Win7 and Windows Server 2008 and R2 SMBv2 and v2.1 and Riverbed

Who designs distributed network infrastructures with high bandwidth connected sites and accelerates traffic with Riverbed appliances will loose many nice communication features comming with WinVista or Win7 and Windows Server Systems 2008 and 2008R2.

One of the known features in communication between Windows Vista or Windows 7 and Windows Server 2008 or 2008R2 devices is SMBv2.0 or SMBv2.1.

The ‘old’ SMBv1 has been designed centuries ago when 10MBit Ethernet infrastructure was common. It delivers by design maximum of 10 MByte/s data throughput, so even when Ethernet infrastructures reached 100MBit bandwidth, you could easily use maximum SMBv1 delivers.

With Ethernet infrastructures based on high bandwidth, faster protocols are relevant.

So with SMBv2.0 or SMBv2.1 it can be possible to reach a few hundreds of MByte/s data throughput when both devices supporting this.

But if your devices are behind connections which supposed to be fast because you implemented Riverbed appliances, you will possibly fail.

Not only that Riverbed currently doesn’t support SMB Digital Signing, if it is not a member of the Windows domain the client and server belong to, but the Rivebed appliance only support SMBv1.0.

And not worse enough. If there is a pre-existing SMBv2 CIFS session that pre-dates activation of the Riverbed, then the Windows client will cache the fact that it is using SMBv2 session with that particular Windows 2008 server.  There is nothing the Riverbed applicance can do to force that Windows client to use SMBv1 for that server, because the Windows client has already successfully set up an SMBv2 session, and it will always use SMBv2 for that server until it is rebooted.  Because the appliance can’t address protocol chattiness issues for SMBv2, it will disable latency optimization and only apply SDR data reduction.  To resolve this situation, you need to reboot the Windows client while the applicance is active, and the Riverbed device will force the client to use SMBv1 when the client re-establishes the CIFS session after reboot.

If optimization for SMB signing is configured, then the Riverbed will deliver optimized performance for the SMB signed SMBv1 traffic after forcing the negotiation down from SMBv2.

 



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