Ask the Expert: Understanding OTV (Overlay Transport Virtualization) on Nexus 7K

[ciscomoderator]

Welcome to the Cisco Support Community Ask the Expert conversation.  This is an opportunity to learn and ask questions about Overlay Transport Virtualization (OTV)

Overlay Transport Virtualization (OTV) on the N7K is an industry-first technology that significantly simplifies extending Layer 2 applications across distributed data centers. You can now deploy Data Center Interconnect (DCI) between sites without changing or reconfiguring your existing network design.

OTV is an IP-based functionality that has been designed from the ground up to provide Layer 2 extension capabilities over any transport infrastructure: Layer 2 based, Layer 3 based, IP switched, label switched, and so on. The only requirement from the transport infrastructure is providing IP connectivity between remote data center sites. In addition, OTV provides an overlay that enables Layer 2 connectivity between separate Layer 2 domains while keeping these domains independent and preserving the fault-isolation, resiliency, and load-balancing benefits of an IP-based interconnection.

Sandip Rathod is a Network Consulting Engineer in the Cisco AS Team based in Bangalore, India. He has worked and designed various project of many large customers like KPN, BT, Infosys, ITENOS, Vodacom etc. His areas of expertise include data center, routing, switching, MPLS. He has extensively worked on many Data Center end to end projects. He has been in the networking industry for 10 years, which includes five years in the service provider industry and five years in Cisco AS, and is a dual CCIE, in the routing and switching and service provider tracks.

Hemant Bharati is a Network Consulting Engineer in the Cisco AS Design Services Team based in Bangalore, India. His areas of expertise include Enterprise Networking , IPv6  and Data center. He has been in the networking industry for 10 years. He holds a CCIE certification in Routing and switching

Remember to use the rating system to let Sandip and Hemant know if he has given you an adequate response. 

Because of the volume expected during this event, Sandip and Hemant might not be able to answer every question. Remember that you can continue the conversation in the Other Data Subjects under the sub-community Data Center & Virtualization, shortly after the event. This event lasts through August 29, 2014. Visit this forum often to view responses to your questions and the questions of other Cisco Support Community members.

[vdkhoa83csm]

Hi,

I have a question about implementation OTV. Can OTV encapsulation and SVIs routing coexistence on the same VDC with linecard F3?

Thanks,

Vo

[Sandip Rathod]

Hi Vo,

It will be supported on F3 line card in future release

Regards,

Sandip

[tenaro.gusatu.novici]

Hi guys,

here is one basic question: there are so many methods to tunnel data between two points and now you guys are introducing another one for Nexus 7k. Plus, it is proprietary protocol. Can you compare OTV vs. some other tunneling protocols (like L2TPv3, MPLS, GRE tunnels, PPTP...)

BTW, is OTV available on any other platform except N7k, for example Nexus 5k?

Thanks,

Tenaro

[Sandip Rathod]

Hi Tenaro

OTV is supported on ASR1K as well apart from N7K

OTV is mainly designed for Data Center, You just need IP rechability between two site to run OTV, you do not specifically need MPLS as we require for VPLS, AToM. You do not need pseduowire to run OTV.

OTV elimiates flooding as it use multicast and proxy arp to send messages to the clients.

OTV is simpler to configure and manage.

Many more advantages of deploying OTV compare to other tunneling protocol you can find in this document

http://www.cisco.com/c/en/us/products/collateral/switches/nexus-7000-series-switches/white_paper_c11-574984.html

Please let us know if you have any further query

Regards,

[tenaro.gusatu.novici]

Thanks guys,

here is another basic one: does it mean that OTV is transparently carry both Ethernet and Fibre Channel protocols between Data Centers? BTW, if I'm using 10Gbps Ethernet ports between DCs, will I be able to transport FC traffic that is coming from 8Gbps ports via FCoE?

FC8 -(N7k)- 10Gbps FCoE between DCs -(N7k)- FC8

[Hemant Bharati]

Hi Tenaro,

OTV is a LAN Extension Technology : This means only Layer 2 ethernet frames/VLANs are extended between Datacenters using IP encapsulation. For Storage Extension you will need to look at either FC over IP or Dark fiber connectivity for storage high availablity.  In a typical DC FCOE traffic is carried from the UCS to the Fabric Interconnects or to the Nexus 5000/Nexus 7000 and than get split to LAN or SAN networks.  Please refer below links for more info.

http://www.cisco.com/c/en/us/solutions/data-center-virtualization/data-center-interconnect/index.html#~overview

http://www.cisco.com/c/en/us/td/docs/solutions/Enterprise/Data_Center/DCI/4-0/EMC/dciEmc.html

[g.fabre]

Hi guys

 2 quick questions for you :
- is a specific VDC for OTV still required on current releases ?

- is Anycast HSRP supported to build Active/Active topologies between DC ?

Thanks.

[Sandip Rathod]

Hi

Answer to your question

Q.1 is a specific VDC for OTV still required on current releases ?

Ans.1: Yes, you still need separate VDC for OTV, in future release OTV and SVI will be supported in single VDC

- is Anycast HSRP supported to build Active/Active topologies between DC ?

Ans. 2: Anycast HSRP supported sure for Fabricpath used as DCI

Regards,

Sandip

[g.fabre]

thanks for your answer

my 2nd question was about the support for Anycast HSRP (or at least HSRP localization) if we use OTV as the DataCenter connection protocol in order to have Active/Active DC but not to cross DCI link for intraDC routing.
 

[Sandip Rathod]

Hi

You need FP to run Anycast HSRP. With OTV you can localize HSRP between two DC via HSRP Filtering.

Please find required configuration for HSRP filtering in this document

http://www.cisco.com/c/en/us/solutions/collateral/data-center-virtualization/overlay-transport-virtualization-otv/white_paper_c11-702185.html#wp9001588

Please let us know if you need any further clarification

Regards,

Sandip

[waleedmatter]

I have three sites connected through dark fiber as in the pic and it is working fine but when the link between KDC & JDR goes down as well as the OTV ISIS adjacency between them goes down , the OTV control plane route in the KDC interrupted and didnt learn the MAC addresses from the GDC anymore so my question if the OTV ISIS adjacency should be up forever between three sites because once the link between JDR & KDC goes down (OTV ISIS adjacency between KDC & JDR goes down) , the toplogy became partialy and not full mesh between three sites 

otv r1

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