Cisco Datacenter: Default Cisco OTV Configurations

Today I am going to talk about the Cisco OTV configuration and what components we need to configure when you are extended your L2 traffic over the L3 interface between the two Datacenter. 

What is Cisco OTV ?

Cisco OTV stands for Overlay Transport Virtualization, So OTV is a Cisco propriety protocol used in Cisco Datacenter environment basically on Cisco Nexus device Cisco Nexus 7k to extend the L2 traffic via L3 route between two different datacenter. 

OTV will provides a native built-in multi-homing capability with automatic detection, critical to increasing high availability of the overall solution. Cisco OTV has the concept of dynamic encapsulation for Layer 2 flows that need to be sent to remote locations. 

Each Ethernet frame is individually encapsulated into an IP packet and delivered across the transport network. Cisco OTV eliminates the need to establish virtual circuits, called Pseudowires, between the data center locations and you can say that it os one of the demanding technology in datacenter environment where you have Cisco Nexus devices.

Cisco OTV required the one single VDC to work, it means if you are going to have a one Cisco Nexus 7k switch you need to have the separate VDC for Cisco OTV.

Cisco OTV has three kinds of interfaces which are 

• OTV internal interface: Cisco internal interface is a Layer 2 interfaces, where the Layer 2 traffic is usually received, are named internal interfaces.
• OTV join interface: Cisco join interface is a Layer 3 entity and can only be defined as a physical interface (or subinterface) or as a logical one. You can also say that it is a Layer 3 port channel or Layer 3 port channel sub-interface
• OTV overlay interface: Cisco OTV Overlay interface is a logical multi-access and multicast-capable interface that must be explicitly defined by the user and where the entire OTV configuration is applied.

Below is just a example of the network diagram showing connectivity between the two datacenter and have Cisco OTV between them to extend the Layer 2 traffic from one Data-Center to another.

Fig 1.1- Sample Cisco OTV connectivity

How configurations are done on the Cisco Nexus 7k Switch with OTV VDC. Below are the configurations. All the IP's and the interfaces used here in the below example is only to explain and has no relevance with any of the live or enterprise datacenter networks.

Enabling OTV Features

ttlbits_switch# configure terminal

ttlbits_switch(config)#

ttlbits_switch(config)# feature otv

ttlbits_switch(config)# show feature | include otv

Overlay Interface

ttlbits_switch(config)# interface overlay 1

ttlbits_switch(config-if-overlay)#

ttlbits_switch(config-if-overlay)# description site 4

ttlbits_switch(config-if-overlay)# show otv overlay 1

ttlbits_switch(config-if-overlay)# copy running-config startup-config

Configuring the Multicast Group Address

ttlbits_switch(config)# interface overlay 1

ttlbits_switch(config-if-overlay)#

ttlbits_switch(config-if-overlay)# otv control-group 239.1.1.1

ttlbits_switch(config-if-overlay)# otv data-group 232.1.1.0/28

ttlbits_switch(config-if-overlay)# show otv datagroup

ttlbits_switch(config-if-overlay)# copy running-config startup-config

Physical Interface to the Overlay Interface

ttlbits_switch(config)# interface overlay 1

ttlbits_switch(config-if-overlay)#

ttlbits_switch(config-if-overlay)# otv join-interface ethernet 2/1

ttlbits_switch(config-if-overlay)# show otv overlay 1

ttlbits_switch(config-if-overlay)# copy running-config startup-config

Assigning the Extended VLAN Range

ttlbits_switch(config)# interface overlay 1

ttlbits_switch(config-if-overlay)#

ttlbits_switch(config-if-overlay)# otv extends-vlan 2,5-34

ttlbits_switch(config-if-overlay)# otv extends-vlan add 3

ttlbits_switch(config-if-overlay)# show otv vlan 2

ttlbits_switch(config-if-overlay)# copy running-config startup-config

Site VLAN and Site Identifier

ttlbits_switch(config)# otv site-vlan 10

ttlbits_switch(config)# otv site-identifier 256

ttlbits_switch(config)# show otv site

ttlbits_switch(config)# copy running-config startup-config

Preparing OTV for ISSU

edge-device-1(config)# interface overlay1

edge-device-1(config-if-overlay)# shutdown

edge-device-1(config)# otv site-identifier 256

edge-device-1(config)# switchback

ttlbits_switch# configure terminal

ttlbits_switch(config)#

ttlbits_switch(config)# copp profile strict

ttlbits_switch(config)# switchto vdc edge-device-1

edge-device-1# configure terminal

edge-device-1(config)#

edge-device-1(config)# interface overlay1

edge-device-1(config-if-overlay)# no shutdown

edge-device-2(config)# interface overlay1

edge-device-2(config-if-overlay)# shutdown