Catalyst Report

The following columns are used in the Catalyst 5000 report.

Port

The card and port number of an individual Ethernet segment.

Name

An ASCII description for the port.

VL (VLAN)

The VLAN number that the port is connected to. For individual department reports, this value will likely have the same value on every line in the report.

T (Trunk)

Indicates wheither the port is a VLAN trunk port or not. Trunk ports carry traffic for more than one VLAN. A Trunk is indicated by a T in the column, otherwise the column is a dash (-). A departmental report will likely have all ports non-trunked. Trunking is normally reserved for between CITES backbone switches only.

dp (Duplex)

Indicates if the connection is half-duplex (HD) or full-duplex (FD). Normal Ethernet is half-duplex. Only point-to-point links (ones not connecting to repeaters) can be full-duplex. Likewise, each device at each end of the point-to-point link must support full-duplex for this option to work.

%Col (Percent Collision)

Indicates the percentage collisions on this link. This value is not useful for full-duplex links (since they do not experience collisions). Large percent collisions may indicate heavy traffic, synchronized network activity, or a problem on the network.

InMB (Input megabytes)

The total number of traffic (in megabytes) sent to the Catalyst switch. Note that a "k" in this field (e.g. 102k) indicates traffic in gigabytes, and a "m" in this field (e.g. 234m) indicates terabytes.

OutMB (Output megabytes)

The total number of traffic (in megabytes) sent from the Catalyst switch. Note that a "k" in this field (e.g. 102k) indicates traffic in gigabytes, and a "m" in this field (e.g. 234m) indicates terabytes.

Dsc (Discards)

The number of packets discarded by the Catalyst for this port. It includes both the number of packets sent to the Catalyst discarded (e.g. switch congestion) and the number of packets that the Catalyst wanted to transmit (e.g. due to excessive collisions on the Ethernet).

Algn (Alignment Errors)

The number of packets sent to the Catalyst that had alignment errors in them. An alignment error is defined as packets that "do not have an integral number" of bytes. A high number of alignment errors usually indicates a problem on the network.

CRC

The number of packets sent to the Catalyst that had a CRC (a.k.a. FCS) error. These packets do not have alignment errors, but do not have the correct value for the CRC check at the end of the packet. A high number of CRC errors usually indicates a problem on the network.

Lt (Late)

The number of packets transmitted by the Catalyst that was involved in a late collision. A late collision is an Ethernet collision that occurrs after the normal collision window.

Opinion: Even a small number of late collisions can cause a large performance problem on the network.

Exc (Excessive Collisions)

The number of packets that the Catalyst switch tried to transmit and could not due to colliding too many times. A large number indicates a very busy network or a problem on the network.

Gnt (Giant)

The number of packets that the Catalyst received that was larger than Ethernet's maximum size.

CS (Carrier Sense Errors)

The number of times that the carrier sense was lost (or fluctuated) when a packet was transmitted from the Catalyst.

Other Notes

If a value for a field does not fit in the field, the value will be "scaled" by 1,000 (or 1,000,000, etc.). The letter "k" is put on the end of the value if the number is scaled by 1,000. Likewise "m" is used for x 1,000,000, etc.

If there is no data for a field, it's value will be a DASH (-) instead.

Many of these fields are from standard SNMP MIBs. You may want to look at the following RFC's for further reference.

RFC1213

MIB-II: The main MIB for SNMP

RFC1284

MIB variables for Ethernet (and Ethernet-like) devices

RFC1573

Additional variables for MIB-II