Information About ISL Diagnostics
ISL Diagnostics feature helps in validating the health of interswitch links between the Cisco MDS switches in a network.
The following tests can be performed using ISL diagnostics:
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Latency test
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Single Hop Traffic Test
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Multihop End-to-End Traffic Test
Supported Platforms
ISL diagnostics is supported on the following platforms:
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Cisco MDS 9500 Series Switches
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Cisco MDS 9700 Series Switches
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Cisco MDS 9396S Switch
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Cisco MDS 9396T Switch
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Cisco MDS 9148T Switch
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Cisco MDS 9132T Switch
ISL diagnostics is supported on the following FC modules of the Cisco MDS 9700 Switches:
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16-Gbps modules on Cisco MDS 9700 Series Switches
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DS-X9448-768K9
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DS-X9334-K9
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32-Gbps modules on Cisco MDS 9700 Series Switches
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DS-X9648-1536K9
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ISL diagnostics is not supported on the following FC modules of the Cisco MDS 9500 Switches:
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DS-X9224-96K9
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DS-X9248-96K9
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DS-X9248-48K9
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DS-X9304-18K9
Guidelines and Limitations
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The diagnostic tests can be performed between two supported modules of different switch families on either side.
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The ISL diagnostic support on the modules is limited to the generator and reflector ports only.
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ISL diagnostics are not supported on other non-MDS switches such as Nexus 2000, Nexus 5000, and so on.
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ISL diagnostics are not supported on any of the FCoE and IPS ports of the Cisco MDS Switches.
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ISL diagnostics are not supported on 16 Gbps FEC-enabled links, but it is supported on 16 Gbps links without FEC.
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ISL diagnostics is not supported on Dense Wavelength-Division Multiplexing (DWDM) links.
Latency Test
Latency test measures the latency of an ISL between two Cisco MDS switches. You can run the latency test on ports that are on the same switch. You can use the diagnostic isl reflector and diagnostic isl generator commands for running the test. For more information, see Configuring Interswitch Link Diagnostics.
The frame is looped back by the reflector switch port to the generator switch where the timestamps are captured.
Timestamps allow the latency of the link to be measured in both directions as well as the latency of the reflector port. The cable length is calculated using only the link latencies. The accuracy of the reported cable length is +/- 2 meters. On Cisco MDS switches, the cable length (for latency test) is validated up to 50 meters of the cable length.
Note |
When a latency test is executed, both the generator and reflector ports must be in a admin down ('shutdown') state and not part of any port-channel. |
Latency Test shows the details for the latency test.
Single Hop Traffic Test
The single hop traffic test validates the health of an ISL by checking the efficiency of the ISL to handle traffic at various frame rates. You can run the single hop traffic test on ports that are on the same switch. You can use the diagnostic isl reflector and diagnostic isl generator commands for running the test. For more information, see Configuring Interswitch Link Diagnostics.
Fibre Channel (FC) frames are generated in the generator switch using the internal traffic generator facility available in the MAC hardware. These frames are transmitted from the generator switch port over the ISL under test. The reflector switch receives the frames, switches them via the normal fabric switching path and transmits the frames back through the received port onto the ISL under test.
The efficiency of the ISL traffic is calculated based on the number of packets received back on the generator switch port.
Note |
When a single hop test is executed, both the generator and reflector ports must be in a admin down ('shutdown') state and not part of any port-channel. |
The traffic test returns with an error in the following scenarios:
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If the ISL is not up.
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If the generator port does not have an internal traffic generator facility.
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When the reflector is not put in a loopback mode.
Single Hop Traffic Test shows the details for Single Hop Traffic Test:
The traffic traverses through all the crossbar links.
Multihop End-to-End Traffic Test
The Multihop test evaluates the health of the ISL between a host switch and a target switch in a fabric.
Before connecting a host to a target in a fabric, test the fabric path between the host port and the target port, using a Multihop test.
Multiple hops can exist between the host switch and the target switch. No specific configuration is required on the intermediate switches.
Note |
The intermediate switches in the fabric can have any interface or link, for example, FC, FCoE, IPS, and so on, between them, as long as a route exists between the generator and the reflector port. |
Fibre channel (FC) frames are generated at the generator switch port and transmitted to the first hop link. These frames traverse intermediate switches until they reach the reflector switch. The reflector switch then switches the frames and returns them to the generator switch. Based on the number of packets received on the generator switch, the efficiency of the ISL is displayed.
The Multihop traffic test is based on the domain IDs of the generator and reflector switches.
Note |
When a Multihop traffic test is executed , both the generator and reflector ports must be in a admin down ('shutdown') state and not part of any port-channel however, there can be traffic running over the ISLs that is used by the Multihop traffic test. |
Multihop End-to-End Traffic Test shows the details for Multihop End-to-End Traffic Test:
The traffic traverses through all the crossbar links.