Licensing Requirements
For a complete explanation of Cisco NX-OS licensing recommendations and how to obtain and apply licenses, see the Cisco NX-OS Licensing Guide and the Cisco NX-OS Licensing Options Guide.
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This chapter provides an overview of Cisco NX-OS IP Service Level Agreements (SLAs).
For a complete explanation of Cisco NX-OS licensing recommendations and how to obtain and apply licenses, see the Cisco NX-OS Licensing Guide and the Cisco NX-OS Licensing Options Guide.
Starting with Cisco NX-OS release 7.0(3)I7(1), use the Nexus Switch Platform Support Matrix to know from which Cisco NX-OS releases various Cisco Nexus 9000 and 3000 switches support a selected feature.
Many companies conduct most of their business online and any loss of service can affect the profitability of the company. Internet service providers (ISPs) and even internal IT departments now offer a defined level of service--a service level agreement--to provide their customers with a degree of predictability.
The latest performance requirements for business-critical applications, voice over IP (VoIP) networks, audio and visual conferencing, Multiprotocol Label Switching (MPLS), and Virtual Private Networks (VPNs) are creating internal pressures on converged IP networks to become optimized for performance levels. Network administrators are increasingly required to support service level agreements that support application solutions. IP Service Level Agreements (SLAs) allow you to manage IP service levels for IP applications and services.
The Cisco NX-OS IP SLAs use active traffic monitoring--the generation of traffic in a continuous, reliable, and predictable manner--for measuring network performance. Cisco NX-OS IP SLAs send data across the network to measure performance between multiple network locations or across multiple network paths. It simulates network data and IP services and collects network performance information in real time. The information collected includes data about the response time, one-way latency, jitter (interpacket delay variance), packet loss, voice quality scoring, network resource availability, application performance, and server response time. Cisco NX-OS IP SLAs performs active monitoring by generating and analyzing traffic to measure performance either between Cisco NX-OS devices or from a Cisco NX-OS device to a remote IP device such as a network application server. Measurement statistics provided by the various Cisco NX-OS IP SLAs operations can be used for troubleshooting, problem analysis, and designing network topologies.
Note |
IPSLA do not support rollback. The rollback is related to IPSLA configuration via CLI. |
Cisco NX-OS IP SLAs provides the following improvements over a traditional service level agreement:
End-to-end measurements—The ability to measure performance from one end of the network to the other allows a broader reach and more accurate representation of the end-user experience.
Sophistication--Statistics such as delay, jitter, packet sequence, Layer 3 connectivity, and path and download time that are broken down into bidirectional and round-trip numbers provide more data than just the bandwidth of a Layer 2 link.
Ease of deployment--Leveraging the existing Cisco devices in a large network makes Cisco NX-OS IP SLAs easier and cheaper to implement than the physical probes often required with traditional service level agreements.
Application-aware monitoring--Cisco NX-OS IP SLAs can simulate and measure performance statistics generated by applications running over Layer 3 through Layer 7. Traditional service level agreements can only measure Layer 2 performance.
Pervasiveness--Cisco NX-OS IP SLAs support exists in Cisco networking devices that range from low-end to high-end switches. This wide range of deployment gives Cisco NX-OS IP SLAs more flexibility over traditional service level agreements.
The following figure shows how Cisco NX-OS IP SLAs have taken the traditional concept of Layer 2 service level agreements and applied a broader scope to support end-to-end performance measurement, including support of applications.
Using Cisco NX-OS IP SLAs, you can measure, provide, and verify service level agreements. You can also analyze and troubleshoot network performance for IP services and applications. Depending on the specific Cisco NX-OS IP SLAs operation, statistics of delay, packet loss, jitter, packet sequence, connectivity, path, server response time, and download time can be monitored within the Cisco device and stored in both CLI and SNMP MIBs. The packets have configurable IP and application layer options such as a source and destination IP address, User Datagram Protocol (UDP)/TCP port numbers, a type of service (ToS) byte (including Differentiated Services Code Point [DSCP] and IP prefix bits), a Virtual Private Network (VPN) routing/forwarding instance (VRF), and a URL web address.
Because Cisco NX-OS IP SLAs are accessible using SNMP, it also can be used by performance monitoring applications such as CiscoWorks Internetwork Performance Monitor (IPM) and other third-party, Cisco partner performance management products.
SNMP notifications based on the data gathered by a Cisco NX-OS IP SLAs operation allow the switch to receive alerts when performance drops below a specified level and when problems are corrected. Cisco NX-OS IP SLAs use the Cisco RTTMON MIB for interaction between external Network Management System (NMS) applications and the Cisco NX-OS IP SLAs operations running on the Cisco devices. For a complete description of the object variables referenced by the Cisco NX-OS IP SLAs feature, see the text of the CISCO-RTTMON-MIB.my file, available from the Cisco MIB website.
Using Cisco NX-OS IP SLAs, you can monitor the performance between any area in the network: core, distribution, and edge. Monitoring can be done anytime, anywhere, without deploying a physical probe.
Cisco NX-OS IP SLAs use generated traffic to measure network performance between two networking devices such as switches. The following figure shows how Cisco NX-OS IP SLAs start when the Cisco NX-OS IP SLAs device sends a generated packet to the destination device. After the destination device receives the packet, and depending on the type of Cisco NX-OS IP SLAs operation, the device responds with time-stamp information for the source to make the calculation on performance metrics. A Cisco NX-OS IP SLAs operation performs a network measurement from the source device to a destination in the network using a specific protocol such as UDP.
To implement a Cisco NX-OS IP SLAs network performance measurement, you must perform these tasks:
The various types of Cisco NX-OS IP SLAs operations include the following:
UDP jitter
UDP jitter for VoIP
UDP echo
Transmission Control Protocol (TCP) connect
Multioperation Scheduler
Proactive Threshold Monitoring
The responder is a component that is embedded in the destination Cisco routing device that allows the system to anticipate and respond to Cisco NX-OS IP SLAs request packets. The IP SLAs Responder provides accurate measurements without the need for dedicated probes and additional statistics that are not available via standard ICMP-based measurements. The Cisco NX-OS IP SLAs Control Protocol is used by the IP SLAs Responder to provide a mechanism through which the responder can be notified on which port it should listen and respond. Only a Cisco NX-OS device can be a source for a destination responder.
The IP SLAs Responder listens on a specific port for control protocol messages sent by a Cisco NX-OS IP SLAs operation. Upon receipt of the control message, the responder enables the specified UDP or TCP port for the specified duration. During this time, the responder accepts the requests and responds to them. The responder disables the port after it responds to the Cisco NX-OS IP SLAs packet or when the specified time expires.
Enabling the IP SLAs Responder on the destination device is not required for all IP SLAs operations. For example, if services that are already provided by the destination switch (such as Telnet or HTTP) are chosen, the IP SLAs Responder does not need to be enabled. For non-Cisco devices, the IP SLAs Responder cannot be configured and Cisco NX-OS IP SLAs can send operational packets only to services native to those devices.
After a Cisco NX-OS IP SLAs operation has been configured, you must schedule the operation to begin capturing statistics and collecting error information. When scheduling, an operation can start immediately or start at a certain month, day, and hour. There is a pending option to set the operation to start at a later time. The pending option is also an internal state of the operation visible through SNMP. The pending state is also used when an operation is a reaction (threshold) operation waiting to be triggered. You can schedule a single Cisco NX-OS IP SLAs operation or a group of operations at one time.
Multioperations scheduling allows you to schedule multiple Cisco NX-OS IP SLAs operations using a single command through the Cisco NX-OS CLI or the CISCO RTTMON-MIB. This feature allows you to control the amount of IP SLAs monitoring traffic by scheduling the operations to run at evenly distributed times. This distribution of IP SLAs operations allows you to minimize the CPU utilization and enhance the scalability of the network.
For more details about the IP SLAs multioperations scheduling functionality, see the IP SLAs Multioperation Scheduler section.
To support successful service level agreement monitoring or to proactively measure network performance, threshold functionality is essential. Consistent reliable measurements immediately identify issues and can save troubleshooting time. To roll out a service level agreement, you must have mechanisms that notify you immediately of any possible violations. Cisco NX-OS IP SLAs can send SNMP traps that are triggered by events such as the following:
Alternately, a Cisco NX-OS IP SLAs threshold violation can trigger another Cisco NX-OS IP SLAs operation for further analysis.
For more details on using thresholds with Cisco NX-OS IP SLAs operations, see the Proactive Threshold Monitoring for IP SLAs Operations section.
The Cisco NX-OS IP SLAs MPLS VPN Awareness feature allows you to monitor IP service levels within Multiprotocol Label Switching (MPLS) Virtual Private Networks (VPNs). Using IP SLAs within MPLS VPNs allows service providers to plan, provision, and manage IP VPN services according to the service level agreement for a customer. IP SLAs operations can be configured for a specific VPN by specifying a VPN routing and forwarding (VRF) name.
Cisco NX-OS IP SLAs maintain the following three types of history statistics:
IP SLAs have the following guidelines and limitations:
show commands with the internal keyword are not supported.
The Cisco Nexus 34180YC platform switch does not support IP SLA.
IP SLAs do not support the Cisco NX-OS rollback feature.
IPv6 for ICMP echo operation is supported for Cisco Nexus 9300 and 9500 Series switches.
The Cisco Nexus 3232C and 3264Q switches do not support policy-based routing (PBR).
One-way delay (latency) measurements do not support the microsecond unit of measurement. Other units of measurement, such as the millisecond, are supported.
In situations involving many simultaneous
interface state changes, such as a switch reboot, an IP SLA track might take
several minutes to come up. In this situation, check for a high number of glean
drops. Run the sh policy-map interface control-plane
command and look for continuous drops or violations in steady state of the
switch under match exception glean
. As a workaround, you can
increase the hardware ip glean throttle maximum to
10,000 from its default of 1000.
The restrictions for Cisco NX-OS IP SLAs include the following:
Note |
IPv6 is available from Cisco NX-OS Release 7.0(3)I6(1). |
The maximum number of IP SLA configurable operations supported by Cisco NX-OS is 500.
The current validated scale numbers for scheduling operations are as follows:
The number of UDP echo operations is 300 operations with default frequency
The number of UDP jitter operations is 200 operations with default frequency
The number of ICMP IPv4 or IPv6 echo operations is 500 operations with default frequency
The number of TCP connect operations is 100 operations with default frequency
We do not recommend scheduling more than 10 operations per second at the same start time, as this may affect the performance. We recommend using the group scheduling configuration.
Note |
Setting the frequency to less than 60 seconds will increase the number of packets that will be sent. But this could negatively impact the performance of IP SLA operation when the scheduled operations have the same start time. IP SLA is not HA capable. Consider the following guidelines before configuring the frequency, timeout, and threshold commands: For the UDP and ICMP jitter operation, the following guidelines are recommended:
For all other IP SLAs operations:
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