MAC Swap Loopback Features Supported by the Switch
Local MAC Swap Loopback Test
A local MAC swap loopback test checks connectivity and performance of the network between a tester and a tested switch, as well as performance of the tested switch. In Figure 1, Ethernet frames sent by a tester traverse an Ethernet network and reach the tested switch (SwitchB). After the tested switch receives the Ethernet frames, it forwards them to the interface where local MAC swap loopback is configured. The tested switch swaps the source and destination MAC addresses of all Ethernet frames that match the local MAC swap loopback configuration and sends the Ethernet frames back to the tester through the interface where local MAC swap loopback is configured. The tester then analyzes network performance based on Ethernet frames sent from the tested switch.
When a local MAC swap test is performed on an interface, services on the interface are interrupted, but services on other interfaces are not affected. If a large number of test packets are sent, test packets occupy bandwidth of other services on the interface that sends test packets back to the tester.
Remote MAC Swap Loopback Test
A remote MAC swap loopback test checks connectivity and performance of the network between a tester and a tested switch but does not check performance of the tested switch. In Figure 2, Ethernet frames sent by a tester traverse an Ethernet network and reach the tested switch (SwitchB). After the tested switch receives the Ethernet frames, the switch swaps the source and destination MAC addresses of all Ethernet frames that match the remote MAC swap loopback configuration and sends the Ethernet frames back to the tester through the interface where remote MAC swap loopback is configured. The tester then analyzes network performance based on Ethernet frames sent from the tested switch.
A remote MAC swap loopback test modifies only Ethernet frames matching the MAC swap loopback configuration on an interface, and other Ethernet frames can still be forwarded on the interface. However, if a large number of test packets are sent, test packets occupy bandwidth of other services on the interface.
