Brocade Fabric OS Administrator's Guide Supporting Fabric OS v6.3.0 (53-1001336-02, November 2009)

40 Fabric OS Administrator’s Guide
53-1001336-02
Gateway links
2
FIGURE 4 ICL triangular topology
Virtual Fabrics considerations: In Virtual Fabrics, the ICL ports can be split across the logical
switch, base switch and default switch. The triangular topology requirement still needs to be met
for each fabric individually. The present restriction on ICL being part of only logical switches with
“Allow XISL Use” attribute off still applies.
Gateway links
A gateway merges SANs into a single fabric by establishing point-to-point E_Port connectivity
between two Fibre Channel switches that are separated by a network with a protocol such as IP or
SONET.
Except for link initialization, gateways are transparent to switches; the gateway simply provides
E_Port connectivity from one switch to another.
By default, switch ports initialize links using the Exchange Link Parameters (ELP) mode 1. However,
gateways expect initialization with ELP mode 2, also referred to as ISL R_RDY mode. Therefore, to
enable two switches to link through a gateway, the ports on both switches must be set for ELP
mode 2.
Any number of E_Ports in a fabric can be configured for gateway links, provided the following
guidelines are followed:
• All switches in the fabric are using the core PID format, as described in “Configuring a link
through a gateway” on page 41.
• The switches connected to both sides of the gateway are included when determining switch
count maximums.
• Extended links (those created using the Extended Fabrics licensed feature) are not supported
through gateway links.
ICL 3
ICL 1 ICL 2
Chassis 2
Chassis 1 Chassis 3