Seven steps to network lab automation--Part III

Step 5. The Architecture of the Solution
Planning the lab architecture is a critical deployment step. As noted in Step No. 1, it requires carefully assessing a lab's existing infrastructure to determine where and how devices are generally used and connected to each other. This requires understanding, as an example, that there may be communities of interest or devices that are typically connected to each other for specific types of tests or logical reasons; a traffic generator is typically not connected directly to another traffic generator, for instance, but to some device or system under test.

In developing this architecture, what a lab manager doesn't want to do is as important as what should be done. For instance, one major mistake would be to connect all of the test equipment to one switch, and all devices under test to a separate switch. That would essentially force a situation in which most connections, which are typically between the test gear and the devices under test, are forced to cross to a different switch. This is costly, because it eats up switch ports for unnecessary inter-switch linking, and it is an inefficient way to run a test environment.

So, if the number of ports under test is larger than the number of ports on the largest switch available--in the case of Ethernet, this is probably around 288 ports--care must be taken to consider the connection patterns expected and to distribute the equipment among multiple switches so as to minimize the instance of using inter-switch links to connect devices. Divide the devices so most typical or common ports that a device needs to connect to can be found on same switch. This minimizes having to cross switches to make a typical connection, which not only minimizes the number of switch ports that are required, but also reduces potential signal degradation factors that may result from many hops through the switching infrastructure.

In many labs, however, in order to achieve the required reach of devices across the lab, daisy-chaining or otherwise interconnecting physical-layer switches cannot be avoided. Transparent set-up, management, use and optimization of such links is another key component of a lab-management software solution.

Understanding how the devices need to be interconnected to each other, planning how to connect them appropriately to the switching infrastructure and interconnecting the switches to each other in such a way as to allow required connections to be made is a very important step in the lab automation process.

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