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  • Table of Contents
  • Layer 2 Technologies
    • Ethernet Switching
      • L2 Switch Operations
      • Spanning Tree
        • 802.1d – STP
        • 802.1w – RSTP
        • 802.1s – MSTP
      • VTP 101
      • Private VLANs
      • VLANs
      • EtherChannel 101
    • Layer 2 WAN Protocols
      • HDLC
        • HDLC 101
      • PPP
        • PPP 101
        • PPP Authentication - PAP
        • PPP Authentication – CHAP
        • PPP Authentication – EAP
        • PPP Multilink
        • PPPoFR – PPP over Frame Relay
        • PPPoE – PPP over Ethernet
      • Frame Relay
        • Frame Relay 101
        • Frame Relay 102
        • Frame Relay Encapsulations – IETF vs Cisco
        • Multilink Frame Relay
        • Frame Relay Switching
        • Routing over Frame Relay
      • Bridging
        • Bridging on a router
        • MTU 101
    • Wireless
      • Wireless Principles
      • Wireless Implementations
      • Wireless Roaming
      • Wireless Authentication
        • WPA2 PSK
        • WPA2 802.1X
  • IPv4
    • IPv4 Addressing
      • Backup Interfaces
      • FHRP 101
      • DHCP 101
      • DNS 101
      • ARP 101
      • IPv4 101
      • Tunnel Interfaces
        • GRE Tunnels
      • BFD – Bidirectional Forwarding Detection
    • IPv4 Routing
      • How the routing table is built
        • How CEF works
        • Routing Order of Operations
        • NSF – Non Stop Forwarding
      • RIP
        • RIP 101
      • EIGRP
        • EIGRP 101
        • EIGRP Metric
        • More EIGRP Features
      • OSPF
        • OSPF 101
        • OSPF Areas
        • OSPF LSAs
        • OSPF Mechanics
      • IS-IS
        • IS-IS 101
        • IS-IS Mechanics – CLNP
      • BGP
        • BGP 101
        • BGP Attributes
        • More BGP
      • Route Redistribution
      • Policy based Routing
      • PfR 101 – Perfromance Routing
      • ODR
  • IPv6
    • IPv6-101
    • IPv6 Routing
    • Interconnecting IPv6 and IPv4
  • MPLS
    • MPLS 101
    • MPLS L3 VPN
  • Multicast
    • Multicast 101
    • PIM 101
    • IGMP 101
    • Inter Domain Multicast
    • IPv6 Multicast
    • Multicast features on switches
  • Security
    • NAT 101
    • NAT for Overlapping Networks
    • ACLs 101
    • ACLs 102
    • Cisco IOS Firewall
    • Zone Based Firewall
    • AAA 101
    • Controlling CLI Access
    • Control Plane
    • Switch Security
      • Switchport Traffic Control
      • Switchport Port Security
      • DHCP Snooping and DAI
      • 802.1x
      • Switch ACLs
    • IPSec VPN 101
      • IKE / ISAKMP 101
      • IPSEC Crypto Maps 101
      • IPSEC VTI 101
      • DMVPN 101
    • EAP 101
  • Network Services
    • NTP 101
    • HTTP 101
    • File Transfer 101 – TFTP & FTP
    • WCCP 101
  • QoS
    • QoS 101
    • Classification and Marking
    • Congestion Management
      • Legacy Congestion Management
      • SPD – Selective Packet Discard
      • CBWFQ
      • IP RTP Priority
    • Congestion Avoidance – WRED
    • Policing and Shaping
      • CAR 101
    • Compression and LFI
      • Header and Payload Compression
      • LFI for MultiLink PPP
    • Frame Relay QoS
      • Per VC Frame Relay QoS
    • RSVP 101
    • Switching QoS
  • Network Optimization
    • NetFlow 101 – TNF – Traditional NetFlow
    • NetFlow 102 – FNF – Flexible NetFlow
    • IP SLA 101
    • IP Accounting 101
    • Logging 101
    • SNMP and RMON 101
    • Cisco CLI Tips and Tricks
    • AutoInstall
    • Enhanced Object Tracking
    • Troubleshooting 101
    • SPAN, RSPAN, ERSPAN
  • Network Architecture
    • Hierarchical Network Architecture
    • SD Access
    • SD WAN
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On this page
  • About IP SLA
  • Configuring IP SLA
  • Define the IP SLA Operation
  • Schedule or start the operation
  • Configure the responder, if needed
  • Monitoring SLA
  • Proactive Monitoring

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  1. Network Optimization

IP SLA 101

About IP SLA

IP SLA is a feature that enables a router to monitor the status of a connection by measuring different KPIs. The SLA can be measured end-to-end from one host to another and is independent of the Layer 2 encapsulation.

Configuring IP SLA

Define the IP SLA Operation

First, you must define a SLA Operation:

R(config)# ip sla SLA-ID

Then, you must choose the SLA type:

R(config-ip-sla)# ?
IP SLAs entry configuration commands:
  dhcp         DHCP Operation
  dns          DNS Query Operation
  ftp          FTP Operation
  http         HTTP Operation
  icmp-echo    ICMP Echo Operation
  icmp-jitter  ICMP Jitter Operation
  path-echo    Path Discovered ICMP Echo Operation
  path-jitter  Path Discovered ICMP Jitter Operation
  tcp-connect  TCP Connect Operation
  udp-echo     UDP Echo Operation
  udp-jitter   UDP Jitter Operation
  voip         Voice Over IP Operation

Each type of SLA is doing a type of measuring and it has paritcular options that can be configured:

  • dhcp – measures RTT (routing-trip-time) taken to discover a DHCP server and obtain a leased IP

  • dns – measures RTT (routing-trip-time) taken to receive a DNS reply

  • ftp – time taken to download a file from an FTP Server

  • http – time taken to retrive a web page from an HTTP Server

  • icmp-echo – measures end-to-end response time between the router and another IP device

  • icmp-jitter – measures jitter, latency and packet-loss of the ICMP echos and echo-replies

  • path-echo – measures end-to-end and hop-by-hop respone time

  • path-jitter – measures end-to-end and hop-by-hop jitter, latency and packet-loss

  • path-jitter – measures end-to-end and hop-by-hop jitter, latency and packet-loss

  • tcp-connect – measures time to perform a TCP connect with a host

  • udp-echo – measures end-to-end response when sending UDP packets

  • udp-jitter – measures jitter when sending UDP packets. Useful for troubleshooting VoIP performance

  • voip – voip related measurements

Once the operation type is selected, you can define even more options, like:

! Frequency of the operation
R(config-ip-sla-echo)# frequency SECONDS
! Timeout of the response:
R(config-ip-sla-echo)# timeout MSEC
! Limit of the rising threshold 
R(config-ip-sla-echo)# threshold MSEC
! Size of the Padding:
R(config-ip-sla-echo)# request-data-size BYTES
! ToS value of the packets sent
R(config-ip-sla-echo)# tos TOS-VALUE
! Force the router to check for data-corruption:
R(config-ip-sla-echo)# verify-data
! SNMP Owner
R(config-ip-sla-echo)# owner STRING

IP SLA maintains several history statistics. They can be configured with the history command:

R(config-ip-sla-echo)#history ?
  buckets-kept                      Maximum number of history buckets to collect
  distributions-of-statistics-kept  Maximum number of statistics distribution buckets to capture
  enhanced                          Enable enhanced history collection
  filter                            Add operation to History when...
  hours-of-statistics-kept          Maximum number of statistics hour groups to capture
  lives-kept                        Maximum number of history lives to collect
  statistics-distribution-interval  Statistics distribution interval size

Schedule or start the operation

R(config)# ip sla schedule SLA-ID [start-time WHEN] [recurring] [life {SEC|forever}] [ageout SEC] 
! life = how long to run the SLA operation
! ageout = how long to keep the Entry when inactive
! recurring = reschedule it daily
! start-time: WHEN can be one of the following:
!       HH:MM:[SS] - start at the specified time
!       after HH:MM:SS - start HH hours, MM minuts, SS seconds later
!       now - start now
!       pending - does not collect information

You can restart a SLA operation using:

R(config)# ip sla restart SLA-ID

Configure the responder, if needed

The responder should be configured on a router that responds to IP SLA requests

! TCP Connect or UDP Echo:
R(config)# ip sla responder {tcp-connect|udp-echo} IP-ADDR port PORT
! Frame-Relay:
R(config)# ip sla responder frame-relay all

A SLA responder and an initiator can be authenticated using a Key-chain:

R(config)# ip sla key-chain KEY-CHAIN

Monitoring SLA

You can monitor the status of the SLA operations using:

R# show ip sla statistics SLA-ID [details]
! or some other show ip sla commands
R# show ip sla {configuration...|history...| ...}

Proactive Monitoring

Proactive monitoring allows a router to take action when a SLA operation is below requirements. You can enable sending of trap messages using:

R(config)# ip sla logging traps

A reaction can be defined with the following command:

R(config)# ip sla reaction-configuration SLA-ID react EVENT ... 
! The reaction can be to send a trap, to generate a trigger, both or none

If a trap is generated then the SNMP server must be configured to send that kind of trap:

R(config)# snmp-server enable traps TRAP

If a trigger is generated, it can put into an active state other SLA operations:

R(config)# ip sla reaction-trigger SLA-ID TRIGGERED-SLA-ID
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Last updated 3 years ago

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