Border Gateway Protocol (BGP) is not merely a protocol—it’s the backbone of the...
2.7.1 Irpflowd Configuration
Irpflowd is a NetFlow/sFlow collector that receives and analyzes network traffic information, generated by your router(s).- NetFlow – an IP network statistics protocol developed by Cisco Systems, Inc. for collecting and transferring statistics regarding IP traffic information from network devices such as switches/routers to network analysis applications.
Irpflowdcurrently supports the following NetFlow versions: v1, v5, v9.
- sFlow – is a protocol designed for monitoring network, wireless and host devices. Developed by the sFlow.org Consortium, it is supported by a wide range of network devices, as well as software routing and network solutions.
Flow collector use is mandatory for Multiple Routing Domain networks since SPAN does not carry attributes to distinguish traffic between different providers.
2.7.1.1 Flow agents #
Multi-router networks usually simultaneously carry traffic to a prefix over multiple providers. Flow collector needs to know the exact details of such a configuration in order to correctly determine the overall provider volume and active flows. Each provider configured in IRP can be explicitly set to match Flow statistics to specific Flow agents and help IRP Flow collector assign accurate statistics for each provider.
Flow agents have been added in order to support Optimization for multiple Routing Domains but when available they are used to enhance IRP capabilities in other areas too. For example a correct set of Flow agents for all providers enables IRP to accurately determine a prefix’s current route. IRP components, especially Core during decision making can spot the latest prefix statistics matching a given Flow agent(s) and infer amount of traffic is sent over individual Providers. Collected data is later used to make Performance and Bandwidth decisions with knowing about multiple best routes.
In case Flow agent data is missing IRP relies on past probing data to determine the current route of a prefix.Flow agents are specified in the form of:
IPv4/interfaceID
where IPv4 is the source IP address of the packets coming from the agent and interfaceID is a numerical identifier of the interface in the range 1- 4294967295. The interface ID is usually its SNMP Interface ID on the router.
A collection of such values is assigned when multiple physical interfaces are used. For example:
peer.X.flow_agents = 8.8.8.8/1 8.8.8.8/2 8.8.8.8/3 8.8.8.8/4
The value is set via parameter peer.X.flow_agents or under Providers and Peers configuration in Frontend. The Frontend will also retrieve and suggest a list of available values that can be matched with the provider.
2.7.1.2 Configuration #
To use the
irpflowd collector, the following steps must be completed:- NetFlow/sFlow/jFlow must be configured on the router(s), which must send traffic flow information to the main IRP server IP (Figure Figure: Flow export configuration). See (Vendor-specific NetFlow configuration examples) for specific network device configuration instructions
- Irpflowd must be enabled (by setting the collector.flow.enabled parameter):
collector.flow.enabled = 1
- A list of all the networks, advertised by the edge routers that IRP will optimize, should be added to the configuration. This information should be specified in the collector.ournets parameter.
- For security reasons, the list of valid Flow sending IP addresses must be configured in the collector.flow.sources, to protect
irpflowdfrom unauthorized devices sending Flow data.
Example:
collector.flow.sources = 10.0.0.0/29
- In case the Flow exporters are configured to use non-standard port numbers (
2055for NetFlow/jFlow and6343for sFlow), then collector.flow.listen.nf and collector.flow.listen.sf must be adjusted accordingly:
collector.flow.listen.nf = 2055 collector.flow.listen.sf = 6343
2.7.1.3 Vendor-specific NetFlow configuration examples #
The following sections contain vendor-specific configuration examples, along with possible pitfalls and version-specific issues
NetFlow configuration on Cisco 7600/6500 series routers #
Refer also to the Cisco NetFlow Software Configuration GuideListing 2.1: Global MLS settings configuration
(config)# mls netflow (config)# mls flow ip interface-full (config)# mls flow ipv6 interface-full (config)# mls sampling packet-based 512 8192 (config)# mls nde sender version 7
Please replace the IP address and port with the actual IRP host IP and the collector UDP port (2055 by default)Listing 2.2: Global NetFlow settings and export configuration
(config)# ip flow-cache entries 524288 (config)# ip flow-cache timeout inactive 60 (config)# ip flow-cache timeout active 1 (config)# ip flow-export version 9 (config)# ip flow-export destination 10.11.12.14 2055
Ingress flow collection must be enabled on all interfaces facing the internal network. MLS NetFlow sampling must be enabled to preserve router resources.Listing 2.3: Per-interface NetFlow settings configuration
(config)# int GigabitEthernet 3/6 (config-if)# mls netflow sampling (config-if)# ip flow ingress
Flexible NetFlow configuration on Cisco 6500 series routers IOS 15.0SY series #
Listing 2.4: Flexible NetFlow monitor configuration
(config)# flow monitor IRP-FLOW-MONITOR (config-flow-monitor)# record platform-original ipv4 full (config-flow-monitor)# exporter IRP-FLOW-EXPORTER (config-flow-monitor)# cache timeout inactive 60 (config-flow-monitor)# cache timeout active 60 (config-flow-monitor)# cache entries 1048576
Listing 2.5: Flexible NetFlow exporter configuration
(config)# flow exporter IRP-FLOW-EXPORTER (config-flow-exporter)# destination 10.11.12.14 (config-flow-exporter)# source Loopback0 (config-flow-exporter)# transport udp 2055 (config-flow-exporter)# template data timeout 120
Please replace the IP address and port with the actual IRP host IP and the collector UDP port (2055 by default). Also replace the source interface with the actual one.Listing 2.6: Flexible NetFlow sampler configuration
(config)# sampler flow-sampler (config-sampler)# mode random 1 out-of 1024
Listing 2.7: Per-interface Flexible NetFlow settings configuration
(config)# interface FastEthernet0/0 (config-if)# ip flow monitor IRP-FLOW-MONITOR sampler flow-sampler input (config-if)# ip flow monitor IRP-FLOW-MONITOR sampler flow-sampler output
NetFlow configuration on Cisco 7200/3600 series routers #
Please replace the IP address and port with the actual IRP host IP and the collector UDP port (2055 by default)
Do not attempt to configure 7600/6500 series routers according to 7200/3600 router’s configuration guide.Listing 2.8: NetFlow configuration on Cisco 7200/3600 series routers
Router(config)# ip flow-cache entries 524288 Router(config)# ip flow-cache timeout inactive 60 Router(config)# ip flow-cache timeout active 1 Router(config)# ip flow-export version 9 Router(config)# ip flow-export destination 10.11.12.14 2055
Ingress/egress flow export configuration on peering interfaces #
According to Cisco IOS NetFlow Command Reference regarding the “ip flow” command history in IOS releases, this feature was introduced in IOS 12.3(11)T, 12.2(31)SB2, 12.2(18)SXE, 12.2(33)SRA.NetFlow exporting must be configured on each peering interface which is used to send and/or receive traffic:
Listing 2.9: Ingress/egress flow export configuration on peering interfaces
Router(config)#interface FastEthernet 1/0 Router(config-if)#ip flow ingress Router(config-if)#ip flow egress
Ingress flow export configuration (earlier IOS releases) #
Ingress flow export must be enabled on all interfaces facing the internal network. Prior to IOS 12.3(11)T, 12.2(31)SB2, 12.2(18)SXE, 12.2(33)SRA, flow export can be enabled only for ingress traffic, therefore it must be enabled on each interface that transmits/receives traffic from/to networks that must be improvedListing 2.10: Ingress flow export configuration
Router(config)#interface FastEthernet 1/0 Router(config-if)#ip route-cache flow
NetFlow/sFlow configuration examples for Vyatta routers (VC 6.3) #
Do not configure both NetFlow and sFlow export for the same router interface. It will lead to traffic statistics distortion.Sampling interval must be set to at least 2000 for 10G links and 1000 for 1G links in order to save resources.Listing 2.11: Configuring NetFlow export on Vyatta
vyatta@vyatta# set system flow-accounting netflow server 10.11.12.14 port 2055 vyatta@vyatta# set system flow-accounting netflow version 5
Listing 2.12: Configuration of an interface for the flow accounting
vyatta@vyatta# set system flow-accounting interface eth0 vyatta@vyatta# commit
jFlow export configuration for Juniper routers #
Routing Engine-based sampling supports up to eight flow servers for both version 5 and version 8 configurations. The total number of collectors is limited to eight, regardless of how many are configured for version 5 or version 8. During the sampling configuration, the export packets are replicated to all the collectors, configured to receive them. If two collectors are configured to receive version 5 records, then both collectors will receive records for a specified flow.
Default export interval for active/inactive flows on some Juniper routers is 1800 seconds. IRP requires significantly more frequent updates. The export interval recommended by IRP is 60 seconds. Refer your JunOS documentation on how to set export intervals. These parameters are named flow-active-timeout and flow-inactive-timeout.Listing 2.13: Juniper flow export configuration
forwarding-options {
sampling {
input {
family inet {
rate 1000;
}
}
}
family inet {
output {
flow-server 10.10.3.2 {
port 2055;
version 5;
source-address 10.255.255.1;
}
}
}
}
NetFlow export must be configured on all the interfaces facing the providers. In some cases, it may also be necessary to enable NetFlow forwarding on the interfaces facing the internal network.
Listing 2.14: Per-interface NetFlow sampling configuration
interfaces {
xe-0/0/0 {
unit 0 {
family inet {
sampling {
input output;
}
}
}
}
}