# Port Counters

This section displays the Receive and Transmit data shown below. Refer to Appendix A Port Counters Overview for more information.

Receive Counters
Data Displayed | Description
--- | ---
RcvData | The total number of fabric packet flits received. This counter includes all fabric packet flits received with and without errors (such as PktBadTail). Only includes flits actually received (for example, `PktLen` in header may exceed actual flits received in certain error situations, in which case only actual flits received are counted. In IB mode: The total number of data octets, divided by 4, received.
RcvPkts | The total number of fabric packets received. This counter includes all fabric packet head flits received with and without errors (such as `PktBadHead`).
MulticastRcvPkts | The total number of multicast and collective packets received. This counter includes all valid packets and all packets with a header up to and including the DLID, where the DLID is within the configured range for multicast or collectives. Packets within the configured multicast or collective address space are counted, even if later checks determine the packet is unroutable or exceeds the SwitchInfo.MulticastFDBCap, SwitchInfo.CollectiveFDBCap, configured SwitchInfo.MulticastFDBTop or configured SwitchInfo.CollectiveFDBTop.
RcvErrors | This counter indicates the total number of packets containing an error that were received by the port, including physical errors and malformed packets. It may indicate possible misconfiguration of a port, either by the SM or (more likely) by user intervention (e.g., using a tool such as opaportconfig).
RcvConstraintErrors | This counter is incremented when partition key or source LID violations are detected in a received packet, indicating a possible security issue or misconfiguration of device security settings.
RcvSwitchRelayErrors | This counter indicates the number of packets that were dropped due to internal routing errors. It is indicative of the possible misconfiguration of a switch by the SM.
RcvRemotePhysicalErrors | This counter indicates the number of downstream effects of signal integrity problems. It is indicative of an SI issue in the upstream path.
RcvFECN | When a device receives a packet with the FECN (Forward Explicit Congestion Notification) bit set to one, this counter is incremented.
RcvBECN | When a device receives a packet with the BECN (Backward Explicit Congestion Notification) bit set to one, this counter is incremented.
RcvBubble | This counter indicates the total number of "flit times" where one or more packets have been started to be received, but receiver received idle flits from the wire.

Transmit Counters
Data Displayed | Description
--- | ---
XmitData | The total number of fabric packet flits transmitted. Does not include idle nor other LF command flits. This counter includes all fabric packet flits transmitted without and with errors (such as PktBadTail). Only includes flits actually transmitted (e.g., PktLen in header may exceed actual flits transmitted in certain error situations, in which case only actual flits transmitted are counted).
XmitPkts | The total number of fabric packets transmitted. This counter includes all fabric packet head flits transmitted with and without errors (such as PktBadHead).
MulticastXmitPkts | The total number of multicast and collective packets transmitted
Transmit Discards | The number of packets dropped due to one of the following errors: Switch lifetime Limit exceeded Switch head-of-queue lifetime limit exceeded Output port not in active state Packet length exceeded maximum fabric packet size for MTU for VL Flow control disabled and insufficient credits available SC2VL_t mapping invalid for given SC
XmitConstraintErrors | This counter is incremented when partition key or source LID violations are detected in a packet attempting to be transmitted, indicating a possible security issue or misconfiguration of device security settings.
XmitWait | This counter indicates the amount of time (in "flit times") any virtual lane had data but was unable to transmit (for reasons such as no credits available, or that the link was busy sending non-data packets such as link layer retraining or flow control).
XmitTimeCong | This counter indicates the total number of "flit times" that the counter was in a congested state.
XmitWastedBW | This counter indicates the number of "flit times" where one or more packets have been started but the transmitters is forced to send idles due to bubbles.
XmitWaitData | This counter indicates the number of "flit times" where one or more packets have been started but interrupted due to bubbles in the ingress stream.