Glossary
5 Switching Functions
Switching refers to all the rules and mechanisms in the EFN324, which
collectively decide what will happen to a packet which arrives at a certain port:
Will the packet be discarded, or will it be forwarded?
To which port, or ports, will it be forwarded?
Will the content be modified, and if so, how?
All available switching mechanisms are described in the following sections,
starting with basic switching mechanisms and ending with options like IP
validation, Quality of Service and so on.
5.1 Main Switching Steps
When a packet arrives at an Ethernet port, the main question is whether there
is a matching ingress connection. If not, the packet is discarded. If there is a
matching connection, the packet is forwarded to the switching domain
identified by that connection.
Figure 13 Ingress port switching
Similarly, when the packet arrives at a switching domain, the main question is
whether there is a matching egress connection.
switching
domain
Ethernet
port
Incoming
packet
VLAN ID = x
switching
domain
switching
domain
? ?
?
Is there an
ingress
connection
for VLAN ID
= x ?
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