Configuration Example

To create a link bundle between two routers, you must complete the following configurations:

1. Create a bundle instance

2. Map physical interface (s) to the bundle.

For an Ethernet bundle to be active, you must perform the same configuration on both connection endpoints of the bundle.

Configuration

/* Enter the global configuration mode and create the ethernet link bundle */
Router# configure
Router(config)# interface Bundle-Ether 3
Router(config-if)# ipv4 address 10.1.2.3 255.0.0.0
Router(config-if)# bundle maximum-active links 32 hot-standby
Router(config-if)# bundle minimum-active links 1
Router(config-if)# bundle minimum-active bandwidth 30000000
Router(config-if)# exit

/* Map physical interfaces to the bundle */
/* Note: Mixed link bundle mode is supported only when active-standby operation is configured */
Router(config)# interface HundredGigE 0/0/0/0
Router(config-if)# bundle id 3 mode active
Router(config-if)# no shutdown
Router(config)# exit

Router(config)# interface HundredGigE 0/0/0/1
Router(config-if)# bundle id 3 mode active
Router(config-if)# no shutdown
Router(config-if)# exit

Router(config)# interface HundredGigE 0/0/0/2
Router(config-if)# bundle id 3 mode active
Router(config-if)# no shutdown
Router(config-if)# exit

Running Configuration

Router# show running-configuration
configure
interface Bundle-Ether 3
 ipv4 address 10.1.2.3 255.0.0.0
 bundle maximum-active links 32 hot-standby
 bundle minimum-active links 1
 bundle minimum-active bandwidth 30000000
!
interface HundredGigE 0/0/0/0
 bundle-id 3 mode active
!

interface HundredGigE 0/0/0/1
 bundle-id 3 mode active
!
interface HundredGigE 0/0/0/2
 bundle-id 3 mode active
!

Verification

Verify that interfaces forming the bundle are active and the status of the bundle is Up.

Router# show bundle bundle-ether 3 
Tue Feb  4 18:24:25.313 UTC

Bundle-Ether1
  Status:                                    Up
  Local links <active/standby/configured>:   3 / 0 / 3
  Local bandwidth <effective/available>:     30000000 (30000000) kbps
  MAC address (source):                      1234.1234.1234 (Configured)
  Inter-chassis link:                        No
  Minimum active links / bandwidth:          1 / 1 kbps
  Maximum active links:                      32
  Wait while timer:                          2000 ms
  Load balancing:                            Default
  LACP:                                      Operational
    Flap suppression timer:                  Off
    Cisco extensions:                        Disabled
    Non-revertive:                           Disabled
  mLACP:                                     Not configured
  IPv4 BFD:                                  Not configured

  Port                  Device           State        Port ID         B/W, kbps
  --------------------  ---------------  -----------  --------------  ----------
  Hu0/0/0/0            Local            Active       0x8000, 0x0000    10000000
      Link is Active
  Hu0/0/0/1            Local            Active       0x8000, 0x0000    10000000
      Link is Active
  Hu0/0/0/2            Local            Active       0x8000, 0x0000    10000000
      Link is Active

Characteristics of Link Bundles

• Any type of Ethernet interfaces can be bundled, with or without the use of LACP (Link Aggregation Control Protocol).

• Physical layer and link layer configuration are performed on individual member links of a bundle.

• Configuration of network layer protocols and higher layer applications is performed on the bundle itself.

• A bundle can be administratively enabled or disabled.

• Each individual link within a bundle can be administratively enabled or disabled.

• Ethernet link bundles are created in the same way as Etherokinet channels, where the user enters the same configuration on both end systems.

• The MAC address that is set on the bundle becomes the MAC address of the links within that bundle.

• When LACP configured, each link within a bundle can be configured to allow different keepalive periods on different members.

• Load balancing is done by flow instead of by packet. Data is distributed to a link in proportion to the bandwidth of the link in relation to its bundle.

• QoS is supported and is applied proportionally on each bundle member.

• Link layer protocols, such as CDP, work independently on each link within a bundle.

• Upper layer protocols, such as routing updates and hello messages, are sent over any member link of an interface bundle.

• Bundled interfaces are point to point.

• A link must be in the UP state before it can be in distributing state in a bundle.

• Access Control List (ACL) configuration on link bundles is identical to ACL configuration on regular interfaces.

• Multicast traffic is load balanced over the members of a bundle. For a given flow, internal processes select the member link and all traffic for that flow is sent over that member.

Cisco IOS-XR software supports the following methods of forming bundles of Ethernet interfaces:

Cisco IOS-XR software supports the following methods of forming bundles of Ethernet interfaces:

• IEEE 802.3ad—Standard technology that employs a Link Aggregation Control Protocol (LACP) to ensure that all the member links in a bundle are compatible. Links that are incompatible or have failed are automatically removed from a bundle.

  For each link configured as bundle member, 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.

  The information from the peer system is combined with the information from the local system to determine the compatibility of the links configured to be members of a bundle.

  Bundle MAC addresses in the routers come from a set of reserved MAC addresses in the backplane. This MAC address stays with the bundle as long as the bundle interface exists. The bundle uses this MAC address until the user configures a different MAC address. The bundle MAC address is used by all member links when passing bundle traffic. Any unicast or multicast addresses set on the bundle are also set on all the member links.

• EtherChannel—Cisco proprietary technology that allows the user to configure links to join a bundle, but has no mechanisms to check whether the links in a bundle are compatible.

Link Aggregation Through LACP

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. For a router, the peer can be either another router or a switch. LACP monitors the operational state of link bundles to ensure these:

• 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.