Course Content
Spanning Tree
An overview of how switches become aware of other switches and prevent loops.
0/2
Multiple Spanning Tree Protocol (MST)
0/1
Advanced OSPF
The (OSPF) protocol scales well with proper network planning. IP addressing schemes, area segmentation, address summarization, and hardware capabilities for each area should considered when designing a network.
0/6
Introduction to Automation Tools  
To provide a high-level overview of some of the most common configuration management and automation tools that are available.
0/3
ENCOR Course
About Lesson

Virtual Extensible Local Area Network (VXLAN)

describes VXLAN as a data plane protocol that is open to operate with any control plane protocol.

  • Server Virtualization has placed an increased demand on legacy network infrastructure.
  • Layer 2 networks were not designed to support hundreds of thousands of MAC addresses and tens of thousands of VLANs.
  • VXLAN is designed to address the issues being seen in traditional Layer 2 networks.

Issues with Legacy Layer 2 Networks

Virtualization has led to a number of problems with traditional Layer 2 Networks:

  • The 12-bit VLAN ID yields 4000 VLANs, which are insufficient for server virtualization.
  • Large MAC address tables are needed due to the hundreds of thousands of VMs and containers attached to the network.
  • STP blocks links to avoid loops, and this results in a large number of disabled links, which is unacceptable.
  • ECMP is not supported.
  • Host mobility is difficult to implement.

VXLAN Network Identifier

VXLAN has a 24-bit VXLAN network identifier (VNI), which allows for up to 16 million VXLAN segments (more commonly known as overlay networks) to coexist within the same infrastructure.

  • VNI is located in the VXLAN shim header that encapsulates the original inner MAC frame originated by an endpoint. The VNI is used to provide segmentation for Layer 2 and Layer 3 traffic.
  • To facilitate the discovery of VNIs over the underlay Layer 3 network, virtual tunnel endpoints (VTEPs) are used.
  • Each VTEP has two interfaces:

 

Local LAN interfaces – These interfaces on the local LAN segment provide bridging between local hosts.

 

IP interface – This is a core-facing network interface for VXLAN. The IP interface’s IP address helps identify the VTEP in the network.

VXLAN Headers

 

  • There are minor differences between the Layer 2 LISP specification and the VXLAN specification headers. LISP fields not ported over to VXLAN are reserved for future use.
  • Cisco Software Defined Access (SD-Access) is an example of an implementation of VXLAN with the LISP control plane.

Other useful information:

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