To minimize the possibility of dropping frames on congested ports, each RFL
3000 4K24 Switch dynamically allocates buffer space from a 1MB memory pool,
ensuring that heavily used ports receive very large buffer space for packet storage.
(Many other switches have their packet buffer storage space divided evenly across all
ports, resulting in a small, fixed number of packets to be stored per port. When the port
buffer fills up, dropped packets may result.) This dynamic buffer allocation provides the
capability for the maximum resources of the RFL 3000 4K24 unit to be applied to all
traffic loads, even when the traffic activity is unbalanced across the ports. Since the
traffic on an operating network is constantly varying in packet density per port and in
aggregate density, the RFL 3000 4K24 Switches are constantly adapting internally to
provide maximum network performance with the least dropped packets.
When the 4K24 Switch detects that its free buffer queue space is low, the Switch
sends industry standard (full-duplex only) PAUSE packets out to the devices sending
packets to cause “flow control”. This tells the sending devices to temporarily stop
sending traffic, which allows a traffic catch-up to occur without dropping packets. Then,
normal packet buffering and processing resumes. This flow-control sequence occurs in a
small fraction of a second and is transparent to an observer. See Section 4.6 for
additional details.
Another feature implemented in RFL 3000 4K24 Switches is a collision-based
flow-control mechanism (when operating at half-duplex only). When the Switch detects
that its free buffer queue space is low, the Switch prevents more frames from entering by
forcing a collision signal on all receiving half-duplex ports in order to stop incoming
traffic.
The latency (the time the frame spends in the Switch before it is sent along or
forwarded to its destination) of the 4K24 Switches varies with the port-speed types, and
the length of the frame is a variable here as it is with all store-and-forward switches. The
4K24 Switch’s latency is 5 microseconds plus the packet time. See Section 1.1,
Specifications.
2.3
Features and Benefits
100Mb switching services for high performance Ethernet LANs
RFL 3000 4K24 Switches provide Fast Ethernet switching on all ports. They
perform high speed filter/forward operations on the traffic, giving each port’s
segment a full 100Mb (or 10 Mb) of bandwidth.
Option to configure with one or two fiber ports
Fiber port modules are available with one or two 100Mb mm-ST, SC, MTRJ
or single-mode SC. The configuration flexibility of fiber ports allows 4K24
switches to adapt to mixed and changing fiber types.
RJ-45 (copper) ports, with N-way auto-negotiation
