- Cisco IOS NetFlow Overview
- Cisco IOS NetFlow Features Roadmap
- Getting Started with Configuring NetFlow and NetFlow Data Export
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- Configuring NetFlow BGP Next Hop Support for Accounting and Analysis
- Configuring MPLS Egress NetFlow Accounting and Analysis
- Configuring SNMP and using the NetFlow MIB to Monitor NetFlow Data
- NetFlow Reliable Export With SCTP
- Detecting and Analyzing Network Threats With NetFlow
- Configuring NetFlow Aggregation Caches
- Using NetFlow Filtering or Sampling to Select the Network Traffic to Track
- NetFlow Layer 2 and Security Monitoring Exports
- Configuring MPLS-aware NetFlow
- Configuring NetFlow Multicast Accounting
- Configuring NetFlow Top Talkers using Cisco IOS CLI Commands or SNMP Commands
- NetFlow v9 for IPv6
- NDE for VRF Interfaces
- Finding Feature Information
- Contents
- Prerequisites for Configuring NetFlow Multicast Accounting
- Restrictions for Configuring NetFlow Multicast Accounting
- Information About Configuring NetFlow Multicast Accounting
- How to Configure NetFlow Multicast Accounting
- Configuring NetFlow Multicast Accounting in Cisco IOS Releases 12.4(12), 12.4(11)T, 12.2(33)SRB, 12.2(33)SXH, 12.2(33)SB, and Newer Releases
- Configuring NetFlow Multicast Accounting in Cisco IOS Releases Prior to 12.4(12), 12.4(11)T, 12.2(33)SRB, 12.2(33)SXH, and 12.2(33)SB
- Verifying the NetFlow Multicast Accounting Configuration
- Configuration Examples for NetFlow Multicast Accounting
Configuring NetFlow Multicast Accounting
This document contains information about and instructions for configuring NetFlow multicast accounting. NetFlow multicast accounting allows you to capture multicast-specific data (both packets and bytes) for multicast flows.
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.
Finding Feature Information
Your software release may not support all the features documented in this module. For the latest feature information and caveats, see 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 for Configuring NetFlow Multicast Accounting" section.
Use Cisco Feature Navigator to find information about platform support and Cisco IOS and Catalyst OS software image support. To access Cisco Feature Navigator, go to http://www.cisco.com/go/cfn. An account on Cisco.com is not required.
Contents
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Prerequisites for Configuring NetFlow Multicast Accounting
•Restrictions for Configuring NetFlow Multicast Accounting
•Information About Configuring NetFlow Multicast Accounting
•How to Configure NetFlow Multicast Accounting
•Configuration Examples for NetFlow Multicast Accounting
•Feature Information for Configuring NetFlow Multicast Accounting
Prerequisites for Configuring NetFlow Multicast Accounting
Before you can configure NetFlow multicast accounting, you must:
•Configure the router for IP routing
•Configure Multicast fast switching or multicast distributed fast switching (MDFS); multicast Cisco Express Forwarding (CEF) switching is not supported.
•Configure Multicast routing.
•Configure NetFlow v9 (Version 9) data export (otherwise, multicast data is visible in the cache but is not exported).
Restrictions for Configuring NetFlow Multicast Accounting
Memory Impact
If traffic is heavy, the additional flows might fill the global flow hash table. If you must increase the size of the global flow hash table, you must also add memory to the router.
NetFlow has a maximum cache size of 65,536 flow record entries of 64 bytes each. To deduce the packet-replication factor, multicast accounting adds 16 bytes (for a total of 80 bytes) to each multicast flow record.
Performance Impact
Ingress multicast accounting does not greatly affect performance. Because of the additional accounting-related computation that occurs in the traffic-forwarding path of the router, egress NetFlow multicast accounting might degrade network performance slightly, but it does not limit the functionality of the router.
Multicast Addresses
NetFlow data cannot be exported to multicast addresses.
Information About Configuring NetFlow Multicast Accounting
•Multicast Ingress and Multicast Egress Accounting
•NetFlow Multicast Flow Records
NetFlow Multicast Benefits
NetFlow multicast allows you to capture multicast-specific data (both packets and bytes) for multicast flows. For example, you can capture the packet-replication factor for a specific flow as well as for each outgoing stream. NetFlow multicast provides complete end-to-end usage information about network traffic for a complete multicast traffic billing solution.
You can use NetFlow multicast accounting to identify and count multicast packets on the ingress side or the egress side (or both sides) of a router. Multicast ingress accounting provides information about the source and how many times the traffic was replicated. Multicast egress accounting monitors the destination of the traffic flow.
NetFlow multicast lets you enable NetFlow statistics to account for all packets that fail the reverse path forwarding (RPF) check and that are dropped in the core of the service provider network. Accounting for RPF-failed packets provides more accurate traffic statistics and patterns.
Multicast Ingress and Multicast Egress Accounting
NetFlow multicast lets you select either multicast ingress accounting, in which a replication factor (equal to the number of output interfaces) indicates the load, or multicast egress accounting, in which all outgoing multicast streams are counted as separate streams, or both multicast ingress and multicast egress accounting.
NetFlow multicast lets you collect information about how much data is leaving the interfaces of the router (egress and multicast ingress accounting) or how much multicast data is received (multicast ingress accounting).
On the ingress side, multicast packets are counted as with unicast packets, but with two additional fields (for number of replicated packets and byte count). With multicast ingress accounting, the destination interface field is set to null, and the IP next hop field is set to 0 for multicast flows.
NetFlow Multicast Flow Records
Multicast ingress accounting creates one flow record that indicates how many times each packet is replicated. Multicast egress accounting creates a unique flow record for each outgoing interface.
How to Configure NetFlow Multicast Accounting
•Verifying the NetFlow Multicast Accounting Configuration (optional)
Configuring NetFlow Multicast Accounting in Cisco IOS Releases 12.4(12), 12.4(11)T, 12.2(33)SRB, 12.2(33)SXH, 12.2(33)SB, and Newer Releases
Perform the steps in this required task to configure NetFlow multicast accounting.
Prerequisites
You must have already configured IP multicast on the networking devices in your network. See the Cisco IOS IP Multicast Configuration Guide, for more information on configuring IP multicast.
SUMMARY STEPS
1. enable
2. configure terminal
3. ip multicast-routing [vrf vrf-name] [distributed]
4. ip multicast netflow rpf-failure
5. ip multicast netflow output-counters
6. interface type number
7. ip flow ingress
8. end
DETAILED STEPS
Troubleshooting Tips
If there are no multicast flow records in the NetFlow cache, check the multicast switching counters for the existence of process-switched packets (NetFlow exports only fast-switched or MDFS-switched packets). If process-switched packets are present, check the MDFS routing table to help determine potential problems.
Configuring NetFlow Multicast Accounting in Cisco IOS Releases Prior to 12.4(12), 12.4(11)T, 12.2(33)SRB, 12.2(33)SXH, and 12.2(33)SB
•Configuring NetFlow Multicast Egress Accounting
•Configuring NetFlow Multicast Ingress Accounting
Configuring NetFlow Multicast Egress Accounting
Perform the steps in this required task to configure NetFlow multicast egress accounting.
Prerequisites
You must have already configured IP multicast on the networking devices in your network. See the Cisco IOS IP Multicast Configuration Guide, for more information on configuring IP multicast.
SUMMARY STEPS
1. enable
2. configure terminal
3. ip multicast-routing [vrf vrf-name] [distributed]
4. ip multicast netflow rpf-failure
5. interface type number
6. ip multicast netflow egress
7. end
DETAILED STEPS
Troubleshooting Tips
If there are no multicast flow records in the NetFlow cache, check the multicast switching counters for the existence of process-switched packets (NetFlow exports only fast-switched or MDFS-switched packets). If process-switched packets are present, check the MDFS routing table to help determine potential problems.
Configuring NetFlow Multicast Ingress Accounting
Perform the steps in this required task to configure NetFlow multicast ingress accounting.
Multicast ingress NetFlow accounting is enabled by default.
Prerequisites
You must have already configured IP multicast on the networking devices in your network. See the Cisco IOS IP Multicast Configuration Guide, for more information on configuring IP multicast.
SUMMARY STEPS
1. enable
2. configure terminal
3. ip multicast-routing [vrf vrf-name] [distributed]
4. ip multicast netflow rpf-failure
5. interface type number
6. ip multicast netflow ingress
7. end
DETAILED STEPS
Troubleshooting Tips
If there are no multicast flow records in the NetFlow cache, check the multicast switching counters for the existence of process-switched packets (NetFlow exports only fast-switched or MDFS-switched packets). If process-switched packets are present, check the MDFS routing table to help determine potential problems.
Verifying the NetFlow Multicast Accounting Configuration
Perform the steps in this optional task to verify the NetFlow multicast accounting configuration.
SUMMARY STEPS
1. enable
2. show ip cache verbose flow
DETAILED STEPS
Step 1 enable
Use this command to enable privileged EXEC mode. Enter your password if required. For example:
Router> enable
Router#
Step 2 show ip cache verbose flow
Use this command to verify that NetFlow multicast accounting is configured. Look for the two additional fields related to multicast data, that is, the number of IP multicast output packet and byte counts. For example:
Router# show ip cache verbose flow
IP packet size distribution (5149 total packets):
1-32 64 96 128 160 192 224 256 288 320 352 384 416 448 480
.997 .002 .000 .000 .000 .000 .000 .000 .000 .000 .000 .000 .000 .000 .000
512 544 576 1024 1536 2048 2560 3072 3584 4096 4608
.000 .000 .000 .000 .000 .000 .000 .000 .000 .000 .000
IP Flow Switching Cache, 278544 bytes
2 active, 4094 inactive, 14 added
468 ager polls, 0 flow alloc failures
Active flows timeout in 30 minutes
Inactive flows timeout in 15 seconds
IP Sub Flow Cache, 25800 bytes
1 active, 1023 inactive, 1 added, 1 added to flow
0 alloc failures, 0 force free
1 chunk, 1 chunk added
last clearing of statistics never
Protocol Total Flows Packets Bytes Packets Active(Sec) Idle(Sec)
-------- Flows /Sec /Flow /Pkt /Sec /Flow /Flow
UDP-other 12 0.0 1 52 0.0 0.1 15.6
Total: 12 0.0 1 52 0.0 0.1 15.6
SrcIf SrcIPaddress DstIf DstIPaddress Pr TOS Flgs Pkts
Port Msk AS Port Msk AS NextHop B/Pk Active
IPM: OPkts OBytes
Et0/0 10.1.1.1 Null 224.192.16.1 01 55 10 5164
0000 /0 0 0000 /0 0 0.0.0.0 20 262.8
IPM: 15K 309K
Et0/0 10.1.1.1 Null 255.255.255.255 11 C0 10 1
0208 /0 0 0208 /0 0 0.0.0.0 52 0.0
Router#
The Opkts column displays the number of IP multicast (IPM) output packets, the OBytes column displays the number of IPM output bytes, and the DstIPaddress column displays the destination IP address for the IPM output packets.
Configuration Examples for NetFlow Multicast Accounting
Configuring NetFlow Multicast Accounting in Cisco IOS Releases 12.4(12), 12.4(11)T, 12.2(33)SRB, 12.2(33)SXH, 12.2(33)SB, and Newer Releases
The following example shows how to configure multicast NetFlow accounting:
configure terminal
ip multicast-routing
ip multicast netflow rpf-failure
ip multicast netflow output-counters
!
interface ethernet 0/0
ip flow ingress
end
Configuring NetFlow Multicast Accounting in Cisco IOS Releases Prior to 12.4(12), 12.4(11)T, 12.2(33)SRB, 12.2(33)SXH, and 12.2(33)SB
•Configuring NetFlow Multicast Egress Accounting: Example
•Configuring NetFlow Multicast Ingress Accounting: Example
Configuring NetFlow Multicast Egress Accounting: Example
The following example shows how to configure multicast egress NetFlow accounting on the egress Ethernet 0/0 interface:
configure terminal
ip multicast-routing
ip multicast netflow rpf-failure
!
interface ethernet 0/0
ip multicast netflow egress
end
Configuring NetFlow Multicast Ingress Accounting: Example
The following example shows how to configure multicast ingress NetFlow accounting on the ingress Ethernet 1/0 interface:
configure terminal
ip multicast-routing
ip multicast netflow rpf-failure
!
interface ethernet 1/0
ip multicast netflow ingress
end
Additional References
Related Documents
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Overview of Cisco IOS NetFlow |
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List of the features documented in the Book Title configuration guide |
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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 |
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Tasks for configuring Configuring MPLS Aware NetFlow |
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Tasks for configuring MPLS egress NetFlow accounting |
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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 |
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Tasks for configuring NetFlow BGP next hop support |
Configuring NetFlow BGP Next Hop Support for Accounting and Analysis |
Tasks for detecting and analyzing network threats with NetFlow |
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Tasks for configuring NetFlow Reliable Export With SCTP |
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Tasks for configuring NetFlow Layer 2 and Security Monitoring Exports |
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Tasks for configuring the SNMP NetFlow MIB |
Configuring SNMP and using the NetFlow MIB to Monitor NetFlow Data |
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
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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
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No new or modified RFCs are supported by this feature, and support for existing RFCs has not been modified by this feature. |
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Technical Assistance
Feature Information for Configuring NetFlow Multicast Accounting
Table 1 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 1 lists only the Cisco IOS software release that introduced support for a given feature in a given Cisco IOS software release train. Unless noted otherwise, subsequent releases of that Cisco IOS software release train also support that feature.
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NetFlow Multicast Support |
12.3(1), 12.2(18)S, 12.2(27)SBC, |
The NetFlow Multicast Support feature lets you capture multicast-specific data (both packets and bytes) for multicast flows. For example, you can capture the packet-replication factor for a specific flow as well as for each outgoing stream. This feature provides complete end-to-end usage information about network traffic for a complete multicast traffic billing solution. The following sections provide information about this feature: • • • The following commands were introduced by this feature: ip multicast netflow egress, ip multicast netflow ingress, and ip multicast netflow rpf-failure. |
NetFlow Multicast Support1 |
12.4(11)T, 12.4(12), 12.(33)SRB, 12.2(33)SB, |
The ip multicast netflow [ingress | egress] interface configuration command was replaced by the ip multicast netflow output-counters global configuration command. |
1 This was a minor modification to the existing NetFlow Multicast Support feature. Minor feature modifications are not included in Feature Navigator. |
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.
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.
egress traffic—Traffic leaving the network.
fast switching—Cisco feature in which a route cache is used for expediting packet switching through a router.
ingress traffic—Traffic entering the network.
multicast data—Single packets copied by the network and sent to a specific subset of network addresses. These addresses are specified in the Destination Address field.
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 called 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.
RPF—Reverse Path Forwarding. Multicasting technique in which a multicast datagram is forwarded out of all but the receiving interface if the receiving interface is the one used to forward unicast datagrams to the source of the multicast datagram.
ToS byte—type of service byte. Second byte in the IP header that indicates the desired quality of service (QoS) for a particular datagram.
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