Re: [Idr] Possible to set up priority for Tunnels established by draft-ietf-idr-tunnel-encaps-09 ?

[Eric C Rosen <[e-mail]>]

If you want a controller to use BGP to convey instructions for a 
particular node, there is a draft that does something very similar: 
draft-ietf-idr-segment-routing-te-policy.  That draft defines a new 
AFI/SAFI for conveying segment routing te policies, and the policies are 
encoded as Tunnel Encapsulation attributes.  That draft does require the 
use of the NO_ADVERTISE community when an UPDATE is a command targeted 
to a single router.  The draft also allows the use of Route Targets to 
cover the case where a given  command is targeted to a set of routers, 
as well as the case where the targeted router is separated from the 
controller by a RR or ASBR.  While your application is not about 
sr-te-policies, the way a controller would use BGP to pass the commands 
to the targeted routers is similar; you should take a look.

On 7/9/2018 4:13 PM, Linda Dunbar wrote:
>
> Eric,
>
> draft-ietf-idr-tunnel-encaps-09 discussed ways to resolve conflicts of 
> multiple UPDATE messages with Tunnel Encap attributes.
>
> Is it possible to have following capability?
>
> -Have a bit indicating a specific UPDATE is from authoritative source, 
> therefore overwrite all other Tunnel Attributes for the Prefix X to 
> avoid recursive next hop issues and tunnel selection at the receiving 
> Router?
>

This is not a good idea.  If you want to verify that a particular UPDATE 
is from an authoritative source, you need a lot more than can be 
conveyed in a single bit.


> -Have a bit indicating that a specific UPDATE only contain Tunnel 
> attributes for the receiving Router, therefore can’t be forwarded?
>

Please compare draft-ietf-idr-segment-routing-te-policy, and its use of 
NO_ADVERTISE and Route Targets.

> You said that SAFI 7 is deprecated because no one seemed interested in 
> using it. We are very interested in using it because
>
> -it can be easily distinguished from normal  BGP UPDATE
>
> - The receiving router doesn’t have to “Filter” the tunnel attributes 
> before forwarding to others.
>
> -Can even be used for passing reconfigured IPsec keys to two ends of a 
> tunnel.
>
> Therefore we think SAFI 7 should be reserved.
>

It sounds like you need to write a draft proposing the specifics of how 
you would like to use BGP as part of your SD-WAN control.  The draft 
would then be free to propose a new SAFI, much as 
draft-ietf-idr-segment-routing-te-policy did.