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

["Ali Sajassi (sajassi)" <[e-mail]>]

Linda,

I am catching up with this email thread. You are making a lot of incorrect assumption about [tunnel-encap]. We had a two-hour discussions at the last IETF meeting and I explained many of these points. I will provide further clarifications as I go through this email thread. Please refer to my comments inline marked w/ [AS].

From: Idr <[e-mail]> on behalf of John E Drake <jdrake=[e-mail]>
Date: Thursday, June 20, 2019 at 12:13 PM
To: Linda Dunbar <[e-mail]>, "[e-mail]" <[e-mail]>, "[e-mail]" <[e-mail]>
Subject: Re: [Idr] Tunnel-Encap Gaps for SD-WAN described in draft-ietf-rtgwg-net2cloud-gap-analysis-02.txt

Linda,

Comments inline.

Yours Irrespectively,

John



Juniper Internal
From: Idr <[e-mail]> On Behalf Of Linda Dunbar
Sent: Wednesday, June 19, 2019 4:09 PM
To: [e-mail]; [e-mail]
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.

[AS] What functionality is that ???  [Tunel-Encap] provides lot of flexibility:

  *   You can attached the attribute to VPNv4 or VPNv6 routes
  *   You can attach the attribute to IPv4 or IPv6 routes

·         You can do recursive resolutions and inherit tunnel attribute via such recursion

·         You can do coloring of VPN routes (instead of sending the attribute) and inherit the attribute info via such coloring

-       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 (https://tools.ietf.org/html/draft-sajassi-bess-secure-evpn-01).  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

[AS] Furthermore, secure-evpn draft discusses how you can inherit the tunnel attribute via route hierarchy and specifies different level of hiearchcy.

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

[AS] Tunnel is setup point-to-point whereas the signaling is done P2MP. I think this point is being missed.

-       [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

[AS] That is incorrect. [Tunnel-Encap] does not require all VPN routes be sent with tunnel attribute. That’s why they have the notion of recursive route resolution and coloring exist in that draft. Furthermore, you can have multiple tunnels for the same pair of end-point tunnel addresses.

-       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.

[AS] Linda, [Tunnel-Encap] doesn’t require fake routes as the attribute can be attached to any updates – i.e., it can be attached to a WAN-port that is identified by IPv4 or IPv6 AFI/SAFI which is different from VPNv4  or VPNv6 routes.

Cheers,
Ali

-----------------
More are in the document: https://datatracker.ietf.org/doc/draft-ietf-rtgwg-net2cloud-gap-analysis/<https://urldefense.proofpoint.com/v2/url?u=https-3A__datatracker.ietf.org_doc_draft-2Dietf-2Drtgwg-2Dnet2cloud-2Dgap-2Danalysis_&d=DwMFAg&c=HAkYuh63rsuhr6Scbfh0UjBXeMK-ndb3voDTXcWzoCI&r=CRB2tJiQePk0cT-h5LGhEWH-s_xXXup3HzvBSMRj5VE&m=svEApaK250yroEYlWy7i4KW3lGckXW5jGBoYG61yxjk&s=2rIUQFCJoAFnuwwnL1FIll46MZ2jNT4KwtrUUUbtLes&e=>

We look forward to comments, suggestions and objections.

Thank you very much.

Linda

-----Original Message-----
From: rtgwg <[e-mail]<mailto:[e-mail]>> On Behalf Of [e-mail]<mailto:[e-mail]>
Sent: Wednesday, June 19, 2019 2:57 PM
To: [e-mail]<mailto:[e-mail]>
Cc: [e-mail]<mailto:[e-mail]>
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

Abstract:
   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.


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