TLOC Route - Carrier Attribute

written by: Ehsan Emad

In this article, we want to practice with a TLOC attribute for path selection.

Based on our topology, we have three sites, and each section has two transport clouds. One is mpls, and another one is metro.

Each vEdge router connects to a local csr router. There is OSPF neighborship between vEdge routers on each site to their csr routers, and omp redistributed to OSPF vice versa.

By default, each vEdge router can use both transport clouds to reach other sites' networks.

For example in Tokyo site with have two individual routes to reach csr router on Sanjose site.

In our challenge, we want the Paris site to advertise routes (loopback of CSR router) via metro cloud with higher preference. If connectivity to metro lost, then Paris vEdge start advertising routes via mpls cloud. Or in other words, metro cloud gets the primary for Paris and mpls cloud act as the backup.

Based on this challenge, from Sanjose or Tokyo's point of view, we can see only metro cloud path to reach Paris, and if metro path fails, it goes to mpls as a backup transport cloud. Its like BGP protocol.

We can accomplish the challenge with different methods in the cisco sd-wan solution, but I want to use the TLOC route, and in this scenario, I want to play with carrier attribute.

Note: in this scenario, vmanage is managing the vsmart.

Just for review:

TLOC routes advertise the following attributes:

  • TLOC private address—Private IP address of the interface associated with the TLOC.
  • TLOC public address—NAT-translated address of the TLOC.
  • Carrier—An identifier of the carrier type, which is generally used to indicate whether the transport is public or private.
  • Color—Identifies the link type.
  • Encapsulation type—Tunnel encapsulation type.
  • Preference—Degree of preference that is used to differentiate between TLOCs that advertise the same OMP route.
  • Site ID—Identifier of a site within the Viptela overlay network domain to which the TLOC belongs.
  • Tag—Optional, transitive path attribute that an OMP speaker can use to control the flow of routing information toward a TLOC. When an OMP route is advertised along with its TLOC, both or either can be distributed with a community TAG, to be used to decide how to send traffic to or receive traffic from a group of TLOCs.
  • Weight—Value that is used to discriminate among multiple entry points if an OMP route is reachable through two or more TLOCs.

Configuration Steps

Step 1:

In Paris, we need to mark mpls tunnel with carrier1 and metro tunnel as carrier2.

Later in vmanage, we can use these labels to prioritize path.

 

Step 2:

Create a policy based on TLOC attribute in vmanage

Please follow the screenshots from vmanage.

cisco vmange

1. In the vmanage choose configuration > policies menu.

cisco vmanage

2. Add new a centralized policy.

cisco vmanage

3. In topology choose custom control (route and TLOC).

cisco vmanage

4. Based on our scenario we choose TLOC.

cisco vmanage

5. Make default action enabled.

cisco vmanage

6. Now add rules.

cisco vmanage

7. Write a match based on carrier.

cisco vmanage

cisco vmanage

8. Assign preference 100 to carrier1(mpls).

cisco vmanage

cisco vmanage

9. Assign preference 200 to carrier2(metro).

cisco vmanage

10. Apply the rule.

cisco vmanage

11. Activate the rule.

 

Step 3 - Verification:

Now we go to Tokyo vEdge to verify Paris routes and paths.

tokyo vedge

As you can see, we have only now metro path, and there is no more mpls path. Now we want to see which TLOC routes are coming from Paris site.

tokyo vedge

Because we applied the rule to the inbound direction of vsmart, all other sites (Sanjose / Tokyo) will receive it.

If you want to apply Paris rule only for a specific site, you can use it on the outbound direction to that particular site.

If we apply outbound direction to, for example, Tokyo, now the output for other site will be different.

vedge config

In Tokyo, we have only metro cloud path, but in Sanjose site, we can reach Paris through metro and mpls clouds.

I hope you enjoy it, waiting for your feedback.

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