- Cisco IOS NetFlow Overview
- Getting Started with Configuring Cisco IOS NetFlow and NetFlow Data Export
- Configuring NetFlow and NetFlow Data Export
- Configuring NetFlow Aggregation Caches
- Using NetFlow Filtering or Sampling to Select the Network Traffic to Track
- Configuring NetFlow BGP Next Hop Support for Accounting and Analysis
- Configuring MPLS Egress NetFlow Accounting and Analysis
- Configuring MPLS-aware NetFlow
- Configuring NetFlow Multicast Accounting
- Configuring SNMP and using the NetFlow MIB to Monitor NetFlow Data
- Configuring NetFlow Top Talkers using Cisco IOS CLI Commands or SNMP Commands
- NetFlow Layer 2 and Security Monitoring Exports
- NetFlow Reliable Export With SCTP
- Detecting and Analyzing Network Threats With NetFlow
- Index
Contents
- Configuring SNMP and using the NetFlow MIB to Monitor NetFlow Data
- Finding Feature Information
- Prerequisites for Configuring SNMP and the NetFlow MIB to Monitor NetFlow Data
- Restrictions for Configuring SNMP and the NetFlow MIB to Monitor NetFlow Data
- Information About Configuring SNMP and the NetFlow MIB to Monitor NetFlow Data
- NetFlow MIB Feature Benefits
- NetFlow MIB Overview
- Terminology Used
- Using SNMP and MIBs to Extract NetFlow Information
- Objects That are Used by the NetFlow MIB
- How to Configure SNMP and use the NetFlow MIB to Monitor NetFlow Data
- Configuring the Router to use SNMP
- Configuring Options for the Main Cache
- Configuring Options for the Main Cache
- Identifying the Interface Number to use for Enabling NetFlow with SNMP
- Configuring NetFlow on an Interface
- Configuring NetFlow on an Interface
- Configuring the Destination-Prefix Aggregation Cache
- Configuring the Destination-Prefix Aggregation Cache
- Configuring NetFlow Export from the Main NetFlow Cache using the Version 9 Export Format
- Configuring NetFlow Export from the Main NetFlow Cache using the Version 9 Export Format
- Configuration Examples using SNMP and the NetFlow MIB to Monitor NetFlow Data
- Configuring the Minimum Mask for a Source Prefix Aggregation Scheme using SNMP Example
- Configuring NetFlow Data Export for the Source Prefix Aggregation Scheme using SNMP Example
- Configuring a NetFlow Minimum Mask for a Prefix Aggregation Cache using SNMP Example
- Using SNMP to Gather Flow Information From the Router Example
- Additional References
- Feature Information for Configuring SNMP and using the NetFlow MIB to Monitor NetFlow Data
- Glossary
Configuring SNMP and using the NetFlow MIB to Monitor NetFlow Data
NetFlow is a technology that provides highly granular per-flow statistics on traffic in a Cisco router. The NetFlow MIB feature provides MIB objects to allow users to configure NetFlow and to monitor flow cache information, the current NetFlow configuration, and statistics.
- Finding Feature Information
- Prerequisites for Configuring SNMP and the NetFlow MIB to Monitor NetFlow Data
- Restrictions for Configuring SNMP and the NetFlow MIB to Monitor NetFlow Data
- Information About Configuring SNMP and the NetFlow MIB to Monitor NetFlow Data
- How to Configure SNMP and use the NetFlow MIB to Monitor NetFlow Data
- Configuration Examples using SNMP and the NetFlow MIB to Monitor NetFlow Data
- Additional References
- Feature Information for Configuring SNMP and using the NetFlow MIB to Monitor NetFlow Data
- Glossary
Finding Feature Information
Your software release may not support all the features documented in this module. For the latest caveats and feature information, see Bug Search Tool and the release notes for your platform and software release. To find information about the features documented in this module, and to see a list of the releases in which each feature is supported, see the feature information table at the end of this module.
Use Cisco Feature Navigator to find information about platform support and Cisco software image support. To access Cisco Feature Navigator, go to www.cisco.com/go/cfn. An account on Cisco.com is not required.
Prerequisites for Configuring SNMP and the NetFlow MIB to Monitor NetFlow Data
Before you enable NetFlow you must:
Configure the router for IP routing
Ensure that one of the following is enabled on your router, and on the interfaces that you want to configure NetFlow on: Cisco Express Forwarding (CEF), distributed CEF, or fast switching
Understand the resources required on your router because NetFlow consumes additional memory and CPU resources
Configure SNMP on the router on which the NetFlow MIB feature is to be used. Refer to the Configuring the Router to use SNMP for more information. For more information on configuring an SNMP server, refer to the Configuring SNMP Support in the Cisco IOS Network Management Configuration Guide .
Restrictions for Configuring SNMP and the NetFlow MIB to Monitor NetFlow Data
Cisco IOS Releases 12.2(14)S, 12.0(22)S, or 12.2(15)T
If your router is running a version of Cisco IOS prior to releases 12.2(14)S, 12.0(22)S, or 12.2(15)T the ip route-cache flow command is used to enable NetFlow on an interface.
If your router is running Cisco IOS release 12.2(14)S, 12.0(22)S, 12.2(15)T, or later the ip flow ingress command is used to enable NetFlow on an interface.
Information About Configuring SNMP and the NetFlow MIB to Monitor NetFlow Data
- NetFlow MIB Feature Benefits
- NetFlow MIB Overview
- Using SNMP and MIBs to Extract NetFlow Information
- Objects That are Used by the NetFlow MIB
NetFlow MIB Feature Benefits
NetFlow is a technology that collects traffic flow statistics on routing devices. NetFlow has been used for a variety of applications, including traffic engineering, usage-based billing, and denial of service (DoS) attack monitoring.
The NetFlow MIB feature is useful for obtaining IP flow information from a Cisco router when a NetFlow export operation is not possible. NetFlow exporting does not have to be enabled for the NetFlow MIB feature to be used. The NetFlow MIB feature can be implemented instantaneously at any point in the network to obtain flow information.
With the NetFlow MIB feature, system information that is stored in the flow cache can be accessed in real time by utilizing a MIB implementation based on SNMP. This information is accessed using get and set commands entered on the network management system (NMS) workstation for which SNMP has been implemented. The NMS workstation is also known as the SNMP manager.
NetFlow MIB Overview
The Netflow MIB provides a simple and easy method to configure NetFlow, NetFlow aggregation caches, and NetFlow Data Export. You use the snmpget and snmpwalk tools to get NetFlow cache information and current NetFlow configuration information. The NetFlow MIB feature enables medium to small size enterprises to take advantage of NetFlow technology over SNMP at a reduced infrastructure cost. The MIB is created to provide Netflow information in these areas:
Cache information and configuration.
Export information and configuration.
Export Statistics.
Protocol Statistics.
Version 9 Export Template information.
Top Flows information.
Terminology Used
Flow
A flow is defined as an unidirectional sequence of packets between a given source and destination endpoints. Network flows are highly granular; flow endpoints are identified both by IP address as well as by transport layer application port numbers. NetFlow also utilizes the IP Protocol type, Type of Service (ToS) and the input interface identifier to uniquely identify flows.
Exporter
A device (for example, a router) with NetFlow services enabled. The exporter monitors packets entering an observation point and creates flows out of these packets. The information from these flows are exported in the form of Flow Records to the collector. You can configure NetFlow data export using the NetFlow MIB.
Flow Record
A Flow Record provides information about an IP Flow that exists on the Exporter. The Flow Records are commonly referred to as NetFlow Services data or NetFlow data.
Collector
The NetFlow Collector receives Flow Records from one or more Exporters. It processes the received export packet, i.e. parses, stores the Flow Record information. The flow records may be optionally aggregated before storing into the hard disk.
Template
NetFlow Version 9 Export format is template based. Version 9 record format consists of a packet header followed by at least one or more template or data FlowSets. A template FlowSet (collection of one or more template) provides a description of the fields that will be present in future data FlowSets. Templates provide an extensible design to the record format, a feature that should allow future enhancements to NetFlow services without requiring concurrent changes to the basic flow-record format.
One additional record type is also a part of Version 9 specification: an options template. Rather than supplying information about IP flows, options are used to supply meta-data about the NetFlow process itself.
Top Flows
This feature provides a mechanism which allows the top N flows in the NetFlow cache to be viewed in real time.
Criteria can be set to limit the feature to particular flows of interest, which can aid in DoS detection.
Only the number of flows (TopN) and the sort criteria (SortBy) need be set.
Top Flows is not intended as a mechanism for exporting the entire netflow cache.
For more information on the Top Flows and the NetFlow MIB refer to the Configuring NetFlow Top Talkers using Cisco IOS CLI Commands or SNMP Commands.
Egress flows
This feature analyzes traffic that is being forwarded by the router. This feature is often referred to as Egress NetFlow.
Using SNMP and MIBs to Extract NetFlow Information
SNMP has historically been used to collect network information. SNMP permits retrieval of critical information from network elements such as routers, switches, and workstations. The NetFlow MIB feature uses SNMP to configure NetFlow and to gather NetFlow statistics.
The NetFlow MIB feature allows NetFlow statistics and other NetFlow data for the managed devices on your system to be retrieved by SNMP. You can specify retrieval of NetFlow information from a managed device (for example, a router) either by entering commands on that managed device or by entering SNMP commands from the NMS workstation to configure the router via the MIB. If the NetFlow information is configured from the NMS workstation, no access to the router is required and all configuration can be performed via SNMP. The NetFlow MIB request for information is sent from an NMS workstation via SNMP to the router and is retrieved from the router. This information can then be stored or viewed, thus allowing NetFlow information to be easily accessed and transported across a multi-vendor programming environment.
Objects That are Used by the NetFlow MIB
The NetFlow MIB feature defines managed objects that enable a network administrator to remotely monitor the following NetFlow information:
Flow cache configuration information
NetFlow export information
General NetFlow statistics
How to Configure SNMP and use the NetFlow MIB to Monitor NetFlow Data
 Note | Some of the tasks in this section include examples of the SNMP CLI syntax used to set configuration parameters on the router, and to read values from MIB objects on the router. These SNMP CLI syntax examples are taken from a Linux workstation using public domain SNMP tools. The SNMP CLI syntax for your workstation might be different. Refer to the documentation that was provided with your SNMP tools for the correct syntax for your network management workstation. |
- Configuring the Router to use SNMP
- Configuring Options for the Main Cache
- Configuring Options for the Main Cache
- Identifying the Interface Number to use for Enabling NetFlow with SNMP
- Configuring NetFlow on an Interface
- Configuring NetFlow on an Interface
- Configuring the Destination-Prefix Aggregation Cache
- Configuring the Destination-Prefix Aggregation Cache
- Configuring NetFlow Export from the Main NetFlow Cache using the Version 9 Export Format
- Configuring NetFlow Export from the Main NetFlow Cache using the Version 9 Export Format
Configuring the Router to use SNMP
Before the NetFlow MIB feature can be used, the router must be configured to support SNMP. To enable SNMP on the router, perform this task.
Note | The SNMP community read-only (RO) string for the examples is public. The SNMP community read-write (RW) string for the examples is private. You should use more complex strings for these values in your configurations. |
1.
enable
2.
configure
terminal
3.
snmp-server
community
string
ro
4.
snmp-server
community
string
rw
5.
end
DETAILED STEPS
Configuring Options for the Main Cache
This optional task describes the procedure for modifying the parameters for the NetFlow main cache. Perform the steps in this optional task using either the router CLI commands or the SNMP commands to modify the parameters for the NetFlow main cache.
1.
enable
2.
configure
terminal
3.
ip
flow-cache
entries
number
4.
ip
flow-cache
timeout
active
minutes
5.
ip
flow-cache
timeout
inactive
seconds
6.
end
DETAILED STEPS
| Command or Action | Purpose | |||
|---|---|---|---|---|
| Step 1 |
enable
Example: Router> enable |
(Required) Enables privileged EXEC mode.
| ||
| Step 2 |
configure
terminal
Example: Router# configure terminal |
(Required) Enters global configuration mode. | ||
| Step 3 |
ip
flow-cache
entries
number
Example: Router(config)# ip flow-cache entries 4000 |
(Optional) Specifies the maximum number of entries to be captured for the main flow cache.
| ||
| Step 4 |
ip
flow-cache
timeout
active
minutes
Example: Router(config)# ip flow-cache timeout active 30 |
(Optional) Configures operational parameters for the main cache.
| ||
| Step 5 |
ip
flow-cache
timeout
inactive
seconds
Example: Router(config)# ip flow-cache timeout inactive 100 |
(Optional) Configures operational parameters for the main cache.
| ||
| Step 6 |
end
Example: Router(config)# end |
(Required) Exits the current configuration mode and returns to privileged EXEC mode. |
Configuring Options for the Main Cache
1.
snmpset
-c
private
-m
all
-v2c
[ip-address | hostname] cnfCICacheEntries.type unsigned number
2.
snmpset
-c
private
-m
all
-v2c
[ip-address | hostname] cnfCIActiveTimeOut.type unsigned number
3.
snmpset
-c
private
-m
all
-v2c
[ip-address | hostname] ccnfCIInactiveTimeOut.type unsigned number
DETAILED STEPS
| Command or Action | Purpose | |||
|---|---|---|---|---|
| Step 1 |
snmpset
-c
private
-m
all
-v2c
[ip-address | hostname] cnfCICacheEntries.type unsigned number Example: workstation% snmpset -c private -m all -v2c 10.4.9.62 cnfCICacheEntries.0 unsigned 4000 |
(Optional) Defines the maximum number of entries to be captured for the main flow cache.
| ||
| Step 2 |
snmpset
-c
private
-m
all
-v2c
[ip-address | hostname] cnfCIActiveTimeOut.type unsigned number Example: workstation% snmpset -c private -m all -v2c 10.4.9.62 cnfCIActiveTimeOut.0 unsigned 60 |
(Optional) Specifies the number of seconds that an active flow remains in the main cache before it times out.
| ||
| Step 3 |
snmpset
-c
private
-m
all
-v2c
[ip-address | hostname] ccnfCIInactiveTimeOut.type unsigned number Example: workstation% snmpset -c private -m all -v2c 10.4.9.62 cnfCIInactiveTimeOut.0 unsigned 30 |
(Optional) Specifies the number of seconds that an inactive flow remains in the main cache before it times out.
|
Identifying the Interface Number to use for Enabling NetFlow with SNMP
Before you can use SNMP to enable NetFlow on an interface, you must identify the correct SNMP interface number on the router. To identify the interface number for the interface that you want to enable NetFlow on, perform the steps in this task.
1.
enable
2.
show
snmp
mib
ifmib
ifindex
type
number
DETAILED STEPS
| Step 1 |
enable
Enters privileged EXEC mode. Enter the password if prompted. Example: Router> enable |
| Step 2 |
show
snmp
mib
ifmib
ifindex
type
number
Displays the SNMP interface number for the interface specified. Example: Router# show snmp mib ifmib ifindex fastethernet 0/0 Ethernet0/0: Ifindex = 1 |
Configuring NetFlow on an Interface
Perform the task using either the router CLI commands or the SNMP commands to enable NetFlow on the router.
1.
enable
2.
configure
terminal
3.
interface
type
number
4.
ip
flow
{ingress | egress}
5.
exit
6. Repeat Steps 3 through 5 to enable NetFlow on other interfaces.
7.
end
DETAILED STEPS
| Command or Action | Purpose | |||
|---|---|---|---|---|
| Step 1 |
enable
Example: Router> enable |
(Required) Enables privileged EXEC mode.
| ||
| Step 2 |
configure
terminal
Example: Router# configure terminal |
(Required) Enters global configuration mode. | ||
| Step 3 |
interface
type
number
Example: Router(config)# interface fastethernet0/0 |
(Required) Specifies the interface that you want to enable NetFlow on and enters interface configuration mode. | ||
| Step 4 |
ip
flow
{ingress | egress} Example: Router(config-if)# ip flow ingress Example: and/or Example: Router(config-if)# ip flow egress |
(Required) Enables NetFlow on the interface.
| ||
| Step 5 |
exit
Example: Router(config-if)# exit |
(Optional) Exits interface configuration mode and returns to global configuration mode.
| ||
| Step 6 | Repeat Steps 3 through 5 to enable NetFlow on other interfaces. |
(Optional) -- | ||
| Step 7 |
end
Example: Router(config-if)# end |
(Required) Exits the current configuration mode and returns to privileged EXEC mode. |
Configuring NetFlow on an Interface
1.
snmpset
-c
private
-m
all
-v2c
[ip-address | hostname] cnfCINetflowEnable.interface-number integer [0 | 1 | 2 | 3]
2. Repeat Step 1 to enable NetFlow on other interfaces
DETAILED STEPS
| Command or Action | Purpose | |||
|---|---|---|---|---|
| Step 1 |
snmpset
-c
private
-m
all
-v2c
[ip-address | hostname] cnfCINetflowEnable.interface-number integer [0 | 1 | 2 | 3] Example: workstation% snmpset -c private -m all -v2c 10.4.9.62 cnfCINetflowEnable.1 integer 1 |
(Required) Configures NetFlow for an interface.
The values for the direction argument are:
| ||
| Step 2 | Repeat Step 1 to enable NetFlow on other interfaces |
(Optional) -- |
Configuring the Destination-Prefix Aggregation Cache
This task describes the procedure for modifying the parameters for aggregation caches. The destination-prefix is used in this task. With the exception of specifying the aggregation cache that you want to modify, the steps are the same for modifying these parameters for the other aggregation caches.
Perform this task using either the router CLI commands or the SNMP commands to modify configuration parameters for an aggregation cache.
You must enable NetFlow on at least one interface before configuring a NetFlow aggregation cache.
1.
enable
2.
configure
terminal
3.
ip
flow-aggregation
cache
destination-prefix
4.
cache
entries
number
5.
cache
timeout
active
minutes
6.
cache
timeout
inactive
seconds
7. enable
8.
end
DETAILED STEPS
| Command or Action | Purpose | |||
|---|---|---|---|---|
| Step 1 |
enable
Example: Router> enable |
(Required) Enables privileged EXEC mode.
| ||
| Step 2 |
configure
terminal
Example: Router# configure terminal |
(Required) Enters global configuration mode. | ||
| Step 3 |
ip
flow-aggregation
cache
destination-prefix
Example: Router(config)# ip flow-aggregation cache destination-prefix |
(Required) Enters aggregation cache configuration mode for the destination-prefixaggregation cache.
| ||
| Step 4 |
cache
entries
number
Example: Router(config-flow-cache)# cache entries 4000 |
(Optional) Defines the number of entries that are allowed in the aggregation flow cache. | ||
| Step 5 |
cache
timeout
active
minutes
Example: Router(config)# cache timeout active 30 |
(Optional) Specifies the number of minutes that an active flow remains in the cache before it times out.
| ||
| Step 6 |
cache
timeout
inactive
seconds
Example: Router(config-flow-cache) # cache timeout inactive 100 |
(Optional) Specifies the number of seconds that an inactive flow remains in the cache before it times out.
| ||
| Step 7 |
enable Example: Router(config-flow-cache) # enable |
(Required) Activates the destination-prefixaggregation cache. | ||
| Step 8 |
end
Example: Router(config-if)# end |
(Required) Exits the current configuration mode and returns to privileged EXEC mode. |
Configuring the Destination-Prefix Aggregation Cache
1.
snmpset
-c
private
-m
all
-v2c
[ip-address | hostname] cnfCICacheEnable.type integer truth-value
2.
snmpset
-c
private
-m
all
-v2c
[ip-address | hostname] cnfCICacheEntries. type unsigned number
3.
snmpset
-c
private
-m
all
-v2c
[ip-address | hostname] cnfCIActiveTimeOut. type unsigned number
4.
snmpset
-c
private
-m
all
-v2c
[ip-address | hostname] ccnfCIInactiveTimeOut. type unsigned number
DETAILED STEPS
| Command or Action | Purpose | |||
|---|---|---|---|---|
| Step 1 |
snmpset
-c
private
-m
all
-v2c
[ip-address | hostname] cnfCICacheEnable.type integer truth-value Example: workstation% snmpset -c private -m all -v2c 10.4.9.14 cnfCICacheEnable.4 integer 1 |
(Required) Enables the aggregation cache.
| ||
| Step 2 |
snmpset
-c
private
-m
all
-v2c
[ip-address | hostname] cnfCICacheEntries. type unsigned number Example: workstation% snmpset -c private -m all -v2c 10.4.9.62 cnfCICacheEntries.4 unsigned 4000 |
(Optional) Defines the maximum number of entries to be captured for the aggregation flow cache.
| ||
| Step 3 |
snmpset
-c
private
-m
all
-v2c
[ip-address | hostname] cnfCIActiveTimeOut. type unsigned number Example: workstation% snmpset -c private -m all -v2c 10.4.9.14 cnfCIActiveTimeOut.4 unsigned 60 |
(Optional) Specifies the number of seconds that an active flow remains in the cache before it times out.
| ||
| Step 4 |
snmpset
-c
private
-m
all
-v2c
[ip-address | hostname] ccnfCIInactiveTimeOut. type unsigned number Example: workstation% snmpset -c private -m all -v2c 10.4.9.14 cnfCIInactiveTimeOut.4 unsigned 30 |
(Optional) Specifies the number of seconds that an inactive flow remains in the cache before it times out.
|
Configuring NetFlow Export from the Main NetFlow Cache using the Version 9 Export Format
The following example shows how to configure the router to export statistics from the NetFlow main cache (0), including peer autonomous system and BGP-related information using export Version 9.
Perform this task using either the router CLI commands or the SNMP commands to configure the router to export statistics from the main cache using the Version 9.
1.
enable
2.
configure
terminal
3.
ip
flow-export
version
9
[
origin-as
|
peer-as]
[
bgp-nexthop
]
4.
ip
flow-export
destination
{ip-address | hostname} udp-port}
5. Repeat Step 4 to add a second NetFlow collector
6.
end
DETAILED STEPS
| Command or Action | Purpose | |||
|---|---|---|---|---|
| Step 1 |
enable
Example: Router> enable |
(Required) Enables privileged EXEC mode.
| ||
| Step 2 |
configure
terminal
Example: Router# configure terminal |
(Required) Enters global configuration mode. | ||
| Step 3 |
ip
flow-export
version
9
[
origin-as
|
peer-as]
[
bgp-nexthop
]
Example: Router(config)# ip flow-export version 9 peer-as bgp-nexthop |
(Required) Enables the export of information in NetFlow cache entries.
| ||
| Step 4 |
ip
flow-export
destination
{ip-address | hostname} udp-port} Example: Router(config)# ip flow-export destination 10.0.19.2 999 |
(Required) Specifies the IP address, or hostname of the NetFlow collector, and the UDP port the NetFlow collector is listening on. | ||
| Step 5 | Repeat Step 4 to add a second NetFlow collector |
(Optional) -- | ||
| Step 6 |
end
Example: Router(config)# end |
(Required) Exits the current configuration mode and returns to privileged EXEC mode. |
Configuring NetFlow Export from the Main NetFlow Cache using the Version 9 Export Format
1.
snmpset
-c
private
-m
all
-v2c
[ip-address | hostname] cnfEIExportVersion.type unsigned version cnfEIPeerAS. type integer truth-value cnfEIBgpNextHop.type integer truth-value
2.
snmpset
-c
private
-m
all
-v2c
[ip-address | hostname] cnfEICollectorStatus. type . address-type . ip-version . ip-address . port integer [4 | 6]
3. Repeat Step 2 to add another collector
DETAILED STEPS
| Command or Action | Purpose | |
|---|---|---|
| Step 1 |
snmpset
-c
private
-m
all
-v2c
[ip-address | hostname] cnfEIExportVersion.type unsigned version cnfEIPeerAS. type integer truth-value cnfEIBgpNextHop.type integer truth-value Example: workstation% snmpset -c private -m all -v2c 10.4.9.14 cnfEIExportVersion.0 unsigned 9 cnfEIPeerAS.0 integer 1 cnfEIBgpNextHop.0 integer 1 |
(Required) Specifies the export format and that the export statistics include peer autonomous system and BGP-related information.
|
| Step 2 |
snmpset
-c
private
-m
all
-v2c
[ip-address | hostname] cnfEICollectorStatus. type . address-type . ip-version . ip-address . port integer [4 | 6] Example: workstation% snmpset -c private -m all -v2c 10.4.9.14 cnfEICollectorStatus.0.1.4.10.0.19.2.3 integer 4 |
(Required) Enables the exporting of information in NetFlow cache entries.
|
| Step 3 | Repeat Step 2 to add another collector |
(Optional) -- |
Configuration Examples using SNMP and the NetFlow MIB to Monitor NetFlow Data
- Configuring the Minimum Mask for a Source Prefix Aggregation Scheme using SNMP Example
- Configuring NetFlow Data Export for the Source Prefix Aggregation Scheme using SNMP Example
- Configuring a NetFlow Minimum Mask for a Prefix Aggregation Cache using SNMP Example
- Using SNMP to Gather Flow Information From the Router Example
Configuring the Minimum Mask for a Source Prefix Aggregation Scheme using SNMP Example
The following example enables a Source-Prefix aggregation cache and sets the source prefix mask to 16 bits.
workstation% snmpset -c private -m all -v2c 10.4.9.14 cnfCICacheEnable.3 integer 1 CISCO-NETFLOW-MIB::cnfCICacheEnable.sourcePrefix = INTEGER: true(1) workstation% snmpset -c private -m all -v2c 10.4.9.14 cnfCIMinSourceMask.3 unsigned 16 CISCO-NETFLOW-MIB::cnfCIMinSourceMask.sourcePrefix = Gauge32: 16
Configuring NetFlow Data Export for the Source Prefix Aggregation Scheme using SNMP Example
The following example enables a Source-Prefix aggregation cache and configures NetFlow Data Export for the aggregation cache.
workstation% snmpset -c private -m all -v2c 10.4.9.14 cnfCICacheEnable.3 integer 1 CISCO-NETFLOW-MIB::cnfCICacheEnable.sourcePrefix = INTEGER: true(1) workstation% snmpset -c private -m all -v2c 10.4.9.14 cnfEICollectorStatus.3.1.4.10.0.19.2.3 integer 4 CISCO-NETFLOW-MIB::cnfEICollectorStatus.sourcePrefix.ipv4."....".3 = INTEGER: createAndGo(4)
Configuring a NetFlow Minimum Mask for a Prefix Aggregation Cache using SNMP Example
The following example enables a Prefix aggregation cache and sets the prefix mask to 16 bits.
workstation% snmpset -c private -m all -v2c 10.4.9.14 cnfCICacheEnable.5 integer 1 CISCO-NETFLOW-MIB::cnfCICacheEnable.prefix = INTEGER: true(1) workstation% snmpset -c private -m all -v2c 10.4.9.14 cnfCIMinSourceMask.5 unsigned 16 CISCO-NETFLOW-MIB::cnfCIMinSourceMask.prefix = Gauge32: 16
Using SNMP to Gather Flow Information From the Router Example
The following examples show how to retrieve NetFlow status and statistics using SNMP.
Retrieving Netflow Statistics using SNMP
This command will retrieve the Netflow Statistics from the main cache using the MIB.
workstation% snmpget -c public -v2c 10.4.9.14 cnfPSPacketSizeDistribution.0 cnfPSPacketSizeDistribution.0 = 00 00 00 00 03 e8 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
The IP packet size distribution values are in the same order as shown in the CLI, with each pair of bytes representing a value of 1000 times the respective value in the CLI.
For example, for the packet range 65-96, the byte pair is 0x03e8 which is 1000 times 1. So to obtain the same values as the CLI, divide the value by 1000.
View the NetFlow Main Cache Timeout Values using SNMP
This command will retrieve the cache timeout values from the main cache using the MIB.
workstation% snmpget -c public -v2c 10.4.9.14 cnfCIActiveFlows.0 cnfCIInactiveFlows.0 cnfCIActiveTimeOut.0 cnfCIInactiveTimeOut.0 CISCO-NETFLOW-MIB::cnfCIActiveFlows.main = Gauge32: 1 CISCO-NETFLOW-MIB::cnfCIInactiveFlows.main = Gauge32: 3999 CISCO-NETFLOW-MIB::cnfCIActiveTimeOut.main = Gauge32: 60 minutes CISCO-NETFLOW-MIB::cnfCIInactiveTimeOut.main = Gauge32: 30 seconds
Additional References
Related Documents
|
Related Topic |
Document Title |
|---|---|
|
Overview of Cisco IOS NetFlow |
"Cisco IOS NetFlow Overview" |
|
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 |
"Configuring NetFlow and NetFlow Data Export" |
|
Tasks for configuring Configuring MPLS Aware NetFlow |
Configuring MPLS Aware NetFlow |
|
Tasks for configuring MPLS egress NetFlow accounting |
Configuring MPLS Egress NetFlow Accounting and Analysis |
|
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 |
"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 |
"Configuring NetFlow Multicast Accounting" |
|
Tasks for detecting and analyzing network threats with NetFlow |
Detecting and Analyzing Network Threats With NetFlow |
|
Tasks for configuring NetFlow Reliable Export With SCTP |
NetFlow Reliable Export With SCTP |
|
Tasks for configuring NetFlow Layer 2 and Security Monitoring Exports |
"NetFlow Layer 2 and Security Monitoring Exports" |
|
Tasks for configuring the NetFlow MIB and Top Talkers feature |
"Configuring NetFlow Top Talkers using Cisco IOS CLI Commands or SNMP Commands" |
|
Information for installing, starting, and configuring the CNS NetFlow Collection Engine |
Standards
|
Standards |
Title |
|---|---|
|
No new or modified standards are supported by this feature, and support for existing standards has not been modified by this feature. |
-- |
MIBs
|
MIBs |
MIBs Link |
|---|---|
|
To locate and download MIBs for selected platforms, Cisco IOS releases, and feature sets, use Cisco MIB Locator found at the following URL (requires CCO login account): |
RFCs
|
RFCs |
Title |
|---|---|
|
No new or modified RFCs are supported by this feature, and support for existing RFCs has not been modified by this feature. |
-- |
Technical Assistance
|
Description |
Link |
|---|---|
|
The Cisco Technical Support website contains thousands of pages of searchable technical content, including links to products, technologies, solutions, technical tips, and tools. Registered Cisco.com users can log in from this page to access even more content. |
Feature Information for Configuring SNMP and using the NetFlow MIB to Monitor NetFlow Data
The following table provides release information about the feature or features described in this module. This table lists only the software release that introduced support for a given feature in a given software release train. Unless noted otherwise, subsequent releases of that software release train also support that feature.
Use Cisco Feature Navigator to find information about platform support and Cisco software image support. To access Cisco Feature Navigator, go to . An account on Cisco.com is not required.|
Feature Name |
Releases |
Feature Configuration Information |
|---|---|---|
|
NetFlow MIB |
12.3(7)T, 12.2(25)S 12.2(27)SBC 12.2(33)SRD |
The NetFlow MIB feature provides MIB objects to allow users to monitor NetFlow cache information, the current NetFlow configuration, and statistics. The following command was introduced by this feature: ip flow-cache timeout. |
Glossary
AS --autonomous system. A collection of networks under a common administration sharing a common routing strategy. Autonomous systems are subdivided by areas. An autonomous system must be assigned a unique 16-bit number by the Internet Assigned Numbers Authority (IANA).
BGP --Border Gateway Protocol. Interdomain routing protocol that replaces Exterior Gateway Protocol (EGP). 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 specific destination.
CEF --Cisco Express Forwarding. A Layer 3 IP switching technology that optimizes network performance and scalability for networks with large and dynamic traffic patterns.
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.
MIB --Management Information Base. Database of network management information that is used and maintained by a network management protocol, such as Simple Network Management Protocol (SNMP) or the Common Management Information Protocol (CMIP). The value of a MIB object can be changed or retrieved using SNMP or CMIP commands, usually through a GUI network management system. MIB objects are organized in a tree structure that includes public (standard) and private (proprietary) branches.
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 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 for 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.
NMS --network management system. A system responsible for managing at least part of a network. An NMS is generally a reasonably powerful and well-equipped computer, such as an engineering workstation. NMSs communicate with agents to help keep track of network statistics and resources.
SNMP --Simple Network Management Protocol. A network management protocol used almost exclusively in TCP/IP networks. SNMP provides a means to monitor and control network devices, and to manage configurations, statistics collection, performance, and security.
SNMP communities --An authentication scheme that enables an intelligent network device to validate SNMP requests.
ToS byte --type of service byte. Second byte in the IP header that indicates the desired quality of service for a particular datagram.