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Cisco MDS 9000 Family NX-OS Interfaces Configuration Guide
OL-29284-01, Release 6.x
Chapter 2 Configuring Interfaces
Information About Interfaces
Figure 2-3 shows examples of TL port translation support.
Figure 2-3 TL Port Translation Support Examples
TL Port ALPA Caches
Although TL ports cannot be automatically configured, you can manually configure entries in arbitrated
loop physical address (ALPA) caches. Generally, ALPA cache entries are automatically populated when
an ALPA is assigned to a device. Each device is identified by its port world wide name (pWWN). When
a device is allocated an ALPA, an entry for that device is automatically created in the ALPA cache.
A cache contains entries for recently allocated ALPA values. These caches are maintained on various TL
ports. If a device already has an ALPA, the Cisco NX-OS software attempts to allocate the same ALPA
to the device each time. The ALPA cache is maintained in persistent storage and saves information across
switch reboots. The maximum cache size is 1000 entries. If the cache is full, and a new ALPA is
allocated, the Cisco NX-OS software discards an inactive cache entry (if available) to make space for
the new entry. See the
“TL Port” section on page 2-4 for more information on TL ports.
Port Guard
The port guard feature is intended for use in environments where the system and application environment
does not adapt quickly and efficiently to a port going down and back up, or to a port rapidly cycling up
and down, which can happen in some failure modes. For example, if a system takes five seconds to
stabilize after a port goes down, but the port is going up and down once a second, a more severe failure
in the fabric might occur.
NL port
NL port
NL port
NL port
NL port
N port
N port
F port
F port
TL port
TL port
FL port
Private
loop
Private
loop
Public
loop
Private
initiator (I4)
Private
initiator (I1)
Public
initiator (I2)
Public
initiator (I3)
Public
target (T2)
Private
target (T1)
Public
target (3)
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