SYSTEM LUX 10n

10/100Mbit Modular Switched Hub

Obsolete

Basic Architecture

The system works on the store and forward principle i.e. an input message is stored and then sent to the desired output, the input message being interrogated to determine both its source and destination address.

The source addresses are used to construct an address table such that messages will only be sent to the unique destination port. The hub has to learn the port address from the input messages. Until the address is learnt the message is sent to all ports. If no message is received from that port for a specified time then it is deleted from the address table ( this process is called 'ageing' ). This gives some protection against terminals being moved between ports as it will not be recognized until either a packet is sent from the new port or it is 'aged' out.

Port Auto-negotiation (copper only)

Each port will negotiate with its link partner to be able to connect using the maximum data rate that is mutually achievable, in this order :-

100Mbit Full Duplex

100Mbit Half Duplex

10Mbit Full Duplex

10Mbit Half Duplex

Module options

STP 4 port 10/100 RJ45 connector

STP 1 port 10/100 RJ45 connector

FO 1 port 10 ST connectors

FO 1 port 100 ST or SC connectors

FO 1 port 1Gbit MT-RJ connector

Specification

Power 85~264Vac 50~60Hz 40VA IEC inlet

Cooling Forced air by 2 internal fans

Indicators Link - green

( all modules) Data - red

Dimensions 432 x 285 x 44 (rack mounts add 25mm each side)

Temperature 0 deg.C ~ 55 deg.C (operating)

Humidity 10% ~ 90% (non-condensing)

Standards IEEE 802.3, IEEE802.3u, IEEE802.3z, CE

Optical Receiver sensitivity better than -32.5dBm avg. for 10-9 BER

Transmitter power (mean optical power) better than -20dBm into 62.5/125um fibre of 0.275NA

Wavelength 830nm (1300nm for 100 Base FX)

Link length in excess of 2km

* For single mode add £25.00 for each  module

In a switch the least reliable module is the fan and PSU. The fan problem can be reduced by using good quality components and to operate fans in parallel. The fan usually becomes noisy before complete failure so there normally is time to replace it.

The PSU is highly stressed both by transients and temperature. The PSU itself has filters mainly for EMC but they also offer some transient protection. If the operating temperature of the PSU can be reduced then the reliability will be significantly increased. This can be achieved by either de-rating the PSU or dueling PSU's such that they supply half the full current each but supply the full current should the other fail. The system reliability is then further enhanced as the probability of the second PSU failing before replacement of the faulty unit is very low.

VolAmp Ltd has now introduced a load share chassis into its range to cater for the requirement for high reliability. The chassis incorporates two PSU's and a load share monitor circuit. Should any supply fail then an audible signal is emitted and the faulty PSU can be replace at a convenient time. The monitor circuit identifies the faulty supply via LED's which are visible once the lid is removed.

The chassis have been designated as =

VES-B8-LS  for 8 port switch

VES-B16-LS  for 16 port switch

VES-B24-LS  for 24 port switch

Physically the Load Share chassis is identical to the normal single supply unit.