3Com 1005 To best suit your networking requiremen ts, the Switch 1005 allows you , to set one of four frame forwarding modes:, operate in Store and Forward mode until the error count returns to 0., 1005 detects more than 18 packets per second with errors, it will , with errors, it will operate in Fast Forward mode. As soon as the Switch , accordingly. If the Switch 1005 detects less than 18 packets per second , error traffic on the network and changes the forwarding mode , In this mode, the Switch 1005 monitors the amount of , Intelligent, the last bit of the frame, and transmitting the first bit. For the Switch , and Forward mode, latency is measured as the time between receiving , varies between 64s and 1.2ms, depending on frame length. In Store , are passed to their destination. The forwarding delay for this mode , their entirety prior to forwardin g. This ensures that only good frames , In this mode, received packets are buffered in , Store and Forward, network, however, CRC errors are forwarded. The for warding delay, or , ensures that collision fragments are not propagated through the , received frame is buffered prior to the frame being forw arded. This , mode, a minimum of 64 bytes of the , this , In , Fragment F ree, checking time, any collision fragments or error frames received are , latency, for all frames in this mode is just 40 s but with the lack of , destination address is received and verified. The forwarding delay, or , In this mode, frames are forwarded as soon as the , Fast For ward, propagated through the switch., latency, for all frames in this mode is 64 s., 1005, this is 8s.

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To best suit your networking requiremen ts, the Switch 1005 allows you
to set one of four frame forwarding modes:
■ Fast For ward — In this mode, frames are forwarded as soon as the
destination address is received and verified. The forwarding delay, or
latency, for all frames in this mode is just 40µ s but with the lack of
checking time, any collision fragments or error frames received are
propagated through the switch.
■ Fragment F ree — In this mode, a minimum of 64 bytes of the
received frame is buffered prior to the frame being forw arded. This
ensures that collision fragments are not propagated through the
network, however, CRC errors are forwarded. The for warding delay, or
latency, for all frames in this mode is 64 µs.
■ Store and Forward — In this mode, received packets are buffered in
their entirety prior to forwardin g. This ensures that only good frames
are passed to their destination. The forwarding delay for this mode
varies between 64µs and 1.2ms, depending on frame length. In Store
and Forward mode, latency is measured as the time between receiving
the last bit of the frame, and transmitting the first bit. For the Switch
1005, this is 8µs.
■ Intelligent — In this mode, the Switch 1005 monitors the amount of
error traffic on the network and changes the forwarding mode
accordingly. If the Switch 1005 detects less than 18 packets per second
with errors, it will operate in Fast Forward mode. As soon as the Switch
1005 detects more than 18 packets per second with errors, it will
operate in Store and Forward mode until the error count returns to 0.
Any port EXCEPT backbone port
(Multi/Broadcast packet)
Not applicable Forward to all ports
(including backbone
port) within same VLAN
as source port
Backbone port (Unicast packet) Unknown Filter (discard)
Backbone port (Unicast packet) Known on a port (not
backbone port)
Forward to specific port
only
Backbone port
(Multi/Broadcast packet)
Not applicable Forward to all ports
within specific VLAN
Packet Source Destination Address Action