Slow data transfer in one direction

[dbuckley77]

We have an issue where data getting copied between networks works normally in one direction but is extremely slow in the other direction.  I have checked the nics on the VMs we're copying to and they're all set to 1000 full.  Also checked the interfaces on the switches in the possible paths and they're all at 1000 full as well.  Need assistance.

[Philip D'Ath]

How are the devices connected together?

I have seen a similar issue with TCP offloading bugs in NIC's.  You could test this idea by using netsh to temporarily disable these features and seeing what impact it has.

https://support.microsoft.com/en-nz/kb/951037

[dbuckley77]

As I said they are on different subnets so this is how they connect.  We have redunandt layer 3 switches as our core which do routing between our vlans.  It's a hub and spoke topolgy from this core so basically the hosts on one network are hanging off of a few switches from the core and the other network that we're copying to is hanging off a few switches from the core in a different direction. 

I was told it was a one way issue but I just tested it myself and I'm seeing similiar speeds in both directions.  I'm seeing around 8- 15Mbps and pretty much everything from core to access is 1GB interfaces.

[Philip D'Ath]

How are you testing the speed?

Could you test it with an application like iPerf?

[dbuckley77]

I'm just going by what windows is telling me.  I'm copying from share to share.

[AdamBudzinski]

does it occur ONLY when copying from share to share ? if yes, then were does the share reside on ?