Instruction manual

ConneXium Ethernet Switch 499NES18100 8-Port 10/100 Base-TX Quick Reference Guide
31005416 02 August 2004 7
Functional Description
Overview The 10/100 base-T ports provide terminal connections for the connected LAN
segment. You can connect single devices or complete network segments. The
module supports several frame switching, TP/TX interface, and other functions.
Switch
Functions
The ConneXium 499NES18100 supports four frame switching functions:
Store and forward switching:
All data received by the ConneXium 499NES18100 switch from the system bus or
at the ports are stored and checked for validity. Invalid and defective frames (frames
greater than 1536 bytes or with a CRC error) and frame fragments (greater than
64 bytes) are discarded. The switch forwards the valid frames.
Multi-address switching:
The switch learns all its source addresses on a per-port basis. Only packets with
unknown addresses
addresses learned at the specific port
a multi-broadcast address
in the destination address field are sent to the port.
A switch can learn up to 1000 addresses. This becomes necessary if more than one
terminal device is connected to one or more port(s). Multi-address switching allows
several independent subnetworks to be connected to a ConneXium 499NES18100
switch.
Learned address switching?
The switch monitors the age of the learned addresses and deletes entries from the
address table when they exceed a certain age (300 s).
Tagging
The switch includes a VLAN tag (designated by the IEEE 802.1 Q standard) in a
MAC data frame for VLAN and prioritizing functions. The tag comprises four bytes—
a two-byte tag protocol identifier (TPID) and two bytes of tag control information
(TCI). It is inserted between the source address field and the type field. Data packets
with VLAN tags are transmitted unchanged by the 499NES18100.
Note: Restarting deletes the learned address entries.