Configuring IP SLAs TCP Connect Operations

This chapter describes how to configure an IP Service Level Agreements (SLAs) TCP Connect operation to measure the response time taken to perform a TCP Connect operation between a Cisco switch and devices using IPv4. TCP Connect accuracy is enhanced by using the IP SLAs Responder at the destination Cisco switch. This chapter also describes how the results of the TCP Connect operation can be displayed and analyzed to determine how the connection times to servers and hosts within your network can affect IP service levels. The TCP Connect operation is useful for measuring response times for a server used for a particular application or connectivity testing for server availability.

This chapter includes these sections.

Information About the TCP Connect Operation

The IP SLAs TCP Connect operation measures the response time taken to perform a TCP Connect operation between a Cisco switch and devices using IP. TCP is a transport layer (Layer 4) Internet protocol that provides reliable full-duplex data transmission. The destination device can be any device using IP or an IP SLAs Responder.

In the following figure, Switch B is configured as the source IP SLAs device and a TCP Connect operation is configured with the destination device as IP Host 1.





The connection response time is computed by measuring the time taken between sending a TCP request message from Switch B to IP Host 1 and receiving a reply from IP Host 1.

TCP Connect accuracy is enhanced by using the IP SLAs Responder at the destination Cisco device. If the destination switch is a Cisco switch, the IP SLAs Responder makes a TCP connection to any port number that you specified. If the destination is not a Cisco IP host, then you must specify a known destination port number such as 21 for FTP, 23 for Telnet, or 80 for an HTTP server.

Using the IP SLAs Responder is optional for a TCP Connect operation when using Cisco devices. The IP SLAs Responder cannot be configured on non-Cisco devices.

TCP Connect is used to test virtual circuit availability or application availability. Server and application connection performance can be tested by simulating Telnet, SQL, and other types of connections to help you verify your IP service levels.

Guidelines and Limitations for Configuring IP SLAs TCP Connect Operations

Configuring CoPP for IP SLA Packets

When using IP SLA operations on a large scale, a specific CoPP configuration to allow the IP SLA packets to pass through might be needed. Since IP SLA uses user defined UDP ports, there is no way to allow all IP SLA packets to the control plane. However, you can specify each destination/source port that IP SLA can use.

For more information about the verified scalability of the number of IP SLA probes, see the Cisco Nexus 3000 Series NX-OS Verified Scalability Guide.

The following shows an example of a CoPP configuration that allows IP SLA packets to pass through. It assumes destination ports and source ports in the range of 6500-7000. 

ip access-list copp-system-sla-allow
  10 remark ### ALLOW SLA control packets from 1.1.1.0/24
  20 permit udp 1.1.1.0/24 any eq 1967
  30 remark ### ALLOW SLA data packets from 1.1.1.0/24 using ports 6500-7000
  40 permit udp 1.1.1.0/24 any range 6500 7000
  statistics per-entry
ip access-list copp-system-sla-deny
  10 remark ### this is a catch-all to match any other traffic
  20 permit ip any any
  statistics  per-entry
class-map type control-plane match-any copp-system-class-management-allow
  match access-group name copp-system-sla-allow
class-map type control-plane match-any copp-system-class-management-deny
  match access-group name copp-system-sla-deny
policy-map type control-plane copp-system-policy
    class copp-system-class-management-allow
    set cos 7
    police cir 4500 kbps bc 250 ms conform transmit violate drop
    class copp-system-class-management-deny
    police cir 4500 kbps bc 250 ms conform drop violate drop
control-plane
  service-policy input copp-system-policy

Matching the Netstack Port Range

IP SLA only accepts ports within the local netstack port range. The source and destination ports used in the probe's configuration must match the supported netstack ports on the SLA sender and the SLA responder.

You can use the show sockets local-port-range command to view the port range on the sender/responder.

The following is an example of viewing the netstack port range: 

switch# show sockets local-port-range 

Kstack local port range (15001 - 22002)
Netstack local port range (22003 – 65535)

Configuring the IP SLAs Responder on the Destination Device

This section describes how to configure the IP SLAs Responder on the destination device.

Before You Begin

If you are using the IP SLAs Responder, ensure that the networking device to be used as the responder is a Cisco device and that you have connectivity to that device through the network.

Procedure
     Command or ActionPurpose
    Step 1 enable


    Example: 
    switch> enable
     

    Enables privileged EXEC mode.

    Enter your password if prompted.

     
    Step 2configure terminal


    Example: 
    switch# configure terminal
     

    Enters global configuration mode.

     
    Step 3 feature sla responder


    Example: 
    switch(config)# feature sla responder
     

    Enables the IP SLAs responder feature.

     
    Step 4Do one of the following:
    • ip sla responder

      Example: 

       switch(config)# ip sla responder
    • ip sla responder tcp-connect ipaddress ip-address port port

      Example: 

       switch(config)# ip sla responder tcp-connect ipaddress 172.29.139.132 port 5000
     

    -

    • (Optional) Temporarily enables IP SLAs Responder functionality on a Cisco device in response to control messages from source.

    • (Optional) Required only if protocol control is disabled on the source. The command permanently enables the IP SLAs Responder functionality on a specified IP address and port.

      Control is enabled by default.

     
    Step 5 exit


    Example: 
    switch(config)# exit
     

    (Optional) Exits global configuration mode and returns to privileged EXEC mode.

     

    Configuring and Scheduling a TCP Connect Operation on the Source Device

    This section describes how to configure and schedule a TCP connect operation on the source device.

    Perform only one of the following tasks to configure and schedule a TCP connect operation on the source device:

    • Configuring and scheduling a basic TCP connect operation on the source device

    • Configuring and scheduling a TCP connect operation with optional parameters on the source device

    Configuring and Scheduling a Basic TCP Connect Operation on the Source Device

    This section describes how to configure and schedule a basic TCP connect operation on a source device.


    Note

    If an IP SLAs Responder is permanently enabled on the destination IP address and port, use the control disable keywords with the tcp-connect command to disable control messages.


    Tip

    • If the IP SLAs operation is not running and generating statistics, add the verify-data command to the configuration of the operation (while configuring in IP SLA configuration mode) to enable data verification. When enabled, each operation response is checked for corruption. Use the verify-data command with caution during normal operations because it generates unnecessary overhead.

    • Use the debug ip sla sender trace and debug ip sla sender error commands to help troubleshoot issues with an IP SLAs operation.

    Procedure
       Command or ActionPurpose
      Step 1 enable


      Example: 
      switch> enable
       

      Enables privileged EXEC mode.

      Enter your password if prompted.

       
      Step 2 configure terminal


      Example: 
      switch# configure terminal
       

      Enters global configuration mode.

       
      Step 3 feature sla sender


      Example: 
      switch(config)# feature sla sender
       

      Enables the IP SLAs operation feature.

       
      Step 4 ip sla operation-number


      Example: 
      switch(config)# ip sla 10
       

      Begins configuration for an IP SLAs operation and enters IP SLA configuration mode.

       
      Step 5 tcp-connect {destination-ip-address | destination-hostname} destination-port [source-ip {ip-address | hostname} source-portport-number] [control {enable | disable}]


      Example: 
      switch(config-ip-sla)# tcp-connect 172.29.139.132 5000
       

      Defines a TCP Connect operation and enters IP SLA TCP configuration mode.

      Use the control disable keyword combination only if you disable the IP SLAs control protocol on both the source and target switches.

       
      Step 6 frequency seconds


      Example: 
      switch(config-ip-sla-tcp)# frequency 60
       

      (Optional) Sets the rate at which a specified IP SLAs operation repeats.

       
      Step 7 exit


      Example: 
      switch(config-ip-sla-tcp)# exit
       

      Exits IP SLA TCP configuration mode and returns to global configuration mode.

       
      Step 8 ip sla schedule operation-number [life {forever | seconds}] [start-time {hh:mm[:ss] [monthday | daymonth] | pending | now | after hh:mm:ss] [ageout seconds] [recurring]


      Example: 
      switch(config)# ip sla schedule 10 start-time now life forever
       

      Configures the scheduling parameters for an individual IP SLAs operation.

       
      Step 9 exit


      Example: 
      switch(config)# exit
       

      (Optional) Exits the global configuration mode and returns to privileged EXEC mode.

       

      This example shows how to configure an IP SLAs operation type of TCP Connect that will start immediately and run indefinitely: 

      feature sla sender
ip sla 9
 tcp-connect 172.29.139.132 5000
 frequency 10
!
ip sla schedule 9 life forever start-time now
      What to Do Next

      To add proactive threshold conditions and reactive triggering for generating traps or for starting another operation, see the "Configuring Proactive Threshold Monitoring" section.

      To view and interpret the results of an IP SLAs operation, use the show ip sla statistics command. Checking the output for fields that correspond to criteria in your service level agreement helps you to determine whether the service metrics are acceptable.

      Configuring and Scheduling a TCP Connect Operation with Optional Parameters on the Source Device

      This section describes how to configure and schedule a TCP connect operation with optional parameters on a source device.


      Note

      If an IP SLAs Responder is permanently enabled on the destination IP address and port, use the control disable keywords with the tcp-connect command to disable control messages.


      Tip

      • If the IP SLAs operation is not running and generating statistics, add the verify-data command to the configuration of the operation (while configuring in IP SLA configuration mode) to enable data verification. When enabled, each operation response is checked for corruption. Use the verify-data command with caution during normal operations because it generates unnecessary overhead.

      • Use the debug ip sla trace and debug ip sla error commands to help troubleshoot issues with an IP SLAs operation.

      Procedure
         Command or ActionPurpose
        Step 1 enable


        Example: 
        switch> enable
         

        Enables privileged EXEC mode.

        Enter your password if prompted.

         
        Step 2 configure terminal


        Example: 
        switch# configure terminal
         

        Enters global configuration mode.

         
        Step 3 feature sla sender


        Example: 
        switch(config)# feature sla sender
         

        Enables the IP SLAs operation feature.

         
        Step 4 ip sla operation-number


        Example: 
        switch(config)# ip sla 10
         

        Begins configuration for an IP SLAs operation and enters IP SLA configuration mode.

         
        Step 5 tcp-connect {destination-ip-address | destination-hostname} destination-port [source-ip {ip-address | hostname} source-port port-number] [control {enable | disable}]


        Example: 
        switch(config-ip-sla)# tcp-connect 172.29.139.132 5000
         

        Defines a TCP Connect operation and enters IP SLA TCP configuration mode.

        Use the control disable keyword combination only if you disable the IP SLAs control protocol on both the source and target switches.

         
        Step 6 history buckets-kept size


        Example: 
        switch(config-ip-sla-tcp)# history buckets-kept 25
         

        (Optional) Sets the number of history buckets that are kept during the lifetime of an IP SLAs operation.

         
        Step 7 history distributions-of-statistics-kept size


        Example: 
        switch(config-ip-sla-tcp)# history distributions-of-statistics-kept 5
         

        (Optional) Sets the number of statistics distributions kept per hop during an IP SLAs operation.

         
        Step 8 history enhanced [interval seconds] [buckets number-of-buckets]


        Example: 
        switch(config-ip-sla-tcp)# history enhanced interval 900 buckets 100
         

        (Optional) Enables enhanced history gathering for an IP SLAs operation.

         
        Step 9 history filter {none | all | overThreshold | failures}


        Example: 
        switch(config-ip-sla-tcp)# history filter failures
         

        (Optional) Defines the type of information kept in the history table for an IP SLAs operation.

         
        Step 10 frequency seconds


        Example: 
        switch(config-ip-sla-tcp)# frequency 60
         

        (Optional) Sets the rate at which a specified IP SLAs operation repeats.

         
        Step 11 history hours-of-statistics-kept hours


        Example: 
        switch(config-ip-sla-tcp)# history hours-of-statistics-kept 4
         

        (Optional) Sets the number of hours for which statistics are maintained for an IP SLAs operation.

         
        Step 12 history lives-kept lives


        Example: 
        switch(config-ip-sla-tcp)# history lives-kept 5
         

        (Optional) Sets the number of lives maintained in the history table for an IP SLAs operation.

         
        Step 13 owner owner-id


        Example: 
        switch(config-ip-sla-tcp)# owner admin
         

        (Optional) Configures the Simple Network Management Protocol (SNMP) owner of an IP SLAs operation.

         
        Step 14 history statistics-distribution-interval milliseconds


        Example: 
        switch(config-ip-sla-tcp)# history statistics-distribution-interval 10
         

        (Optional) Sets the time interval for each statistics distribution kept for an IP SLAs operation.

         
        Step 15 tag text


        Example: 
        switch(config-ip-sla-tcp)# tag TelnetPollServer1
         

        (Optional) Creates a user-specified identifier for an IP SLAs operation.

         
        Step 16 threshold milliseconds


        Example: 
        switch(config-ip-sla-tcp)# threshold 10000
         

        (Optional) Sets the upper threshold value for calculating network monitoring statistics created by an IP SLAs operation.

         
        Step 17 timeout milliseconds


        Example: 
        switch(config-ip-sla-tcp)# timeout 10000
         

        (Optional) Sets the amount of time an IP SLAs operation waits for a response from its request packet.

         
        Step 18 tos number


        Example: 
        switch(config-ip-sla-jitter)# tos 160


        Example:  

        (Optional) In an IPv4 network only, defines the ToS byte in the IPv4 header of an IP SLAs operation.

         
        Step 19 exit


        Example: 
        switch(config-ip-sla-tcp)# exit
         

        Exits TCP configuration submode and returns to global configuration mode.

         
        Step 20 ip sla schedule operation-number [life {forever| seconds}] [start-time {hh:mm[:ss] [monthday | daymonth] | pending | now | after hh:mm:ss] [ageout seconds] [recurring]


        Example: 
        switch(config)# ip sla schedule 10 start-time now life forever
         

        Configures the scheduling parameters for an individual IP SLAs operation.

         
        Step 21 exit


        Example: 
        switch(config)# exit
         

        (Optional) Exits global configuration mode and returns to privileged EXEC mode.

         
        Step 22 show ip sla configuration [operation-number]


        Example: 
        switch# show ip sla configuration 10
         

        (Optional) Displays configuration values including all defaults for all IP SLAs operations or a specified operation.

         

        This example shows how to configure all the IP SLAs parameters (including defaults) for the TCP Connect operation number 10: 

        switch# show ip sla configuration 10
IP SLAs Infrastructure Engine-III
Entry number: 10
Owner: admin
Tag: TelnetPollServer1
Operation timeout (milliseconds): 10000
Type of operation to perform: tcp-connect
Target address/Source address: 101.101.101.1/0.0.0.0
Target port/Source port: 5000/0
Type Of Service parameter: 0xa0
Vrf Name: default
Control Packets: enabled
Schedule:
   Operation frequency (seconds): 60  (not considered if randomly scheduled)
   Next Scheduled Start Time: Start Time already passed
   Group Scheduled : FALSE
   Randomly Scheduled : FALSE
   Life (seconds): Forever
   Entry Ageout (seconds): never
   Recurring (Starting Everyday): FALSE
   Status of entry (SNMP RowStatus): Active
Threshold (milliseconds): 10000
Distribution Statistics:
   Number of statistic hours kept: 4
   Number of statistic distribution buckets kept: 5
   Statistic distribution interval (milliseconds): 10
Enhanced History:
   Aggregation Interval:900 Buckets: 100
History Statistics:
   Number of history Lives kept: 0
   Number of history Buckets kept: 25
   History Filter Type: Failures
        What to Do Next

        To add proactive threshold conditions and reactive triggering for generating traps or for starting another operation, see the "Configuring Proactive Threshold Monitoring" section.

        To view and interpret the results of an IP SLAs operation, use the show ip sla statistics command. Checking the output for fields that correspond to criteria in your service level agreement helps you to determine whether the service metrics are acceptable.

        Configuration Example for a TCP Connect Operation

        This example shows how to configure a TCP Connect operation from Switch B to the Telnet port (TCP port 23) of IP Host 1 (IP address 10.0.0.1), as shown in the "TCP Connect Operation" figure in the "Information About the IP SLAs TCP Connect Operation" section. The operation is scheduled to start immediately. In this example, the control protocol is disabled on the source (Switch B). IP SLAs use the control protocol to notify the IP SLAs Responder to enable the target port temporarily. This action allows the Responder to reply to the TCP Connect operation. In this example, because the target is not a switch and a well-known TCP port is used, there is no need to send the control message.

        Switch A Configuration

        configure terminal
 feature sla responder
 ip sla responder tcp-connect ipaddress 10.0.0.1 port 23

        Switch B Configuration

        configure terminal
 feature sla sender
 ip sla 9
  tcp-connect 10.0.0.1 23 control disable
  frequency 30
  tos 128
  timeout 1000
  tag FLL-RO
 ip sla schedule 9 start-time now

        This example shows how to configure a TCP Connect operation with a specific port, port 21, and without an IP SLAs Responder. The operation is scheduled to start immediately and run indefinitely. 

        configure terminal
 feature sla sender
 ip sla 9
  tcp-connect 173.29.139.132 21 control disable
  frequency 30
 ip sla schedule 9 life forever start-time now