# How interface report data is calculated

Interface report data is calculated using the following formulas:

- [Interface Traffic](https://www.manageengine.com/network-monitoring/faq/interface-report-formulas.html#Traffic)
- [Interface Utilization](https://www.manageengine.com/network-monitoring/faq/interface-report-formulas.html#Utilization)
- [Packets](https://www.manageengine.com/network-monitoring/faq/interface-report-formulas.html#Packets_per_second)
- [Error Rate](https://www.manageengine.com/network-monitoring/faq/interface-report-formulas.html#Error_rate)
- [Discard Rate](https://www.manageengine.com/network-monitoring/faq/interface-report-formulas.html#Discard_rate)
- [Total Bytes Transferred](https://www.manageengine.com/network-monitoring/faq/interface-report-formulas.html#Total_Bytes_Transferred)
- [Errors and Discards](https://www.manageengine.com/network-monitoring/faq/interface-report-formulas.html#Errors_and_Discards)

## Interface Traffic

This refers to the amount of data transmitted or received via the interface at a given point of time (bits per second).

**In Traffic (bps)**:  
Rx Traffic: **Delta_InOctets * 8 * 1000 / deltatime**

**Out Traffic (bps)**:  
Tx Traffic: **Delta_OutOctets * 8 * 1000 / deltatime**

**Example:**

Lets consider the deltatime to be 15 minutes (900 seconds = 900000 milliseconds).  
InOctets taken at the 1st poll (0th Minute) = 1000  
InOctets taken at the 2nd poll (15th Minute) = 2000  

So, **Rx traffic** = ((2000 − 1000) * 8 * 1000) / 900000 = **8.9 Mbps**

| Metric | OID | Description |
|---|---|---|
| InOctets (bytes) |  | The difference between two ifInOctets collected at subsequent polls. |
| OutOctets (bytes) |  | The difference between two ifOutOctets collected at subsequent polls. |
| ifInOctets (bytes) | .1.3.6.1.2.1.2.2.1.10 | The total number of octets received on the interface, including framing characters. |
| ifOutOctets (bytes) | .1.3.6.1.2.1.2.2.1.16 | The total number of octets transmitted out of the interface, including framing characters. |
| deltatime |  | Time difference between two polls in milliseconds. |

**Note:**

1. Multiplying by 8 is for converting bytes to bits.  
2. Multiplying by 1000 is for converting "per millisecond" to "per second".  
3. The values mentioned in the above formulas (InOctets, OutOctets) are the difference between two ifOctets values and not raw values.

## Interface Utilization

This refers to the Network traffic / interface speed at a given point of time in percentage.

**In Utilization (%)**:  
(InTraffic / InSpeed) * 100 = (Delta_InOctets * 8 * 1000 * 100 / deltatime * InSpeed)

**Out Utilization (%)**:  
(OutTraffic / OutSpeed) * 100 = (Delta_OutOctets * 8 * 1000 * 100 / deltatime * OutSpeed)

| Metric | OID | Description |
|---|---|---|
| InOctets (bytes) |  | The difference between two ifInOctets collected at subsequent polls. |
| OutOctets (bytes) |  | The difference between two ifOutOctets collected at subsequent polls. |
| ifInOctets (bytes) | .1.3.6.1.2.1.2.2.1.10 | The total number of octets received on the interface, including framing characters. |
| ifOutOctets (bytes) | .1.3.6.1.2.1.2.2.1.16 | The total number of octets transmitted out of the interface, including framing characters. |
| deltatime |  | Time difference between two polls. |
| InSpeed / ifSpeed | .1.3.6.1.2.1.2.2.1.5 | An estimate of the interface's current bandwidth in bits per second (can be defined by user). |
| OutSpeed / ifSpeed | .1.3.6.1.2.1.2.2.1.5 | An estimate of the interface's current bandwidth in bits per second (can be defined by user). |

## Packets

This refers to the total number of packets transmitted or received per second.

**Rx Packets** = (INUCAST + INDISCARDS + INERRORS + INUNKNOWNPROTOS + HCINMCAST + HCINBCAST) * 1000 / deltatime  

**Tx Packets** = (OUTUCAST + HCOUTMCAST + HCOUTBCAST) * 1000 / deltatime

| Metric | OID | Description |
|---|---|---|
| InErrors | .1.3.6.1.2.1.2.2.1.14 | The number of inbound packets that contained errors preventing them from being deliverable to a higher-layer protocol. |
| INUCAST | .1.3.6.1.2.1.2.2.1.11 | The number of subnetwork-unicast packets delivered to a higher-layer protocol. |
| OUTUCAST | .1.3.6.1.2.1.2.2.1.17 | The total number of packets that higher-level protocols requested be transmitted to a subnetwork-unicast address, including those that were discarded or not sent. |
| INDISCARDS | .1.3.6.1.2.1.2.2.1.13 | The number of inbound packets which were chosen to be discarded even though no errors had been detected to prevent their being deliverable to a higher-layer protocol. One possible reason could be to free up buffer space. |
| INUNKNOWNPROTOS | .1.3.6.1.2.1.2.2.1.15 | The number of packets received via the interface which were discarded because of an unknown or unsupported protocol. |
| HCINMCAST | .1.3.6.1.2.1.31.1.1.1.8 | The number of packets delivered by this sub-layer to a higher layer addressed to a multicast address. 64-bit version of ifInMulticastPkts. |
| HCOUTMCAST | .1.3.6.1.2.1.31.1.1.1.12 | The total number of packets requested to be transmitted to a multicast address. 64-bit version of ifOutMulticastPkts. |
| HCINBCAST | .1.3.6.1.2.1.31.1.1.1.9 | The number of packets delivered to a broadcast address. 64-bit version of ifInBroadcastPkts. |
| HCOUTBCAST | .1.3.6.1.2.1.31.1.1.1.13 | The total number of packets requested to be transmitted to a broadcast address. 64-bit version of ifOutBroadcastPkts. |

## Error Rate

Error rate is the ratio between total number of Error packets and the total number of packets transmitted and received in percentage. It is calculated using SNMP interface OIDs like InErrors and OutErrors.

**32-bit:**

(InErrors + OutErrors) * 100 / (INUCAST + OUTUCAST + INDISCARDS + OUTDISCARDS + INERRORS + OUTERRORS + INUNKNOWNPROTOS + HCINBCAST + HCOUTBCAST)

**64-bit:**

(InErrors + OutErrors) * 100 / (INUCAST + OUTUCAST + INDISCARDS + OUTDISCARDS + INERRORS + OUTERRORS + INUNKNOWNPROTOS + HCINMCAST + HCOUTMCAST + HCINBCAST + HCOUTBCAST)

| Metric | OID | Description |
|---|---|---|
| InErrors | .1.3.6.1.2.1.2.2.1.14 | The number of inbound packets that contained errors preventing them from being deliverable to a higher-layer protocol. |
| OutErrors | .1.3.6.1.2.1.2.2.1.20 | The number of outbound packets that could not be transmitted because of errors. |
| INUCAST | .1.3.6.1.2.1.2.2.1.11 | The number of subnetwork-unicast packets delivered to a higher-layer protocol. |
| OUTUCAST | .1.3.6.1.2.1.2.2.1.17 | The total number of packets requested to be transmitted to a subnetwork-unicast address. |
| INDISCARDS | .1.3.6.1.2.1.2.2.1.13 | The number of inbound packets discarded even though no errors were detected. |
| OUTDISCARDS | .1.3.6.1.2.1.2.2.1.19 | The number of outbound packets discarded even though no errors were detected. |
| INUNKNOWNPROTOS | .1.3.6.1.2.1.2.2.1.15 | The number of packets discarded because of an unknown or unsupported protocol. |
| INNUCAST | .1.3.6.1.2.1.2.2.1.12 | The number of non-unicast packets delivered to a higher-layer protocol. |
| OUTNUCAST | .1.3.6.1.2.1.2.2.1.18 | The total number of non-unicast packets requested for transmission. |
| HCINMCAST | .1.3.6.1.2.1.31.1.1.1.8 | 64-bit version of ifInMulticastPkts. |
| HCOUTMCAST | .1.3.6.1.2.1.31.1.1.1.12 | 64-bit version of ifOutMulticastPkts. |
| HCINBCAST | .1.3.6.1.2.1.31.1.1.1.9 | 64-bit version of ifInBroadcastPkts. |
| HCOUTBCAST | .1.3.6.1.2.1.31.1.1.1.13 | 64-bit version of ifOutBroadcastPkts. |

## Discard Rate

Discard rate is the total number of discarded packets divided by the total number of packets transmitted and received, expressed as a percentage.

**32-bit:**

(InDiscards + OutDiscards) * 100 / (INUCAST + OUTUCAST + INDISCARDS + OUTDISCARDS + INERRORS + OUTERRORS + INUNKNOWNPROTOS + HCINBCAST + HCOUTBCAST)

**64-bit:**

(InDiscards + OutDiscards) * 100 / (INUCAST + OUTUCAST + INDISCARDS + OUTDISCARDS + INERRORS + OUTERRORS + INUNKNOWNPROTOS + HCINMCAST + HCOUTMCAST + HCINBCAST + HCOUTBCAST)

| Metric | OID | Description |
|---|---|---|
| InErrors | .1.3.6.1.2.1.2.2.1.14 | The number of inbound packets that contained errors. |
| OutErrors | .1.3.6.1.2.1.2.2.1.20 | The number of outbound packets that could not be transmitted because of errors. |
| INUCAST | .1.3.6.1.2.1.2.2.1.11 | The number of subnetwork-unicast packets delivered to a higher-layer protocol. |
| OUTUCAST | .1.3.6.1.2.1.2.2.1.17 | The total number of packets requested to be transmitted to a subnetwork-unicast address. |
| INDISCARDS | .1.3.6.1.2.1.2.2.1.13 | The number of inbound packets discarded even though no errors were detected. |
| OUTDISCARDS | .1.3.6.1.2.1.2.2.1.19 | The number of outbound packets discarded even though no errors were detected. |
| INUNKNOWNPROTOS | .1.3.6.1.2.1.2.2.1.15 | The number of packets discarded because of an unknown or unsupported protocol. |
| INNUCAST | .1.3.6.1.2.1.2.2.1.12 | The number of non-unicast packets delivered to a higher-layer protocol. |
| OUTNUCAST | .1.3.6.1.2.1.2.2.1.18 | The total number of non-unicast packets requested for transmission. |
| HCINMCAST | .1.3.6.1.2.1.31.1.1.1.8 | 64-bit version of ifInMulticastPkts. |
| HCOUTMCAST | .1.3.6.1.2.1.31.1.1.1.12 | 64-bit version of ifOutMulticastPkts. |
| HCINBCAST | .1.3.6.1.2.1.31.1.1.1.9 | 64-bit version of ifInBroadcastPkts. |
| HCOUTBCAST | .1.3.6.1.2.1.31.1.1.1.13 | 64-bit version of ifOutBroadcastPkts. |

## Total Bytes Transferred

This refers to the total number of bytes transferred and received in the interface.

Rx Bytes = INOCTETS  
Tx Bytes = OUTOCTETS  
Total Bytes = INOCTETS + OUTOCTETS

| Metric | OID | Description |
|---|---|---|
| InOctets (bytes) |  | The difference between two ifInOctets collected at subsequent polls. |
| OutOctets (bytes) |  | The difference between two ifOutOctets collected at subsequent polls. |
| ifInOctets (bytes) | .1.3.6.1.2.1.2.2.1.10 | The total number of octets received on the interface, including framing characters. |
| ifOutOctets (bytes) | .1.3.6.1.2.1.2.2.1.16 | The total number of octets transmitted out of the interface, including framing characters. |

## Errors and Discards

This refers to the total number of error and discard packets transmitted or received via the interface.

RxError = InErrors  
TxError = INDISCARDS  
RxDiscard = OutErrors  
TxDiscard = OUTDISCARDS

| Metric | OID | Description |
|---|---|---|
| InErrors | .1.3.6.1.2.1.2.2.1.14 | The number of inbound packets that contained errors preventing them from being deliverable to a higher-layer protocol. |
| OutErrors | .1.3.6.1.2.1.2.2.1.20 | The number of outbound packets that could not be transmitted because of errors. |
| INDISCARDS | .1.3.6.1.2.1.2.2.1.13 | The number of inbound packets discarded even though no errors were detected. |
| OUTDISCARDS | .1.3.6.1.2.1.2.2.1.19 | The number of outbound packets discarded even though no errors were detected. |