Azure ExpressRoute Traffic Collector (Preview)

ExpressRoute Traffic Collector enables sampling of network flows sent over your ExpressRoute Direct circuits. Flow logs get sent to a Log Analytics workspace where you can create your own log queries for further analysis. You can also export the data to any visualization tool or SIEM (Security Information and Event Management) of your choice. Flow logs can be enabled for both private peering and Microsoft peering with ExpressRoute Traffic Collector.

Diagram of ExpressRoute traffic collector in an Azure environment.

Use cases

Flow logs can help you look into various traffic insights. Some common use cases are:

Network monitoring

  • Monitor Azure private peering and Microsoft peering traffic
  • Near real-time visibility into network throughput and performance
  • Perform network diagnosis
  • Capacity forecasting

Monitor network usage and cost optimization

  • Analyze traffic trends by filtering sampled flows by IP, port or by applications
  • Top talkers for a source IP, destination IP or applications
  • Optimize network traffic expenses by analyzing traffic trends

Network forensics analysis

  • Identify compromised IPs by analyzing all the associated network flows
  • Export flow logs to a SIEM (Security Information and Event Management) tool to monitor, correlate events, generate security alerts

Flow log collection and sampling

Flow logs are collected at an interval of every 1 minute. All packets collected for a given flow get aggregated and imported into a Log Analytics workspace for further analysis. During flow collection, not every packet is captured into its own flow record. ExpressRoute Traffic Collector uses a sampling rate of 1:4096, meaning 1 out of every 4096 packets gets captured. Therefore, sampling rate short flows (in total bytes) may not get collected. This sampling size doesn't affect network traffic analysis when sampled data is aggregated over a longer period of time. Flow collection time and sampling rate are fixed and can't be changed.

Flow log schema

Column Type Description
ATCRegion string ExpressRoute Traffic Collector (ATC) deployment region.
ATCResourceId string Azure resource ID of ExpressRoute Traffic Collector (ATC).
BgpNextHop string Border Gateway Protocol (BGP) next hop as defined in the routing table.
DestinationIp string Destination IP address.
DestinationPort int TCP destination port.
Dot1qCustomerVlanId int Dot1q Customer VlanId.
Dot1qVlanId int Dot1q VlanId.
DstAsn int Destination Autonomous System Number (ASN).
DstMask int Mask of destination subnet.
DstSubnet string Destination subnet of destination IP.
ExRCircuitDirectPortId string Azure resource ID of Express Route Circuit's direct port.
ExRCircuitId string Azure resource ID of Express Route Circuit.
ExRCircuitServiceKey string Service key of Express Route Circuit.
FlowRecordTime datetime Timestamp (UTC) when Express Route Circuit emitted this flow record.
Flowsequence long Flow sequence of this flow.
IcmpType int Protocol type as specified in IP header.
IpClassOfService int IP Class of service as specified in IP header.
IpProtocolIdentifier int Protocol type as specified in IP header.
IpVerCode int IP version as defined in the IP header.
MaxTtl int Maximum time to live (TTL) as defined in the IP header.
MinTtl int Minimum time to live (TTL) as defined in the IP header.
NextHop string Next hop as per forwarding table.
NumberOfBytes long Total number of bytes of packets captured in this flow.
NumberOfPackets long Total number of packets captured in this flow.
OperationName string The specific ExpressRoute Traffic Collector operation that emitted this flow record.
PeeringType string Express Route Circuit peering type.
Protocol int Protocol type as specified in IP header.
_ResourceId string A unique identifier for the resource that the record is associated with
SchemaVersion string Flow record schema version.
SourceIp string Source IP address.
SourcePort int TCP source port.
SourceSystem string
SrcAsn int Source Autonomous System Number (ASN).
SrcMask int Mask of source subnet.
SrcSubnet string Source subnet of source IP.
_SubscriptionId string A unique identifier for the subscription that the record is associated with
TcpFlag int TCP flag as defined in the TCP header.
TenantId string
TimeGenerated datetime Timestamp (UTC) when the ExpressRoute Traffic Collector emitted this flow record.
Type string The name of the table

Region availability

ExpressRoute Traffic Collector is supported in the following regions:

North America

  • Canada East
  • Canada Central
  • Central US
  • Central US EUAP
  • North Central US
  • South Central US
  • West Central US
  • East US
  • East US 2
  • West US
  • West US 2
  • West US 3

South America

  • Brazil South
  • Brazil Southeast


  • West Europe
  • North Europe
  • UK South
  • UK West
  • France Central
  • France South
  • Germany North
  • Sweden Central
  • Sweden South
  • Switzerland North
  • Switzerland West
  • Norway East
  • Norway West


  • East Asia
  • Central India
  • South India
  • Japan West
  • Korea South
  • UAE North


  • South Africa North
  • South Africa West


  • Australia Central
  • Australia Central 2
  • Australia East
  • Australia Southeast

Next steps