Table Of Contents
NetFlow Reliable Export With SCTP
Prerequisites for NetFlow Reliable Export With SCTP
Restrictions for NetFlow Reliable Export With SCTP
Information About NetFlow Reliable Export With SCTP
NetFlow Cisco IOS Packaging Information
Elements of a NetFlow Network Flow
NetFlow Reliable Export With SCTP
How to Configure NetFlow Reliable Export with SCTP
Configuring NetFlow SCTP Export for One Export Destination
Configuring NetFlow SCTP Export for One Export Destination with Partial Reliability
Configuring NetFlow SCTP Export for One Export Destination with No Reliability
Configuring NetFlow SCTP Export for One Export Destination and One Backup Export Destination
Configuring NetFlow SCTP Export for Two Export Destinations and Two Backup Export Destinations
Working with Multiple SCTP Export Destinations
Configuring NetFlow SCTP Export for One Fully Reliable and One Partially Reliable Export Destination
Configuring NetFlow SCTP Export for the NetFlow Source-Prefix Aggregation Cache
Working With NetFlow Aggregation caches and SCTP Export Destinations
SCTP Export for NetFlow Aggregation Caches
Verifying NetFlow Reliable Export With SCTP
Configuration Examples for NetFlow Reliable Export With SCTP
Feature Information for NetFlow Reliable Transport Using SCTP
NetFlow Reliable Export With SCTP
NetFlow is a Cisco IOS application that provides statistics on packets flowing through the router. It is emerging as a primary network accounting and security technology. This document describes the NetFlow application and the new NetFlow Reliable Export With Stream Control Transmission Protocol (SCTP) feature.
The NetFlow Reliable Export with SCTP feature adds the ability for NetFlow to use the reliable and congestion-aware SCTP when exporting statistics to a network management system that supports the NetFlow data export formats, such as a system running CNS NetFlow Collection Engine (NFC).
Module History
This module was first published on October 31st, 2005, and last updated on April 30th, 2007.
Finding Feature Information in This Module
Your Cisco IOS software release may not support all features. To find information about feature support and configuration, use the "Feature Information for NetFlow Reliable Transport Using SCTP" section.
Contents
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Prerequisites for NetFlow Reliable Export With SCTP
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Prerequisites for NetFlow Reliable Export With SCTP
NetFlow and Cisco Express Forwarding (CEF), distributed CEF (dCEF), or fast switching must be configured on your system.
Restrictions for NetFlow Reliable Export With SCTP
The NetFlow SCTP collector must support SCTP.
Information About NetFlow Reliable Export With SCTP
To configure the NetFlow feature, you should understand the following concepts:
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NetFlow Data Capture
NetFlow identifies packet flows for both ingress and egress IP packets. It does not involve any connection-setup protocol. NetFlow is completely transparent to the existing network, including end stations and application software and network devices like LAN switches. Also, NetFlow capture and export are performed independently on each internetworking device; NetFlow need not be operational on each router in the network.
NetFlow is supported on IP and IP encapsulated traffic over most interface types and Layer 2 encapsulations.
You can display and clear NetFlow statistics. NetFlow statistics consist of IP packet size distribution, IP flow switching cache information, and flow information.
NetFlow Benefits
NetFlow captures a rich set of traffic statistics. These traffic statistics include user, protocol, port, and type of service (ToS) information that can be used for a wide variety of purposes such as network application and user monitoring (user monitoring is performed by monitoring the IP addresses of the devices that users are running applications on), network analysis and planning, denial of service (DoS) and security analysis, accounting and billing, traffic engineering, and data mining.
NetFlow can capture a rich set of traffic statistics. These traffic statistics include user, protocol, port, and type of service (ToS) information that can be used for a wide variety of purposes, including network traffic analysis and capacity planning, security, enterprise accounting and departmental chargebacks, Internet Service Provider (ISP) billing, data warehousing, and data mining for marketing purposes.
Network Application and User Monitoring
NetFlow data enables you to view detailed, time and application based usage of a network. This information allows you to plan and allocate network and application resources, and provides for extensive near real-time network monitoring capabilities. It can be used to display traffic patterns and application-based views. NetFlow provides proactive problem detection and efficient troubleshooting, and it facilitates rapid problem resolution. You can use NetFlow information to efficiently allocate network resources and to detect and resolve potential security and policy violations.
Network Analysis and Planning
You can use NetFlow to capture data for extended periods of time, which enables you to track network utilization and anticipate network growth and plan upgrades. NetFlow service data can be used to optimize network planning, which includes peering, backbone upgrades, and routing policy planning. It also enables you to minimize the total cost of network operations while maximizing network performance, capacity, and reliability. NetFlow detects unwanted WAN traffic, validates bandwidth and quality of service (QoS) behavior, and enables the analysis of new network applications. NetFlow offers valuable information that you can use to reduce the cost of operating the network.
Denial of Service and Security Analysis
You can use NetFlow data to identify and classify in real time denial of service (DoS) attacks, viruses, and worms. Changes in network behavior indicate anomalies that are clearly reflected in NetFlow data. The data is also a valuable forensic tool that you can use to understand and replay the history of security incidents.
Accounting and Billing
NetFlow data provides fine-grained metering for highly flexible and detailed resource utilization accounting. For example, flow data includes details such as IP addresses, packet and byte counts, timestamps, and information about type of service (ToS) and application ports. Service providers might utilize the information for billing based on time-of-day, bandwidth usage, application usage, or QoS. Enterprise customers might utilize the information for departmental charge-back or cost allocation for resource utilization.
Traffic Engineering
NetFlow provides autonomous system (AS) traffic engineering details. You can use NetFlow-captured traffic data to understand source-to-destination traffic trends. This data can be used for load-balancing traffic across alternate paths or for forwarding traffic along a preferred route. NetFlow can measure the amount of traffic crossing peering or transit points. You can use the data to help you decide if a peering arrangement with other service providers is fair and equitable.
NetFlow Data Storage and Data Mining
NetFlow data can be stored for later retrieval and analysis in support of marketing and customer service programs. For example, the data can be mined to find out which applications and services are being used by internal and external users and target the users for improved service and advertising. In addition, NetFlow data gives market researchers access to the who, what, where, and how long information relevant to enterprises and service providers.
NetFlow Cisco IOS Packaging Information
Cisco 7200/7500/7400/MGX/AS5850
Although NetFlow functionality is included in all software images for these platforms, you must purchase a separate NetFlow feature license. NetFlow licenses are sold on a per-node basis.
Other Routers
Use Cisco Feature Navigator to find information about platform support and Cisco IOS software image support. Access Cisco Feature Navigator at http://www.cisco.com/go/fn. You must have an account on Cisco.com. If you do not have an account or have forgotten your username or password, click Cancel at the login dialog box and follow the instructions that appear.
Elements of a NetFlow Network Flow
A NetFlow network flow is defined as a unidirectional stream of packets between a given source and destination. The source and destination are each defined by a network-layer IP address and transport-layer source and destination port numbers. Specifically, a flow is defined by the combination of the following seven key fields:
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These seven key fields define a unique flow. If a packet has one key field different from another packet, it is considered to belong to another flow. A flow might also contain other accounting fields (such as the AS number in the NetFlow export Version 5 flow format). The fields that a given flow contains depend on the export record version that you configure. Flows are stored in the NetFlow cache.
NetFlow Main Cache Operation
The key components of NetFlow are the NetFlow cache that stores IP flow information and the NetFlow export or transport mechanism that sends NetFlow data to a network management collector, such as the NetFlow Collection Engine. NetFlow operates by creating a NetFlow cache entry (a flow record) for each active flow. NetFlow maintains a flow record within the cache for each active flow. Each flow record in the NetFlow cache contains values for the fields that are being monitored that can later be exported to a collection device, such as the NetFlow Collection Engine.
NetFlow Data Capture
NetFlow captures data from ingress (incoming) and egress (outgoing) packets. NetFlow gathers data for the following ingress IP packets:
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NetFlow captures data for all egress (outgoing) packets through use of the following features:
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NetFlow Export Formats
NetFlow exports data in User Datagram Protocol (UDP) datagrams in one of five formats: Version 9, Version 8, Version 7, Version 5, or Version 1. Version 9 export format, the latest version, is the most flexible and extensible format. Version 1 was the initial NetFlow export format; Version 8 only supports export from aggregation caches, and Version 7 is supported only on certain platforms. (Versions 2 through 4 and Version 6 were either not released or are not supported.)
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On a Catalyst 6000 series switch with an MSFC, you can export using either the Version 7 or the Version 8 format.•
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NetFlow Reliable Export With SCTP
Prior to the introduction of the NetFlow Reliable Export With SCTP feature in Cisco IOS Release 12.4(4)T exporting NetFlow information was unreliable because NetFlow encapsulated the exported traffic in UDP packets for transmission to the NFC. Using an unreliable transport protocol such as UDP for sending information across a network has two major disadvantages:
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The NetFlow Reliable Export With SCTP feature uses the SCTP to overcome the two major disadvantages of using UDP as the transport layer protocol:
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SCTP is a reliable message-oriented transport layer protocol, which allows data to be transmitted between two end-points in a reliable, partially reliable, or unreliable manner. An SCTP session consists of an association between two end-points, which may contain one or more logical channels called streams. SCTP's stream based transmission model facilitates the export of a mix of different data types, such as NetFlow templates and NetFlow data, over the same connection. The maximum number of inbound and outbound streams supported by an end-point is negotiated during the SCTP association initialization process.
When you configure the NetFlow Version 9 Export and NetFlow Reliable Export features, NetFlow creates a minimum of two streams—stream 0 for templates and options, and one or more streams for carrying data, as required. The following commands are not applicable when you configure the NetFlow Version 9 Export and NetFlow Reliable Export features together because NetFlow Reliable Export export connections use SCTP reliable stream 0 for NetFlow Version 9 Export, and these commands apply only to NetFlow export connections that use UDP:
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When more than one cache (main cache and one or more aggregation caches) is exporting data, each cache creates its own streams with their own configured reliability levels. For example, you can configure the main cache to use SCTP in full reliability mode and the NetFlow prefix aggregation cache to use partial reliability mode to send messages to the same collector using the same SCTP port.
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Security
SCTP contains several built-in features to counter many common security threats such as the syn-flood type of DoS attack.
SCTP uses the following techniques to resist flooding attacks:
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Reliability Options
SCTP allows data to be transmitted between two end-points (a router running NetFlow SCTP export and a collector that is receiving and acknowledging the SCTP messages) in a reliable manner. In addition to the default behavior of full reliability, SCTP can be configured for partially-reliable or unreliable transmission for applications that do not require full reliability.
When SCTP is operating in full reliability mode, it uses a selective-acknowledgment scheme to guarantee the ordered delivery of messages. The SCTP protocol stack buffers messages until their receipt has been acknowledged by the receiving end-point. (collector). SCTP has a congestion control mechanism that can be used to limit how much memory is consumed by SCTP for buffering packets.
If a stream is specified as unreliable, then the packet is simply sent once and not buffered on the exporter. If the packet is lost enroute to the receiver, the exporter cannot retransmit it.
When a stream is specified as partially-reliable a limit is placed on how much memory should be dedicated to storing un-acknowledged packets. The limit on how much memory should be dedicated to storing unacknowledged packets is configurable by means of the buffer-limit limit command. If the limit on how much memory should be dedicated to storing unacknowledged packets is exceeded and the router attempts to buffer another packet, the oldest unacknowledged packet is discarded. When SCTP discards the oldest unacknowledged packet, a message called a forward-tsn (transmit sequence number) is sent to the collector to indicate that this packet will not be received. This prevents NetFlow from consuming all the free memory on a router when a situation has arisen which requires many packets to be buffered, for example when SCTP is experiencing long response times from an SCTP peer connection.
When SCTP is operating in partially reliable mode, the limit on how much memory should be dedicated to storing un-acknowledged packets should initially be set as high as possible. The limit can be reduced if other processes on the router begin to run out of memory. Deciding on the best value for the limit involves a trade-off between avoiding starving other processes of the memory that they require to operate and dropping SCTP messages that have not been acknowledged by the collector.
Unreliable SCTP can be used when the collector that you are using doesn't support UDP as a transport protocol for receiving NetFlow export datagrams and you do not want to allocate the resources on your router required to provide reliable, or partially reliable, SCTP connections.
Congestion Avoidance
SCTP uses congestion avoidance algorithms that are similar to those for TCP. An SCTP end-point advertises the size of its receive window (rWnd) to ensure that a sender cannot flood it with more messages than it can store in its input queues.
Each SCTP sender also maintains a congestion window (cWnd), which determines the number of unacknowledged packets that can be outstanding at a given time. SCTP uses the same 'slow-start' algorithm as TCP, in which it starts with a small cWnd and gradually increases it until it reaches its optimum size.
Whenever a packet isn't acknowledged within the given timeout period, the value of cWnd is halved. This method of congestion avoidance is known as added increase / multiplicative decrease and has been shown to be the most effective congestion avoidance algorithm in most circumstances.
SCTP also employs the fast-retransmit algorithm whereby it retransmits a message if it receives acknowledgments from four messages which were sent after the message in question. This is preferable to waiting for the timeout period to elapse and triggering a retransmit of the message.
Options for Backup Collectors
You can configure a backup collector for SCTP. It is used as a message destination in the event that the primary collector becomes unavailable. When connectivity with the primary collector has been lost, and a backup collector is configured, SCTP begins using the backup collector. The default period of time that SCTP waits until it starts using the backup collector is 25 milliseconds (msec). You can configure a different value for interval with the fail-over time command.
The router sends periodic SCTP heartbeat messages to the SCTP collectors that you have configured. The router uses the SCTP heartbeat message acknowledgements from the collectors to monitor the status of each collector. This allows an application, such as NetFlow, to be quickly informed when connectivity to a collector is lost.
You can configure SCTP backup in fail-over or redundant mode. When the router is configured with SCTP backup in fail-over mode, the router waits to activate the association with the backup collector until the router has not received acknowledgements for the SCTP heartbeat messages from the primary collector for the time specified by the fail-over time command (or the default of 25 msec if this parameter has not been modified).
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When the router is configured with SCTP backup in redundant mode, the router activates the association with the backup collector immediately, and if NetFlow v9 export is configured the router sends the (options) templates in advance. The router will not start sending other SCTP messages to a backup collector in redundant mode until the router has not received acknowledgments for the SCTP heartbeat messages from the primary collector for the time specified by the fail-over time command. Fail-over mode is the preferred method when the backup collector is on the end of an expensive lower-bandwidth link such as ISDN.
During the time that SCTP is using the backup collector, SCTP continues to try to restore the association with the primary collector. This goes on until connectivity is restored or the primary SCTP collector is removed from the configuration.
When connectivity to the primary collector is available again, the router waits for a period of time before reverting to using it as the primary destination. You configure the value of the period of time that SCTP waits until reverting to the primary collector with the restore-time time command. The default period of time that SCTP waits until it reverts to the primary collector is 25 sec.
Under either fail-over mode any records which have been queued between losing connectivity with the primary destination and establishing the association with the backup collector might be lost. A count is maintained of how many records were lost. It can be viewed with the show ip flow export sctp verbose command.
To avoid a flapping SCTP association with a collector (the SCTP association goes up and down in quick succession), the time period configured with the restore-time time command should be greater than the period of a typical connectivity problem. For example, your router is configured to use IP fast convergence for its routing table and you have a LAN interface that is going up and down repeatedly (flapping). That causes the IP route to the primary collector to be added and removed from the routing table repeatedly (route flapping) every 2000 msec (2 sec). you need to configure the restore time for a value greater than 2000 msecs.
The backup connection uses stream 0 for sending templates, options templates, and option data record. The data stream(s) inherit the reliability settings of the primary connection.
Export to Multiple Collectors
You can configure your networking device to export NetFlow data to a maximum of two export destinations (collectors) per cache (main and aggregation caches), using any combination of UDP and SCTP. A destination is identified by a unique combination of hostname or IP address and port number or port type. Table 1 shows examples of permitted multiple NetFlow export destinations for each cache.
The most common use of the multiple-destination feature is to send the NetFlow cache entries to two different destinations for redundancy. Therefore, in most cases the second destination IP address is not the same as the first IP address. The port numbers can be the same when you are configuring two unique destination IP addresses. If you want to configure both instances of the command to use the same destination IP address, you must use unique port numbers. You receive a warning message when you configure the two instances of the command with the same IP address. The warning message is, "%Warning: Second destination address is the same as previous address <ip-address>".
SCTP Support For Export Formats
SCTP based reliable transport is available for all NetFlow export formats: Versions 1, 5, 8 and 9.
How to Configure NetFlow Reliable Export with SCTP
You can configure two primary SCTP export destinations (collectors) and two backup SCTP export destinations for each NetFlow cache (main cache and aggregation caches). The backup SCTP export destinations inherit the reliability characteristics of the primary SCTP export destination. For example, if you configure partial reliability with a buffer limit of 2000 packets for the primary SCTP export destination, the backup SCTP destination also uses partial reliability and a buffer limit of 2000 packets.
You can use several permutations when you configure NetFlow Reliable Export With SCTP. The most basic configuration requires only one SCTP export destination. The other tasks below explain how to configure some of the more common permutations of NetFlow Reliable Export With SCTP.
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Configuring NetFlow SCTP Export for One Export Destination
This is the most basic NetFlow SCTP export configuration. This NetFlow SCTP export configuration uses full reliability.
Prerequisites
You must have NetFlow enabled on at least one interface in your router before you can export NetFlow data.
You must have a NetFlow collector in your network that supports NetFlow SCTP export.
SUMMARY STEPS
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DETAILED STEPS
Step 1
Enters privileged EXEC mode.
Router> enableStep 2
Enters global configuration mode.
Router# configure terminalStep 3
Configures an export destination using SCTP on port 100.
Router (config)# ip flow-export destination 172.16.12.200 100 sctpStep 4
Returns to privileged EXEC mode.
Router(config-flow-export-sctp)# endStep 5
Displays the status and statistics for NetFlow SCTP export. Reliability is set to the default of full.
Router# show ip flow export sctp verboseIPv4 main cache exporting to 172.16.12.200, port 100, fullstatus: connectedbackup mode: redundant4 flows exported in 4 sctp messages.0 packets dropped due to lack of SCTP resourcesfail-over time: 25 milli-secondsrestore time: 25 seconds
Configuring NetFlow SCTP Export for One Export Destination with Partial Reliability
This NetFlow SCTP export configuration uses partial reliability.
Prerequisites
You must have NetFlow enabled on at least one interface in your router before you can export NetFlow data.
You must have a NetFlow collector in your network that supports NetFlow SCTP export.
SUMMARY STEPS
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DETAILED STEPS
Step 1
Enters privileged EXEC mode.
Router> enableStep 2
Enters global configuration mode.
Router# configure terminalStep 3
Configures an export destination using SCTP on port 100.
Router (config)# ip flow-export destination 172.16.12.200 100 sctpStep 4
Configures partial reliability for this SCTP export destination and sets the packet buffer limit to 3000.
Router(config-flow-export-sctp)# reliability partial buffer-limit 3000Step 5
Returns to privileged EXEC mode.
Router(config-flow-export-sctp)# endStep 6
Displays the status and statistics for NetFlow SCTP export. Reliability is now set to partial.
Router# show ip flow export sctp verbosePv4 main cache exporting to 172.16.12.200, port 100, partialstatus: connectedbackup mode: redundant11 flows exported in 11 sctp messages.0 packets dropped due to lack of SCTP resourcesfail-over time: 25 milli-secondsrestore time: 25 seconds
Configuring NetFlow SCTP Export for One Export Destination with No Reliability
Reliability is disabled in this NetFlow SCTP export configuration.
Prerequisites
You must have NetFlow enabled on at least one interface in your router before you can export NetFlow data.
You must have a NetFlow collector in your network that supports NetFlow SCTP export.
SUMMARY STEPS
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DETAILED STEPS
Step 1
Enters privileged EXEC mode.
Router> enableStep 2
Enters global configuration mode.
Router# configure terminalStep 3
Configures an export destination using SCTP on port 100.
Router (config)# ip flow-export destination 172.16.12.200 100 sctpStep 4
Configures partial reliability for this SCTP export destination and sets the packet buffer limit to 3000.
Router(config-flow-export-sctp)# reliability noneStep 5
Returns to privileged EXEC mode.
Router(config-flow-export-sctp)# endStep 6
Displays the status and statistics for NetFlow SCTP export. Reliability is now set to none.
Router# show ip flow export sctp verbosePv4 main cache exporting to 172.16.12.200, port 100, nonestatus: connectedbackup mode: redundant15 flows exported in 15 sctp messages.0 packets dropped due to lack of SCTP resourcesfail-over time: 25 milli-secondsrestore time: 25 seconds
Configuring NetFlow SCTP Export for One Export Destination and One Backup Export Destination
This NetFlow SCTP export configuration uses full reliability, a backup SCTP export destination, and redundant mode backup.
Prerequisites
You must have NetFlow enabled on at least one interface in your router before you can export NetFlow data.
You must have a NetFlow collector in your network that supports NetFlow SCTP export.
SUMMARY STEPS
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DETAILED STEPS
Step 1
Enters privileged EXEC mode.
Router> enableStep 2
Enters global configuration mode.
Router# configure terminalStep 3
Configures an export destination using SCTP on port 100.
Router (config)# ip flow-export destination 172.16.12.200 100 sctpStep 4
Configures an SCTP backup destination using SCTP on port 200.
Router(config-flow-export-sctp)# backup destination 192.168.247.198 200Step 5
Returns to privileged EXEC mode.
Router(config-flow-export-sctp)# endStep 6
Displays the status and statistics for NetFlow SCTP export. Backup mode is redundant. The association with the SCTP backup export destination is active (connected). The SCTP backup export destination is not being used because the primary export destination is still active (connected).
Router# show ip flow export sctp verboseIPv4 main cache exporting to 172.16.12.200, port 100, fullstatus: connectedbackup mode: redundant35 flows exported in 35 sctp messages.0 packets dropped due to lack of SCTP resourcesfail-over time: 25 milli-secondsrestore time: 25 secondsbackup: 192.168.247.198, port 200status: connectedfail-overs: 00 flows exported in 0 sctp messages.0 packets dropped due to lack of SCTP resources
Configuring NetFlow SCTP Export for One Export Destination and One Backup Export Destination With Fail-Over Mode Backup
This NetFlow SCTP export configuration uses full reliability, a backup SCTP export destination, and fail-over mode backup.
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Prerequisites
You must have NetFlow enabled on at least one interface in your router before you can export NetFlow data.
You must have a NetFlow collector in your network that supports NetFlow SCTP export.
SUMMARY STEPS
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DETAILED STEPS
Step 1
Enters privileged EXEC mode.
Router> enableStep 2
Enters global configuration mode.
Router# configure terminalStep 3
Configures an export destination using SCTP on port 100.
Router (config)# ip flow-export destination 172.16.12.200 100 sctpStep 4
Configures an SCTP backup destination using SCTP on port 200.
Router(config-flow-export-sctp)# backup destination 192.168.247.198 200Step 5
Configures the router to fail-over mode for the backup export destination.
Router(config-flow-export-sctp)# backup mode fail-over#Step 6
The length of time that the router will wait until failing over to the backup SCTP export destination has been increased to 3500 msec.
Router(config-flow-export-sctp)# backup fail-over 3500Step 7
The length of time that the router will wait until reverting to the primary SCTP export destination has been increased to 1500 msecs.
Router (config)# backup restore-time 1500Step 8
Returns to privileged EXEC mode.
Router(config-flow-export-sctp)# endStep 9
Displays the status and statistics for NetFlow SCTP export. Backup mode is fail-over. The association with the SCTP backup export destination is not active (not connected) because NetFlow SCTP export waits to activate the association with the backup destination until the primary export destination is no longer available.
Router# show ip flow export sctp verboseIPv4 main cache exporting to 172.16.12.200, port 100, fullstatus: connectedbackup mode: fail-over114 flows exported in 93 sctp messages.0 packets dropped due to lack of SCTP resourcesfail-over time: 3500 milli-secondsrestore time: 1500 secondsbackup: 192.168.247.198, port 200status: not connectedfail-overs: 00 flows exported in 0 sctp messages.0 packets dropped due to lack of SCTP resources
Configuring NetFlow SCTP Export for Two Export Destinations and Two Backup Export Destinations
This configuration is the most basic SCTP export configuration that uses multiple export destinations.
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Working with Multiple SCTP Export Destinations
Each SCTP export destination has its own area in the configuration file for the options that you can configure for it such as fail-over mode, fail-over timers and reliability. Therefore you must make certain that the last SCTP export destination that you entered in the router's configuration is the SCTP export destination that you want to modify.
For example, if you enter these commands in this order:
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The backup destination 192.168.100.2 200 is assigned to the ip flow-export destination 172.16.45.57 100 sctp command.
Tip
Prerequisites
You must have NetFlow enabled on at least one interface in your router before you can export NetFlow data.
You must have a NetFlow collector in your network that supports NetFlow SCTP export.
SUMMARY STEPS
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DETAILED STEPS
Step 1
Enters privileged EXEC mode.
Router> enableStep 2
Enters global configuration mode.
Router# configure terminalStep 3
Configures an export destination using SCTP on port 100.
Router (config)# ip flow-export destination 172.16.12.200 100 sctpStep 4
Configures an SCTP backup destination using SCTP on port 200.
Router(config-flow-export-sctp)# backup destination 192.168.247.198 200Step 5
Configures a second export destination using SCTP on port 100.
Router (config)# ip flow-export destination 172.16.45.57 100 sctpStep 6
Configures a second SCTP backup destination using SCTP on port 200.
Router(config-flow-export-sctp)# backup destination 192.168.100.2 200Step 7
Returns to privileged EXEC mode.
Router(config-flow-export-sctp)# endStep 8
Displays the status and statistics for the two primary and backup NetFlow SCTP export destinations. Reliability is set to the default of full.
Router# show ip flow export sctp verboseIPv4 main cache exporting to 172.16.12.200, port 100, fullstatus: connectedbackup mode: redundant219 flows exported in 176 sctp messages.0 packets dropped due to lack of SCTP resourcesfail-over time: 3500 milli-secondsrestore time: 10 secondsbackup: 192.168.247.198, port 200status: connectedfail-overs: 00 flows exported in 0 sctp messages.0 packets dropped due to lack of SCTP resourcesIPv4 main cache exporting to 172.16.45.57, port 100, fullstatus: connectedbackup mode: redundant66 flows exported in 47 sctp messages.0 packets dropped due to lack of SCTP resourcesfail-over time: 25 milli-secondsrestore time: 25 secondsbackup: 192.168.100.2, port 200status: connectedfail-overs: 10 flows exported in 0 sctp messages.0 packets dropped due to lack of SCTP resources
Configuring NetFlow SCTP Export for One Fully Reliable and One Partially Reliable Export Destination
This SCTP export configuration uses two SCTP export destinations. One of the export destinations uses full reliability and the other export destination uses partial reliability.
Prerequisites
You must have NetFlow enabled on at least one interface in your router before you can export NetFlow data.
You must have a NetFlow collector in your network that supports NetFlow SCTP export.
SUMMARY STEPS
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3.
4.
5.
6.
7.
DETAILED STEPS
Step 1
Enters privileged EXEC mode.
Router> enableStep 2
Enters global configuration mode.
Router# configure terminalStep 3
Configures an export destination using SCTP on port 100.
Router (config)# ip flow-export destination 172.16.12.200 100 sctpStep 4
Configures a second export destination using SCTP on port 100.
Router (config)# ip flow-export destination 172.16.45.57 100 sctpStep 5
Configures partial reliability for this SCTP export destination and sets the packet buffer limit to 3000.
Router(config-flow-export-sctp)# reliability partial buffer-limit 3000Step 6
Returns to privileged EXEC mode.
Router(config-flow-export-sctp)# endStep 7
Displays the status and statistics for NetFlow export with SCTP. Reliability is set to full for SCTP export destination 172.16.12.200 and to partial SCTP export destination 172.16.45.57.
Router# show ip flow export sctp verboseIPv4 main cache exporting to 172.16.12.200, port 100, fullstatus: connectedbackup mode: redundant229 flows exported in 186 sctp messages.0 packets dropped due to lack of SCTP resourcesfail-over time: 3500 milli-secondsrestore time: 10 secondsbackup: 192.168.247.198, port 200status: connectedfail-overs: 00 flows exported in 0 sctp messages.0 packets dropped due to lack of SCTP resourcesIPv4 main cache exporting to 172.16.45.57, port 100, partialstatus: connectedbackup mode: redundant76 flows exported in 57 sctp messages.0 packets dropped due to lack of SCTP resourcesfail-over time: 25 milli-secondsrestore time: 25 secondsbackup: 192.168.100.2, port 200status: connectedfail-overs: 10 flows exported in 0 sctp messages.0 packets dropped due to lack of SCTP resources
Configuring NetFlow SCTP Export for the NetFlow Source-Prefix Aggregation Cache
This SCTP export example shows how to configure NetFlow SCTP export for the NetFlow source prefix aggregation cache.
Note
Working With NetFlow Aggregation caches and SCTP Export Destinations
When you enter NetFlow aggregation cache configuration mode in the router the current router prompt changes to reflect this mode.
For example, if the current router prompt is, Router(config)# and you enter the ip flow-aggregation cache prefix command, the router prompt is changed to the NetFlow aggregation cache configuration prompt of Router(config-flow-cache)#.
You need to pay close attention when you are configuring NetFlow SCTP export options for NetFlow aggregation caches because the NetFlow aggregation cache configuration prompt is changed to the NetFlow SCTP export prompt when you enter a NetFlow SCTP export command in NetFlow aggregation cache configuration mode, even though you are still working in NetFlow aggregation cache configuration mode.
For example, if your current prompt is the NetFlow aggregation cache configuration prompt, Router(config-flow-cache)#, and you enter the export destination 172.16.12.200 100 sctp command, the router prompt will change to the NetFlow SCTP export configuration mode prompt, Router(config-flow-export-sctp)#. The NetFlow SCTP export commands that you configure are assigned to the NetFlow aggregation cache that you are modify with NetFlow SCTP export options.
Tip
Prerequisites
You must have NetFlow enabled on at least one interface in your router before you can export NetFlow data.
You must have a NetFlow collector in your network that supports NetFlow SCTP export.
SCTP Export for NetFlow Aggregation Caches
All of the NetFlow SCTP options that are available for the main NetFlow cache are also available in NetFlow Aggregation cache mode.
SUMMARY STEPS
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DETAILED STEPS
Step 1
Enters privileged EXEC mode.
Router> enableStep 2
Enters global configuration mode.
Router# configure terminalStep 3
Enters NetFlow aggregation cache mode for the cache type.
Router (config)# ip flow-aggregation cache source-prefixStep 4
Activates the NetFlow aggregation cache.
Router(config-flow-cache)# enableStep 5
Configures an export destination using SCTP for the aggregation cache.
Router (config-flow-cache)# export destination 172.16.12.200 100 sctpStep 6
Returns to privileged EXEC mode.
Router(config-flow-export-sctp)# endStep 7
Displays the status and statistics for NetFlow export with SCTP.
Router# show ip flow export sctp verbosesource-prefix cache exporting to 172.16.12.200, port 100, fullstatus: connectedbackup mode: redundant0 flows exported in 0 sctp messages.0 packets dropped due to lack of SCTP resourcesfail-over time: 25 milli-secondsrestore time: 25 seconds
Verifying NetFlow Reliable Export With SCTP
The show ip flow export sctp [verbose] command provides information on the status and statistics of the options that you have configured for the NetFlow Reliable Export With SCTP feature.
Cisco IOS also provides commands for monitoring and troubleshooting the status and statistics for all of the SCTP features (including NetFlow Reliable Export With SCTP) that you have configured on the networking device. Refer to the Stream Control Transmission Protocol (SCTP), Release 2 configuration guide /en/US/docs/ios/12_2t/12_2t8/feature/guide/ft_sctp2.html for more information on interpreting the output from these commands, and the other commands that are available for monitoring and troubleshooting SCTP.
SUMMARY STEPS
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DETAILED STEPS
Step 1
Shows the list of SCTP associations.
Router# show ip sctp association list** SCTP Association List **AssocID: 0, Instance ID: 0Current state: ESTABLISHEDLocal port: 51882, Addrs: 172.16.6.2Remote port: 100, Addrs: 172.16.12.200AssocID: 1, Instance ID: 1Current state: ESTABLISHEDLocal port: 59004, Addrs: 172.16.6.2Remote port: 200, Addrs: 192.168.247.198Step 2
Displays the current parameters for the association ID.
Router# show ip sctp association parameters 0** SCTP Association Parameters **AssocID: 0 Context: 1 InstanceID: 0Assoc state: ESTABLISHED Uptime: 00:19:44.504Local port: 51882Peers Adaption layer indication is NOT setLocal addresses: 172.16.6.2Remote port: 100Primary dest addr: 172.16.12.200Effective primary dest addr: 172.16.12.200Destination addresses:172.16.12.200: State: ACTIVE(CONFIRMED)Heartbeats: Enabled Timeout: 500 msRTO/RTT/SRTT: 5000/0/3 ms TOS: 0 MTU: 1500cwnd: 3000 ssthresh: 9000 outstand: 0Num retrans: 0 Max retrans: 2 Num times failed: 0Local vertag: DAF7029F Remote vertag: A3923131Num inbound streams: 20 outbound streams: 20Max assoc retrans: 2 Max init retrans: 2CumSack timeout: 200 ms Bundle timeout: 100 msMin RTO: 5000 ms Max RTO: 5000 msMax Init RTO (T1): 1000 msLocalRwnd: 9000 Low: 9000 RemoteRwnd: 9000 Low: 8936Congest levels: 0 current level: 0 high mark: 1Step 3
Shows any SCTP errors that have occurred.
Router# show ip sctp errors** SCTP Error Statistics **No SCTP errors logged.Step 4
Shows the details and status for the SCTP instances.
Router# show ip sctp instances** SCTP Instances **Instance ID: 0 Local port: 51882 State: availableLocal addrs: 172.16.6.2Default streams inbound: 20 outbound: 20Adaption layer indication is not setCurrent associations: (max allowed: 6)AssocID: 0 State: ESTABLISHED Remote port: 100Dest addrs: 172.16.12.200Instance ID: 1 Local port: 59004 State: availableLocal addrs: 172.16.6.2Default streams inbound: 20 outbound: 20Adaption layer indication is not setCurrent associations: (max allowed: 6)AssocID: 1 State: ESTABLISHED Remote port: 200Dest addrs: 192.168.247.198Step 5
Shows the SCTP overall statistics:
Router# show ip sctp statistics** SCTP Overall Statistics **Control ChunksSent: 615 Rcvd: 699Data Chunks SentTotal: 57 Retransmitted: 0Ordered: 57 Unordered: 0Total Bytes: 3648Data Chunks RcvdTotal: 0 Discarded: 0Ordered: 0 Unordered: 0Total Bytes: 0Out of Seq TSN: 0SCTP DgramsSent: 671 Rcvd: 699ULP DgramsSent: 57 Ready: 0 Rcvd: 0Additional StatsAssocs Currently Estab: 2Active Estab: 2 Passive Estab: 0Aborts: 0 Shutdowns: 0T1 Expired: 1 T2 Expired: 0
Configuration Examples for NetFlow Reliable Export With SCTP
The following example includes these NetFlow accounting and NetFlow SCTP export features:
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Router# show running-config...interface Ethernet0/0.1ip address 172.16.6.2 255.255.255.0ip flow ingress!!interface Ethernet1/0.1ip address 172.16.7.1 255.255.255.0ip flow egress!ip flow-export destination 172.16.45.57 100 sctpreliability partial buffer-limit 3000backup destination 192.168.100.2 200!ip flow-export destination 172.16.12.200 100 sctpreliability partial buffer-limit 3000backup destination 192.168.247.198 200!ip flow-aggregation cache protocol-portexport destination 172.16.12.200 100 sctpreliability partial buffer-limit 3000backup destination 192.168.247.198 200backup mode fail-overexport destination 172.16.45.57 100 sctpreliability partial buffer-limit 3000backup destination 192.168.100.2 200backup mode fail-overenabled!ip flow-aggregation cache bgp-nexthop-tosexport version 9export destination 172.16.12.200 100 sctpbackup destination 192.168.247.198 200export destination 172.16.45.57 100 sctpbackup destination 192.168.100.2 200enabled!!The display output of the show ip flow export sctp verbose command shows the status and statistics for this configuration example:
Router# show ip flow export sctp verboseIPv4 main cache exporting to 172.16.45.57, port 100, partialstatus: connectedbackup mode: redundant104 flows exported in 84 sctp messages.0 packets dropped due to lack of SCTP resourcesfail-over time: 25 milli-secondsrestore time: 25 secondsbackup: 192.168.100.2, port 200status: connectedfail-overs: 20 flows exported in 0 sctp messages.0 packets dropped due to lack of SCTP resourcesIPv4 main cache exporting to 172.16.12.200, port 100, partialstatus: connectedbackup mode: redundant104 flows exported in 84 sctp messages.0 packets dropped due to lack of SCTP resourcesfail-over time: 25 milli-secondsrestore time: 25 secondsbackup: 192.168.247.198, port 200status: connectedfail-overs: 10 flows exported in 0 sctp messages.0 packets dropped due to lack of SCTP resourcesprotocol-port cache exporting to 172.16.12.200, port 100, partialstatus: connectedbackup mode: fail-over19 flows exported in 18 sctp messages.0 packets dropped due to lack of SCTP resourcesfail-over time: 25 milli-secondsrestore time: 25 secondsbackup: 192.168.247.198, port 200status: connectedfail-overs: 00 flows exported in 0 sctp messages.0 packets dropped due to lack of SCTP resourcesprotocol-port cache exporting to 172.16.45.57, port 100, partialstatus: connectedbackup mode: fail-over15 flows exported in 15 sctp messages.0 packets dropped due to lack of SCTP resourcesfail-over time: 25 milli-secondsrestore time: 25 secondsbackup: 192.168.100.2, port 200status: connectedfail-overs: 00 flows exported in 0 sctp messages.0 packets dropped due to lack of SCTP resourcesbgp-nexthop-tos cache exporting to 172.16.12.200, port 100, fullstatus: connectedbackup mode: redundant20 flows exported in 10 sctp messages.0 packets dropped due to lack of SCTP resourcesfail-over time: 25 milli-secondsrestore time: 25 secondsbackup: 192.168.247.198, port 200status: connectedfail-overs: 00 flows exported in 0 sctp messages.0 packets dropped due to lack of SCTP resourcesbgp-nexthop-tos cache exporting to 172.16.45.57, port 100, fullstatus: connectedbackup mode: redundant20 flows exported in 10 sctp messages.0 packets dropped due to lack of SCTP resourcesfail-over time: 25 milli-secondsrestore time: 25 secondsbackup: 192.168.100.2, port 200status: connectedfail-overs: 00 flows exported in 0 sctp messages.0 packets dropped due to lack of SCTP resourcesAdditional References
The following sections provide references related to the NetFlow Reliable Export with SCTP feature.
Related Documents
Overview of Cisco IOS NetFlow
List of the features documented in the Cisco IOS NetFlow Configuration Guide configuration guide
The minimum information about and tasks required for configuring NetFlow and NetFlow Data Export
"Getting Started with Configuring NetFlow and NetFlow Data Export"
Tasks for configuring NetFlow to capture and export network traffic data
Tasks for configuring MPLS-aware NetFlow
Tasks for configuring MPLS egress NetFlow accounting
Tasks for configuring NetFlow input filters
"Using NetFlow Filtering or Sampling to Select the Network Traffic to Track"
Tasks for configuring Random Sampled NetFlow
"Using NetFlow Filtering or Sampling to Select the Network Traffic to Track"
Tasks for configuring NetFlow aggregation caches
Tasks for configuring NetFlow BGP next hop support
"Configuring NetFlow BGP Next Hop Support for Accounting and Analysis"
Tasks for configuring NetFlow multicast support
Tasks for configuring NetFlow Layer 2 and Security Monitoring Exports
Tasks for configuring the SNMP NetFlow MIB
"Configuring SNMP and the NetFlow MIB to Monitor NetFlow Data"
Tasks for configuring the NetFlow MIB and Top Talkers feature
"Configuring the NetFlow MIB and Top Talkers to Analyze Selected NetFlow Traffic Data"
Information for installing, starting, and configuring the CNS NetFlow Collection Engine
Standards
No new or modified standards are supported by this feature, and support for existing standards has not been modified by this feature.
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MIBs
RFCs
RFC 3954
RFC2690
RFC 3578
Cisco Systems NetFlow Services Export Version 9
http://www.ietf.org/rfc/rfc3954.txt
Stream Control Transmission Protocol
http://www.ietf.org/rfc/rfc2960.txt
Stream Control Transmission Protocol-Partial Reliability Extension
Technical Assistance
Glossary
CEF—Cisco Express Forwarding. A Layer 3 IP switching technology that optimizes network performance and scalability for networks with large and dynamic traffic patterns.
BGP—Border Gateway Protocol. Interdomain routing protocol that replaces Exterior Border Gateway Protocol (EBGP). A BGP system exchanges reachability information with other BGP systems. BGP is defined by RFC 1163.
BGP next hop—IP address of the next hop to be used to reach a certain destination.
data record—Provides information about an IP flow that exists on the device that produced an export packet. Each group of data records (meaning each data flowset), refers to a previously transmitted template ID, which can be used to parse the data within the records.
dCEF—distributed Cisco Express Forwarding. A type of CEF switching in which line cards (such as Versatile Interface Processor (VIP) line cards) maintain identical copies of the forwarding information base (FIB) and adjacency tables. The line cards perform the express forwarding between port adapters; this relieves the Route Switch Processor of involvement in the switching operation.
export packet—A type of packet built by a device (for example, a router) with NetFlow services enabled. The packet is addressed to another device (for example, the NetFlow Collection Engine). The packet contains NetFlow statistics. The other device processes the packet (parses, aggregates, and stores information on IP flows).
fast switching—A Cisco feature in which a route cache is used to expedite packet switching through a router.
flow—A unidirectional stream of packets between a given source and destination, each of which is defined by a network-layer IP address and transport-layer source and destination port numbers.
flowset—A collection of flow records that follow the packet header in an export packet. A flowset contains information that must be parsed and interpreted by the NetFlow Collection Engine. There are two different types of flowsets: template flowsets and data flowsets. An export packet contains one or more flowsets, and both template and data flowsets can be mixed in the same export packet.
NetFlow—A Cisco IOS application that provides statistics on packets flowing through the router. It is emerging as a primary network accounting and security technology.
NetFlow Aggregation—A NetFlow feature that lets you summarize NetFlow export data on an IOS router before the data is exported to a NetFlow data collection system such as the NetFlow Collection Engine. This feature lowers bandwidth requirements for NetFlow export data and reduces platform requirements for NetFlow data collection devices.
NetFlow Collection Engine (formerly NetFlow FlowCollector)—A Cisco application that is used with NetFlow on Cisco routers and Catalyst 5000 series switches. The NetFlow Collection Engine collects packets from the router that is running NetFlow and decodes, aggregates, and stores them. You can generate reports on various aggregations that can be set up on the NetFlow Collection Engine.
NetFlow v9—NetFlow export format Version 9. A flexible and extensible means of carrying NetFlow records from a network node to a collector. NetFlow Version 9 has definable record types and is self-describing for easier NetFlow Collection Engine configuration.
options data record—A special type of data record used in the NetFlow process. It is based on an options template and has a reserved template ID that provides information about the NetFlow process itself.
options template—A type of template record used to communicate the format of data related to the NetFlow process.
packet header—First part of an export packet. It provides basic information about the packet (such as the NetFlow version, number of records contained in the packet, and sequence numbering) so that lost packets can be detected.
SCTP—Stream Control Transmission Protocol. The Stream Control Transmission Protocol (SCTP) is a transport layer protocol defined in 2000 by the IETF Signaling Transport (SIGTRAN) working group. The protocol is defined in RFC 2960, and an introductory text is provided by RFC 3286.
template flowset—A collection of template records that are grouped in an export packet.
template ID—A unique number that distinguishes a template record produced by an export device from other template records produced by the same export device. A NetFlow Collection Engine application can receive export packets from several devices. You should be aware that uniqueness is not guaranteed across export devices. The NetFlow Collection Engine should cache the address of the export device that produced the template ID in order to enforce uniqueness.
template record—Defines the format of subsequent data records that might be received in current or future export packets. A template record within an export packet does not necessarily indicate the format of data records within that same packet. A NetFlow Collection Engine application must cache any template records received and then parse any data records it encounters by locating the appropriate template record in the cache.
Note
Feature Information for NetFlow Reliable Transport Using SCTP
Table 2 lists the features in this module and provides links to specific configuration information. Only features that were introduced or modified in Cisco IOS Release 12.2(1) or 12.0(3)S or a later release appear in the table.
Not all commands may be available in your Cisco IOS software release. For details on when support for a specific command was introduced, see the command reference documentation.
For information on a feature in this technology that is not documented here, see the "Cisco IOS NetFlow Features Roadmap" module.
Cisco IOS software images are specific to a Cisco IOS software release, a feature set, and a platform. Use Cisco Feature Navigator to find information about platform support and Cisco IOS software image support. Access Cisco Feature Navigator at http://www.cisco.com/go/fn. You must have an account on Cisco.com. If you do not have an account or have forgotten your username or password, click Cancel at the login dialog box and follow the instructions that appear.
Note
Table 2 Feature Information for NetFlow Reliable Transport Using SCTP
NetFlow Reliable Export With SCTP
12.4(4)T
The NetFlow Reliable Export With SCTP feature provides a more robust and flexible method for exporting NetFlow data to collectors than UDP, which was the only transport option prior to the introduction of this feature.
NetFlow Reliable Export With SCTP has the following benefits:
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The following sections provide information about this feature:
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The following commands were introduced or modified by this feature: ip flow export, show ip flow export, and export.
Copyright © 2005 Cisco Systems, Inc. All rights reserved.
This module first published <<October 31st, 2005>>. Last updated <<April 30th, 2007>>.
