OTV overlay over trunks to the core

[Jorge Goya Perez]

OTVHello,

I have a L3 network inter-sites but using SVI over trunks because I need to extend VLANs L2 intersites too. One of these VLANs are SVI that permit routing intersites.

As I know, OTV join interface must be L3, but I have a L3-SVI.

I would like to know if there is a way to configure OTV on my N77, where the join interfaces are going to be trunks ports where I use a VLAN (SVI) for interconnect to L3 the Edge Sites ?

I have some try configuration using loopback feature without success:

# show otv

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

Overlay interface Overlay1

VPN name : Overlay1
VPN state : UP
Extended vlans : 600 (Total:1)
Control group : 239.1.1.1
Data group range(s) : 232.1.1.0/24
Broadcast group : 239.1.1.1
Join interface(s) : Lo0 (10.1.1.5)
Site vlan : 605 (up)
AED-Capable : No (No extended vlan operationally up)   <-----
Capability : Multicast-Reachable

a show otv adja is empty.

here a show runn otv:

version 8.2(4)
feature otv

otv site-vlan 605

interface Overlay1
otv join-interface loopback0
otv control-group 239.1.1.1
otv data-group 232.1.1.0/24
otv extend-vlan 600
no shutdown
otv site-identifier 0x1

Best regards, Jorge.

[Sergiu.Daniluk]

Hi @Jorge Goya Perez

As I can see from your outputs, actually you are using loopback interface as join interface. However, I understand that you are asking if the OTV uplink interfaces, facing the core, can be trunk. Answer is no. It needs to be L3 point to point interfaces. Since you are using Loopback as join interface, you will have to enable pim on the L3 uplinks. But what prevents on your core switch to configure the ports facing the OTV edge device as L3 interfaces, with a different subnet, which can be added to the routing?

Regards,

Sergiu

[Jorge Goya Perez]

Thank you Sergiu,

my question about a join-interface over trunk has been cleared.

I have 4 sites in my company, each of them with one border router. I have point-to-point links bewteen them drawing a square. The point-to-point link is 802.1q spreading some vlans to all the sites and each border router has a VLAN as point-to-point link (using SVI and OSPF instance) to build the L3 network.

These borders routers have the OTV license installed and I wanted to replace vlans transport with 802.1q for OTV. My problem is I want to use the same border router as edge and core and avoid to change border gateways 802.1q links.

I see a way to workaround: changing border routers links from 802.1q to Physical L3, but it may be disruptive. I have discovered that OTV has limitations for putting in production in Campus LAN.

Regards, Jorge.

[Sergiu.Daniluk]

Hi,

You can go for OTV on a stick.

It will be something like this:

Legend: red link = L3 port , black link = L2 port.

From the OTV perspective, as long as there is IP reachability with the other OTV edge device, then is ok.

With this, you do not modify the inter-site connectivity. You only configure 1 additional link towards OTV VDC.

Better drawing can be found OTV design guide: http://www.cisco.com/en/US/docs/solutions/Enterprise/Data_Center/DCI/whitepaper/DCI3_OTV_Intro_WP.pdf (figure 1-46).

Sergiu

[Jorge Goya Perez]

Hello,

many thanks for your reply. I will consider this solution but firstly I need to check the license because I haven´t VDC license right now (I have LAN_ENTERPRISE).

Another option I am lookng is to switch to VxLAN with MP-BGP although I bought OTV license for not being used. 

Regards, Jorge Goya.