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So first, let's take a look at how Cloud OnRAMP for SaaS

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chooses between multiple exits at the same branch location.

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It's going to follow a very specific list of rules,

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so let's go ahead and jump in and take a look at that path selection process.

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So what we're going to be discussing is the very specific procedure that Cloud

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OnRAMP is going to follow when it's making this decision as far as which exit
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OnRAMP is going to follow when it's making this decision as far as which exit

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to forward the traffic through out of a particular branch.

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Now again, the assumption here is that there's multiple DIA links out of the

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same branch.

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If we're going to use another option, well, those are some other things we'll

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cover later.

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But for now, these are multiple links out of the same branch.

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So the first thing that's going to happen is the WAN edge router at that branch

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location is going to do a DNS lookup, and it's going to do this over each link
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location is going to do a DNS lookup, and it's going to do this over each link

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to each available service provider.

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Now, in order for it to do that, there's of course going to be a requirement

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here that you're going to have to have a separate DNS server for VPN zero based

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on the ISP.

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Now, there's also the possibility that those different ISPs would still resolve

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the DNS name to the same IP address.
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the DNS name to the same IP address.

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However, since most of these SIS providers are global, they're usually going to

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have different DNS resolutions for different regions.

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So you may actually get different answers.

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But once we get that answer, the next thing that's going to happen is we're

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going to do a periodic or active HTTP ping to each of the different SaaS
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going to do a periodic or active HTTP ping to each of the different SaaS

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applications that we have configured.

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Now, of course, since we're trying to choose between multiple exits, this ping

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is going to be done on each available circuit, because again we're trying to

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compare those circuits to figure out which one's better.

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Well, how do we do that?

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Well, quite simply, we have something called the quality of experience or the Q

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oE.

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This is a score that is calculated based on the results of that HTTP ping.
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This is a score that is calculated based on the results of that HTTP ping.

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Well, what about the results?

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Well, specifically, it's going to be looking at packet loss and latency. Those

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are the two main things that are going to create the QoE score.

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What's the score? Well, it's actually a scale of one to 10, where 10 is the

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highest and therefore the best.

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So it's going to then look at both circuits, choose which one has the best QoE,
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So it's going to then look at both circuits, choose which one has the best QoE,

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and that's the exit that it's going to use for that application out of that

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branch office.

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Well, how does it manipulate that? It's okay to make a decision, but how do we

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then implement it?

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Well, what's going to happen is the client is then going to initiate a

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connection to the application, and it's going to then do its own DNS query.

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That's just what the client operating system is going to do.
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That's just what the client operating system is going to do.

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So what's going to happen is once again on the edge router, we're going to do a

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DPI or a deep packet inspection of that DNS query.

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So we're going to intercept the client asking for the host name to IP address

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query.

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Once we've intercepted it, we're going to look at that query, and we're going

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to see if that is for a monitored SaaS application.
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to see if that is for a monitored SaaS application.

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If it is, we're then just going to forward that request over again the highest

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scoring path to the DNS server for that ISP.

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In other words, we're simply going to intercept the DNS request and send it to

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the DNS server for the path that we being SD WAN or specifically cloud on ramp

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has already chosen as the best path.
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has already chosen as the best path.

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Now, if three is not true.

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In other words, if this is not a monitored application, we're just going to

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forward any other DNS requests based on just standard SD WAN routing.

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In other words, we're just going to forward it over whatever path is best

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according to things like routing protocols or administrative distance, things

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like that.

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Now, of course, just getting the DNS query to the right device isn't quite

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enough.
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The final step, of course, is the traffic itself is then going to be forwarded

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out that best path using application aware routing.

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This again is the equivalent to the old policy based routing, but this is how

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we handle forwarding traffic out of a branch over the best path based on the

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applications needs using cloud on ramp for SaaS.

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So in this video, we focused on how cloud on ramp for SaaS forwards the traffic
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So in this video, we focused on how cloud on ramp for SaaS forwards the traffic

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to the correct path if both paths are coming from the same branch.

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Next, let's take a look at what happens if maybe we're going through something

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like a regional gateway.