Cabletron Systems SmartSTACK ELS100 - Manual (Page 20)

6 Product Overview ELS100-24TX
Feature Summaries
The following summaries provide a brief description of ELS100-24TX
features in areas such as standards compliance, functionality,
performance, and options.
IEEE 802.1D Bridge
The ELS100-24TX switch is fully compliant with IEEE 802.1D transparent
bridging specifications. An aggregate address table containing 4096
entries per 8 switch ports is provided for learning, filtering, and forwarding.
The switch can support up to a maximum of 12,288 addresses.
Addresses are automatically learned by the switch, and can be
individually assigned specific forwarding treatment by the network
administrator if desired. Forwarding table configuration can be made out-
of-band via the console interface or in-band via SNMP or Telnet. Static
and dynamic addresses are both stored in this table. One static address
is assigned per port by default. The Forwarding Table Configuration
screen in the console menus allows you to assign additional static
addresses if required.
Spanning Tree Protocol
The ELS100-24TX switch supports the IEEE 802.1D Spanning Tree
Protocol. This protocol allows redundant connections to be created
between different LAN segments for purposes of fault tolerance. Two or
more physical paths between different segments can be created through
the switch, with the Spanning Tree Protocol choosing a single path at any
given time and disabling all others. If the chosen path fails for any reason,
a disabled alternative is activated, thereby maintaining the connection.
This prevents network traffic from circulating in an endless loop formed by
multiple connections to the same LAN segment.
Spanning Tree parameters are configurable in the Spanning Tree
Configuration Menu using the console menus or via SNMP (see Appendix
B, “Spanning Tree Concepts,” for more information).
Frame Buffering and Frame Latency
The ELS100-24TX switch is a store-and-forward switching device. Each
frame is copied into switch memory before being forwarded to another
port. This method ensures that all forwarded frames conform to a
standard Ethernet frame size and have a correct cyclic redundancy check
(CRC) for data integrity. This switching method prevents bad frames from
traversing the network and using up valuable network bandwidth, as with
cut-through switching technology.
To minimize the possibility of dropping frames on congested ports, the
ELS100-24TX switch provides 4 MB of dynamically allocated frame
buffering per 8 ports. This buffer space is used to queue packets for
transmission on congested networks. This is an additional advantage
over cut-through switching technology, which drops packets immediately
when experiencing collisions.