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24 Chapter 1: Design Overview
Figure 1-10
Distribution Layer
The distribution layer connects networks that can also connect access layer networks that are
located in the same corporate/campus network. The distribution layer can be compared to a
boulevard or thoroughfare that provides a link to the existing infrastructure. Implement policy
at the distribution layer.
The following issues might be determined by the network administrator and controlled at the
distribution layer:
·
Access to parts of the internetwork
·
Access to services on the internetwork
·
Definition of path metrics
Security is an example of policy that should be defined at the distribution layer. Cisco IOS
features implement security by:
·
Filtering by source or destination address
·
Filtering on input or output ports
·
IP accounting
·
SNMP traps
·
Hiding internal network numbers by route filtering
·
Static routing
File
servers
Campus
backbone
To core
layer
To access
layer
Campus
backbone
R1
R2
87200333.book Page 24 Wednesday, August 22, 2001 2:18 PM