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This document describes the Low Latency Queueing for Frame Relay feature. It includes information about the benefits of this new feature, supported platforms, related documents, and more.
This document includes the following sections:
Low Latency Queueing for Frame Relay is a new feature that provides a strict priority queue (PQ) for voice traffic and weighted fair queues for other classes of traffic. Before the release of this feature, low latency queueing was available at the interface and ATM virtual circuit (VC) levels. It is now available at the Frame Relay VC level when Frame Relay traffic shaping is configured.
Low Latency Queueing, also called priority queueing/class-based weighted fair queueing (PQ/CBWFQ), is a superset of and more flexible than previous Frame Relay Quality of Service offerings, in particular Real-Time Transport Protocol (RTP) prioritization and priority queueing/weighted fair queueing (PQ/WFQ).
With RTP prioritization and PQ/WFQ, traffic that matches a specified User Datagram Protocol (UDP)/RTP port range is considered high priority and allocated to the PQ. With Low Latency Queueing for Frame Relay, you set up classes of traffic according to protocol, interface, or access lists, and then define policy maps to establish how the classes are handled in the priority queue and weighted fair queues.
Queues are set up on a per-permanent virtual circuit (PVC) basis: each PVC has a PQ and an assigned number of fair queues. The fair queues are assigned weights proportional to the bandwidth requirements of each class; a class requiring twice the bandwidth of another will have half the weight. Oversubscription of the bandwidth is not permitted. The command line interface (CLI) will reject a change of configuration that would cause the total bandwidth to be exceeded. This functionality differs from that of WFQ, in which flows are assigned a weight based on IP precedence. WFQ allows higher precedence traffic to obtain proportionately more of the bandwidth, but the more flows there are, the less bandwidth is available to each flow.
The PQ is policed to ensure that the fair queues are not starved of bandwidth. When you configure the PQ, you specify in kbps the maximum amount of bandwidth available to that queue. Packets that exceed that maximum are dropped. There is no policing of the fair queues.
Low Latency Queueing for Frame Relay is configured using a combination of class-map, policy-map and Frame Relay map-class commands. The class-map command defines traffic classes according to protocol, interface, or access list. The policy-map command defines how each class is treated in the queueing system according to bandwidth, priority, queue limit, or Weighted Random Early Detection (WRED). The service-policy output map-class command attaches a policy-map to a Frame Relay VC.
Policies not directly related to low latency queueing---for example, traffic shaping, setting IP precedence, and policing---are not supported by the class-map and policy-map commands for Frame Relay VCs. You must use other configuration mechanisms, such as map-class commands, to configure these policies.
Low Latency Queueing for Frame Relay can be used in conjunction with the features listed in the following sections:
RTP prioritization provides a strict priority queueing scheme for voice traffic. Voice traffic is identified by its RTP port numbers and classified into a priority queue configured by the frame-relay ip rtp priority map-class command. You classify traffic as voice by specifying an RTP port number range. If traffic matches the specified range, it is classified as voice and queued in the low latency queueing PQ, as well as the interface priority queue. If traffic does not fall within the specified RTP port range, it is classified by the service policy of the low latency queueing scheme.
The ip rtp priority command is available in both interface configuration mode and map-class frame-relay configuration mode. Only the frame relay ip rtp priority map-class configuration command is supported in this feature.
Voice over Frame Relay (VoFR) uses the low latency queueing PQ rather than its own priority queueing mechanism. The frame-relay voice bandwidth map-class command configures the total bandwidth available for VoFR traffic. The visible bandwidth made available to the other queues will be the minimum commited information rate (CIR) less the voice bandwidth.
The frame-relay voice bandwidth map-class command also configures a call admission control function, which ensures that there is sufficient VoFR bandwidth remaining before allowing a call. There is no policing of the voice traffic once the call has been established.
For VoFR with no data, all voice and call control packets are queued in the low latency queueing PQ. For VoFR with data, a VoFR PVC may carry both voice and data packets in different subchannels. VoFR data packets are fragmented and interleaved with voice packets to ensure good latency bounds for voice packets as well as scalability for voice and data traffic.
Note that when VoFR is enabled, there is no need to configure a priority class map for voice. The only VoFR commands to be used with Low Latency Queueing for Frame Relay are the frame-relay voice bandwidth map-class configuration command and the vofr data interface-dlci configuration command.
 |
Note It is possible---though not recommended---to configure other traffic for the PQ at the same time as VoFR. Doing so could cause delays because interleaving non-VoFR packets in the PQ would not be possible, causing the PQ (and any VoFR packets on it) to be held up during fragmentation until the entire fragmented packet has been transmitted. |
The purpose of Frame Relay fragmentation (FRF.12) is to support voice and data packets on lower-speed links without causing excessive delay to the voice packets. Large data packets are fragmented and interleaved with the voice packets.
When FRF.12 is configured with low latency queueing, small packets classified for the PQ pass through unfragmented onto both the low latency queueing PQ and the high priority interface queue. Large packets destined for PQ are shaped and fragmented when dequeued.
Use the frame-relay fragment and service-policy map-class configuration commands to enable low latency queueing with FRF.12 .
IP Cisco express forwarding (CEF) switching is not affected by low latency queueing functionality.
Strict Priority Service
Strict priority queueing improves quality of service by allowing delay-sensitive traffic, such as voice, to be pulled from the queue and sent before other classes of traffic.
Flexibility
Low Latency Queueing for Frame Relay allows you to define classes of traffic according to protocol, interface, or access lists. You can then assign characteristics to those classes, including priority, bandwidth, queue limit, and WRED.
Only the following class-map and policy-map commands are supported:
The following features and technologies are related to low latency queueing for Frame Relay:
The following documents provide information related to low latency queueing for Frame Relay:
The Low Latency Queueing for Frame Relay feature runs on the following platforms:
Standards
No new or modified standards are supported by this feature.
MIBs
No new or modified MIBs are supported by this feature.
For descriptions of supported MIBs and how to use MIBs, see the Cisco MIB web site on Cisco Connection Online (CCO) at http://www.cisco.com/public/sw-center/netmgmt/cmtk/mibs.shtml.
RFCs
No new or modified RFCs are supported by this feature.
The following tasks must be completed before Low Latency Queueing for Frame Relay can be enabled:
See the following sections for configuration tasks for the Low Latency Queueing for Frame Relay feature. Each task in the list is identified as either optional or required.
To create a class map containing match criteria against which a packet is checked to determine if it belongs to a class, begin with the class-map command in global configuration mode.
| Command | Purpose | |
|---|---|---|
Step 1 | Router(config)#class-map class-map-name | Specifies the name of the class map to be created. |
Step2 | Router(config-cmap)# match access-group {access-group
| name access-group-name}
|
Specifies the name of the input interface used as a match criterion against which packets are checked to determine if they belong to the class.
Specifies the name of the protocol used as a match criterion against which packets are checked to determine if they belong to the class. |
For more details about defining class maps, see the Cisco IOS Quality of Service Solutions Configuration Guide.
To configure a policy map and create class policies that make up the service policy, begin with the policy-map command to specify the policy map name. Then use one or more of the following commands to configure the policy for a standard class or the default class:
For each class that you define, you can use one or more of the commands listed above to configure the class policy. For example, you might specify bandwidth for one class and both bandwidth and queue limit for another class.
You can configure class policies for as many classes as are defined on the router, up to the maximum of 64. However, the total amount of bandwidth allocated for all classes in a policy map must not exceed the minimum CIR configured for the VC less any bandwidth reserved by the frame-relay voice bandwidth and frame-relay ip rtp priority commands. If the minimum CIR is not configured, it defaults to one half of the CIR. If all of the bandwidth is not allocated, the remaining bandwidth is allocated proportionally among the classes on the basis of their configured bandwidth.
To configure class policies in a policy map, perform the tasks in the following sections:
| Command | Purpose | |
|---|---|---|
Step1 | Router(config)# policy-map policy-map | Specifies the name of the policy map to be created or modified. |
Step2 | Router(config-pmap)# class class-name | Specifies the name of a class to be created and included in the service policy. |
Step3 | Router(config-pmap-c)# | Creates a strict priority class and specifies the amount of bandwidth in kbps to be assigned to the class. |
To configure policy for more than one class in the same policy map, repeat Steps 2 through 4.
The class-default class is used to classify traffic that does not fall into one of the defined classes. Even though the class-default class is predefined when you create the policy map, you still have to configure it. If a default class is not configured, then traffic that does not match any of the configured classes is given "best-effort" treatment, which means that the network will deliver the traffic if it can, without any assurance of reliability, delay prevention, or throughput.
| Command | Purpose | |
Step1 | Router(config)# policy-map policy-map | Specifies the name of the policy map to be created or modified. |
Step2 | Router(config-pmap)# class class-default default-class-name | Specifies the default class so that you can configure or modify its policy. |
Step3 | Router(config-pmap-c)# | Specifies the amount of bandwidth in kbps to be assigned to the class.
Specifies the number of dynamic queues to be reserved for use by flow-based WFQ running on the default class. The number of dynamic queues is derived from the bandwidth of the interface. |
Step4 | Router(config-pmap-c)# queue-limit number-of-packets | Specifies the maximum number of packets that the queue for the default class can accumulate. |
For more details about configuring class policy in the policy map, see the Cisco IOS Quality of Service Solutions Configuration Guide.
| Command | Purpose |
|---|---|
Router(config-map-class)#service-policy output policy-map | Attaches the specified service policy map to the output interface and enables Low Latency Queueing for Frame Relay. |
To display the contents of a specific policy map or all policy maps configured on an interface, use one of the following commands in global configuration mode:
For a list of commands that can be used to monitor Low Latency Queueing for Frame Relay, see the previous section, "Verifying Configuration of Policy Maps and Their Classes."
This section provides a configuration example for Low Latency Queueing for Frame Relay configuration.
The following example shows how to configure a PVC shaped to a 64K CIR with fragmentation. The shaping queue is configured with a class for voice, two data classes for IP precedence traffic, and a default class for best-effort traffic. WRED is used as the drop policy on one of the data classes.
The following commands define class maps and the match criteria for the class maps:
!class-map voicematch access-group 101!class-map immediate-datamatch access-group 102!class-map priority-datamatch access-group 103!access-list 101 permit udp any any range 16384 20000access-list 102 permit ip any any precedence immediateaccess-list 103 permit ip any any precedence priority
The following commands create and define a policy map called "mypolicy":
!policy-map mypolicyclass voicepriority 16class immediate-databandwidth 32random-detectclass priority-databandwidth 16class class-defaultfair-queue 64queue-limit 20
The following commands enable Frame Relay fragmentation and attach the policy map to DLCI 100:
!interface Serial1/0.1 point-to-pointframe-relay interface-dlci 100class fragment!map-class frame-relay fragmentframe-relay cir 64000frame-relay mincir 64000frame-relay bc 640frame-relay fragment 50service-policy output mypolicy
Syntax Description
input Attaches the specified policy map to the input interface or input VC. output Attaches the specified policy map to the output interface or output VC. policy-map The name of a service policy map (created using the policy-map command) to be attached.
Defaults
No service policy is specified.
Command Modes
Global configuration
VC submode (for a standalone VC)
Bundle-vc configuration (for ATM VC bundle members)
Map-class configuration (for Frame Relay VCs)
Command History
12.0(5)T This command was introduced. 12.1(2)T This command was modified to enable low latency queueing on FrameRelay VCs.
Release
Modification
Usage Guidelines
You can attach a single policy map to one or more interfaces or one or more VCs to specify the service policy for those interfaces or VCs.
Currently a service policy specifies class-based weighted fair queueing (CBWFQ). The class policies that make up the policy map are then applied to packets that satisfy the class map match criteria for the class.
To enable Low Latency Queueing for Frame Relay (PQ/CBWFQ), you must first enable Frame Relay traffic shaping on the interface using the frame-relay traffic-shaping command in interface configuration mode. You will then attach an output service policy to the Frame Relay VC using the service-policy command in map-class configuration mode.
For a policy map to be successfully attached to an interface or ATM VC, the aggregate of the configured minimum bandwidths of the classes that make up the policy map must be less than or equal to 75 percent of the interface bandwidth or the bandwidth allocated to the VC. For a Frame Relay VC, the total amount of bandwidth allocated must not exceed the minimum CIR configured for the VC less any bandwidth reserved by the frame-relay voice bandwidth and frame-relay ip rtp priority map-class commands. If not configured, the minimum CIR defaults to half of the CIR.
Configuring CBWFQ on a physical interface is possible only if the interface is in the default queueing mode. Serial interfaces at E1 (2.048 Mbps) and below use WFQ by default; other interfaces use FIFO by default. Enabling CBWFQ on a physical interface overrides the default interface queueing method. Enabling CBWFQ on an ATM PVC does not override the default queueing method.
Attaching a service policy and enabling CBWFQ on an interface renders ineffective any commands related to fancy queueing such as commands pertaining to fair queueing, custom queueing, priority queueing, and Weighted Random Early Detection (WRED). You can configure these features only after you remove the policy map from the interface.
You can modify a policy map attached to an interface or a VC, changing the bandwidth of any of the classes that make up the map. Bandwidth changes that you make to an attached policy map are effective only if the aggregate of the bandwidth amounts for all classes that make up the policy map, including the modified class bandwidth, is less than or equal to 75 percent of the interface bandwidth or the VC bandwidth. If the new aggregate bandwidth amount exceeds 75 percent of the interface bandwidth or VC bandwidth, the policy map is not modified.
Examples
The following exampleshow how to attache the service policy map called "policy9" to DLCI 100 on output interface Serial1 and enables Low Latency Queueing for Frame Relay:
interface Serial1/0.1 point-to-pointframe-relay interface-dlci 100class fragment!map-class frame-relay fragmentservice-policy output policy9
The following example illustrates attaching the service policy map called "policy9" to the input interface Serial1:
interface Serial1 service-policy input policy9
The following example illustrates attaching the service policy map called "policy9" to the input permanent virtual circuit (PVC) called "cisco":
pvc cisco 0/34
service-policy input policy9 vbr-nt 5000 3000 500
precedence 4-7
The following example illustrates attaching the policy called "policy9" to the output interface serial1 to specify the service policy for the interface and enable CBWFQ on it:
interface serial1 service-policy output policy9
The following example illustrates attaching the service policy map called "policy9" to the output PVC called "cisco":
pvc cisco 0/5
service-policy output policy9
vbr-nt 4000 2000 500
precedence 2-3
Related Commands
policy-map Creates or modifies a policy map that can be attached to one or more interfaces to specify a service policy. show frame-relay pvc Displays statistics about PVCs for Frame Relay interfaces. show policy-map Displays the configuration of all classes that make up the specified service policy map or all classes for all existing policy maps. show policy-map interface Displays the configuration of classes configured for service policies on the specified interface or PVC.
Command
Description
Syntax Description
interface (Optional) Indicates a specific interface for which PVC information will be displayed. interface (Optional) Interface number containing the DLCIs for which you wish to display PVC information. dlci (Optional) A specific DLCI number used on the interface. Statistics for the specified PVC are displayed when a DLCI is also specified.
Defaults
No default behavior or values.
Command Modes
Privileged EXEC
Command History
10.0 This command was introduced. 12.0(1)T This command was modified to display statistics about virtual access interfaces used for PPP connections over Frame Relay. 12.0(3)XG This command was modified to include the fragmentation type and size associated with a particular PVC when fragmentation is enabled on the PVC. 12.0(4)T This command was modified to include the fragmentation type and size associated with a particular PVC when fragmentation is enabled on the PVC. 12.0(5)T This command was modified to include information on the special voice queue that is created using the queue keyword of the frame-relay voice bandwidth command. 12.1(2)T This command was modified to include information about the policy map attached to a specific PVC.
Release
Modification
Usage Guidelines
Use this command to monitor the PPP link control protocol (LCP) state as being open with an "up" state, or closed with a "down" state.
When "vofr" or "vofrcisco" has been configured on the PVC, and a voice bandwidth has been allocated to the class associated with this PVC, configured voice bandwidth and used voice bandwidth are also displayed.
Statistics Reporting
To obtain statistics about PVCs on all Frame Relay interfaces, use this command with no arguments.
To obtain statistics about a PVC that include policy-map configuration, use this command with the DLCI argument.
Per-VC counters are not incremented at all when either autonomous or silicon switching engine (SSE) switching is configured; therefore, PVC values will be inaccurate if either switching method is used.
Traffic Shaping
Congestion control mechanisms are currently not supported, but the switch passes forward explicit congestion notification (FECN) bits, backward explicit congestion notification (BECN) bits, and discard eligible (DE) bits unchanged from entry to exit points in the network.
If a Local Management Interface (LMI) status report indicates that a PVC is not active, then it is marked as inactive. A PVC is marked as deleted if it is not listed in a periodic LMI status message.
Examples
The various displays in this section show sample output for a variety of PVCs. Some of the PVCs carry data only; some carry a combination of voice and data.
The following is sample output from the show frame-relay pvc command for a PVC shaped to a 64K CIR with fragmentation. A policy map is attached to the PVC and is configured with a priority class for voice, two data classes for IP precedence traffic, and a default class for best-effort traffic. WRED is used as the drop policy on one of the data classes:
ed2-36b# show frame-relay pvc 100
PVC Statistics for interface Serial1/0 (Frame Relay DTE)
DLCI = 100, DLCI USAGE = LOCAL, PVC STATUS = INACTIVE, INTERFACE = Serial1/0.1
input pkts 0 output pkts 0 in bytes 0
out bytes 0 dropped pkts 0 in FECN pkts 0
in BECN pkts 0 out FECN pkts 0 out BECN pkts 0
in DE pkts 0 out DE pkts 0
out bcast pkts 0 out bcast bytes 0
pvc create time 00:00:42, last time pvc status changed 00:00:42
service policy mypolicy
Class voice
Weighted Fair Queueing
Strict Priority
Output Queue: Conversation 72
Bandwidth 16 (kbps) Packets Matched 0
(pkts discards/bytes discards) 0/0
Class immediate-data
Weighted Fair Queueing
Output Queue: Conversation 73
Bandwidth 60 (%) Packets Matched 0
(pkts discards/bytes discards/tail drops) 0/0/0
mean queue depth: 0
drops: class random tail min-th max-th mark-prob
0 0 0 64 128 1/10
1 0 0 71 128 1/10
2 0 0 78 128 1/10
3 0 0 85 128 1/10
4 0 0 92 128 1/10
5 0 0 99 128 1/10
6 0 0 106 128 1/10
7 0 0 113 128 1/10
rsvp 0 0 120 128 1/10
Class priority-data
Weighted Fair Queueing
Output Queue: Conversation 74
Bandwidth 40 (%) Packets Matched 0 Max Threshold 64 (packets)
(pkts discards/bytes discards/tail drops) 0/0/0
Class class-default
Weighted Fair Queueing
Flow Based Fair Queueing
Maximum Number of Hashed Queues 64 Max Threshold 20 (packets)
Output queue size 0/max total 600/drops 0
fragment type end-to-end fragment size 50
cir 64000 bc 640 be 0 limit 80 interval 10
mincir 64000 byte increment 80 BECN response no
frags 0 bytes 0 frags delayed 0 bytes delayed 0
shaping inactive
traffic shaping drops 0
The following is sample output from the show frame-relay pvc command that shows the PVC statistics for serial interface 5 (slot 1 and DLCI 55 is up) during a PPP session over Frame Relay:
Router# show frame-relay pvc 55
PVC Statistics for interface Serial5/1 (Frame Relay DTE)
DLCI = 55, DLCI USAGE = LOCAL, PVC STATUS = ACTIVE, INTERFACE = Serial5/1.1
input pkts 9 output pkts 16 in bytes 154
out bytes 338 dropped pkts 6 in FECN pkts 0
in BECN pkts 0 out FECN pkts 0 out BECN pkts 0
in DE pkts 0 out DE pkts 0
out bcast pkts 0 out bcast bytes 0
pvc create time 00:35:11, last time pvc status changed 00:00:22
Bound to Virtual-Access1 (up, cloned from Virtual-Template5)
The following is sample output from the show frame-relay pvc command for a PVC carrying Voice over Frame Relay configured via the vofr cisco command. The frame-relay voice bandwidth command has been configured on the class associated with this PVC, as has fragmentation. The fragmentation employed is proprietary to Cisco.
A sample configuration for this scenario is shown first, followed by the output for the show frame-relay pvc command:
interface serial 0
encapsulation frame-relay
frame-relay traffic-shaping
frame-relay interface-dlci 108
vofr cisco
class vofr-class
map-class frame-relay vofr-class
frame-relay fragment 100
frame-relay fair-queue
frame-relay cir 64000
frame-relay voice bandwidth 25000
Router# show frame-relay pvc 108
PVC Statistics for interface Serial0 (Frame Relay DTE)
DLCI = 108, DLCI USAGE = LOCAL, PVC STATUS = STATIC, INTERFACE = Serial0
input pkts 1260 output pkts 1271 in bytes 95671
out bytes 98604 dropped pkts 0 in FECN pkts 0
in BECN pkts 0 out FECN pkts 0 out BECN pkts 0
in DE pkts 0 out DE pkts 0
out bcast pkts 1271 out bcast bytes 98604
pvc create time 09:43:17, last time pvc status changed 09:43:17
Service type VoFR-cisco
configured voice bandwidth 25000, used voice bandwidth 0
voice reserved queues 24, 25
fragment type VoFR-cisco fragment size 100
cir 64000 bc 64000 be 0 limit 1000 interval 125
mincir 32000 byte increment 1000 BECN response no
pkts 2592 bytes 205140 pkts delayed 1296 bytes delayed 102570
shaping inactive
shaping drops 0
Current fair queue configuration:
Discard Dynamic Reserved
threshold queue count queue count
64 16 2
Output queue size 0/max total 600/drops 0
Note that the "fragment type" field in the show frame-relay pvc display can have the following entries:
Below is sample output from the show frame-relay pvc command for an application employing pure FRF.12 fragmentation. A sample configuration for this scenario is shown first, followed by the output for the show frame-relay pvc command:
interface serial 0
encapsulation frame-relay
frame-relay traffic-shaping
frame-relay interface-dlci 110
class frag
map-class frame-relay frag
frame-relay fragment 100
frame-relay fair-queue
frame-relay cir 64000
Router# show frame-relay pvc 110
PVC Statistics for interface Serial0 (Frame Relay DTE)
DLCI = 110, DLCI USAGE = LOCAL, PVC STATUS = STATIC, INTERFACE = Serial0
input pkts 0 output pkts 243 in bytes 0
out bytes 7290 dropped pkts 0 in FECN pkts 0
in BECN pkts 0 out FECN pkts 0 out BECN pkts 0
in DE pkts 0 out DE pkts 0
out bcast pkts 243 out bcast bytes 7290
pvc create time 04:03:17, last time pvc status changed 04:03:18
fragment type end-to-end fragment size 100
cir 64000 bc 64000 be 0 limit 1000 interval 125
mincir 32000 byte increment 1000 BECN response no
pkts 486 bytes 14580 pkts delayed 243 bytes delayed 7290
shaping inactive
shaping drops 0
Current fair queue configuration:
Discard Dynamic Reserved
threshold queue count queue count
64 16 2
Output queue size 0/max total 600/drops 0
Note that when voice is not configured, voice bandwidth output is not displayed.
The following is sample output from the show frame-relay pvc command for multipoint subinterfaces carrying data only. The output displays both the subinterface number and the DLCI. This display is the same whether the PVC is configured for static or dynamic addressing. Note that neither fragmentation nor voice is configured on this PVC.
Router# show frame-relay pvc DLCI = 300, DLCI USAGE = LOCAL, PVC STATUS = ACTIVE, INTERFACE = Serial0.103 input pkts 10 output pkts 7 in bytes 6222 out bytes 6034 dropped pkts 0 in FECN pkts 0 in BECN pkts 0 out FECN pkts 0 out BECN pkts 0 in DE pkts 0 out DE pkts 0 outbcast pkts 0 outbcast bytes 0 pvc create time 0:13:11 last time pvc status changed 0:11:46 DLCI = 400, DLCI USAGE = LOCAL, PVC STATUS = ACTIVE, INTERFACE = Serial0.104 input pkts 20 output pkts 8 in bytes 5624 out bytes 5222 dropped pkts 0 in FECN pkts 0 in BECN pkts 0 out FECN pkts 0 out BECN pkts 0 in DE pkts 0 out DE pkts 0 outbcast pkts 0 outbcast bytes 0 pvc create time 0:03:57 last time pvc status changed 0:03:48
The following is sample output from the show frame-relay pvc command for a PVC carrying voice and data traffic, with a special queue specifically for voice traffic created using the frame-relay voice bandwidth command queue keyword:
Router# show frame-relay pvc interface serial 1 45
PVC Statistics for interface Serial1 (Frame Relay DTE)
DLCI = 45, DLCI USAGE = LOCAL, PVC STATUS = STATIC, INTERFACE = Serial1
input pkts 85 output pkts 289 in bytes 1730
out bytes 6580 dropped pkts 11 in FECN pkts 0
in BECN pkts 0 out FECN pkts 0 out BECN pkts 0
in DE pkts 0 out DE pkts 0
out bcast pkts 0 out bcast bytes 0
pvc create time 00:02:09, last time pvc status changed 00:02:09
Service type VoFR
configured voice bandwidth 25000, used voice bandwidth 22000
fragment type VoFR fragment size 100
cir 20000 bc 1000 be 0 limit 125 interval 50
mincir 20000 byte increment 125 BECN response no
fragments 290 bytes 6613 fragments delayed 1 bytes delayed 33
shaping inactive
traffic shaping drops 0
Voice Queueing Stats: 0/100/0 (size/max/dropped)
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Current fair queue configuration:
Discard Dynamic Reserved
threshold queue count queue count
64 16 2
Output queue size 0/max total 600/drops 0
Table 1 provides a listing of the fields in these displays and a description of each field.
| Field | Description |
|---|---|
DLCI | One of the data-link connection identifier (DLCI) numbers for the PVC. |
DLCI USAGE | Lists SWITCHED when the router or access server is used as a switch, or LOCAL when the router or access server is used as a DTE. |
PVC STATUS | Status of the PVC: ACTIVE, INACTIVE, or DELETED. |
INTERFACE | Specific subinterface associated with this DLCI. |
input pkts | Number of packets received on this PVC. |
output pkts | Number of packets sent on this PVC. |
in bytes | Number of bytes received on this PVC. |
out bytes | Number of bytes sent on this PVC. |
dropped pkts | Number of incoming and outgoing packets dropped by the router at the Frame Relay level. |
in FECN pkts | Number of packets received with the FECN bit set. |
in BECN pkts | Number of packets received with the BECN bit set. |
out FECN pkts | Number of packets sent with the FECN bit set. |
out BECN pkts | Number of packets sent with the BECN bit set. |
in DE pkts | Number of DE packets received. |
out DE pkts | Number of DE packets sent. |
out bcast pkts | Number of output broadcast packets. |
out bcast bytes | Number of output broadcast bytes. |
pvc create time | Time at which the PVC was created. |
last time pvc status changed | Time at which the PVC changed status (active to inactive). |
Service type | Type of service performed by this PVC. Can be VoFR or VoFR-cisco. |
configured voice bandwidth | Amount of bandwidth in bits per second reserved for voice traffic on this PVC. |
used voice bandwidth | Amount of bandwidth in bits per second currently being used for voice traffic. |
voice reserved queues | Queue numbers reserved for voice traffic on this PVC. This field was removed in Cisco IOS Release 12.0(5)T. |
service policy | Name of the output service policy applied to the VC. |
Class | Class of traffic being displayed. Output is displayed for each configured class in the policy. |
Output Queue | The WFQ conversation to which this class of traffic is allocated. |
Bandwidth | Bandwidth in kpbs or percentage configured for this class. |
Packets Matched | Number of packets that matched this class. |
Max Threshold | Maximum queue size for this class when WRED is not used. |
pkts discards | Number of packets discarded for this class. |
bytes discards | Number of bytes discarded for this class. |
tail drops | Number of packets discarded for this class because the queue was full. |
mean queue depth | Average queue depth based on the actual queue depth on the interface and the exponential weighting constant. It is a moving average. The minimum and maximum thresholds are compared against this value to determine drop decisions. |
drops: | WRED parameters. |
| IP Precedence value |
| Number of packets randomly dropped when the mean queue depth is between the minimum threshold value and the maximum threshold value for the specified IP Precedence value. |
| Number of packets dropped when the mean queue depth is greater than the maximum threshold value for the specified IP Precedence value. |
| Minimum WRED threshold in number of packets. |
| Maximum WRED threshold in number of packets. |
| Fraction of packets dropped when the average queue depth is at the maximum threshold. |
Maximum Number of Hashed Queues | (Applies to class-default only) Number of queues available for unclassified flows. |
fragment type | Type of fragmentation configured for this PVC. Possible types are: end-to-end---Fragmented packets contain the standard FRF.12 header VoFR---Fragmented packets contain the FRF.11 Annex C header VoFR-cisco---Fragmented packets contain the Cisco proprietary header |
fragment size | Size of the fragment payload in bytes. |
cir | Current committed information rate (CIR), in bits per second. |
bc | Current committed burst size, in bits. |
be | Current excess burst size, in bits. |
limit | Maximum number of bytes transmitted per internal interval (excess plus sustained). |
interval | Interval being used internally (may be smaller than the interval derived from Bc/CIR; this happens when the router determines that traffic flow will be more stable with a smaller configured interval). |
mincir | Minimum committed information rate (CIR) for the PVC. |
byte increment | Number of bytes that will be sustained per internal interval. |
BECN response | Indication that Frame Relay has BECN Adaptation configured. |
pkts | Number of packets associated with this PVC that have gone through the traffic shaping system. |
frags | Total number of fragments shaped on this VC. |
bytes | Number of bytes associated with this PVC that have gone through the traffic shaping system. |
pkts delayed | Number of packets associated with this PVC that have been delayed by the traffic shaping system. |
frags delayed | Number of fragments delayed in the shaping queue before being transmitted. |
bytes delayed | Number of bytes associated with this PVC that have been delayed by the traffic shaping system. |
shaping | Indication that shaping will be active for all PVCs that are fragmenting data; otherwise, shaping will be active if the traffic being sent exceeds the CIR for this circuit. |
shaping drops | Number of packets dropped by the traffic shaping process. |
Voice Queueing Stats | Statistics showing the size of packets, the maximum number of packets, and the number of packets dropped in the special voice queue created using the frame-relay voice bandwidth command queue keyword. |
Discard threshold | Maximum number of packets that can be stored in each packet queue. If additional packets are received after a queue is full, they will be discarded. |
Dynamic queue count | Number of packet queues reserved for best-effort traffic. |
Reserved queue count | Number of packet queues reserved for voice traffic. |
Output queue size | Size in bytes of each output queue. |
max total | Maximum number of packets of all types that can be queued in all queues. |
drops | Number of frames dropped by all output queues. |
Related Commands
frame-relay pvc Configures Frame Relay PVCs for FRF.8 Frame Relay-ATM Service Interworking. service-policy Attaches a policy map to an input interface or VC, or an output interface or VC, to be used as the service policy for that interface or VC. show dial-peer voice Displays configuration information and call statistics for dial peers. show frame-relay fragment Displays Frame Relay fragmentation details. show frame-relay vofr Displays details about FRF.11 subchannels being used on Voice over Frame Relay DLCIs. show interfaces serial Displays information about a serial interface. show policy-map interface Displays the configuration of classes configured for service policies on the specified interface or PVC. show traffic-shape queue Displays information about the elements queued at a particular time at the VC (DLCI) level.
Command
Description
Syntax Description
interface-name Name of the interface or subinterface whose policy configuration is to be displayed. vc (Optional) For ATM interfaces only, shows the policy configuration for a specified PVC. The name can be up to 16characters long. vpi/ (Optional) ATM network virtual path identifier (VPI) for this PVC. The absence of the "/" and a vpi value defaults the vpi value to 0. On the Cisco 7200 and 7500 series routers, this value ranges from 0 to 255. The arguments vpi and vci cannot both be set to 0; if one is 0, the other cannot be 0. If this value is omitted, information for all VCs on the specified ATM interface or subinterface is displayed. vci (Optional) ATM network virtual channel identifier (VCI) for this PVC. This value ranges from 0 to 1 less than the maximum value set for this interface by the atm vc-per-vp command. Typically, lower values from 0 to 31 are reserved for specific traffic (for example, F4 OAM, SVC signalling, ILMI, and so on) and should not be used. The VCI is a 16-bit field in the header of the ATM cell. The VCI value is unique only on a single link, not throughout the ATM network, because it has local significance only. The arguments vpi and vci cannot both be set to 0; if one is 0, the other cannot be 0. dlci (Optional) Indicates a specific PVC for which policy configuration will be displayed. dlci (Optional) A specific DLCI number used on the interface. Policy configuration for the corresponding PVC will be displayed when a DLCI is specified.
Defaults
There is no default behavior.
Command Modes
Global configuration
Command History
12.0(5)T This command was introduced. 12.1(2)T This command was modified to display information about the policy for all Frame Relay PVCs on the interface, or, if a DLCI is specified, the policy for that specific PVC.
Release
Modification
Usage Guidelines
The show policy-map interface command displays the configuration for classes on the specified interface or the specified PVC only if a service policy has been attached to the interface or the PVC.
You can use the pvc-name argument to display output for a PVC only for Enhanced ATM port adapters (PA-A3) that support per-VC queueing.
The counters displayed after entering the show policy-map interface command are updated only if congestion is present on the interface.
The show policy-map interface command will display policy information about Frame Relay PVCs only if Frame Relay traffic shaping is enabled on the interface.
Examples
The following example shows how to display class configuration and policy map statistics for all VCs on interface s1/0. A policy map called "mypolicy" is attached to DLCI 100, and a policy-map called "test" is attached to DLCI 200.
ed2-36b# show policy-map interface s1/0
Serial1/0.1: DLCI 100 -
output : mypolicy
Class voice
Weighted Fair Queueing
Strict Priority
Output Queue: Conversation 72
Bandwidth 16 (kbps) Packets Matched 0
(pkts discards/bytes discards) 0/0
Class immediate-data
Weighted Fair Queueing
Output Queue: Conversation 73
Bandwidth 60 (%) Packets Matched 0
(pkts discards/bytes discards/tail drops) 0/0/0
mean queue depth: 0
drops: class random tail min-th max-th mark-prob
0 0 0 64 128 1/10
1 0 0 71 128 1/10
2 0 0 78 128 1/10
3 0 0 85 128 1/10
4 0 0 92 128 1/10
5 0 0 99 128 1/10
6 0 0 106 128 1/10
7 0 0 113 128 1/10
rsvp 0 0 120 128 1/10
Class priority-data
Weighted Fair Queueing
Output Queue: Conversation 74
Bandwidth 40 (%) Packets Matched 0 Max Threshold 64 (packets)
(pkts discards/bytes discards/tail drops) 0/0/0
Class class-default
Weighted Fair Queueing
Flow Based Fair Queueing
Maximum Number of Hashed Queues 64 Max Threshold 20 (packets)
Serial1/0.2: DLCI 200 -
output : test
Class tcp
Weighted Fair Queueing
Output Queue: Conversation 25
Bandwidth 20 (kbps) Packets Matched 0
(pkts discards/bytes discards/tail drops) 0/0/0
mean queue depth: 0
drops: class random tail min-th max-th mark-prob
0 0 0 64 128 1/10
1 0 0 71 128 1/10
2 0 0 78 128 1/10
3 0 0 85 128 1/10
4 0 0 92 128 1/10
5 0 0 99 128 1/10
6 0 0 106 128 1/10
7 0 0 113 128 1/10
rsvp 0 0 120 128 1/10
The following example shows how to display the configuration of classes that make up the policy map for a specific Frame Relay VC on interface s1/0.
ed2-36b# show policy-map interface s1/0.1 dlci 100
Serial1/0.1: DLCI 100 -
output : mypolicy
Class voice
Weighted Fair Queueing
Strict Priority
Output Queue: Conversation 72
Bandwidth 16 (kbps) Packets Matched 0
(pkts discards/bytes discards) 0/0
Class immediate-data
Weighted Fair Queueing
Output Queue: Conversation 73
Bandwidth 60 (%) Packets Matched 0
(pkts discards/bytes discards/tail drops) 0/0/0
mean queue depth: 0
drops: class random tail min-th max-th mark-prob
0 0 0 64 128 1/10
1 0 0 71 128 1/10
2 0 0 78 128 1/10
3 0 0 85 128 1/10
4 0 0 92 128 1/10
5 0 0 99 128 1/10
6 0 0 106 128 1/10
7 0 0 113 128 1/10
rsvp 0 0 120 128 1/10
Class priority-data
Weighted Fair Queueing
Output Queue: Conversation 74
Bandwidth 40 (%) Packets Matched 0 Max Threshold 64 (packets)
(pkts discards/bytes discards/tail drops) 0/0/0
Class class-default
Weighted Fair Queueing
Flow Based Fair Queueing
Maximum Number of Hashed Queues 64 Max Threshold 20 (packets)
The following example shows how to display configurations for classes on the output interface e1/1:
Router# show policy-map interface output e1/1
Ethernet1/1 output : po1
Weighted Fair Queueing
Class class1
Output Queue: Conversation 264
Bandwidth 937 (kbps) Max Threshold 64 (packets)
(total/discards/tail drops) 11548/0/0
Class class2
Output Queue: Conversation 265
Bandwidth 937 (kbps) Max Threshold 64 (packets)
(total/discards/tail drops) 11546/0/0
Class class3
Output Queue: Conversation 266
Bandwidth 937 (kbps) Max Threshold 64 (packets)
(total/discards/tail drops) 11546/0/0
Class class4
Output Queue: Conversation 267
Bandwidth 937 (kbps) Max Threshold 64 (packets)
(total/discards/tail drops) 11702/0/0
Class class5
Output Queue: Conversation 268
Bandwidth 937 (kbps) Max Threshold 64 (packets)
(total/discards/tail drops) 11701/0/0
Class class6
Output Queue: Conversation 269
Bandwidth 937 (kbps) Max Threshold 64 (packets)
(total/discards/tail drops) 11702/0/0
Class class7
Output Queue: Conversation 270
Bandwidth 937 (kbps) Max Threshold 64 (packets)
(total/discards/tail drops) 11857/0/0
Class class8
Output Queue: Conversation 271
Bandwidth 937 (kbps) Max Threshold 64 (packets)
(total/discards/tail drops) 11858/1/0
The following example shows how to display configurations for classes that make up the service policy for the output VC 0/101 on the output interface atm2/0.6:
qos4-72a# show policy-map interface atm2/0.6
ATM2/0.6: VC 0/101 - output : p1
Weighted Fair Queueing
Class c-vc1-c1
Output Queue: Conversation 264
Bandwidth 31 (kbps)
mean queue depth: 1
drops: class random tail min-th max-th mark-prob
0 0 0 100 200 1/10
1 0 0 105 200 1/10
2 0 0 110 200 1/10
3 0 0 115 200 1/10
4 0 0 120 200 1/10
5 0 0 125 200 1/10
6 0 0 130 200 1/10
7 0 0 135 200 1/10
rsvp 0 0 140 200 1/10
Class c-vc1-c2
Output Queue: Conversation 265
Bandwidth 54 (kbps)
mean queue depth: 1
drops: class random tail min-th max-th mark-prob
0 0 0 60 100 1/10
1 0 0 65 100 1/10
2 0 0 70 100 1/10
3 0 0 75 100 1/10
4 0 0 80 100 1/10
5 0 0 83 100 1/10
6 0 0 85 100 1/10
7 0 0 87 100 1/10
rsvp 0 0 90 100 1/10
Class c-vc1-c3
Output Queue: Conversation 266
Bandwidth 77 (kbps)
mean queue depth: 0
drops: class random tail min-th max-th mark-prob
0 0 0 1 10 1/10
1 0 0 2 10 1/10
2 0 0 3 10 1/10
3 0 0 4 10 1/10
4 0 0 5 10 1/10
5 0 0 6 10 1/10
6 0 0 7 10 1/10
7 0 0 7 10 1/10
rsvp 0 0 7 10 1/10
Class c-vc1-c4
Output Queue: Conversation 267
Bandwidth 100 (kbps)
mean queue depth: 9
drops: class random tail min-th max-th mark-prob
0 0 0 1 10 1/10
1 9 220 2 10 1/10
2 24 645 3 10 1/10
3 22 844 4 10 1/10
4 0 0 5 10 1/10
5 23 351 6 10 1/10
6 28 213 7 10 1/10
7 59 540 7 10 1/10
rsvp 0 0 7 10 1/10
Class c-vc1-c5
Output Queue: Conversation 268
Bandwidth 123 (kbps)
mean queue depth: 150
drops: class random tail min-th max-th mark-prob
0 120 1777 50 150 1/50
1 136 1549 60 150 1/50
2 88 2354 70 150 1/50
3 121 1569 80 150 1/50
4 122 1717 80 150 1/50
5 0 0 90 150 1/50
6 0 0 100 150 1/50
7 105 2058 110 150 1/50
rsvp 0 0 120 150 1/50
Class c-vc1-c6
Output Queue: Conversation 269
Bandwidth 146 (kbps) Max Threshold 64 (packets)
(total/discards/tail drops) 50216/32696/0
Class c-vc1-c7
Output Queue: Conversation 270
Bandwidth 216 (kbps) Max Threshold 64 (packets)
(total/discards/tail drops) 74577/51994/0
Class class-default
Flow Based Fair Queueing
Number of Hashed Queues 256
drops: class random tail min-th max-th mark-prob
0 101 828 50 150 1/50
1 87 1154 60 150 1/50
2 115 476 70 150 1/50
3 116 444 80 150 1/50
4 123 338 80 150 1/50
5 92 1042 90 150 1/50
6 79 1068 100 150 1/50
7 110 740 110 150 1/50
rsvp 0 0 120 150 1/50
Table 2 provides a listing of the fields in these displays and a description of each field.
| Field | Description |
|---|---|
output | Name of the output service policy applied to the VC. |
Class | Class of traffic being displayed. Output is displayed for each configured class in the policy. |
Output Queue | The WFQ conversation to which this class of traffic is allocated. |
Bandwidth | Bandwidth in kbps or percentage configured for this class. |
Packets Matched | Number of packets that matched this class. |
Max Threshold | Maximum queue size for this class when WRED is not used. |
pkts discards | Number of packets discarded for this class. |
bytes discards | Number of bytes discarded for this class. |
tail drops | Number of packets discarded for this class because the queue was full. |
mean queue depth | Average queue depth based on the actual queue depth on the interface and the exponential weighting constant. It is a moving average. The minimum and maximum thresholds are compared against this value to determine drop decisions. |
drops: | WRED parameters. |
| IP Precedence value |
| Number of packets randomly dropped when the mean queue depth is between the minimum threshold value and the maximum threshold value for the specified IP Precedence value. |
| Number of packets dropped when the mean queue depth is greater than the maximum threshold value for the specified IP Precedence value. |
| Minimum WRED threshold in number of packets. |
| Maximum WRED threshold in number of packets. |
| Fraction of packets dropped when the average queue depth is at the maximum threshold. |
Maximum Number of Hashed Queues | (Applies to class-default only) Number of queues available for unclassified flows. |
Related Commands
show frame-relay pvc Displays statistics about PVCs for Frame Relay interfaces. show policy-map Displays the configuration of all classes that make up the specified service policy map or all classes for all existing policy maps. show policy-map class Displays the configuration for the specified class of the specified policy map.
Command
Description
CBWFQ---Class-Based Weighted Fair Queueing. Extends the standard WFQ functionality to provide support for user-defined traffic classes.
CIR---Commited Information Rate. Rate at which a Frame Relay network agrees to transfer information under normal conditions, averaged over a minimum increment of time.
Class-Based Weighted Fair Queueing---See CBWFQ.
DLCI---Data-link connection identifier. Value that specifies a permanent virtual circuit (PVC) or switched virtual circuit (SVC) in a Frame Relay network.
FIFO queueing--- First-in, first-out queueing. FIFO involves buffering and forwarding of packets in the order of arrival. FIFO embodies no concept of priority or classes of traffic. There is only one queue, and all packets are treated equally. Packets are sent out an interface in the order in which they arrive.
Frame Relay Traffic Shaping---See FRTS.
FRF.12---The FRF.12 Implementation Agreement was developed to allow long data frames to be fragmented into smaller pieces and interleaved with real-time frames. In this way, real-time voice and non-real-time data frames can be carried together on lower-speed links without causing excessive delay to the real-time traffic.
FRTS---Frame Relay Traffic Shaping. FRTS uses queues on a Frame Relay network to limit surges that can cause congestion. Data is buffered and then sent into the network in regulated amounts to ensure that the traffic will fit within the promised traffic envelope for the particular connection.
PQ/CBWFQ---Priority Queueing/Class-Based Weighted Fair Queueing. A feature that brings strict priority queueing to CBWFQ. Strict priority queueing allows delay-sensitive data such as voice to be dequeued and sent first (before packets in other queues are dequeued), giving delay-sensitive data preferential treatment over other traffic.
RTP---Real-Time Transport Protocol. One of the IPv6 protocols. RTP is designed to provide end-to-end network transport functions for applications transmitting real-time data, such as audio, video, or simulation data, over multicast or unicast network services. RTP provides services such as payload type identification, sequence numbering, time-stamping, and delivery monitoring to real-time applications.
UDP---User Datagram Protocol. Connectionless transport layer protocol in the TCP/IP protocol stack. UPD is a simple protocol that exchanges datagrams without acknowledgment or guaranteed delivery, requiring that error processing and retransmission be handled by other protocols.
VoFR---Voice over Frame Relay. Enables a router to carry voice traffic over a Frame Relay network. When sending voice traffic over Frame Relay, the voice traffic is segmented and encapsulated for transit across the Frame Relay network using FRF.12 encapsulation.
Voice over Frame Relay---See VoFR.
WFQ---Weighted Fair Queueing. Congestion management algorithm that identifies conversations (in the form of traffic streams), separates packets that belong to each conversation, and ensures that capacity is shared fairly among these individual conversations. WFQ is an automatic way of stabilizing network behavior during congestion and results in increased performance and reduced retransmission.
WRED---Weighted Random Early Detection. Combines IP Precedence and standard Random Early Detection (RED) to allow for preferential handling of voice traffic under congestion conditions without exacerbating the congestion. WRED uses and interprets IP Precedence to give priority to voice traffic over data traffic, dropping only data packets.
Posted: Thu May 18 13:30:03 PDT 2000
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