Enterasys Networks Enterasys Vertical Horizon VH-8G - Manual (Page 19)

9033639 Product Overview 5
Spanning Tree Protocol
The VH-8G 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 using the Spanning Tree
Configuration Menu of the console menus, the on-board Web agent, or
via SNMP (see Appendix A, “Spanning Tree Concepts,” in the VH-8G
Management Guide for more information).
Frame Buffering and Frame Latency
The VH-8G 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
VH-8G switch provides 1 MB of frame buffering per port. 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.
Software Download
The VH-8G switch supports the industry-standard Trivial File Transfer
Protocol (TFTP) for downloading software to the switch. All switch
software is stored in a 2 MB sectored flash ROM. The download feature
allows you to easily install software upgrades to the unit. Software can
alternatively be downloaded via the serial console port using the
XMODEM protocol.
A TFTP software download is invoked via the Management Setup Menu
using the console menus. A TFTP download can also be invoked using
the on-board Web agent or via SNMP.
Non-volatile Parameter Storage
Important operating parameters such as IP addresses, Spanning Tree
configuration, and management security parameters, are stored in non
volatile Flash memory. These values are retained when the switch
experiences power interruptions or is powered down for normal
maintenance.
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