Does Windows 7 support 802.3ad (link aggregation) natively?

Question

I'm trying to understand what's needed to make Windows 7 combine two Ethernet ports into one virtual 2 gigabit port. I know I need 802.3ad compatible switch, my NAS also supports 802.3ad, but it's not sure what's needed on the desktop side.

I know I can buy an expensive 2-port server NIC, and Intel drivers have "teaming" support in them. However, my motherboard already has an integrated NIC. If I put a second, cheap regular network adapter, is there a way to enable 802.3ad over them in Windows?

Solution

For NIC teaming or link aggregation support, you'll need to contact your network adaptor vendor or OEM (e.g. Dell offers a teaming driver). They will need to provide you a driver that enables NIC teaming, since Windows does not offer this functionality in the core OS.

Source: http://answers.microsoft.com/en-us/windows/forum/windows_other-networking/does-windows-natively-support-link-aggregation/81e647f9-d89e-4028-8370-7e8bb0e3dc2f?msgId=6ca73c70-5ea7-4054-a75a-1be66d545b8a

Comments

[Ramhound]

You need the proper hardware. Here is a good discussion on that topic. forums.smallnetbuilder.com/showthread.php?t=427

[haimg]

It depends on usage patterns... If you, say, copy two files simultaneously it will be beneficial. Moreover, starting with Windows Server 2012 and Windows 8, SMB 3.0 supports multichannel: blogs.technet.com/b/josebda/archive/2012/06/28/…

[bokan]

@haimg : Coping two files does not work (or I have been very unluky). But thank you for pointing the new feature of SMB3

[Mark]

802.3ad aggregation can split a TCP/IP session just fine, since it works at the Ethernet level rather than the IP level. You just need hardware at both ends of the link that supports it.

[bokan]

@Mark : could you please verify and give reference for this statement ? For me it does not work. The algorithm for choosing wich link will be used by a TCP session is fairly simple, it's something like : hash(SoucreMac + DestMac) mod number_of_links. I tested various configurations and I could never get more than gigabit transfer per TCP/IP session. If the file transfert is splited over 2 TCP sessions, like SMB3 does, it works. Why would Microsoft have developed multichannel if 802.3ad were able to do it ?

[Mark]

@bokan, 802.3ad requires that the entire path support it in order to benefit: if your client supports it, your server supports it, but the switch in between doesn't, you only get one cable's worth of bandwidth. SMB multichannel looks like it's mainly about dealing with inefficiencies at the TCP level, with a side benefit of permitting link aggregation even if the hardware in between doesn't support it, but can only divide bandwidth at the TCP stream level, not the Ethernet packet level.

[bokan]

@Mark Of course I tested on high end professional hardware and the link was up ok. The server could even serve several clients at 1Gb/s each, but clients connected with a team of links were not faster. Have you ever build such a setup ? Have you ever seen a file transfer over 112MB/s using 802.3ad ? Please tell us how you did it, or admit it is not possible. Thank you.