Spotlight on Oracle 11.0 - Getting Started Guide

TCP/IP (Transmission Control Protocol/Internet Protocol) is one means by which computers communicate across a network. It is the basic protocol used for communication across the Internet.

Communication programs that use the TCP/IP protocol are built in two layers:

The TCP layer converts a data stream into a series of packets for transmission across a network. When these packets are received at their destination, another TCP layer reassembles the data stream.
The IP layer ensures that data packets reach the right destination.

To open the TCPIP page

Select the Spotlight on Windows connection in the Spotlight Browser.
Click Network | TCPIP.

Charts on the TCPIP page

Notes:

Click an item in the legend to highlight its series (line) in the chart. Click a second time to return the series to its normal appearance.
Move the mouse pointer over an item in the legend to view the current value for that series within the chart.

Chart

Description

TCP Segments

When TCP transfers a stream data, it breaks up the stream into small segments. The TCP Segments chart displays three different graphs representing the rate at which TCP segments are transmitted or received in the current Windows system.

Graph	Description
Sent	The rate at which TCP segments are transmitted by the current system.
Received	The rate at which TCP segments are received by the current system.
Retransmitted	The rate of transmission of TCP segments that have already been sent, but need to be retransmitted because of packet time-out or some other transmission error.

Sent, Received and Retransmitted are each represented by a single line on the chart, and by an item in the legend at the right of the chart.

IP Fragments

When data packets are transmitted across a network via TCP/IP, they may be further fragmented en route, and need to be reassembled. The IP Fragments chart displays the rates at which the fragmented packets are received and rebuilt.

The graphs on the chart display one of the following features of IP fragmentation:

Graph	Description
Received	The rate at which IP fragments are received successfully.
Created	The rate at which IP datagram fragments are generated as a result of fragmentation.
Re-assembled	The rate at which IP fragments are rebuilt into their original data packets. Packets are fragmented when they travel through a router that needs to send packets that are smaller than the packets received.
Datagrams	The rate at which IP fragments are created on the current system. This applies only to routed packets.
Failures	The rate at which the current system receives data packets that are too large to be transmitted, and that cannot be fragmented. The cause may be the presence of a "do not fragment" flag in the IP packet header.
Reassembly failures	The rate at which errors are reported when IP fragments are reassembled into data packets. This may be due to an error in one or more fragments.

Each data series in the IP Fragments chart is represented by a single line, and by an item in the legend at the right of the chart.

UDP Datagrams

UDP (User Datagram Protocol) is an alternative communications protocol to the Transmission Control Protocol (TCP).

Unlike TCP, UDP does not provide a sequencing service, so when UDP datagrams (packets) arrive at a destination, they are reassembled into a complete message via an end-point application that is active on the port(s) specified in the datagram. The UDP Datagrams chart displays three different graphs representing the rate at which UDP datagrams are transmitted or received in the current Windows system.

Graph	Description
Sent	The rate at which UDP datagrams are transmitted by the current system.
Received	The rate at which UDP datagrams are received by the current system.
No port	During transmission, UDP provides port numbers to distinguish different user requests. The No Port metric displays the number of packets received per second that do not have an end-point application active on the specified port.

Sent, Received and No Port are each represented by a single line on the chart, and by an item in the legend at the right of the chart.

IP Datagrams / IP Datagram Errors

IP datagrams (packets) are the message units that are transmitted across a network (and across the Internet) via the Internet Protocol.

Use the IP Datagrams control to choose to view IP Datagrams or IP Datagram Errors.

The IP Datagrams chart:

The rate at which IP packets are sent, received, and routed to other destinations.

Graph	Description
Sent	The rate at which IP datagrams (packets) are being sent by the current system.
Received	The rate at which IP datagrams are being received by the current system.
Forwarded	The rate at which the current system is routing IP datagrams to another destination.
Received delivered	The rate at which the system successfully receives and accepts IP packets.

The IP Datagram Errors chart:

The number of errors that occur when IP packets are sent, received, and routed to other destinations.

Graph	Description
Outbound discarded	The number of outbound packets discarded because of an issue unrelated to the packets themselves (for example, if the send buffer is full).
Outbound no route	The number of outbound packets discarded because the system cannot route the packets to the destination IP address.
Received address errors	The number of times that the system has received packets that do not have a valid return address.
Received discarded	The rate at which received packets are discarded because of an issue unrelated to the packets themselves (for example, if the receive buffer is full).
Received header errors	The number of times that the system has received packets that have errors in the IP header area (for example, a packet checksum error).
Received unknown protocol	The number of times that the system has received packets that are correctly addressed, but that use a protocol unsupported by the IP handler on the system.

Notes:

Each data series in the IP Datagrams chart is represented by a single line, and by an item in the legend at the right of the chart.
The information represents the number of errors detected since the chart was last refreshed.

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Spotlight on Oracle 11.0 - Getting Started Guide

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