Over time the use of multiple paths within the modern corporate network has increased. We’ve gone through a whole series of phases, and now are emerging into the 4th generation of the technology. I’ve had the (good?) fortune to experience all of these at various points, and to design networks around the deployment of these, so can speak from experience that this isn’t a particularly easy thing to do.
Lets look at some of the options:
- static host routing
- application specific routing (Policy Based routing)
- path selection technology
- application path selection against objectives using smart|path
The static routing option was quick and easy to implement, but was terrible from an operational standpoint, since a failure of a link somewhere in the network would most likely cause the traffic to blackhole, (since the static routes invariable wouldn’t fail out of the network.
Policy Based routing was more successful, especially if you wrapped the traffic in a GRE tunnel across the network, since this could be setup in later Cisco IOS releases to send keepalives that failed the tunnel if there was an issue in the network, and PBR would then fold back to the other route in the network. However, like the static routing, it’s still a bit of a nightmare trying to isolate the faults, and to scale the solution (especially if there are changes to the PBR rules for a different application or host, since you’d need to change lots (possibly 100′s or 1000′s in large networks) of router configs)
Only recently has the software and equipment been available to make this easier, and now it’s possible using Ipanema to use two networks (e.g. MPLS and Internet, or dual supplier), and to still gain all the objective based application benefits that Ipanema Technologies provides.
Admittedly, we’re not first to market with a path-selection routine, most notably Juniper has a similar feature in the WX platform. But we are the first (since we’re the only ones that have the capability) to extend our network-wide per-flow objective based management into a autonomous multi-path solution.
Smart|path allows for the selection of specific user classes, (a group of applications with similar performance requirements) to be optionally routed over upto 3 paths in the network. This means that you could have all the benifits of a path-selection technology to split traffic onto multiple routes to take advantage of some of those expensive tail circuits that are used for backup (your network provider may want to charge you for the additional IP bandwidth in use in the network core too!).
Unlike traditional path selection techniques, which force traffic down a single link until either delay or packet-loss or failure cause it to reroute, the Ipanema solution will dynamically select a path based on the delay, jitter and loss requirements of the user class. This means that should all the paths in the network be capable of delivering an application, it could route seperate flows over upto three different links. For the security-minded, this can be disabled on a user class by user class basis, so that sensitive information never leaves a more secure route.
So smart|path provides the following benifits to an organisation:
- Use of the expensive tails that are provided for backup (you might need to spend a little more for your provider to allow the bandwidth on the spare link to be utilised at the same time)
- objective based management of user classes to deliver applications against business requirements
- comprehensive monitoring and reporting on traffic
- the ability to send different traffic flows over multiple links at the same time (other technologies limit this to a single path)
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