Link Aggregation Through Lacp - Cisco 6000 Series Configuration Manual

Link Aggregation Through LACP

• Upper layer protocols, such as routing updates and hellos, are sent over any member link of an interface
• All links within a single bundle must terminate on the same two systems. Both systems must be directly
• Bundled interfaces are point-to-point.
• A bundle can contain physical links only. Tunnels and VLAN sub-interfaces cannot be bundle members.
• An IPv4 address configuration on link bundles is identical to an IPv4 address configuration on regular
• Multicast traffic is load balanced over the members of a bundle. For a given flow, internal processes
•
Link Aggregation Through LACP
Aggregating interfaces on different modular services cards and on SPAs within the same services cards
provides redundancy, allowing traffic to be quickly redirected to other member links when an interface or
modular services card failure occurs.
The optional Link Aggregation Control Protocol (LACP) is defined in the IEEE 802 standard. LACP
communicates between two directly connected systems (or peers) to verify the compatibility of bundle members.
The peer can be either another router or a switch. LACP monitors the operational state of link bundles to
ensure the following:
• All links terminate on the same two systems.
• Both systems consider the links to be part of the same bundle.
• All links have the appropriate settings on the peer.
LACP transmits frames containing the local port state and the local view of the partner system's state. These
frames are analyzed to ensure both systems are in agreement.
IEEE 802.3ad Standard
The IEEE 802.3ad standard typically defines a method of forming Ethernet link bundles.
For each link configured as bundle member, the following information is exchanged between the systems that
host each end of the link bundle:
• A globally unique local system identifier
• An identifier (operational key) for the bundle of which the link is a member
• An identifier (port ID) for the link
• The current aggregation status of the link
This information is used to form the link aggregation group identifier (LAG ID). Links that share a common
LAG ID can be aggregated. Individual links have unique LAG IDs.
The system identifier distinguishes one router from another, and its uniqueness is guaranteed through the use
of a MAC address from the system. The bundle and link identifiers have significance only to the router
assigning them, which must guarantee that no two links have the same identifier, and that no two bundles
have the same identifier.
Interface and Hardware Component Configuration Guide for Cisco NCS 6000 Series Routers, IOS XR Release 6.4.x
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bundle.
connected.
However, you can create VLANs as sub-interfaces of bundles.
interfaces.
select the member link, and all traffic for that flow is sent over that member.
Configuring Link Bundling