Information Technology Reference
In-Depth Information
Firewalls
to control and filter access
■
Intrusion detection devices
to detect network attacks
■
Core
Distribution
Layer
DC
Access Layer
Blade Chassis
with Integrated Switch
L2 Clusters
NIC Teaming
Blade Chassis
with Passthru
L3 Access
Mainframe
Figure 3-15
Enterprise Data Center
Campus LAN QoS Considerations
For the acces s layer of the c ampus L AN, you c an clas sify and mark frames or packets to
apply quality of service (QoS) policies in the distribution or at the enterprise edge. Classi-
fication is a fundamental building block of QoS and involves recognizing and distinguish-
ing between different traffic streams. For example, you distinguish between HTTP/
HTTPS, FTP, and VoIP traffic. Without classification, all traffic is treated the same.
Marking sets certain bits in a packet or frame that has been classified. Marking is also
called coloring or tagging. Layer 2 has two methods to mark frames for CoS:
Inter-Switch Link (ISL)
■
IEEE 802.1p/802.1Q
■
The IEEE 802.1D-1998 standard describes IEEE 802.1p traffic class expediting.
encapsulation method for carrying VLANs over Fast Ethernet or Gigabit Ethernet interfaces.
