Information Technology Reference
In-Depth Information
Redistribution between routing domains (for example, between two different routing
protocols)
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Demarcation between static and dynamic routing protocols
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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
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Filtering on input or output ports
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Hiding internal network numbers by route filtering
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Static routing
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QoS mechanisms, such as priority-based queuing
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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
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High availability
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Port security
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Broadcast suppression
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QoS classification and marking and trust boundaries
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Rate limiting/policing
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Address Resolution Protocol (ARP) inspection
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Virtual access control lists (VACL)
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Spanning tree
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Tr u st clas s ific at ion
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Power over Ethernet (PoE) and auxiliary VLANs for VoIP
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Auxiliary VLANs
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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.