2013
03.19

I just started to read a post by Keith Mayer (Microsoft) on BranchCache and I got to wondering “how could I build a nice demo rig to demonstrate this stuff?”.  Way back when I started showing DFS-R in Windows Server 2008 R2, we used some network appliance that the guys called a “network nightmare” to throttle our network and show off how efficient DFS-R could be with redundant block (cross file) replication.  I want something like that … but virtual … and free.

Actually, it’s really easy and effective.

I’ve got 2 VMs, VM01 (the client) and VM02 (the remote file server).  What I’m going to do is restrict the outbound bandwidth from VM02 in the NIC settings of VM02 in Hyper-V Manager – also possible using PowerShell.

Before I do, I’m going log into VM01 and copy a Ubuntu 12.04 ISO from a file share on VM02 to VM01:

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After a few runs, that takes 11 seconds.  Both VMs are on the same host, virtual switch, and simple subnet.  Now to hammer that.

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I’ve enabled bandwidth management and set Maximum Bandwidth to 10 Mbps, not an uncommon speed for branch offices.  Click OK and that’s done.  There’s no need to shutdown or reboot the VM.

Now do the copy again …

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That file copy is going to take a bit longer Smile  Point proven!  Now you can head over to Keith’s blog, set up BranchCache, and show how Windows Server 2012 and Windows 8 Enterprise can add value to a business by overcoming limited bandwidth to/from branch offices.

If you want to build this out into a bigger virtual WAN, then you could do that.  Just set up a VM with multiple NICs.  It could be an appliance (I haven’t looked at Vyatta in quite a while) or maybe you set up a Windows Server VM with RRAS and enable simple RIP routing.  Now you can restrict the NICs on the router to simulate a bandwidth challenged WAN.

Before you comment – yes I know, this solution won’t simulate latency.

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