Brocade Fabric OS Command Reference Manual v6.2.0 (53-1001186-01, April 2009)

Fabric OS Command Reference 429
53-1001186-01
linkCost
2
linkCost
Sets or displays the Fabric Shortest Path First (FSPF) cost of a link.
Synopsis linkcost [[slotnumber/]portnumber [cost]]
Description Use this command to set or display the cost of an interswitch link (ISL). The cost of a link is a
dimensionless positive number. The FSPF protocol compares the cost of various paths between a
source switch and a destination switch by adding the costs of all the ISLs along each path. FSPF
chooses the path with minimum cost. If multiple paths exist with the same minimum cost, FSPF
distributes the load among these paths.
Every ISL has a default cost that is inversely proportional to its bandwidth. For a 1 Gbps ISL, the
default cost is 1000. For a 2 Gbps ISL, the default cost is 500. This simple algorithm is not effective
when dealing with trunking ISLs greater than 2 Gbps and less than 1 Gbps bandwidths. Link cost
default values are shown in Table 19.
When executed without operands, the command displays the current cost of each port on the
switch, including non-ISLs. An E_PORT suffix is appended to the interface number of active ISLs. If
a static cost is assigned to a port, a STATIC suffix is appended to the link cost. In this case, only the
current link cost displays. Use interfaceShow to display both the default and current link costs.
Notes This command sets a non-default, “static” cost for any port except EX/VEX ports. Use
fcrRouterPortCost to configure EX/VEX ports.
The execution of this command is subject to Virtual Fabric or Admin Domain restrictions that may
be in place. Refer to chapter 1, "Using Fabric OS commands" and Appendix A, "Command
Availability" for details.
This command cannot be executed on a logical ISL (LISL).
Operands When invoked without operands, this command displays the cost for all ports. The following
operands are optional:
slotnumber For bladed systems only, specifies the slot number for which to set or display
the cost, followed by a slash (/).
portnumber Specifies the port number for which to set or display the cost, relative to its
slot for bladed systems. Use switchShow to list of valid ports.
TABLE 19 Link cost defaults
Link type
Link cost (ISL bandwidth in Mbps)
< 1 Gbps ISL 2000
1 Gbps ISL 1000
2-Gbps ISL 500
> 2 Gbps trunks 500
4 Gbps ISL 500
8 Gbps ISL 500
10 Gbps ISL 500