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Server Load Balancer:NLB monitoring metrics

Last Updated:Jun 10, 2026

Network Load Balancer (NLB) provides monitoring metrics that help you track instance load and performance, and troubleshoot issues such as request timeouts and traffic throttling.

Usage notes

When you call the CloudMonitor API, you must specify the following parameters: Namespace, Period, MetricName, and Dimensions.

  • The Namespace is acs_nlb.

  • The default Period is 60 seconds. You can set this parameter to any multiple of 60.

  • The Dimensions parameter is a JSON string, such as [{"instanceId":"nlb-defs3vztfty3nm****"}]. The instanceId value in Dimensions is the NLB instance ID.

NLB monitoring metrics

Console, API, and SDK metrics

Metric category

Metric

Description

MetricName

Dimensions

Statistics

Instance connection metrics

New connections to an instance per second

The number of new TCP and UDP connections processed by the NLB instance per second. Unit: Count/s

InstanceNewConnection

userId, instanceId

Average

Dropped connections to an instance per second

The number of TCP and UDP connections dropped by the NLB instance per second. Unit: Count/s

InstanceDropConnection

userId, instanceId

Average

Active connections to an instance

The number of TCP connections to the NLB instance that are in the ESTABLISHED state. Unit: Count

Note

If you use persistent connections, a single connection can handle multiple requests.

InstanceActiveConnection

userId, instanceId

Average

Inactive connections to an instance

The number of TCP connections to the NLB instance that are not in the ESTABLISHED state and all UDP connections to the instance. Unit: Count

InstanceInactiveConnection

userId, instanceId

Average

Concurrent connections to an instance

The total number of TCP and UDP connections processed by the NLB instance. Unit: Count

InstanceMaxConnection

userId, instanceId

Average

Instance bandwidth metrics

Inbound packets received per second by an instance

The number of inbound TCP and UDP packets received by the NLB instance per second. Unit: Count/s

InstancePacketRX

userId, instanceId

Average

Outbound packets sent per second by an instance

The number of outbound TCP and UDP packets sent by the NLB instance per second. Unit: Count/s

InstancePacketTX

userId, instanceId

Average

Inbound bits received per second by an instance

The amount of inbound TCP and UDP traffic received by the NLB instance per second. Unit: bit/s

InstanceTrafficRX

userId, instanceId

Average

Outbound bits sent per second by an instance

The amount of outbound TCP and UDP traffic sent by the NLB instance per second. Unit: bit/s

InstanceTrafficTX

userId, instanceId

Average

Inbound packets dropped per second by an instance

The number of inbound TCP and UDP packets that the NLB instance fails to receive per second. Unit: Count/s

InstanceDropPacketRX

userId, instanceId

Average

Outbound packets dropped per second by an instance

The number of outbound TCP and UDP packets that the NLB instance fails to send per second. Unit: Count/s

InstanceDropPacketTX

userId, instanceId

Average

Inbound bits dropped per second by an instance

The amount of inbound TCP and UDP traffic that the NLB instance fails to receive per second. Unit: bit/s

InstanceDropTrafficRX

userId, instanceId

Average

Outbound bits dropped per second by an instance

The amount of outbound TCP and UDP traffic that the NLB instance fails to send per second. Unit: bit/s

InstanceDropTrafficTX

userId, instanceId

Average

Listener connection metrics

Active connections to a listener

The number of TCP connections to the listener port that are in the ESTABLISHED state. Unit: Count

Note

If you use persistent connections, a single connection can handle multiple requests.

ActiveConnection

userId, instanceId, listenerPort, listenerProtocol

Average

Inactive connections to a listener

The number of TCP connections to the listener port that are not in the ESTABLISHED state and all UDP connections to the listener port. Unit: Count

InactiveConnection

userId, instanceId, listenerPort, listenerProtocol

Sum

Concurrent connections to a listener

The total number of TCP or UDP connections processed by the listener port. Unit: Count

MaxConnection

userId, instanceId, listenerPort, listenerProtocol

Average

Dropped connections to a listener per second

The number of TCP or UDP connections that are dropped on the listener port per second. Unit: Count/s

DropConnection

userId, instanceId, listenerPort, listenerProtocol

Average

New connections to a listener per second

The number of new TCP or UDP connections processed by the listener port per second. Unit: Count/s

NewConnection

userId, instanceId, listenerPort, listenerProtocol

Average

Listener bandwidth metrics

Outbound packets sent per second by a listener

The number of outbound TCP or UDP packets sent from the listener port per second. Unit: Count/s

ListenerPacketTX

userId, instanceId, listenerPort, listenerProtocol

Average

Inbound packets received per second by a listener

The number of inbound TCP or UDP packets received by the listener port per second. Unit: Count/s

ListenerPacketRX

userId, instanceId, listenerPort, listenerProtocol

Average

Outbound listener bandwidth

The amount of outbound TCP or UDP traffic sent from the listener port per second. Unit: bit/s

TrafficTXNew

userId, instanceId, listenerPort, listenerProtocol

Average

Inbound listener bandwidth

The amount of inbound TCP or UDP traffic received by the listener port per second. Unit: bit/s

TrafficRXNew

userId, instanceId, listenerPort, listenerProtocol

Average

Inbound packets dropped per second by a listener

The number of TCP or UDP packets that the listener port fails to receive per second. Unit: Count/s

DropPacketRX

userId, instanceId, listenerPort, listenerProtocol

Average

Outbound packets dropped per second by a listener

The number of TCP or UDP packets that the listener port fails to send per second. Unit: Count/s

DropPacketTX

userId, instanceId, listenerPort, listenerProtocol

Average

Outbound bits dropped per second by a listener

The amount of outbound TCP or UDP traffic that the listener port fails to send per second. Unit: bit/s

DropTrafficTX

userId, instanceId, listenerPort, listenerProtocol

Average

Inbound bits dropped per second by a listener

The amount of inbound TCP or UDP traffic that the listener port fails to receive per second. Unit: bit/s

DropTrafficRX

userId, instanceId, listenerPort, listenerProtocol

Average

Listener health check metric

Unhealthy backend instances for a listener

The number of backend instances for the listener port that are in an unhealthy state. Unit: Count

ListenerUnhealthyServerCount

userId, instanceId, listenerPort, listenerProtocol

Maximum

VIP (zone) connection metrics

Active connections to a VIP

The number of ESTABLISHED TCP connections for a specific VIP in a zone. Unit: Count

VipActiveConnection

userId, instanceId, vip

Average

Inactive connections to a VIP

For a specific VIP in a zone, this metric counts all UDP connections and TCP connections that are not in the ESTABLISHED state. Unit: Count

VipInactiveConnection

userId, instanceId, vip

Average

Concurrent connections to a VIP

The total number of TCP and UDP connections processed by a specific VIP in a zone. Unit: Count

VipMaxConnection

userId, instanceId, vip

Average

Dropped connections to a VIP per second

The number of TCP and UDP connections that are dropped by a specific VIP in a zone per second. Unit: Count/s

VipDropConnection

userId, instanceId, vip

Average

New connections to a VIP per second

The number of new TCP and UDP connections processed by a specific VIP in a zone per second. Unit: Count/s

VipNewConnection

userId, instanceId, vip

Average

VIP (zone) bandwidth metrics

Outbound bits through a VIP per second

The amount of outbound TCP and UDP traffic sent through a specific VIP in a zone per second. Unit: bit/s

VipTrafficTX

userId, instanceId, vip

Average

Inbound bits through a VIP per second

The amount of inbound TCP and UDP traffic received through a specific VIP in a zone per second. Unit: bit/s

VipTrafficRX

userId, instanceId, vip

Average

Outbound packets through a VIP per second

The number of outbound TCP and UDP packets sent through a specific VIP in a zone per second. Unit: Count/s

VipPacketTX

userId, instanceId, vip

Average

Inbound packets through a VIP per second

The number of inbound TCP and UDP packets received through a specific VIP in a zone per second. Unit: Count/s

VipPacketRX

userId, instanceId, vip

Average

Dropped outbound bits through a VIP per second

The amount of TCP and UDP traffic that a specific VIP in a zone fails to send per second. Unit: bit/s

VipDropTrafficTX

userId, instanceId, vip

Average

Dropped inbound bits through a VIP per second

The amount of TCP and UDP traffic that a specific VIP in a zone fails to receive per second. Unit: bit/s

VipDropTrafficRX

userId, instanceId, vip

Average

Dropped inbound packets through a VIP per second

The number of TCP and UDP packets that a specific VIP in a zone fails to receive per second. Unit: Count/s

VipDropPacketRX

userId, instanceId, vip

Average

Dropped outbound packets through a VIP per second

The number of TCP and UDP packets that a specific VIP in a zone fails to send per second. Unit: Count/s

VipDropPacketTX

userId, instanceId, vip

Average

API and SDK metrics

Metric category

Metric

Description

MetricName

Dimensions

Statistics

VIP (zone)

Inbound reset packets per second from VIP client

The number of TCP reset (RST) packets received from clients per second by a specific VIP in a zone. Unit: Count/s

VipClientResetPacket

userId, instanceId, vip

Average

Inbound reset packets per second from backend servers

The number of TCP reset (RST) packets sent from backend servers to clients per second through a specific VIP in a zone. Unit: Count/s

RealServerResetPacket

userId, instanceId, vip

Average

Related information

View NLB monitoring data