Enterasys Vertical Horizon VH-8TX1MF, User Manual, Page: 23 / 54

9033718-01
Product Overview 9
that could add to a congestion condition. The VH-8TX1UM/VH-8TX1MF
switch supports flow control per the IEEE 802.3x standard. Note that flow
control is disabled on all ports by default but can be enabled on a per-port
basis by using the console interface menus, the on-board Web agent, or
via SNMP. See Appendix B, “Flow Control,” for more information on this
feature.
Virtual LANs (VLANs)
VLANs allow you to connect users to a specific LAN segment regardless
of their physical location. The VH-8TX1UM/VH-8TX1MF switch supports
tagged VLANs per the IEEE 802.1Q draft standard. With frame tagging,
a short tag is appended to every frame that crosses the network
backbone. The tag identifies which VLAN the frame belongs to. See
Appendix B, “Virtual LANs,” in the Management Guide for more
information.
Class of Service
Class of Service support allows you to assign a higher priority to selected
traffic passing through the switch. The VH-8TX1UM/VH-8TX1MF switch
supports Class of Service attributes per the IEEE 802.1p standard using
a priority queuing mechanism. This feature ensures that traffic during
congestion periods will not interfere with traffic assigned a higher priority.
Traffic assigned a lower priority is subject to discard when memory is in
short supply. See Appendix C, “Class of Service,” in the Management
Guide for more information.
Port Trunking
Port trunking allows you to combine ports into an aggregate connection
between VH-8TX1UM/VH-8TX1MF switches. Besides balancing the load
across each port in the trunk, the additional ports provide redundancy by
taking over the load if a port in the trunk should fail. The VH-8TX1UM/VH-
8TX1MF allows up to four RJ-45 ports to be joined together as a trunk.
The switch supports only one trunk group per unit.
NOTE: If flow control is desired for one port, it is recommend-
ed that it be enabled on all ports. However, note that flow con-
trol should not be used if a port is connected to a hub. Also, be
aware that when interconnecting high-speed LANs (such as
Gigabit Ethernet) and low-speed LANs, flow control can cause
traffic from the high-speed LAN to be blocked for all other
ports on the switch.