Information Technology Reference
In-Depth Information
Redistribution between routing domains (for example, between two different routing
protocols)
Demarcation between static and dynamic routing protocols
Yo u can use several Cisco IOS Software feat ure s to implement policy at the distribu-
tion layer:
Filtering by source or destination address
Filtering on input or output ports
Hiding internal network numbers by route filtering
Static routing
QoS mechanisms, such as priority-based queuing
The distribution layer provides aggregation of routes providing route summarization to
the core. In the campus LANs, the distribution layer provides routing between VLANs
that also apply security and QoS policies.
Access Layer
The access layer provides user access to local segments on the network. The access layer is
characterized by switched LAN segments in a campus environment. Microsegmentation
using LAN switches provides high bandwidth to workgroups by reducing the number of
devices on Ethernet segments. Functions of the access layer include the following:
Layer 2 switching
High availability
Port security
Broadcast suppression
QoS classification and marking and trust boundaries
Rate limiting/policing
Address Resolution Protocol (ARP) inspection
Virtual access control lists (VACL)
Spanning tree
Tr u st clas s ific at ion
Power over Ethernet (PoE) and auxiliary VLANs for VoIP
Auxiliary VLANs
Yo u i m p l e m e n t h i g h a v a i l a b i l i t y m o d e l s a t t h e a c c e s s l a y e r. T h e s e c t i o n , “ N e t w o r k
Availabilit y,” covers availabilit y models. The L AN sw itch in the acces s layer c an control
access to the port and limit the rate at which traffic is sent to and from the port. You can
access lists.
 
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