Lab V ( Nexus7k, Overlay Transport Virtualization )

OTV: Overlay Transport Virtualization

OTV(Overlay Transport Virtualization) is a technology that provide layer2 extension capabilities between different data centers.
I
n its most simplest form OTV is a new DCI (Data Center Interconnect) technology that routes MAC-based information by encapsulating traffic in normal IP packets for transit.

  • Transparent workload mobility
  • Business resiliency
  • Superior computing resource efficiencies
 DescriptionConfig
Overlay InterfaceLogical OTV Tunnel interfaceinterface Overlay1
OTV Join InterfaceThe physical link or port-channel that you use to route upstream towards the datacenter interconnectotv join-interface Ethernet2/1
OTV Control GroupMulticast address used to discover the remote sites in the control plane.otv control-group 224.100.100.100
OTV Data GroupUsed for tunneling multicast traffic over the OTV in the dataplaneotv data-group 232.1.2.0/24
Extend VLANsVLANs that will be tunneled over OTV.otv extend-vlan 100
Site VLANUsed to synchronize the Authoritative Edge Device (AED) role within an OTV site. otv site-vlan 999
Site IdentifierShould be unique per Datacenter. Used in AED Election.otv site-identifier 0x1

References:

Cisco: OTV Quick Start Guide

Cisco: NX-OS OTV Configuration Guide

Cisco: OTV Best Practices

Cisco: OTV Whitepaper

OTV Encapsulation

OTV adds a further 42 bytes on all packets traveling across the overlay network. The OTV Edge device removes the CRC and 802.1Q fields from the original Layer2 frame. It then adds an OTV Shim Header which includes this 802.1Q field (this includes the priority P-bit value) and the Overlay ID information. It also includes an external IP header for the transport network. All OTV packets have Don’t Fragment (DF) bit set to 1 in the external IP header.

Configs:

 

otv site-vlan 999
otv site-identifier 0x1

vlan 100
  name OTV-EXTEND
vlan 999
  name OTV-SITE-VLAN

interface Overlay1
  otv join-interface Ethernet2/1
  otv control-group 224.100.100.100
  otv data-group 232.1.2.0/24
  otv extend-vlan 100
  no shutdown

interface Ethernet2/1
  no switchport
  mac-address 0000.0000.002f
  ip address 1.1.1.2/30
  ip igmp version 3
  no shutdown
 sh otv

OTV Overlay Information
Site Identifier 0000.0000.0001
Encapsulation-Format ip - gre

Overlay interface Overlay1

 VPN name            : Overlay1
 VPN state           : UP
 Extended vlans      : 100 (Total:1)
 Control group       : 224.100.100.100
 Data group range(s) : 232.1.2.0/24
 Broadcast group     : 224.100.100.100
 Join interface(s)   : Eth2/1 (1.1.1.2)
 Site vlan           : 999 (up)
 AED-Capable         : Yes
 Capability          : Multicast-Reachable

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