.. _l2:

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Layer 2
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This section identifies the features associated with Layer 2:

MAC Layer
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* Ethernet

Discovery
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* Cisco Discovery Protocol v2 (CDP)
* Link Layer Discovery Protocol (LLDP)

Link Layer Control Protocol
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* Bit Index Explicit Replication – Link Layer Multi-cast forwarding.
* Link Layer Control (LLC) - multiplex protocols over the MAC layer. 
* Spatial Reuse Protocol (SRP)
* High-Level Data Link Control (HDLC)
* Logical link control (LLC)
* Link Agg Control Protocol (Active/Active, Active/Passive) – 18.04 

Virtual Private Networks
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* MPLS 
  
  * MPLS-o-Ethernet – Deep label stacks supported

* Virtual Private LAN Service (VPLS)
* VLAN
* Q-in-Q
* Tag-rewrite (VTR) - push/pop/Translate (1:1,1:2, 2:1,2:2)
* Ethernet flow point Filtering
* Layer 2 Cross Connect

Bridging
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* Bridge Domains
* MAC Learning (50k addresses)
* Split-horizon group support
* Flooding

ARP
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* Proxy
* Termination
* Bidirectional Forwarding Detection

Integrated Routing and Bridging (IRB)
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* Flexibility to both route and switch between groups of ports.
* Bridged Virtual Interface (BVI) Support, allows traffic switched traffic to be routed.