Section 13-4. QoS Management

13-4. QoS Management

Common Open Policy Service (COPS) The protocol that communicates QoS policies and enforcement between devices on a network.
COPS management is supported on the Catalyst 6000 COS switch family with a Layer 3 switching engine (PFC or PFC2).
Policy Decision Point (PDP) Maintains QoS policies and rules that will be enforced within the network. Traffic conditions can be polled and can affect how the policies are implemented. A typical PDP might be a host running Cisco QoS Policy Manager (QPM).
Policy Enforcement Point (PEP) A device consisting of physical interfaces, controlled by a PDP. QoS policies are sent down to a PEP, where they are enforced in a granular fashion. Typical PEPs are routers and switches.
COPS configures QoS policies for PEP switch ports using role names rather than physical switch module and port numbers. This gives COPS a more abstract view of network QoS. All switch ports that will be controlled by COPS must be assigned arbitrary role names.
Resource Reservation Protocol (RSVP) Used to request and reserve bandwidth for a specific traffic flow. The reservation is set up end-to-end across a network.
RSVP-for-COPS uses the COPS mechanism to gather and control RSVP requests.
Designated Subnet Bandwidth Manager (DSBM) One switch on a network segment is elected to coordinate all RSVP activity. All RSVP-for-COPS client devices forward RSVP messages to the DSBM.

QoS Management Configuration

Select the source for QoS policies.

a. Set the source for global policy information:

COS	set qos policy-source {local \| cops}
IOS	N/A

By default, all QoS policy information is taken from the local switch configuration (local). Use the cops keyword to accept global QoS information from a COPS device instead.

TIP

Global QoS policies include all DSCP maps, both named and default ACLs, both microflow and aggregate policer definitions, port scheduling (CoS-to-queue mapping), congestion avoidance (queue thresholds), queue weighting, default port CoS, and mappings for ACLs to switch ports.

b. Set the source for specific switch ports:

COS	set port qos policy-source mod/ports {local \| cops}
IOS	N/A

By default, QoS information for every switch port is taken from the local switch configuration (local). Use the cops keyword to accept QoS policy configuration for one or more switch ports (mod/ports) from a COPS device instead.

Communicate with COPS devices.

a. Identify one or more PDP servers:

COS	set cops server ipaddress [port] [primary] diff-serv
IOS	N/A

The PDP server is identified by its IP address ipaddress. An optional TCP port number can be given. You can specify one primary server with the primary keyword. The command can be repeated once without the primary keyword to specify a backup server.

b. Set the COPS domain name:

COS	set cops domain-name domain
IOS	N/A

The COPS domain name is set to domain (text string up to 31 characters; default is a null string). PDP devices can control PEP devices in the same domain.

c. (Optional) Set the COPS retry interval:

COS	set cops retry-interval initial incr max
IOS	N/A

Communication with the COPS server uses a retry interval. The switch waits for the initial interval (0 to 65,535 seconds, default 30 seconds) after the first failed exchange. After each subsequent failure, the retry interval is incremented by incr (0 to 65,535 seconds, default 30 seconds), up to the maximum timeout max (0 to 65,535 seconds, default 300 seconds).

Assign COPS roles to switch ports:

COS	set port cops mod/port roles role1 [role2]...
IOS	N/A

By default, all switch ports have a null role. You can define one or more role names role1, role2, (text string up to 31 characters) and so on to a switch port. The total length of all role names assigned to a switch port cannot exceed 255 characters. You can define up to 64 roles on a switch.

(Optional) Use RSVP with COPS.

a. Enable RSVP support:

COS	set qos rsvp {enable \| disable}
IOS	N/A

By default, RSVP support is disabled.

b. Identify the COPS PDP server:

COS	set cops server ipaddress [port] [primary] rsvp
IOS	N/A

c. Allow the switch to participate in bandwidth management:

COS

[View full width]

 set port rsvp mod/port dsbm-election {enable |  disable} [dsbm-priority]

IOS

N/A

A switch can participate in an election to become a DSBM. Election is allowed on specific switch ports (mod/port). By default, DSBM participation is disabled. The switch priority dsbm-priority (128 to 255, default 128) determines the likelihood of winning the election, because the highest priority wins.

d. (Optional) Take action during the loss of a PDP server.

- (Optional) Set the DSBM timeout interval:

COS	set qos rsvp policy-timeout timeout
IOS	N/A

If the switch is the elected DSBM and it loses contact with the PDP server, it continues to function as the DSBM for timeout (1 to 65,535 minutes, default 30 minutes). During that time, only its cached RSVP policies are used. If the PDP server is not restored within that time, the switch reverts back to being an SBM client.

- (Optional) Handle RSVP requests during the timeout interval:

COS	set qos rsvp local-policy {forward \| reject}
IOS	N/A

- By default, a switch continues to forward all RSVP path messages, even if the PDP server is not accessible. You can choose to reject all new or modified RSVP messages if desired.

Displaying Information About QoS Management

Table 13-10 lists some switch commands that you can use to display helpful information about QoS management.

Table 13-10. Commands to Display QoS Management Information
Display Function	Switch OS	Command
QoS policy source	COS	show qos policy-source
QoS policy source	IOS	N/A
COPS status	COS	show cops info [diff-serv]
COPS status	IOS	N/A
Switch port COPS roles	COS	show cops roles
Switch port COPS roles	IOS	N/A
RSVP status	COS	show qos rsvp info
RSVP status	IOS	N/A
Active RSVP flows	COS	show qos rsvp flow-info
Active RSVP flows	IOS	N/A

13-4. QoS Management

QoS Management Configuration

Displaying Information About QoS Management

Table 13-10. Commands to Display QoS Management Information