QoS on Link
A bundle is a group of
one or more ports that are aggregated together and treated as a single link.
All QoS features currently supported on physical interfaces, are also supported
on all link bundle interfaces. Applying QoS on sub-interfaces is not supported.
function is a forwarding mechanism to distribute traffic over multiple links
based on Layer 3 routing information in the router. Per-destination load
balancing, where the router is allowed to distribute packets over one of the
links in the bundle, is the only supported load balancing in the
Cisco NCS 540 Series Router. 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
QoS is configured on
link bundles in the same way that it is configured on individual interfaces.
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.
You have to
accomplish the following to complete the QoS configuration on link bundles:
policy-map and specifying the respective class-map
action type for the traffic
Attach a Traffic Policy to an Interface
for details on step 1, 2 and 3.
Creating a link
policy to the link bundle
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.