RE: VPN security vs SD-WAN security

"Dongjie (Jimmy)" <> Mon, 30 July 2018 10:38 UTC

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From: "Dongjie (Jimmy)" <>
To: Robert Raszuk <>
CC: "Acee Lindem (acee)" <>, "" <>
Subject: RE: VPN security vs SD-WAN security
Thread-Topic: VPN security vs SD-WAN security
Date: Mon, 30 Jul 2018 10:38:42 +0000
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Hi Robert,

Thanks for your comments. Please see my replies inline:

From: [] On Behalf Of Robert Raszuk
Sent: Saturday, July 28, 2018 9:02 PM
To: Dongjie (Jimmy) <>;
Cc: Acee Lindem (acee) <>;;
Subject: Re: VPN security vs SD-WAN security

Hi Jie,

> (network slicing) is to provide the demanding services with guaranteed performance in a converged network,

Foundation of converged IP network is based on statistical multiplexing of traffic demands. As such it is in its principle quite contradictory to "guaranteed" characteristics (performance, delays, jitter, drops -- you name it).

[Jie] Totally agree that statistic multiplexing is the foundation of IP network. Adding guarantee would reduce the benefit of multiplexing, while statistic multiplexing is still possible under some constraints. For example, traffic within the same slice could have some multiplexing gains.

Application layers usually deal very well with all of the above I would state - normal characteristics of IP networks..

No doubt there will be those trying to offer some network slicing with guarantees and even those who will buy it. Just like today there are those who offer you L2 circuit between endpoints except such L2 circuit is an emulated one with zero OEM visibility to the IP infrastructure underneath.

Now the network slicing is clearly aiming for even more complexity under the hood. And that is not the only problem. The issue is cost. When SP is building the IP network the goal is to mux as many services on it as it simply results in given's SP revenue. Network slicing is promising as potentially just by configuration of few knobs they will be claiming guarantees as RFC says - except RFC will not likely tell you to stop over-provisioning.

Unless the idea is to use strict policing with dedicated queuing on active and back paths or do something like RSVP IntServ also on active and backup paths per customer - I really don't think you can really guarantee much. And if you do that the cost would likely grow really steep.

[Jie] With network slicing SPs aim to introduce more diverse services onto their network, including the demanding services. While the cost of providing such service would be higher than for best effort, the price of such service would also be higher due to the added guarantee it can provide.

Policing, dedicated queueing and IntServ are useful tools to provide the guarantee. There may be scalability concerns, which needs some further discussion.

So what is IMO the solution for assured/guaranteed global IP transit:

*A*  get diversely routed  dark fiber paths between your POPs (can be unprotected) which btw today do not cost that much anymore
*B*  get diversely routed  optical channels alsol between your POPs (can be unprotected)

*C*  use N disjoined by design (single AS Internet providers between your end-points) + proper SD-WAN with active SLA monitoring

Clearly I am big supporter of *C* model for reasons discussed on this and few other recent threads.

I assume network slicing will try to get into be something between A/B & C but it is bounded up front with the cost of the two.

[Jie] A/B are below packet (IP) , C is based on multiple operator diversity, we need to understand what can be done between them.

Best regards,

Many thx,

On Sat, Jul 28, 2018 at 9:51 AM, Dongjie (Jimmy) <<>> wrote:
Hi Robert,

IMO the two approaches are targeting at different use cases and customers.

The former (network slicing) is to provide the demanding services with guaranteed performance in a converged network, while the latter (switching between multiple paralleled networks) provides the customer with the best performance that is available among those candidates. To me the latter is still some kind of best effort, and as Toerless said, it depends on the diversity you can have in the multiple networks.

And I agree with Stewart on “you always pay a price for better than best effort.”

Best regards,

From: rtgwg [<>] On Behalf Of Robert Raszuk
Sent: Wednesday, July 25, 2018 8:24 PM
To: Acee Lindem (acee) <<>>

Subject: Re: VPN security vs SD-WAN security

True network slicing for IP networks means either waist of resources or very strict multi-level queuing at each hop and 100% ingress traffic policing. Yet while this has a chance to work during normal operation at the time of even regular failures this all pretty much melts like cheese on a good sandwich.

It is going to be very interesting to compare how single complex sliced network compares for any end to end robust transport from N normal simple IP backbones and end to end SLA based millisecond switch over between one and another on a per flow basis. Also let's note then while the former is still to the best of my knowledge a draft the latter is already deployed globally in 100s of networks.


On Wed, Jul 25, 2018 at 1:21 PM, Acee Lindem (acee) <<>> wrote:

From: rtgwg <<>> on behalf of Stewart Bryant <<>>
Date: Wednesday, July 25, 2018 at 5:55 AM
To: Robert Raszuk <<>>
Cc: Routing WG <<>>
Subject: Re: VPN security vs SD-WAN security

On 25/07/2018 10:40, Robert Raszuk wrote:
/* Adjusting the subject ... */

​Hello ​

​You have made the below comment in the other thread we are having: ​

Indeed, I would have expected this to be on a secure network of some sort either purely
private or some form of VPN. However, I am sure I read in your text that you were
considering using the Public Internet much in the way of SD-WAN.

​Would you mind as extensively as you can expand on the above statement ?

Specifically on what basis do you treat say L2VPN or L3VPN of naked unencrypted packets often traveling on the very same links as this "bad" Internet traffic to be even slightly more secure then IPSEC or DTLS encrypted SD-WAN carried data with endpoints being terminated in private systems ?


Robert, I think that you have to take it as read that an air traffic control SoF system is encrypting its packets. If it is not, then it is clearly not fit for purpose.

What concerns me is that an air traffic system is one of the most, if not the most, high profile targets in civil society. You get reminded of this each time you travel to IETF.

The thing about safety of flight traffic is that a sustained and effective DDoS attack has global impact in a way that few other such attacks have.

A VPN system ought to sustain resistance to such an attack better than the proposed system which treats the SoF traffic the same as regular traffic.

I guess you are making a case for your network slicing work 😉


- Stewart