Cisco Cisco IOS Software Release 12.2(14)SX
Gateway Load Balancing Protocol
Configuration Tasks
8
Cisco IOS Release 12.2(14)S
Configuring GLBP Weighting
GLBP weighting is used to determine whether a router can act as a virtual forwarder. Initial weighting
values can be set and optional thresholds specified. Interface states can be tracked and a decrement value
set to reduce the weighting value if the interface goes down. When the GLBP router weighting drops
below a specified value, the router will no longer be an active virtual forwarder. When the weighting
rises above a specified value, the router can resume its role as an active virtual forwarder.
values can be set and optional thresholds specified. Interface states can be tracked and a decrement value
set to reduce the weighting value if the interface goes down. When the GLBP router weighting drops
below a specified value, the router will no longer be an active virtual forwarder. When the weighting
rises above a specified value, the router can resume its role as an active virtual forwarder.
To configure GLBP weighting values and object tracking, use the commands listed in
beginning
in global configuration mode.
Table 2
Configuring GLBP Weighting and Object Tracking
Enabling GLBP
GLBP is designed to be easy to configure. Each gateway in a GLBP group must be configured with the
same group number, and at least one gateway in the GLBP group must be configured with the virtual IP
address to be used by the group. All other parameters can be learned.
same group number, and at least one gateway in the GLBP group must be configured with the virtual IP
address to be used by the group. All other parameters can be learned.
If VLANs are in use on an interface, the GLBP group number must be different for each VLAN.
To enable GLBP on an interface, use the commands in
beginning in global configuration mode.
Table 3
Enabling GLBP on an Interface
Command
Purpose
Step 1
Router(config)# track object-number
interface
type number {line-protocol | ip
routing
}
Configures an interface to be tracked where changes in the state
of the interface affect the weighting of a GLBP gateway. This
command configures the interface and corresponding object
number to be used with the glbp weighting track command.
of the interface affect the weighting of a GLBP gateway. This
command configures the interface and corresponding object
number to be used with the glbp weighting track command.
The line-protocol keyword tracks whether the interface is up.
The ip routing keywords also check that IP routing is enabled
on the interface, and an IP address is configured.
The ip routing keywords also check that IP routing is enabled
on the interface, and an IP address is configured.
Step 2
Router(config)# interface type number
Enters interface configuration mode.
Step 3
Router(config-if)# glbp
group
weighting
maximum [lower lower] [upper upper]
Specifies the initial weighting value, and the upper and lower
thresholds, for a GLBP gateway.
thresholds, for a GLBP gateway.
Step 4
Router(config-if)# glbp
group
weighting
track
object-number [decrement value]
Specifies an object to be tracked that affects the weighting of a
GLBP gateway.
GLBP gateway.
The value argument specifies a reduction in the weighting of a
GLBP gateway when a tracked object fails.
GLBP gateway when a tracked object fails.
Command
Purpose
Step 1
Router(config)# interface type number
Enters interface configuration mode.
Step 2
Router(config-if)# glbp group ip
[ip-address [secondary]]
Enables GLBP on an interface and identifies the primary IP
address of the virtual gateway.
address of the virtual gateway.
After you identify a primary IP address, you can use the glbp
group ip command again with the secondary keyword to
indicate additional IP addresses supported by this group.
group ip command again with the secondary keyword to
indicate additional IP addresses supported by this group.