Dell Brocade G620 Brocade 8.0.1 Fabric OS Administratiors Guide - Page 275

Base switch and extended ISLs, VEX_Ports, but no F_Ports.

Page 275 highlights

Figure 24 shows a logical representation of the configuration in Figure 23. FIGURE 24 Logical switches connected to form logical fabrics Managing Virtual Fabrics The ISLs between the logical switches are dedicated ISLs because they carry traffic only for a single logical fabric. In Figure 23, Fabric 128 has two switches (the default logical switches), but they cannot communicate with each other because they have no ISLs between them and they cannot use the ISLs between the other logical switches. NOTE Only logical switches with the same FID can form a fabric. If you connect two logical switches with different FIDs, the link between the switches segments. Base switch and extended ISLs One way to connect logical switches is to use extended ISLs and base switches. When you divide a chassis into logical switches, you can designate one of the switches to be a base switch. A base switch is a special logical switch that is used for interconnecting the physical chassis. A base switch has the following properties: ∙ ISLs connected through the base switch can be used for communication among the other logical switches. ∙ Base switches do not support direct device connectivity. A base switch can have only E_Ports, VE_Ports, EX_Ports, or VEX_Ports, but no F_Ports. ∙ The base switch provides a common address space for communication between different logical fabrics. ∙ A base switch can be configured for the preferred domain ID just like a non-Virtual Fabrics switch. ∙ You can have only one base switch in a physical chassis. A base switch can be connected to other base switches through a special ISL, called a shared ISL or extended ISL (XISL). An extended ISL connects base switches. The XISL is used to share traffic among different logical fabrics. Fabric formation across an XISL is based on the FIDs of the logical switches. Brocade Fabric OS Administration Guide, 8.0.1 53-1004111-02 275

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Figure 24
shows a logical representation of the configuration in
Figure 23
.
FIGURE 24
Logical switches connected to form logical fabrics
The ISLs between the logical switches are
dedicated ISLs
because they carry traffic only for a single logical fabric. In
Figure 23
, Fabric
128 has two switches (the default logical switches), but they cannot communicate with each other because they have no ISLs between
them and they cannot use the ISLs between the other logical switches.
NOTE
Only logical switches with the same FID can form a fabric. If you connect two logical switches with different FIDs, the link
between the switches segments.
Base switch and extended ISLs
One way to connect logical switches is to use extended ISLs and base switches.
When you divide a chassis into logical switches, you can designate one of the switches to be a base switch. A
base switch
is a special
logical switch that is used for interconnecting the physical chassis.
A base switch has the following properties:
ISLs connected through the base switch can be used for communication among the other logical switches.
Base switches do not support direct device connectivity. A base switch can have only E_Ports, VE_Ports, EX_Ports, or
VEX_Ports, but no F_Ports.
The base switch provides a common address space for communication between different logical fabrics.
A base switch can be configured for the preferred domain ID just like a non-Virtual Fabrics switch.
You can have only one base switch in a physical chassis.
A base switch can be connected to other base switches through a special ISL, called a
shared ISL
or
extended ISL
(XISL). An extended
ISL connects base switches. The XISL is used to share traffic among different logical fabrics.
Fabric formation across an XISL is based on the FIDs of the logical switches.
Managing Virtual Fabrics
Brocade Fabric OS Administration Guide, 8.0.1
53-1004111-02
275