Configuring Modular QoS on Link Bundles

This chapter covers the following topics:

QoS on Link Bundles

A bundle is a group of one or more ports that are aggregated together and treated as a single link. The router supports Ethernet interfaces and VLAN interfaces (bundle sub-interfaces) bundles. All QoS features currently supported on physical interfaces, are also supported on all link bundle interfaces. Applying QoS on bundle members is not supported.

Load Balancing

Load balancing function is a forwarding mechanism to distribute traffic over multiple links based on Layer 3 routing information in the router. Per-destination load balancing isonly supported on the router, where the router is allowed to distribute packets over one of the links in the bundle. When the per-destination load balancing is enabled, all packets for a certain source-destination pair goes through the same link, though there are multiple links available. In other words, per-destination load balancing can ensure that packets for a certain source-destination pair could arrive in order.

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.

Configure QoS on Link Bundles

QoS is configured on link bundles in the same way that it is configured on individual interfaces.

Guidelines

  • When a QoS policy is applied on a bundle in the egress direction, it’s also applied at each member interface.

  • When a QoS policy is applied on a bundle (ingress direction), it’s replicated at each NPU core.

  • 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 that is 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 that is applied on bundle is inherited to all its member links and the reference bandwidth that is 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:


Note

The policy works only if it is applied on the ingress direction. The egress is supported on COS, DEI and MPLS exp marking. So the below policy may not work when it is applied on egress.

  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

Running Configuration

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

Verification

  • Verify that the bundle status is UP.

Related Topics

Associated Commands

  • bundle maximu-active links

  • interface Bundle-Ether