Perform this task to configure basic PfR cost-based optimization. Cost-based optimization is configured on a master controller using the cost-minimization command in PfR border exit interface configuration mode (under the external interface configuration). Cost-based optimization supports tiered and fixed billing methods.

In this task, the configuration is performed on the master controller router and it assumes that the border routers are configured. Tier-based billing is configured with three cost tiers and a nickname for the service provider is set to ISP1. The monthly sustained utilization calculation technique is configured to use the sum technique and the last day of the billing cycle is on the 30th day of the month with an offset of 3 hours to allow for a difference in time zones.

The cost-minimization command contains many variations of keywords and arguments. Only one of the required keywords and its associated syntax can be configured on one CLI line, but multiple instances of this command can be entered. Only the fixed and tier keywords are mutually exclusive within the configuration for each border router link. For details about the full syntax, see the Cisco IOS Performance Routing Command Reference.

While basic PfR cost-based optimization can be useful, many organizations have multiple border router exit links and possibly several different service providers charging different billing rates that increase according to the bandwidth utilized. In this situation, some form of traffic load balancing across the links may be required in addition to the cost minimization policy.

Perform this task on the master controller to configure a Performance Routing cost policy to minimize the monthly billing charge for multiple border router exit links while load balancing traffic across the links. In this scenario, the network has both fixed-rate and tier-based billing, and assuming that the customer is paying a monthly fee for the fixed-rate billing and the pre-paid (lowest cost) tier of tier-based billing, PfR can perform traffic load balancing while optimizing for cost.

The figure below shows an example of how different billing rates can be defined for each link using bandwidth and cost parameters that are defined through service level agreements (SLAs) that are identified as rules in the diagram. The main goal of this task is to minimize the billing charge per exit link and to load balance traffic across the exit links. Although Link 1 may be billed at a fixed-rate and Links 2 through 4 are subject to tier-based billing, all the links are set up as PfR tiers. To accomplish the cost minimization the first rule is to utilize 80 percent of Link 1 and 30 percent of Links 2, 3 and 4, as shown in the figure below. The second rule is to distribute additional traffic across Links 2, 3 and 4 to balance the traffic load. To achieve the traffic load balancing while minimizing cost, the solution is to configure a PfR cost policy using multiple tiers representing bandwidth percentages that are assigned artificial costs to ensure that the PfR traffic is optimized for cost and load balanced across all the exits. To illustrate the configured tiers, see the figure below.

The steps in this task create a cost policy in which PfR is configured to direct traffic through any of the lowest cost exits first; Link 1 at 10.1.1.1 and the pre-paid tier of the other three exits. When the pre-paid tier bandwidth at each link is fully utilized, the software determines the next lowest incremental cost between the tiers at all the links. The incremental cost of utilizing the next tier at Link 1 is $990. The incremental cost of utilizing the next tier at Link 2 is only $10. PfR forwards traffic to the next lowest cost tier which is the blue bar representing 40 percent of the bandwidth at Link 2, as shown in the figure below. The process continues to use cost to balance the load across Links 2, 3, and 4. This task illustrates how the monthly billing rate per exit link is minimized by utilizing the pre-paid bandwidth at Links 1 though 4 first, and then the traffic is effectively load balanced across Links 2, 3 and 4 by determining the lowest incremental cost between tiers.

Figure 1. Diagram Showing PfR Cost-Minimization Solution to Minimize Billing and Load Balance Traffic

In the following task steps, the exit link 10.1.1.1 is configured as a tier-based link although it is actually charged at a fixed rate. If a fixed rate link is configured as a tier for load balancing, the monthly cost calculation will not reflect the true cost for that link. Using this solution, the artificial costs assigned to the multiple tiers may affect the accuracy of all the monthly cost calculations.

Only some of the configuration steps for this task scenario are shown in the summary and detailed steps, the full configuration for the master controller is displayed in the Examples section shown after the detailed steps table.

Note	Disable the range and utilization policy priorities because they may conflict with this application of the cost-minimization feature.

Note	Do not configure the periodic(PfR) or the set periodic(PfR) command with a time interval to avoid system churn as the system tries to select the best exit link at specified intervals. This command is disabled by default.

The cost-minimization (PfR) command contains many variations of keywords and arguments. Only one of the required keywords and its associated syntax can be configured on one CLI line, but multiple instances of this command can be entered. Only the fixed and tier keywords are mutually exclusive within the configuration for each border router link. For details about the full syntax, see the Cisco IOS Performance Routing Command Reference.

Perform this task on a master controller to display information to verify any cost-minimization policies and to help debug any issues. After cost-minimization policies are configured and applied to traffic the show command steps allow you to verify that the policy configuration is working as expected. If not, the debug command steps can help troubleshoot any issues. The show and debug commands are all optional and can be entered in any order.

The following example shows how to configure cost-based optimization on a master controller. Cost optimization configuration is applied under the external interface configuration. In this example, a policy is configured for multiple exits with a tiered billing cycle for one exit interface on border router 10.2.1.2 and a fixed fee billing cycle for the other exit interface on border router 10.2.1.2 and both exit interfaces on border router 10.3.1.3.

In this scenario, PfR sends traffic first through the fixed-rate exits, serial interface 3/0 at border router 10.2.1.2 and serial interfaces 2/0 and 3/0 at border router 10.3.1.3, because the bandwidth cost is lower for these fixed fee exits than the tier-based exit. When the fixed-rate exits are all fully utilized, the traffic is sent through serial interface 2/0 on border router 10.2.1.2. If the monthly sustained utilization is 40 percent or lower, the billing fee for the month will be $4000. If the monthly sustained utilization is higher then the tier that matches the monthly sustained utilization is charged. In this example, no calculation configuration was entered and the default behavior is triggered; the calculation is performed separately for egress and ingress samples.

This configuration example assumes that the border routers are already configured.

pfr master
 no periodic
 resolve cost priority 1
 no resolve delay
 no resolve utilization
 border 10.2.1.2 key-chain key_cost1
  interface Serial12/0 external
   cost-minimization tier 100 fee 10000
   cost-minimization tier 75 fee 8000
   cost-minimization tier 40 fee 4000
   cost-minimization end day-of-month 31
  interface Serial13/0 external
   cost-minimization fixed fee 3000
 border 10.3.1.3 key-chain key_cost2
  interface Serial12/0 external
   cost-minimization fixed fee 3000
  interface Serial13/0 external
   cost-minimization fixed fee 3000
   end

The following configuration example shows how to configure cost-minimization policies and balance PfR traffic loads across multiple links. This task is designed to minimize the cost of each link and to precisely control load balancing across multiple border router links. This task controls the load balancing between multiple links by forcing PfR to use the bandwidth of the lowest cost tier first and then use the next lowest cost tiers on all the links.

Keywords in the show pfr master cost-minimization command are used to view the utilization of a specific link with the monthly egress and ingress rollup values. After the monthly billing period ends another keyword option for the billing history shows the sustained monthly utilization and link cost.

Border Router 10.1.1.1

key chain key1
  key 1
    key-string border1
!
pfr border
  logging
  local GigabitEthernet3/0/0
  master 10.1.1.1 key-chain key1

Don’t forget to configure all the border routers using a similar configuration but with appropriate changes. Now configure the master controller.

Master Controller

key chain key1
  key 1
    key-string border1
 key chain key2
  key 1
    key-string border2
 key chain key3
  key 1
    key-string border3
 pfr master
  logging
  border 10.1.1.1 key-chain key1
   interface GigabitEthernet3/0/0 external
    cost-minimization nickname ISP1
    cost-minimization tier 100 fee 50000
    cost-minimization tier 65 fee 10000
    cost-minimization tier 30 fee 500
    cost-minimization end day-of-month 24
    cost-minimization sampling period 5 rollup 1440
    cost-minimization discard absolute 10
    exit
   interface GigabitEthernet3/0/1 internal
   exit
  border 10.2.1.2 key-chain key2
   interface GigabitEthernet3/2/0 external
   interface GigabitEthernet3/0/0 internal
   exit
  border 10.4.1.4 key-chain key3
   interface GigabitEthernet4/0/0 external
    cost-minimization nickname ISP2
    cost-minimization fixed fee 3000
    cost-minimization end day-of-month 24
    exit
   interface GigabitEthernet4/0/2 internal
   exit
  no max range receive
  delay threshold 10000
  loss threshold 1000000
  mode route control  
  mode monitor passive  
  mode select-exit best  
  resolve cost priority 1
  active-probe echo 10.1.9.1
  end

Now enter the show pfr master cost-minimization border command at the master controller to show the configuration and the utilization statistics. The rollup values during the 30-day March through April 24th billing period for the GigabitEthernet interface 3/0/0 on border router 10.1.1.1 are shown in the output:

Router# show pfr master cost-minimization border 10.1.1.1
pM - per Month, pD - per Day
 --------------------------------------------------------------------------------
  Nickname  : ISP1             Border: 10.1.1.1          Interface: Gi3/0/0           
  Calc type : Separate
  End Date  : 24
  Summer time: Disabled
  Fee       : Tier Based
              Tier 1: 100, fee:      50000
              Tier 2:  65, fee:      10000
              Tier 3:  30, fee:        500
  Period    : Sampling 5, Rollup 1440
  Discard   : Type Absolute, Value 10
 
  Rollup Information:
  Total(pM)       Discard(pM)     Remaining(pM)   Collected(pM)   
  31              10              1               29              
 
  Current Rollup Information:
    MomentaryTgtUtil:           75 Kbps    CumRxBytes:                0
   StartingRollupTgt:           75 Kbps    CumTxBytes:                0
    CurrentRollupTgt:           75 Kbps    TimeRemain:         00:00:51
 
  Rollup Utilization (Kbps):
  Egress Utilization Rollups (Descending order)
 
  1   : 0            2   : 89           3   : 80           4   : 71          
  5   : 70           6   : 65           7   : 65           8   : 51          
  9   : 50           10  : 49           11  : 49           12  : 45          
  13  : 42           14  : 39           15  : 35           16  : 34          
  17  : 30           18  : 30           19  : 30           20  : 29          
  21  : 25           22  : 20           23  : 19           24  : 12          
  25  : 10           26  : 10           27  : 9            28  : 8           
  29  : 4            30  : 1           
  Ingress Utilization Rollups (Descending order)
 
  1   : 0            2   : 92           3   : 84           4   : 82          
  5   : 80           6   : 78           7   : 75           8   : 73          
  9   : 72           10  : 70           11  : 63           12  : 62          
  13  : 60           14  : 55           15  : 53           16  : 52          
  17  : 45           18  : 43           19  : 35           20  : 33          
  21  : 31           22  : 25           23  : 23           24  : 21          
  25  : 15           26  : 11           27  : 10           28  : 10          
  29  : 5            30  : 1

If we assume that the March through April 24th billing period is over, we can see the billing for the previous billing period using the show pfr master cost-minimization billing-history command. The monthly sustained utilization is 62 and the cost is $10,000 for the GigabitEthernet interface 3/0/0 link on border router 10.1.1.1.

Router# show pfr master cost-minimization billing-history
Billing History for the past three months
 
         ISP2 on 10.4.1.4          Gi4/0/0           
  No cost min on 10.2.1.2          Gi3/2/0           
         ISP1 on 10.1.1.1          Gi3/0/0           
                  Mon1                  Mon2                  Mon3
 Nickname     SustUtil       Cost   SustUtil       Cost   SustUtil       Cost
 ----------    ------------------    ------------------   ------------------
    ISP2             0       3000        ---NA---             ---NA---     
    ISP1            62      10000        ---NA---             ---NA---     
 
 ----------    ------------------    ------------------   ------------------
 Total Cost                 13000                     0                     0