Layer 3 Load Balancing on Link Bundles

Layer 3 load balancing for link bundles is done on Ethernet Flow Points (EFPs) and is based on the IPv4 source and destination addresses in the packet. When Layer 3 service-specific load balancing is configured, all egress bundles are load balanced based on the IPv4 source and destination addresses. When packets do not have IPv4 addresses, default load-balancing (based on the MAC SA/DA fields in the packet header) is used.

Guidelines

• When a QoS policy is applied on a bundle (ingress or egress direction), the policy is applied at each member interface. The reference bandwidth that is used to calculate shaper or bandwidth values is applied as per the physical member interface bandwidth.

• If a QoS policy is not applied to a bundle interface, both the ingress and egress traffic use the default queue of the per link member port.

• The shape rate specified in the bundle policy-map is not an aggregate for all bundle members. The shape rate applied to the bundle depends on the load balancing of the links. For example, if a policy map with a shape rate of 10 Mbps is applied to a bundle with two member links, and if the traffic is always load-balanced to the same member link, then an overall rate of 10 Mbps applies to the bundle. However, if the traffic is load-balanced evenly between the two links, the overall shape rate for the bundle becomes 20 Mbps.

• If a member is deleted from a bundle, the total bundle statistics changes because the statistics that belongs to the detached link is lost.

• The QoS policy applied on bundle is inherited to all its member links and the reference bandwidth used to calculate shaper/bandwidth is applied as per the physical member interface bandwidth, and not the bundle as a whole.

Configuration Example

You have to accomplish the following to complete the QoS configuration on link bundles:

1. Creating a class-map

2. Creating a policy-map and specifying the respective class-map

3. Specifying the action type for the traffic

   Refer Attach a Traffic Policy to an Interface for details on step 1, 2 and 3.

4. Creating a link bundle

5. Applying traffic policy to the link bundle

/* Configure a class-map */
Router# configure
Router(config)# class-map match-any c1
Router(config-cmap)# match dscp af11
Router(config-cmap)# match precedence 7
Router(config-cmap)# end-class-map
Router(config)# commit

/* Configure a policy-map and specify the police rate */
Router(config)# policy-map p1
Router(config-pmap)# class c1
Router(config-pmap-c)# set qos-group 5
Router(config-pmap-c)# police rate percent 50 burst 1600 bytes
Router(config-pmap-c-police)# exit
Router(config-pmap-c)# exit
Router(config-pmap)# class class-default
Router(config-pmap)# end-policy-map
Router(config)# commit

/* Configure Ether-Bundle and apply traffic policy */
Router(config)# interface Bundle-Ether1
Router(config-if)# service-policy input p1
Router(config-if)# ipv4 address 192.1.1.1 255.255.255.0
Router(config-if)# mac-address 1212.1212.1212 (optional)
Router(config-if)# bundle minimum-active links 1
Router(config-if)# commit

Running Configuration

This example shows how a traffic policy is applied on an Ethernet link bundle, in the ingress direction. The policy is applied to all interfaces that are members of the Ethernet link bundle.

/* Class-map */
configure
 class-map match-any c1
  match dscp af11 
  match precedence 7 
  end-class-map
 ! 

/* Policy-map */
policy-map p1
 class c1
  set qos-group 5
  police rate percent 50 burst 1600 bytes 
  ! 
 ! 
 class class-default
 ! 
 end-policy-map
! 

/* Ether Bundle */
interface Bundle-Ether1
 service-policy input p1
 ipv4 address 192.1.1.1 255.255.255.0
 mac-address 1212.1212.1212
 bundle minimum-active links 1
!

Verification

• Verify that the bundle status is UP.

  
  router# show bundle bundle-ether 1
  
  Bundle-Ether1
    Status:                                    Up
    Local links <active/standby/configured>:   2 / 0 / 3
    Local bandwidth <effective/available>:     20000000 (20000000) kbps
    MAC address (source):                      1212.1212.1212 (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:                                      Not 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
    --------------------  ---------------  -----------  --------------  ----------
    Te0/0/0/1             Local            Active       0x8000, 0x0000    10000000
        Link is Active
    Te0/0/0/2             Local            Configured   0x8000, 0x0000    10000000
        Link is down
    Te0/0/0/7             Local            Active       0x8000, 0x0000    10000000
  
  

• Check the statistics of bundle member link(s) .

  
  router# show policy-map interface Bundle-Ether 1 input member TenGigE0/0/0/7 
   
  Interface:Bundle-Ether1 Member:TenGigE0/0/0/7 input: p1
  
  Class c1
    Classification statistics          (packets/bytes)     (rate - kbps)
      Matched             :                2759/176576               0
      Transmitted         : N/A 
      Total Dropped       :                   0/0                    0
    Policing statistics                (packets/bytes)     (rate - kbps) 
      Policed(conform)    :                2759/176576               0
      Policed(exceed)     :                   0/0                    0
      Policed(violate)    :                   0/0                    0
      Policed and dropped :                   0/0                  
  Class class-default
    Classification statistics          (packets/bytes)     (rate - kbps)
      Matched             :                 255/16372                0
      Transmitted         : N/A 
      Total Dropped       : N/A 
  
  

• Verify that the bundle statistics show the cumulative of member link 1 and 2 .

  
  router# show policy-map interface bundle-ether 1 
   
  Tue Feb 11 11:57:22.532 UTC
  
  Bundle-Ether1 input: p1
  
  Class c1
    Classification statistics          (packets/bytes)     (rate - kbps)
      Matched             :                7588/485632               0
      Transmitted         : N/A 
      Total Dropped       :                   0/0                    0
    Policing statistics                (packets/bytes)     (rate - kbps) 
      Policed(conform)    :                7588/485632               0
      Policed(exceed)     :                   0/0                    0
      Policed(violate)    :                   0/0                    0
      Policed and dropped :                   0/0                  
  Class class-default
    Classification statistics          (packets/bytes)     (rate - kbps)
      Matched             :                 257/16552                0
      Transmitted         : N/A 
      Total Dropped       : N/A 
  Bundle-Ether1 direction output: Service Policy not installed
  
  

Related Topics

• QoS on Link Bundles

Associated Commands

• bundle maximu-active links

• interface Bundle-Ether