User`s guide

236 Implementing an Open IBM SAN
TL_Ports and zoning
Once the translation entries list is created, these TL_Ports can actually talk to
other ports in the fabric.
But the question remains: How does this TL_Port configuration interact with
name server zoning, or with hard zoning?
First, TL_Port configurations cannot cross the boundaries of hard zoning.
Second, name server zoning does not have an impact on TL_Port
communication at all:
򐂰 Private Target TL_Ports propagate all their translative device addresses to
the fabric. However, they can just be used by other Private Initiators. To
enable communication between them the TL-CFG list of this private initiator
must include the address of the private target.
򐂰 Private initiator devices have only access to devices specified in their TL-CFG
list.
򐂰 Even if a TL port is part of a name server zone, it will not see the members of
this name server zone unless they are put into the TL-CFG list.
򐂰 On the other hand, the TL-CFG list of a TL_Port is effective even if the name
server layout would imply it otherwise.
Note that this feature of name server zones is limited to TL_Ports only. Normal
public loop ports will be handled as normal director ports with all the normal
consequences of name server zoning.
Impact of LIP in the fabric
Ports in loop networks use a process called Loop Initialization Primitive
sequence (LIP) to establish their port addresses. All members of that loop are
involved in a LIP.
Loop initialization occurs whenever there is a change in the layout of a loop, such
as adding a new node, leaving of a node, or breaks in service in the loop.
The start of a LIP causes data transfers in progress to stop, thereby severely
affecting the performance and availability of Arbitrated Loops.
Note: Even if the translation entries table for private target ports is updated
automatically, you will not see its content. The auto learning feature is always
used in the background. You cannot deactivate it or activate it.