Y.Y

My PC has two jacks for two Ethernet cables.

My PC is hooked up to one router (Router A) creating my first Local Area Connection.

I was bored, so.... I took my second Ethernet cable and hooked it up to my second router (Router B) using my second Ethernet port.

Now my computer has two LAN connections active, to two different routers that have two different setups in terms of the IP's.

I'ts kind of cool having two different IP's on one PC on my LAN both active, but I was just wondering if I should disable one, and just use one, so far I don't see any problems, at least yet.

Both connections are working fine, but the question was are there any benefits of doing this or any free or open source tools that I could use to analyze my network to see if there is a gain in this setup or not.

My main default gateway router controls the connection to the WAN on which I have these two routers (Router A & Router B) connected. So I was thinking the speed would be regulated here for the most part in addition to the ISP and type of service one is getting from them, and the fact that I have additional connections to two separate routers on one PC should not make a difference..., still not sure?

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up vote 4 down vote accepted

Combining ethernet ports is covered here Unless you have link aggregation enabled, your OS is likely just using one of the ports. Also, you are most likely limited by the WAN connection in your instance.

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Yeah, that's what I was thinking, the WAN connection in my instance is the limit among other variables. Link aggregation? I will read about that, even though a quick ipconfig shows both links are ative. On linux things don't seem to play well, you only get to use one iface. – Registered Oct 19 '09 at 22:54
Damn, typo for active and iface for linux. – Registered Oct 19 '09 at 22:55

Dual NICs are most useful in server environments, particularly in systems that are highly available. At home you probably wouldn't have much use for it unless you had two different ISPs (i.e. cable and DSL).

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I am no expert, but I think most servers only use a single NIC for traffic (another could be used for the management). – Arjan Oct 18 '09 at 8:55
In some cases it is just like having a redundant power supply or hard disk. If one NIC fails, the server automatically switches to the second. In others, dual NICs are used to segment access to resources. For example: one NIC may be the route that the public uses coming in and the other is the route that the server uses to access resources that the public is not allowed to see directly. – Mike Chess Oct 18 '09 at 14:37

You didn't mention what kind of WAN connection you have (e.g. DSL, FIoS, cable, etc.) or the speed of your ethernet connections, but it is most likely that your PC's networks connections (100Mbit? 1Gbit?) are both much faster than what your WAN connection (1Mbit?), so aggregating the two won't really buy you any better speed.

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Dual NICs in a server / Data center environment is for redundancy and link aggregation / teaming. It can also be used for load sharing and load balancing, depending on your port configuration and your network setup. It does not actually increase your bandwidth, but increases throughput, ie, multiple people accessing the same server would not slow down the server. When a server is rated with 1 Gig bandwidth, with 1 active ethernet port, if multiple users are using the server, it can congest the active link, but if you have dual ethernet port, both 1Gig, multiple users have available bandwidth to share available server resources. Thanks

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