CCNP ROUTE 2.0: IP SLA


CCNP ROUTE 2.0 Exam Blueprint:
Configure and verify IP SLA (ICMP) / Configure and Verify Tracking Objects

IP SLA

IP SLA monitors the network performance by measuring response time, network availability, application performance, jitter, throughput and packet loss. On a Cisco IOS device an IP SLA operation type is configured (see list below) to generate a packet to send to a configure destination device.

The various types of IP SLAs operations include the following:

  • Domain Name System (DNS)
  • Dynamic Host Control Protocol (DHCP)
  • File Transfer Protocol (FTP)
  • Hypertext Transfer Protocol (HTTP)
  • ICMP echo
  • ICMP jitter
  • ICMP path echo
  • ICMP path jitter
  • Real-Time Transport Protocol (RTP)-based VoIP
  • Transmission Control Protocol (TCP) connect
  • UDP echo
  • UDP jitter
  • UDP jitter for VoIP
  • VoIP gatekeeper registration delay
  • VoIP post-dial delay

The IP SLA operation must be scheduled to capture the statistics; this can be configured to run immediately or on a certain day, month, year etc (accurate clock must be configured using NTP). If continuous monitoring is required the IP SLA operation can be configured to be run indefinitely.

In the CCNP ROUTE 2.0 Exam blueprint only configuring and verifying IP SLA (ICMP) is tested.

  • Configure an IP SLA Operation (ICMP Echo)

The commands below creates an IP SLA #1, configures and operation type of “icmp-echo” with a destination IP address of 1.1.1.1 using the source interface of fastherthernet 0/1. The timeout command sets the amount of time an IP SLA operation waits for a response (in milliseconds). The frequency command sets the rate at which the specified IP SLA operation repeats.

ip sla 1
icmp-echo 1.1.1.1 source-interface fastethernet 0/1
timeout 10000
frequency 10

  • Schedule IP SLA Operation

The command below schedules the previously created IP SLA operation ID with the parameters to start gathering information, in this instance start-now and a lifetime forever gather results.

ip sla schedule 1 start-time now life forever

  • Verifying IP SLA Results

The command “show ip sla configurationprovides configuration information on the IP SLAs.


The command “ip sla statistics” displays results of the configured SLA (number of successes and failures).


Tracking Objects using the “track” command

IP SLA can be used in conjunction with the “track” command to take action upon an event. In a scenario when a site has 2 ISP connections an IP SLA can be configure to probe the first ISP link, in the event of a failure at the ISP the static default route can be changed to re-route traffic out of ISP2. The IP SLA will be configured as before but this time when the IP SLA operation fails to receive a response after multiple attempts the track command will remove the primary static default route and use a backup route. The backup default route will need an administrative distance greater than the primary default route.

  • Track the state of the configured IP SLA

    Track the configured destination in IP SLA 1 with a delay of 30 seconds of reachability being down for 30 seconds and 30 seconds upon being up before reverting back to the primary route.


    track 1 ip sla 1 reachability
    delay up 30 down 30

  • Create the default static routes

     

    Create
    2 default static routes, add the track command to the primary route. Upon the configure IP SLA failing to receive a response in the configured time interval the default route will be removed and the secondary route will route traffic. Once the IP SLA receives a response from the destination again the primary default route will takeover.

    ip route 0.0.0.0 0.0.0.0 192.168.0.1 track 1
    ip route 0.0.0.0 0.0.0.0 192.168.1.1 200

  • Verifying Track command

The command “show track” will list all tracks configured on the Cisco IOS device.


Tracking multiple SLA Operations

Rather than relying on just the results from one IP SLA operation, multiple operations can be setup and tracked and action taken if all or even a percentage of SLA reachability is down.

  • Create additional IP SLA Operations and schedule

    ip sla 2
    icmp-echo 2.2.2.1 source-interface fastethernet 0/1
    timeout 10000
    frequency 10

    ip sla schedule 2 life forever start-time now

  • Track all of the configured IP SLA Operations

    Track 2 ip sla 2 reachability
    delay up 30 down 30

  • Create a track list Boolean consisting of all of the configured IP SLA Operations

    track 3 list Boolean or
    object 1
    object 2

    NOTE – Use “or” so the tracked object will go down if both tracked objects 1 and 2 are not reachable.

    Boolean = “and” – specify that the list is up if all objects are up or down if one or more objects are down
    Boolean = “or” – specify that the list is up if one object is up or down if all objects are down

  • Remove the old tracked route and create a new track route, ensure you track the list

    no ip route 0.0.0.0 0.0.0.0 192.168.0.1 track 1
    ip route 0.0.0.0 0.0.0.0 192.168.0.1 track 3

Using the configuration above the primary route will be considered down if both 1.1.1.1 and 2.2.2.1 are down and not reachable by the interface fastethernet 0/1. Upon failure of both IP SLA operations 1 and 2 the default route tracked by track 3 will remove the default route and failover to the secondary route.


 

 

 

 

 

 

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