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23-12
Cisco 10000 Series Router Software Configuration Guide
OL-2226-23
Chapter 23 Configuring Gigabit EtherChannel Features
Configuring VLAN-Based Load Balancing
For more information on how to aggregate multiple Ethernet links into one logical channel, see IEEE
802.3ad Link Bundling feature guide at:
http://www.cisco.com/univercd/cc/td/doc/product/software/ios122sb/newft/122sb31/sbcelacp.htm#wp1
053782
Configuring VLAN-Based Load Balancing
In Cisco IOS Release 12.2(33)XNE, there is support for VLAN-based load balancing for the GEC
interface on the Cisco 10000 series routers. The user can enable manual VLAN load balancing and select
the member-links on which a particular VLAN traffic is to be forwarded.
The VLAN load balancing feature can map a VLAN sub-interface to a member-link called a primary
member-link. The egress traffic for the VLAN sub-interface is then transmitted through that primary
member-link. The feature also allows the user to specify a standby member-link called a secondary
member-link for a VLAN sub-interface. The secondary member-link is used if the primary member-link
goes down.
Table 23-2 shows the active and standby links for different primary and secondary states.
Table 23-2 Active and standby links for different primary and secondary states
All packets forwarded over a VLAN sub-interface are considered to be part of the same flow that is
mapped to one bucket. Each bucket is associated with both primary and secondary member-links. The
bucket points to the active interface in the pair, either primary or secondary. Multiple VLAN flows can
be mapped to the same bucket if their primary and secondary member-links mapping is the same.
Restrictions for VLAN-Based Load Balancing
• Only static mapping of VLAN sub-interfaces is supported; internal, dynamic load balancing is not
supported.
• The primary member-link must be configured.
• When service policy is applied to port channel’s main or subinterface, changing the load balancing
mode from VLAN to flow is not supported.
• On a GEC bundle, executing the VLAN-based load balancing feature, along with the VLAN group
QoS feature, requires that all VLAN sub-interfaces in a particular VLAN group have the same
primary and secondary member-links configured.
• When a hierarchical queuing policy is applied on a port channel VLAN sub-interface, the
hierarchical queues related to the policymap are created on both primary and secondary
member-links associated with the VLAN sub-interface. Egress traffic for this VLAN sub-interface
is enqueued on to the corresponding queues, at the primary member-link. In an event of the primary
member-link going down, the traffic for the VLAN sub-interface is redirected to the queues on the
secondary member-link.
Primary Secondary Active Standby
Up Up Primary Secondary
Up Down Primary Secondary
Down Up Secondary Primary
Down Down Primary Secondary