Saturday 10 March 2012

Prioritisation of Traffic in WAFS and WDC Tunnels on a Packeteer

You just gone out and spent all your money on a fleet of Packeteer iShapers (or PacketShapers and iShared) and want to use them to optimise your network. So, you plan to run cram as much TCP traffic down your WDC tunnel as possible to make the most of your expensive bandwidth. Of course, some traffic is more important than others, so you also plan to prioritise some of your traffic that’s going through the tunnel. It’s a great plan. Unfortunately, it’s a plan that won’t work.

The Packeteer PacketShapers (or the Inline plane in the iShapers) uses WCCP to redirect traffic destined to go through the WDC or WAFS tunnels. It does this before the traffic passes through its inspection and classification engine. That’s fair enough – you don’t want to be needlessly shaping traffic before it reaches the tunnel or you wouldn’t gain any benefits from the WDC cache.

The problem is that once the data has entered the WDC or WAFS tunnel, the PacketShaper (or the Inline plane) thinks it’s just WDC or WAFS traffic. It can’t classify it any further. So you can’t tell whether its the Payroll Department trying to use Oracle to get everyone paid, BITS updating an SMS repository or someone skiving off in Facebook. That means you can’t prioritise one over the other. The whole reason for buying a PacketShaper has just gone out the window. You would actually have been better off using the PacketShaper with a caching device from one of Packeteers competitors (Cisco, Citrix, Riverbed, etc.).

It’s just not good enough!

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