Contents

Introduction

Prerequisites

Requirements

Components Used

Configure

Learn-List

Pfr-Map

Link-Group

Network Diagram

Relevant Configuration

Verify

Case 1: Delay on MPLS and INET Cloud is Same and Within Policy Limits

Case 2: Delay on MPLS and INET Cloud is Different and Crosses the Policy Limits

Case 3: Delay on INET Cloud Sees Increase of 100 msec

Troubleshoot

Introduction

This document describes how learn lists and maps are defined and used in Performance Routing version 2 (PfRv2) in order to affect traffic flow for prefixes.

Prerequisites

Requirements

Cisco recommends that you have basic knowledge of PfR.

Components Used

This document is not restricted to specific software and hardware versions.

The information in this document was created from the devices in a specific lab environment. All of the devices used in this document started with a cleared (default) configuration. If your network is live, make sure that you understand the potential impact of any command.

Configure

Learn-List

The learn-list feature in PfRv2 allows the router to learn and group certain traffic classes. An enterprise network is comprised of various types of traffic which includes application, voice, video and so on. Learn-list gives the flexibility to group this traffic as per network requirements. Categorize and group of traffic in learn-lists is generally achieved with an access-list that matches some specific Differentiated Services Code Point (DSCP) value, however a prefix-list can also be used to match prefixes. This is an example of learn-list that learns and groups traffic based on DSCP value "ef".

list seq 10 refname Video-Traffic

traffic-class access-list Video

throughput

!

ip access-list extended Video

permit ip any any dscp ef

A learn list can be subjected to any user defined policy. This is generally achieved with a pfr-map.

Pfr-Map

Pfr-map helps you to define a policy which comprises of a set of parameters. Traffic categorized or grouped via learn-list is then mapped to an individual sequence of a pfr-map. These are some parameters that could be defined using pfr-maps.

- Delay

- Loss

- Unreachable

- Jitter

- Mean Opinion Scores (MOS)

Note: Delay will be used as the key parameter for the rest of this document

A PfR-Map can have multiple sequence numbers like a route-map and each sequence number can reference a different learn-list.

Link-Group

Link-Groups are used to group external interfaces so the traffic could be pushed out of the exit link of the selected border router (BR). A failover link-group can also be defined to do switchover in case the primary link-group goes out of policy. For example, this configuration defines link-group in this fashion:

set link-group INET fallback MPLS

This configuration statement used in pfr-map PFR under sequence 20 defines all DATA traffic to pass through INET as long as INET is in INPOLICY state. In case of a policy breach, traffic will failover to the MPLS link.

pfr-map PFR 20

set link-group INET fallback MPLS

Network Diagram

This image provides a sample topology for the configuration examples:

Devices shown in the diagram:

R1 Server - Initiates traffic.

R3 - PfR Master Router.

R4 & R5 - PfR Border Router.

Clients connected to R9 and R10 are devices that receive the traffic from R1 server.

Relevant Configuration

For the previous scenario two learn lists will be configured, one for application ( APPLICATION-LEARN-LIST) and the other for data (DATA-LEARN-LIST) traffic respectively. This scenario uses a prefix-list in order to define traffic. An access-list can also be used to match traffic types like TCP, UDP, Internet Control Message Protocol (ICMP) and so on. Other options like DSCP, Type of Service (ToS) and so on can also be used in order to match the traffic.

key chain pfr

key 0

key-string cisco

!

policy-rules PFR

!

border 10.4.4.4 key-chain pfr

interface Ethernet0/0 internal

interface Ethernet0/1 external

link-group MPLS

!

border 10.5.5.5 key-chain pfr

interface Ethernet0/0 internal

interface Ethernet0/1 external

link-group INET

!

learn

traffic-class filter access-list DENY-ALL

list seq 10 refname APPLICATION-LEARN-LIST

traffic-class prefix-list APPLICATION

throughput

list seq 20 refname DATA-LEARN-LIST

traffic-class prefix-list DATA

throughput

!

ip prefix-list DATA

seq 5 permit 10.30.0.0/24

!

ip prefix-list APPLICATION

seq 5 permit 10.20.0.0/24

!

pfr-map PFR 10

match pfr learn list APPLICATION-LEARN-LIST

set periodic 90

set delay threshold 25

set mode monitor active

set resolve delay priority 1 variance 10

set active-probe echo 10.20.0.12

set probe frequency 5

set link-group MPLS fallback INET

!

pfr-map PFR 20

match pfr learn list DATA-LEARN-LIST

set periodic 90

set delay threshold 25

set mode monitor both

set resolve delay priority 1 variance 10

set probe frequency 5

set link-group INET fallback MPLS

Verify

When traffic flows through the network, it matches the corresponding prefix-list and learn-list. Accordingly PfR-Map takes action on traffic as per the parameters defined for every learn-list.

Case 1: Delay on MPLS and INET Cloud is Same and Within Policy Limits

Traffic for prefix 10.20.0.0/24 (Application) is in INPOLICY state and flows via link-group MPLS. Similarly, prefix 10.30.0.0/24 (Data) is also in the INPOLICY state and flows via link-group INET.

R3#show pfr master  traffic-class

OER Prefix Statistics:

Pas - Passive, Act - Active, S - Short term, L - Long term, Dly - Delay (ms),

P - Percentage below threshold, Jit - Jitter (ms),

MOS - Mean Opinion Score

Los - Packet Loss (percent/10000), Un - Unreachable (flows-per-million),

E - Egress, I - Ingress, Bw - Bandwidth (kbps), N - Not applicable

U - unknown, * - uncontrolled, + - control more specific, @ - active probe all

# - Prefix monitor mode is Special, & - Blackholed Prefix

% - Force Next-Hop, ^ - Prefix is denied

DstPrefix           Appl_ID Dscp Prot     SrcPort     DstPort SrcPrefix

Flags             State     Time            CurrBR  CurrI/F Protocol

PasSDly  PasLDly   PasSUn   PasLUn  PasSLos  PasLLos      EBw      IBw

ActSDly  ActLDly   ActSUn   ActLUn  ActSJit  ActPMOS  ActSLos  ActLLos

--------------------------------------------------------------------------------

10.20.0.0/24              N    N    N           N           N N

INPOLICY       50          10.4.4.4 Et0/1           BGP

N        N        N        N        N        N        N        N

4        3        0        0        N        N        N        N

10.30.0.0/24            N    N    N           N           N N

INPOLICY        0          10.5.5.5 Et0/1           BGP

1        2        0        0        0        0       14        1

1        1        0        0        N        N        N        N

Case 2: Delay on MPLS and INET Cloud is Different and Crosses the Policy Limits

There is an increase in delay in the MPLS cloud of about 150 ms. This increase in delay violates the configured threshold delay value of 25 ms as per PfR-Map statementset delay threshold 25.

This causes Application traffic (10.20.0.0/24) to failover to link-group INET as per the configured statement set link-group MPLS fallback INET. After a period of time, traffic again gets into the INPOLICY state and flows over link-group INET.

Note: There is no effect seen on DATA traffic as its primary path is INET and no delay has been introduced on it.

R3#show pfr master  traffic-class

OER Prefix Statistics:

Pas - Passive, Act - Active, S - Short term, L - Long term, Dly - Delay (ms),

P - Percentage below threshold, Jit - Jitter (ms),

MOS - Mean Opinion Score

Los - Packet Loss (percent/10000), Un - Unreachable (flows-per-million),

E - Egress, I - Ingress, Bw - Bandwidth (kbps), N - Not applicable

U - unknown, * - uncontrolled, + - control more specific, @ - active probe all

# - Prefix monitor mode is Special, & - Blackholed Prefix

% - Force Next-Hop, ^ - Prefix is denied

DstPrefix           Appl_ID Dscp Prot     SrcPort     DstPort SrcPrefix

Flags             State     Time            CurrBR  CurrI/F Protocol

PasSDly  PasLDly   PasSUn   PasLUn  PasSLos  PasLLos      EBw      IBw

ActSDly  ActLDly   ActSUn   ActLUn  ActSJit  ActPMOS  ActSLos  ActLLos

--------------------------------------------------------------------------------

10.20.0.0/24              N    N    N           N           N N

INPOLICY       72          10.5.5.5 Et0/1           BGP

N        N        N        N        N        N        N        N

2        4        0        0        N        N        N        N

10.30.0.0/24            N    N    N           N           N N

INPOLICY        0          10.5.5.5 Et0/1           BGP

1        1        0        0        0        0       14        1

1        1        0        0        N        N        N        N

R3#show pfr master  traffic-class performance

Traffic-class:

Destination Prefix : 10.20.0.0/24            Source Prefix    : N/A

Destination Port   : N/A                     Source Port      : N/A

DSCP               : N                       Protocol         : N/A

Application Name:  : N/A

General:

Control State                   : Controlled using BGP

Traffic-class status            : INPOLICY

Current Exit                    : BR 10.5.5.5 interface Et0/1, Tie breaker was delay criteria

Time on current exit            : 0d 0:2:40

Time remaining in current state : 31 seconds

Traffic-class type              : Learned

Improper config                 : None

Last Out of Policy event:

Exit                            : BR 10.5.5.5 interface Et0/1

Reason                          : delay criteria

Time since Out of Policy event  : 0d 0:2:52

Active Delay Performance        : 1 msecs

Active Delay Threshold          : 25 msecs

Average Active Performance Current Exit: (Average for last 5 minutes)

Unreachable            : 0% -- Threshold: 50%

Delay                  : 1 msec -- Threshold: 25 msec

Last Resolver Decision:

BR              Interface    Status       Reason       Performance Threshold

--------------- ------------ ------------ ------------ ----------- ---------

10.4.4.4        Et0/1        Eliminated   Delay        162 msecs    25 msecs

10.5.5.5        Et0/1        Best Exit    Delay        13 msecs     25 msecs

From the output you can see up to 162 msecs of surge is seen in delay in the MPLS cloud. This causes violation of policy as threshold delay is configured to be 25 msecs.

Case 3: Delay on INET Cloud Sees Increase of 100 msec

This causes Data traffic(10.30.0.0/24) to failover to link-group MPLS as per the configured statement  set link-group INET fallback MPLS. After a period of time, traffic again gets into INPOLICY state and flows over link-group MPLS.

Note: There is no effect seen on APPLICATION traffic as its primary path is MPLS and no delay has been introduced  on it in this case.

R3#show pfr master  traffic-class

OER Prefix Statistics:

Pas - Passive, Act - Active, S - Short term, L - Long term, Dly - Delay (ms),

P - Percentage below threshold, Jit - Jitter (ms),

MOS - Mean Opinion Score

Los - Packet Loss (percent/10000), Un - Unreachable (flows-per-million),

E - Egress, I - Ingress, Bw - Bandwidth (kbps), N - Not applicable

U - unknown, * - uncontrolled, + - control more specific, @ - active probe all

# - Prefix monitor mode is Special, & - Blackholed Prefix

% - Force Next-Hop, ^ - Prefix is denied

DstPrefix           Appl_ID Dscp Prot     SrcPort     DstPort SrcPrefix

Flags             State     Time            CurrBR  CurrI/F Protocol

PasSDly  PasLDly   PasSUn   PasLUn  PasSLos  PasLLos      EBw      IBw

ActSDly  ActLDly   ActSUn   ActLUn  ActSJit  ActPMOS  ActSLos  ActLLos

--------------------------------------------------------------------------------

10.20.0.0/24              N    N    N           N           N N

INPOLICY       58          10.4.4.4 Et0/1           BGP

N        N        N        N        N        N        N        N

1        2        0        0        N        N        N        N

10.30.0.0/24            N    N    N           N           N N

INPOLICY        0          10.4.4.4 Et0/1           BGP

1        1        0        0        0        0       14        1

2        1        0        0        N        N        N        N

R3#show pfr master  traffic-class performance

Traffic-class:

Destination Prefix : 10.30.0.0/24            Source Prefix    : N/A

Destination Port   : N/A                     Source Port      : N/A

DSCP               : N                       Protocol         : N/A

Application Name:  : N/A

General:

Control State                   : Controlled using BGP

Traffic-class status            : INPOLICY

Current Exit                    : BR 10.4.4.4 interface Et0/1, Tie breaker was delay criteria

Time on current exit            : 0d 0:2:31

Time remaining in current state : 35 seconds

Traffic-class type              : Learned

Improper config                 : None

Last Out of Policy event:

Exit                            : BR 10.4.4.4 interface Et0/1

Reason                          : delay criteria

Time since Out of Policy event  : 0d 0:2:44

Active Delay Performance        : 0 msecs

Active Delay Threshold          : 25 msecs

Passive Delay Performance       : 9 msecs

Passive Delay Threshold         : 25 msecs

Average Passive Performance Current Exit: (Average for last 5 minutes)

Unreachable            : 0% -- Threshold: 50%

Delay                  : 9 msecs -- Threshold: 25 msecs

Loss                   : 0% -- Threshold: 10%

Egress BW              : 4 kbps

Ingress BW             : 1 kbps

Time since last update : 0d 0:0:11

Average Active Performance Current Exit: (Average for last 5 minutes)

Unreachable            : 0% -- Threshold: 50%

Delay                  : 0 msec -- Threshold: 25 msec

Last Resolver Decision:

BR              Interface    Status       Reason       Performance Threshold

--------------- ------------ ------------ ------------ ----------- ---------

10.5.5.5        Et0/1        Eliminated   Delay        96 msecs     25 msecs

10.4.4.4        Et0/1        Best Exit    Delay        5 msecs      25 msecs

Troubleshoot

There is currently no specific troubleshooting information available for this configuration.