Brocade 6910 Ethernet Access Switch Configuration Guide (Supporting R2.2.0.0) - Manual (Page 336)

280 Brocade 6910 Ethernet Access Switch Configuration Guide
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Interface Commands
Loopback Testing
ethernet loopback
This command loops traffic back from destination port to source port. Use the no form to stop the
loopback function.
Syntax
ethernet loopback [vlan vlan-list]
no ethernet loopback
vlan-list - Separate nonconsecutive VLAN identifiers with a comma and no spaces; use a
hyphen to designate a range of IDs. (Range: 1-4093)
Command Mode
Interface Configuration (Ethernet)
Command Usage
• This feature loops incoming frames back to the source. The source MAC address is swapped
with the destination MAC address, reflecting incoming frames back to the source. Testing and
network initialization are critical processes in metro Ethernet networks. Traditional methods of
testing required two technicians and two test sets, one at the remote location and one at the
service provider’s core network. The technicians would test one device at a time to verify
network continuity and performance. This process is time consuming, and cannot be deployed
on demand.
The introduction of the “reflector” function in Ethernet CPE equipment such as this switch
simplifies testing by swapping the source and destination MAC address of a frame, and
sending it back out the same interface it came in on. This allows a single test set to be
installed many hops from the device under test. By enabling the reflector function on remote
CPE devices, an RFC 2544 test generator installed at the network core can use a single test
set for on demand testing of the entire metro Ethernet network serviced from that core. All
frames from the test set will traverse the network, hit the reflector and return to the test set.
The test set can then analyze and display the results. In addition, one single RFC2544 test set
can be used to support the entire metro Ethernet network in the core location.
• This command can bind the loopback function to a specific port, or to a port and one or more
associated VLANs. When loopback is bound to a port and associated VLANs, the port does not
need to be explicitly assigned as a member of the specified VLANs. As long as the inbound
frames match the loopback settings, the frame will be reflected back to the source. Also, note
that the other VLANs to which the port has not been associated with the loopback function will
continue to process traffic normally, allowing non-disruptive loopback testing.
• The loopback function cannot be enabled on a trunk, but can be enabled on any member port
of a trunk.
• Up to 40 VLANs can associated with a port for the loopback function, and up to 240 loopback
entries are supported by the system.
• If test equipment is used to simulate the loopback function, the destination MAC address must
be the MAC address of the local port. If testing with VLAN mode, the injected packets should
also be tagged with the loopback VLAN.