Contemporary Control Systems EIS UL864-Compliant Switches - Manual (Page 5)

TD070500-0IC
5
OPERATION
Switching
The EISwitch can learn and store up to 2K MAC addresses in its address look-up table.
An address-hashing algorithm is used to update the table. Addresses are aged in 300
seconds. Runt packets (less than 64 bytes) are always discarded. Oversize packets
(greater than 1518 or 1522 bytes) or packets with a bad CRC are discarded.
Data Storage
Data storage consists of 768 Kbits of built-in SRAM memory divided into 512 bytes per
block. Received packets will be separated into several 512-byte blocks and chained
together for storage before forwarding. The inter-packet gap (IPG) is the idle time
between any two successive packets from the same port and is typically 96 bit times.
This translates to 9.6 µs for 10 Mbps and 960 ns for 100 Mbps.
Flow Control
Each port automatically negotiates flow control for either half- or full-duplex operation.
In full-duplex mode, the PAUSE function is supported. In half-duplex mode, the
backpressure method is used.
Far End Fault
Auto negotiation provides a mechanism for transferring information from the Local
Station to the link Partner that a remote fault has occurred for 100BASE-TX. As auto
negotiation is not currently specified for operation over fibre, the far end fault indication
function (FEFI) provides this capability for 100BASE-FX applications.
A remote fault is an error in the link that one station can detect while the other cannot.
An example of this is a disconnected wire at a station’s transmitter. This station will be
receiving valid data and detect that the link is good via the link integrity monitor but will
not be able to detect that its transmission is not propagating to the other station.
A 100BASE-FX station that detects such a remote fault may modify its transmitted idle
stream from all ones to a group of 84 ones followed by a single 0. This is referred to as
the FEFI idle pattern.
LEDs
PWR (green) Power — Glows when proper power is supplied to the EISwitch.
LINK (green) Link — Each port has one of these LEDs which glows to indicate
that a valid Ethernet link has been established. The LED flashes
when data transfer is occurring.
HS (yellow) Data Rate — Each port has one of these LEDs which glows to
indicate that data is transferring at 100 Mbps.