Figure 30 Logical Fabric Using Isls And Xisls - Brocade Communications Systems 1606 Administrator's Manual

10
Logical fabric overview
FIGURE 30
By default, the physical ISL path is favored over the logical path (over the XISL) because the
physical path has a lower cost. This behavior can be changed by configuring the cost of the
dedicated physical ISL to match the cost of the LISL.
Base switch ports on different chassis can be connected together to form a fabric, called a base
fabric. Similar to other logical switches, the base switches must have the same FID to be
connected. If the base switches have different fabric IDs, the link between the switches is disabled.
It is a good practice to configure at least two XISLs, for redundancy.
The base fabric follows normal routing policies. As long as physical connectivity is available, the
base fabric maintains connectivity for the logical fabrics.
NOTE
If you disable a base switch, all of the logical ISLs are broken and the logical switches cannot
communicate with each other unless they are connected by a physical ISL.
Logical ports
As shown in
the ports at each end of a logical ISL. A logical port is a software construct only and does not
correspond to any physical port.
Most port commands are not supported on logical ports. For example, you cannot change the state
or configuration of a logical port.
The WWN for logical ports is in NAA=5 format, using the following syntax:
where:
218
Physical chassis 1
Logical switch 1
(Default logical switch)
Fabric ID 128
Logical switch 2
Fabric ID 1
Logical switch 3
Fabric ID 15
Base switch
Fabric ID 8
Logical fabric using ISLs and XISLs
Figure 30, logical ISLs are formed to connect logical switches. A logical port represents
5n:nn:nn:nz:zz:zz:zx:xx
nnnnnn is the Brocade Organizationally Unique Identifier (OUI).
zzzzzz is the logical fabric serial number.
xxx is the logical port number, in the range 0—FFF.
P1
Logical ISL
ISL
P2
Logical ISL
Logical ISL
P5
XISL
P6
Physical chassis 2
P1
Logical switch 5
(Default logical switch)
Fabric ID 128
P2
Logical switch 6
Fabric ID 1
P4
P7
Logical switch 7
Fabric ID 15
P6
P8 P9
Base switch
Fabric ID 8
Fabric OS Administrator's Guide
53-1001763-01