Brocade Multi-Service IronWare Administration Guide (Supporting R05.6.00) - Manual (Page 222)

204 Multi-Service IronWare Administration Guide
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Trace-l2 protocol
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For each hop in the path, trace-l2 displays its input/output port, L2 protocols of the input port, and
the microsecond travel time between hop and hop. It also prints out the hops which form a loop, if
any. Displaying L2 topology lets a user easily obtain information of all hops.
Configuration considerations
The configuration considerations are as follows:
• Trace-l2 is enabled on the Brocade devices. It can be used to trace traffic only to devices.
• The devices that will participate in the trace-l2 protocol must be assigned to a VLAN and all
devices on that VLAN must be Brocade devices that support the trace-l2 protocol.
• Brocade devices, as well as other vendor devices, that do not support the trace-l2 protocol,
simply forward trace-l2 packets without a reply. Hence, these devices are transparent to the
trace-l2 protocol.
• The destination for the packet with the trace-l2 protocol must be a device that supports the
trace-l2 protocol and the destination cannot be a client, such as a personal computer, or
devices from other vendors.
Tracing a traffic path
The trace-l2 protocol is enabled on a VLAN. You can trace the traffic path of a packet by entering a
command such as the following.
Brocade(config)#trace-l2 vlan 10 2.2.2.2
Syntax: [no] trace-l2 vlan vlan-id destination-address
The destination address can be a MAC address, an IP address, or a host. You can enter the
destination-address in one of the following formats:
• HHHH.HHHH.HHHH – Destination MAC address
• A.B.C.D – Destination IP address
• ASCII string – destination host name
If a destination address is not specified or the destination does not exists, trace-l2 collects L2
topology information which can be displayed by issuing a trace-l2 show command. The command
displays the following information.
In the output above, the last hop is the destination. Because 10.1.1.2 and 10.2.2.2 are addresses
of the same device, the device can use 10.1.1.2 in the reply.
In general, trace-l2 first tries to use the IP address of the virtual routing interface that is associated
with a VLAN. If the virtual routing interface is not available, it then uses the loopback address. If
both addresses are not available, it displays MAC address only.
The input and output ports show the path of the hops. Hop 3 has no output port because it is the
destination.
trace-l2 reply vlan 2 from e26, 10.1.1.2, total round trip = 814 microsec
hop input output IP and/or MAC address microsec comment
1 e28 e25 10.1.1.4 0000.003f.c400 316 e28: ring 11
2 e15 e13 10.1.1.1 0000.0057.0d00 235 e15: ring 11
3 e27 10.1.1.2 0000.0057.2500 263 e27: ring 11