Finisar Surveyor TCP Window Probe, Between 206.250.228.69/TCP/IP WKP1988 206.250.228.11/SMTP

Expert Features 10

Transport Layer

TCP Window Probe

Counter

TCP Window Probe is a counter of all TCP Window Probe events over a period of time per segment. A count of all TCP Window Probe events displays in the Overview counters of Expert View. A threshold for this counter can be set in Expert Alarms.

Expert Symptom

TCP Window Probe events are automatically logged as expert symptoms. The Symptom Summary field provides information about the well-known ports (WKP) involved, including the port number and the IP address. For example:

Between [206.250.228.69]/[TCP/IP WKP:1988] and

[206.250.228.11]/[SMTP]

The TCP window size is examined for every packet to check for one-byte data packets. If a TCP/IP packet with one byte of data is encountered, the event is logged. One-byte data packets are sent periodically by the sender to see if the receiver’s window has reopened to allow the sender to resume transmitting.

Diagnostic Details

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Problem Description:

A TCP/IP packet with one byte of data has been sent to check whether the receiver’s window has been reopened.

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Probable Cause(s):

1.The receiver is overloaded.

2.The receiver has run out of buffer space.

3.The non-responsive receiver intends the sender to close the connection.

4.There may be a problem with the receiver’s TCP/IP stack.

5.There are too many connections to the receiver resulting in reduced buffer space.

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Recommended Action(s):

1.Upgrade the receiver’s CPU and/or Memory.

2.Reduce the number of connections to the receiver.

3.Increase the network bandwidth.

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