Cisco Systems DSC9148D8G48PK9 manual TL Port Alpa Caches, Port Guard

Chapter 2 Configuring Interfaces

Information About Interfaces

Figure 2-3shows examples of TL port translation support.

Figure 2-3 TL Port Translation Support Examples

Private

initiator (I1)

Public

target (T2)

NL port

Private

initiator (I4)

Private

Private

N port

loop

target (T1)

NL port

F port

TL port

NL port

Private

TL port

loop

F port

FL port

Public

NL port

Public

target (3)

loop

NL port

Public

initiator (I3)

Public

initiator (I2)

N port

91699

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 2-4for 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.

	Cisco MDS 9000 Family NX-OS Interfaces Configuration Guide
2-14	OL-29284-01, Release 6.x