3com 2226 PLUS User Guide
8
C
HAPTER
1: I
NTRODUCING
THE
B
ASELINE
S
WITCH
SFP Ports
The two SFP ports support fiber Gigabit Ethernet
short-wave (SX) and long-wave (LX) SFP transceivers
in any combination. This offers you the flexibility of
using SFP transceivers to provide connectivity
between the Switch and a 1000 Mbps core network.
When an SFP port is in operation, the corresponding
10/100/1000BASE-T port is disabled.
short-wave (SX) and long-wave (LX) SFP transceivers
in any combination. This offers you the flexibility of
using SFP transceivers to provide connectivity
between the Switch and a 1000 Mbps core network.
When an SFP port is in operation, the corresponding
10/100/1000BASE-T port is disabled.
Traffic Prioritization
The Switch supports two types of traffic prioritization:
■
Prioritization of IP phone traffic
■
Priority Queuing
Prioritization of IP Phone Traffic
The Switch can recognize when an NBX phone is con-
nected to any of the ports 1 to 24. The Switch will
automatically detect the NBX phone when the phone
starts up, and will ensure that traffic to and from the
phone is given the highest priority.
nected to any of the ports 1 to 24. The Switch will
automatically detect the NBX phone when the phone
starts up, and will ensure that traffic to and from the
phone is given the highest priority.
To ensure that the NBX phone is recognized by the
Switch during its initialization, do not connect any
data source through the phone until the phone has
finished its startup sequence.
Switch during its initialization, do not connect any
data source through the phone until the phone has
finished its startup sequence.
Once the phone is available for use, any data source
(for example, a computer) can then be connected to
the phone’s pass-through port. This only applies if
you use a single wall jack for your network connec-
tion and use the pass-through LAN port on the NBX
phone.
(for example, a computer) can then be connected to
the phone’s pass-through port. This only applies if
you use a single wall jack for your network connec-
tion and use the pass-through LAN port on the NBX
phone.
Traffic Priority Queuing
The Switch also offers priority queuing. It examines
each packet that it receives to determine if it is prior-
ity-encoded. If a packet is priority-encoded, the
Switch reads the priority level and determines
whether the packet should be directed through the
normal or high priority channel. This feature is useful,
for example, during periods of excessive network
load, when one type of traffic may require priority
over another. The Switch is configured to comply
with 802.1p, VLAN tagged frames.
each packet that it receives to determine if it is prior-
ity-encoded. If a packet is priority-encoded, the
Switch reads the priority level and determines
whether the packet should be directed through the
normal or high priority channel. This feature is useful,
for example, during periods of excessive network
load, when one type of traffic may require priority
over another. The Switch is configured to comply
with 802.1p, VLAN tagged frames.
Traffic prioritization ensures that high priority data is
forwarded through the Switch without being delayed
by lower priority data. It differentiates traffic into
classes and prioritizes those classes automatically.
forwarded through the Switch without being delayed
by lower priority data. It differentiates traffic into
classes and prioritizes those classes automatically.
Traffic prioritization uses multiple traffic queues that
are present in the hardware of the Switch to ensure
that high priority traffic is forwarded on a different
queue from lower priority traffic, and is given prefer-
ence over that traffic. This ensures that time-sensitive
traffic gets the highest level of service.
are present in the hardware of the Switch to ensure
that high priority traffic is forwarded on a different
queue from lower priority traffic, and is given prefer-
ence over that traffic. This ensures that time-sensitive
traffic gets the highest level of service.
The 802.1D standard specifies eight distinct levels of
priority (0 to 7), each of which relates to a particular
type of traffic. The priority levels and their traffic types
are shown in
priority (0 to 7), each of which relates to a particular
type of traffic. The priority levels and their traffic types
are shown in
Table 3 Priority Levels for Traffic Types
Priority Level
Traffic Type
0
Best effort
1
Background
2
Standard (spare)