finisar
May 11th, 2009

Overcoming Challenge #3: Testing Long-term Network Congestion Management

As I discussed previously, developers of FCoE network equipment face four key challenges when verifying equipment behavior, performance, and responsiveness.  The third testing challenge developers must address lies in testing long-term network congestion management mechanisms.

When performing conventional Ethernet LAN analysis, most tests involve only the switches as the QoS performance of the LAN network is mainly determined by them. FCoE developers may be tempted to employ fabric-only tests which utilize traffic generation tools to simulate the majority of nodes “operating” over the network.  Such fabric-only based testing, however, only exercises a subset of the Enhanced Ethernet capabilities that connect an FCoE network. 

For example, certain Data Center Bridging (DCB) protocols – such as congestion notification (CN) – require that all devices in a link participate in network management.  To comprehensively test CN mechanisms, then, developers must be able to create long-term congestion situations, monitor the resulting CN messages generated, and verify how end stations react to each CN message.

Inline-based testing tools are required here in order to accurately verify network-to-station performance.  Traffic manipulation tools such as error injectors and delay emulators are needed to easily generate long term congestion test cases.  When used in conjunction with an inline-based protocol analyzer, developers can capture CN messages as they are generated at the switch as well as analyze how end components react to each CN message.

Useful inline test tools include protocol analyzers, error injectors (Jammers), and delay emulators. Delay Emulation allows developers to shape traffic bandwidth per priority, re-order frames, and emulate distance delays. For full control of traffic, Delay Emulation technology can be combined with Analyzer and Jammer functions to enable testing of extremely complex networks, including full CN message testing.


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