Re: [Idr] Tunnel-Encap Gaps for SD-WAN described in draft-ietf-rtgwg-net2cloud-gap-analysis-02.txt

John E Drake <> Thu, 20 June 2019 19:11 UTC

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From: John E Drake <>
To: Linda Dunbar <>, "" <>, "" <>
Thread-Topic: Tunnel-Encap Gaps for SD-WAN described in draft-ietf-rtgwg-net2cloud-gap-analysis-02.txt
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Subject: Re: [Idr] Tunnel-Encap Gaps for SD-WAN described in draft-ietf-rtgwg-net2cloud-gap-analysis-02.txt
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Comments inline.

Yours Irrespectively,


Juniper Internal
From: Idr <> On Behalf Of Linda Dunbar
Sent: Wednesday, June 19, 2019 4:09 PM
Subject: [Idr] Tunnel-Encap Gaps for SD-WAN described in draft-ietf-rtgwg-net2cloud-gap-analysis-02.txt

We updated the gap analysis on using Tunnel-Encap for SD-WAN tunnel after some confusions in interpreting the Tunnel-Encap draft are cleared by the IDR's a long thread of email discussion. Many thanks to the IDR Chair and the participants for the discussion.

Here is the highlight of the gaps. We would appreciate greatly to hear comments or objections for our gap analysis.


-       [Tunnel-Encap] doesn't have the functionality that would help the C-PE to register its WAN Port properties.

-       A SD-WAN tunnel, e.g. IPsec-based, requires a negotiation between the tunnel's end points for supported encryption algorithms and tunnel types before it can be properly established, whereas [Tunnel-Encap]  only allow the announcement of one endpoint's supported encapsulation capabilities for specific attached routes and no negotiation between tunnel end points is needed.

[JD]  What you need to do is implement the model described in  the Secure EVPN draft (  Viz, the SD-WAN C-PEs are attached to a route reflector and each uses the route reflector to advertise its security-related  information the other C-PEs.  As we discussed in Prague the tunnel encapsulation attribute is not associated with client routes.  Rather it is associated with the loopback or interface addresses of the advertising SD-WAN C-PE.  I.e., IPv4/IPv6 addresses rather than VPN IPv4/IPv6 addresses

The establishment of a SD-WAN tunnel can fail, e.g., in case the two endpoints support different encryption algorithms. That is why a SD-WAN tunnel needs to be established and maintained independently from advertising client routes attached to the edge node.

[JD]  See above

-       [Tunnel-Encap] requires all tunnels updates are associated with routes. There can be many client routes associated with the SD-WAN IPsec tunnel between two C-PEs' WAN ports; the corresponding destination prefixes (as announced by the aforementioned routes) may also be reached through the VPN underlay without any encryption.. A more realistic approach to separate SD-WAN tunnel management from client routes association with the SD-WAN tunnels.

[JD]  See above

-       When SD-WAN tunnel and clients routes are separate, the SD-WAN Tunnel establishment may not have routes associated.
There is a suggestion on using a "Fake Route" for a SD-WAN node to use [Tunnel-Encap] to advertise its SD-WAN tunnel end-points properties. However, using "Fake Route" can raise some design complexity for large SD-WAN networks with many tunnels. For example, for a SD-WAN network with hundreds of nodes, with each node having many ports & many endpoints to establish SD-WAN tunnels with their corresponding peers, the node would need as many "fake addresses". For large SD-WAN networks (such as those comprised of more than 10000 nodes), each node might need 10's thousands of "fake addresses", which is very difficult to manage and requires lots of configuration tasks to get the nodes properly set up.

[JD]  There is no need for a 'Fake Route'.  We advertise a tunnel encapsulation attribute with security-related information for a specific SD-WAN port on the C-PE as identified by its IPv4/IPv6 interface address.  If a set of SD-WAN ports have common security-related information a tunnel encapsulation attribute can be advertised with a C-PE's loopback address.

More are in the document:<>

We look forward to comments, suggestions and objections.

Thank you very much.


-----Original Message-----
From: rtgwg <<>> On Behalf Of<>
Sent: Wednesday, June 19, 2019 2:57 PM
Subject: I-D Action: draft-ietf-rtgwg-net2cloud-gap-analysis-02.txt

A New Internet-Draft is available from the on-line Internet-Drafts directories.
This draft is a work item of the Routing Area Working Group WG of the IETF.

        Title           : Gap Analysis of Dynamic Networks to Hybrid Cloud DCs
        Authors         : Linda Dunbar
                          Andrew G. Malis
                          Christian Jacquenet
        Filename        : draft-ietf-rtgwg-net2cloud-gap-analysis-02.txt
        Pages           : 18
        Date            : 2019-06-19

   This document analyzes the technological gaps when using SD-WAN to
   dynamically interconnect workloads and applications hosted in
           rd        various 3  party cloud data centers.

The IETF datatracker status page for this draft is:;;sdata=PxMtUZdFrkeIb5gh%2BBSXO5y3aOJ9GkTGIj5OHcKbzjk%3D&amp;reserved=0<>

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A diff from the previous version is available at:;;sdata=rZyP0RdcQHkZvf1y0e8ZqCcuiHKlDSdfx4WlbYUfZeI%3D&amp;reserved=0<>

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