HP-UX HB v13.00 Ch-09 - Networking Basics

HP-UX Handbook – Rev 13.00 Page 15 (of 27)
Chapter 09 Network Basics
October 29, 2013
(10HD/100HD/100FD/1000FD/100000FD…).
If you use 100BaseT interfaces, the whole environment works more stable if you avoid the value
AUTO
If you use Gigabit interfaces, it is strongly suggested to use the value AUTO only.
duplex communication system is a system composed of two connected parties or devices that
can communicate with one another in both directions.
Ref: http://en.wikipedia.org/wiki/Duplex_(telecommunications)
The term multiplexing is used when describing communication between more than two parties
or devices.
A half-duplex system provides communication in both directions, but only one direction at a
time (not simultaneously). Typically, once a party begins receiving a signal, it must wait for the
transmitter to stop transmitting, before replying
A full-duplex or sometimes double-duplex system, allows communication in both directions,
and, unlike half-duplex, allows this to happen simultaneously. Land-line telephone networks are
full-duplex, since they allow both callers to speak and be heard at the same time
Autonegotiation is an Ethernet procedure by which two connected devices choose common
transmission parameters, such as speed, duplex mode, and flow control. In this process, the
connected devices first share their capabilities regarding these parameters and then choose the
highest performance transmission mode they both support.
Ref: http://en.wikipedia.org/wiki/Autonegotiation
Auto-sensing is and Ethernet procedure by which two connected devices can match the line
speed of its link partner but the adapter cannot sense the duplex mode. Auto detection is only a
speed sensing mechanism; it does not support the additional features Auto Negotiation provides.
Flow Control - A sending station (computer or network switch) may be transmitting data faster
than the other end of the link can accept it. Flow control is used to halt or slow down the
transmission of data, (using PAUSE frames) until the receiving side can clear the existing
buffers.
MTU - Maximum transmission unit is the size of the largest packet that a network protocol can
transmit. Most Ethernet traffic is transmitted using a MTU size of 1500 bytes. Jumbo frames can
be anywhere in the range of 1500 – 9000 depending on the implementation in the network.
Path MTU Discovery a technique for determining the path MTU between two IP hosts. The
path MTU is the largest packet size that can traverse this path without suffering fragmentation.
In Ethernet, a “duplex mismatch” is a condition where two connected devices operate in
different duplex modes, that is, one operates in half duplex while the other one operates in full
duplex. The effect of a duplex mismatch is a network that works but is often much slower than
its nominal speed. Duplex mismatch may be caused by manually setting two connected network
interfaces at different duplex modes or by connecting a device that performs Autonegotiation to
one that is manually set to a full duplex mode.
Ref: http://en.wikipedia.org/wiki/Duplex_mismatch
More than one physical interfaces
IP addresses of different active physical interfaces must belong to different logical subnets. Even
if some experienced administrators are capable of configuring their environment differently, we
cannot support this setup. Instead, if there is a need for different physical interfaces to handle