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Switching, Filtering, and Forwarding
Each time a packet arrives at one of the switched ports, a decision is made to
either filter or forward the packet. Packets with source and destination
addresses belonging to the same port segment will be filtered, constraining
those packets to one port, and relieving the rest of the network from the need to
process them. A packet with destination address on another port segment will
be forwarded to the appropriate port, and will not be sent to the other ports
where it is not needed. Packets that are used in maintaining the operation of the
network (such as the occasional multi-cast packet) are forwarded to all ports.
IE-SW-VL16 Switches operate in the store-and-forward switching mode,
which eliminates bad packets and enables peak performance to be achieved
when there is heavy traffic on the network.
Switching and Address Learning
IE-SW-VL16 Switches have an address table that can hold up to 4K node
addresses, which makes it suitable for use with large networks. The address
tables are self-learning, so that as nodes are added or removed, or moved from
one segment to another, the switch automatically keeps up with new node
locations. An address-aging algorithm causes the least-used addresses to be
deleted in favor of newer, more frequently used addresses. To reset the address
buffer, power down the unit and then power it back up.
Auto-Negotiation and Speed Sensing
All of the RJ45 Ethernet ports independently support auto-negotiation for
speeds in the 10BaseT and 100BaseTX modes, with operation according to the
IEEE 802.3u standard. This means that some nodes could be operating at 10
Mbps, while at the same time other nodes are operating at 100 Mbps.
Auto-negotiation takes place when an RJ45 cable connection is made, and then
each time a LINK is enabled. An IE-SW-VL16 Switch advertises its capability
for using either 10 Mbps or 100 Mbps transmission speeds, with the device at
the other end of the cable expected to similarly advertise. Depending on what
type of device is connected, this will result in agreement to operate at a speed
of either 10 Mbps or 100 Mbps.
If an RJ45 Ethernet port is connected to a non-negotiating device, the default
values 10 Mbps speed and half-duplex mode will be set, as required by the
IEEE 802.3u standard.
Specifications
Technology
Standards
IEEE802.3, 802.3u, 802.3x
Forward and Filtering
148810 pps (100M), 14881 pps (10M)
Rate
Packet Buffer Memory
1.25 MB
Processing Type
Store and Forward, with IEEE802.3x full duplex,
back pressure flow control
Address Table Size
4K uni-cast addresses
Interface
RJ45 Ports
10/100BaseT(X) auto negotiation speed, F/H duplex
mode, and auto MDI/MDI-X connection
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