Examining Port Fields
Switch1 (enable) show port 10/3
* = Configured MAC Address
Port Send FlowControl Receive FlowControl RxPause TxPause
admin oper admin oper
----- -------- -------- --------- --------- ---------- ----------
10/3 off off off off 0 0
Port Status Channel Admin Ch
Mode Group Id
----- ---------- -------------------- ----- -----
10/3 connected auto silent 620 0
Port Status ErrDisable Reason Port ErrDisableTimeout Action on Timeout
---- ---------- ------------------- ---------------------- -----------------
10/3 connected - Enable No Change
Port Align-Err FCS-Err Xmit-Err Rcv-Err UnderSize
----- ---------- ---------- ---------- ---------- ---------
10/3 11 0 0 0 6
Port Single-Col Multi-Coll Late-Coll Excess-Col Carri-Sen Runts Giants
----- ---------- ---------- ---------- ---------- --------- --------- ---------
10/3 218713 197092 0 401867 0 27 0
The following define the more important fields associated with
the show port command:
-
Alignment Errors— Frames
received that do not end with an even number of octets. Frame also has a bad
cyclic redundancy check (CRC). Misconfiguration is generally the culprit. Ensure
that adjacent connected devices have the same duplex setting configuration.
-
FCS Errors— Bad CRC on the
frame packet transmitted/received. These packets are dropped by the switch at
the port level.
-
Xmit Errors— Internal transmit
buff is full.
-
RCV Errors— Internal receive
buff is full.
-
Single Collisions— The number
of times the transmitting port had one collision before successfully
transmitting the frame on the wire. Single collisions are part of normal
operation in a half-duplex environment because of carrier sense multiple access
collision detect (CSMA/CD) rule.
-
Multiple Collisions— The
number of times the transmitting port had more than one collision before
successfully transmitting the frame on the wire. Multiple collisions do occur if
the medium is busy enough.
-
Late Collisions— Usually
indicative of the cable exceeding IEEE specifications. Cascading hubs can also
cause the length of the collision domain to increase above specification. A Time
Delay Reflectometer (TDR) can be used to detect cable fault and whether the
cable is within the IEEE standard. Other factors that cause late collisions
include mismatched duplex settings and bad transceivers.
-
Excessive Collisions— The
number of frames that are dropped because the transmitting port saw 16
collisions in a row. This should not occur and can be attributed to possibly a
design flaw that is exacerbating an already congested link.
-
Runts— Frames smaller than 64
bytes with a bad frame check sequence (FCS). Bad cabling or inconsistent duplex
setting usually cause runts.
-
Giants— Frames greater than
1518 with a bad FCS. Investigate NIC issues on the port.
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