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Flow-Based Telemetry (EX4100, EX4100-F, and EX4400 Series)

Flow based telemetry (FBT) enables per-flow-level analytics, using inline monitoring services to create flows, collect them, and export them to a collector using the open standard IPFIX template to organize the flow.

FBT Overview

You can configure flow-based telemetry (FBT) for the EX4100, EX4100-F, and EX4400 Series switches. FBT enables per-flow-level analytics, using inline monitoring services to create flows, collect them, and export them to a collector. With inline monitoring services, you can monitor every IPv4 and IPv6 packet on both ingress and egress directions of an interface. A flow is a sequence of packets that have the same source IP, destination IP, source port, destination port, and protocol on an interface. For each flow, the software collects various parameters and exports the actual packet up to the configured clip length to a collector using the open standard IPFIX template to organize the flow. Once there is no active traffic for a flow, the flow is aged out after the configured inactive-timeout period (configure the flow-inactive-timeout statement at the [edit services inline-monitoring template template-name] hierarchy level). The software exports a IPFIX packet periodically at the configured flow-export timer interval. The observation domain identifier is used in the IPFIX packet to identify which line card sent the packet to the collector. Once set, the software derives a unique identifier for each line card based upon the system value set here.

Benefits of FBT

With FBT, you can:

  • Count packet, TTL, and TCP window ranges
  • Track and count Denial of Service (DoS) attacks
  • Analyze the load distribution of ECMP groups/link aggregation groups (LAG) over the member IDs (EX4100 and EX4100-F only)
  • Track traffic congestion (EX4100 and EX4100-F only)
  • Gather information about multimedia flows (EX4100 and EX4100-F only)
  • Gather information on why packets are dropped (EX4100 and EX4100-F only)

FBT Flow Export Overview

See Figure 1 for a sample template, which shows the information element IDs, names, and sizes:

Figure 1: Sample FBT Information Element TemplateSample FBT Information Element Template

Figure 2 shows the format of a sample IPFIX data template for FBT:

Figure 2: Sample FBT IPFIX Data TemplateSample FBT IPFIX Data Template

Figure 3 shows the format of a sample exported IPFIX flow for FBT:

Figure 3: Sample Exported IPFIX Flow for FBTSample Exported IPFIX Flow for FBT

When you create a new inline monitoring services configuration or change an existing one, the software immediately sends the periodic flow export of the data template to the respective collectors, instead of waiting until the next scheduled send time.

Limitations and Caveats

  • IRB interfaces are supported; however, L2 firewall filters are not supported.
  • Only 8 inline-monitoring instances and 8 collectors per instance are supported.
  • Flow records are limited to 128 bytes in length.
  • The collector must be reachable through either the loopback interface or a network interface, not only through a management interface.
  • You cannot configure an option template identifier or a forwarding class.
  • The IPFIX Option Data Record and IPFIX Option Data Template are not supported.
  • Feature profiles are not supported on EX4400 switches.
  • If you make any changes to the feature-profile configuration, you must reboot the device.
  • (EX4100 and EX4100-F only) If you configure any of the congestion or egress features in the feature profile for an inline-monitoring instance, you cannot configure a counter profile for a template in that instance.
  • (EX4100 and EX4100-F only) Because the congestion and egress features collect a lot of data, you can only configure 4 or 5 of these features per inline-monitoring instance.
  • (EX4100 and EX4100-F only) For multicast flow tracking, one ingress copy can produce multiple egress copies. All copies may update the same entry. Therefore, you can track the aggregate results of all copies of the same multicast flow.

Licenses

You must get a permanent license to enable FBT. To check if you have a license for FBT, issue the show system license command in operational mode:

For the EX4100 and EX4100-F switches, you need license S-EX4100-FBT-P. For the EX4400 switches, you need license S-EX-FBT-P.

Drop Vectors (EX4100 and EX4100-F only)

FBT can report more than 100 drop reasons. Drop vectors are very large vectors, too large to be reasonably accommodated in a flow record. Therefore, the software groups and compresses the drop vectors into a 16-bit compressed drop vector, and then passes that drop vector to the flow table. The 16-bit compressed drop vector corresponds to a particular drop vector group. Table 1 and Table 2 describe how drop vectors are grouped together to form a particular 16-bit compressed drop vector.

Table 1: Ingress Drop Vector Groups (EX4100 and EX4100-F only)
Group ID Drop Reason
1

MMU drop
2

TCAM, PVLAN
3

DoS attack or LAG loopback fail
4

Invalid VLAN ID, invalid TPID, or the port is not in the VLAN
5

Spanning Tree Protocol (STP) forwarding, bridge protocol data unit (BPDU), Protocol, CML

6

Source route, L2 source discard, L2 destination discard, L3 disable, and so on.
7

L3 TTL, L3 Header, L2 Header, L3 source lookup miss, L3 destination lookup miss
8

ECMP resolution, storm control, ingress multicast, ingress next-hop error
Table 2: Egress Drop Vector Groups (EX4100 and EX4100-F only)
Group ID Drop Reason
1

MMU unicast traffic
2

MMU weighted random early detection (WRED) unicast traffic
3

MMU RQE
4

MMU multicast traffic
5

Egress TTL, stgblock
6

Egress field processor drops
7

IPMC drops
8

Egress quality of service (QoS) control drops

Configure FBT (EX4100, EX4100-F, and EX4400 Series)

FBT enables per-flow-level analytics, using inline monitoring services to create flows, collect them, and export them to a collector. A flow is a sequence of packets that have the same source IP, destination IP, source port, destination port, and protocol on an interface. For each flow, various parameters are collected and sent to a collector using the open standard IPFIX template to organize the flow. Once there is no active traffic for a flow, the flow is aged out after the configured inactive-timeout period (configure the flow-inactive-timeout statement at the [edit services inline-monitoring template template-name] hierarchy level). The software exports a IPFIX packet periodically at the configured flow-export timer interval. The observation domain identifier is used in the IPFIX packet to identify which line card sent the packet to the collector. Once set, the software derives a unique identifier for each line card based upon the system value set here.

To configure flow-based telemetry:

  1. Define the IPFIX template.

    To configure attributes of the template:

    In this example, the inactive-flow timeout period is set to 10 seconds, the observation domain ID is set to 25, the template refresh rate is set to 30 seconds, and you've configured a template identifier

  2. Attach a template to the instance and describe the collector.

    To configure the instance and collector:

    In this example, you create a template with the name template_1, create an inline-monitoring instance i1, and create the configuration for the collector c2:

  3. Create a firewall filter and configure the action inline-monitoring-instance.

    To configure the firewall filter:

    In this example, you configure an IPv4 firewall filter named ipv4_ingress, with the term name rule1 containing the action inline-monitoring-instance, and the inline monitoring instance i1 is mapped to it:

  4. Map the firewall filter to the family under the logical unit of the already-configured interface to apply inline monitoring in the ingress direction.

    To map the firewall filter:

    In this example, you map the ipv4_ingress firewall filter to the inet family of logical interface 0 of the physical interface et-0/0/1:

  5. (Optional) Configure the sampling profile and rate, configure the profile for which counters to export to the collector, configure the flow rate and burst size, and enable security analytics for flow-based telemetry:

    To configure the flow-monitoring properties:

    In this example, the sampling profile is set to Random, the sampling rate is set to every 512 bytes, the counter profile is set to Per_flow_6_counters, the flow-rate is set to 100000 kbps, the burst-size is set to 2048 bytes, and security analytics are enabled:

  6. (Optional, EX4100 and EX4100-F switches only) Configure a feature profile to collect more data about packets as they move through the switch.

    For example, you could monitor congestion or collect information about why packets are being dropped. You can enable security analytics either here or in the previous step. To configure a feature profile:

    You must reboot the system for the feature profile to take effect. Because the aggregate interface distribution monitoring, congestion, and egress features collect a lot of data, you can only configure 4 or 5 of these features per inline-monitoring instance. The statements that configure these features are:

    • aggregate-intf-member-id

    • egress-drop-reason

    • inter-departure-time

    • queue-congestion-level

    • shared-pool-congestion

    After you commit the configuration and reboot the system, use the show services inline-monitoring feature-profile-mapping fpc-slot slot-number command to verify that the features have been successfully configured.

  7. After committing the configuration, monitor inline-monitoring statistics with the show services inline-monitoring statistics fpc-slot slot-number command.

Related Documentation

Change History Table

Feature support is determined by the platform and release you are using. Use Feature Explorer to determine if a feature is supported on your platform.

Release
Description
22.2R1
You can now configure flow-based telemetry (FBT) for the EX4100 and EX4100-F Series switches, and configure additional items to track for a flow using the feature-profile name features statement at the [edit inline-monitoring] hierarchy level.
21.1R1
You can configure flow-based telemetry (FBT) for the EX4400 Series switches. FBT enables per-flow-level analytics, using inline monitoring services to create flows, collect them, and export them to a collector.