XCA EDGE Use case

SPEED-ORIENTED ROUTINGOPTIMIZATION

About this document

This document introduces a general use case of the Expereo XCA Edge system. As it

deals with a linear and chronological example, it is a perfect tool to understand the

underlying concepts of our product. It will also help you if you need an overview of all

the benefits you could get from XCA Edge.

Note that this use case only covers one of the several usages of XCA Edge.

However, there is a good chance that a large part of this use case applies to your

own configuration. If not, please have a look to the other use cases.

Moreover, if you need more specific information, please refer to the XCA EdgeAdministrator Manual. It contains a more precise description of the XCA Edge

features, and provides per-page explanations of the graphical user interface.

Abstract

This use case introduces two companies that have critical speed needs, and could

not allow any network failure at any cost. One is a retailer, that need to be ranked

at the top of search engines. The other one is a retargeting agency, that has less

than 100ms to answer to an ad request.

Using XCA Edge and its high-performance probing and routing optimization engines,

they will be able to stretch their networks performance to their limits, and consequently

providing their users with a greater experience.

Situation

Critical need for very fastconnectivity over redundant Internetaccess.

Solution

Activate XCA Edge routing optimization with a proper routing policy.

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1. Introduction

BazIt and QuxMotion are two company that have important speed needs. They

illustrate two of the several reasons why speed might be a critical parameter for

web-based company. Both have a standard setup, with several transits connected to

the Internet.

1.1. BazIt: the retailing company.

BazIt is an Internet retailer. To be competitive against other retailing companies, it

does not only need to be cheap or offer shipping, but must also offer the best

possible user experience. Moreover, it also needs being ranked at the top results of

search engines.

As speed becomes a very important matter for Internet users, web search engines,

like Google, have decided to include speed inside their website ranking algorithm.

Figure 1 is a screenshot of an article from the Google official webmaster central

blog, explaining Google policy regarding websites speed.

As several retailers are fighting for the same keywords on search engines, being in the

top ranked websites is critical for BazIt. Therefore BazIt set up XCA Edge to optimize its

connectivity towards all Internet users.

Thanks to its probing engine and its smart routing optimization algorithms, XCA Edge will choose the best transit to use to reach each remote destination of the Internet.

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Figure 1: Official blog article about Google using speed in web search ranking

1.2. QuxMotion: the retargeting agency.

QuxMotion has similar concerns, it is a retargeting agency that provides websites

with ads. Any time a web user connects to a publisher website, ads might be

dynamically requested. As illustrated on Figure 2, several steps are required to

display the ad:

• 1. The user connects to a publisher website. It downloads the page with an

empty space to fill with an ad.

• 2. A script downloaded by the user automatically connects to a SSP (Supply-

Side Platform). The SSP gathers the data provided by the user (user profile,

dimensions of requested ad...).

• 3. With the information included in the request, the SSP performs an auction.

It connects to DSPs (Demand-Side Platforms) and ask for bids. Each DSP bids

for the ad by responding to the SSP. In this case we consider that QuxMotion

won the auction sale.

• 4. The SSP tells the web browser which DSP won the auction, and tells it

where it can download the ad.

• 5. The web browser request the DSP for the ad. From here, we distinct two

cases: either the DSP directly send the ad to the user or it redirects him to a

marketer adserver (step 6).

• 6 (optional). The web browser request the ad to the marketer adserver.

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QuxMotion is a DSP. Therefore it has a strong speed need: according the contract

with the SSP, it must respond to an auction in less than 100ms. It must also send

the ad as fast possible so that the user has more chances to click on the ad.

Figure 2: QuxMotion retargeting agency operation

As QuxMotion has several transits connections, XCA Edge ill help the company to

optimize its routing strategy and evaluate whenever a destination faces

connectivity problems. XCA Edge can optimize the routing either for well known

destinations, such as the SSPs, but can also optimize routing towards any other

destination. Hence, ads will be sent as fast as possible to the Internet users.

Operations

To optimize their routing to increase their traffic speed, BazIt and QuxMotion

network administrators will have to execute two tasks:

• Set up the probing engine. This will allow the system to evaluate, for

manually or automatically chosen subnets, each transit performance,

• Configure and start the automatic routing optimization.

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2. Use case steps

2.1. Step 1: XCA Edge probing configuration

Probing configuration

The XCA Edge probing engine provides the whole system with an accurate overview

of current transits performances toward distant subnets. Probes are regularly sent

packets that can evaluate delay and packet loss through each transit towards a

destination.

Probes destinations can be either manually or automatically selected:

• Manual probes must be set up whenever specific destinations need to be

monitored. In the case of QuxMotion, each SSP server should have a manual

probe attached to it. These probe destinations are supposed to be always up,

• Automatic probes are created depending upon each destination subnet traffic.

The traffic engine chooses destinations with which the most important traffic

is exchanged: these destinations will be automatically probed. Figure 3

depictes the list of automatically created probes.

Moreover, the XCA Edge system is able to execute outbound probing but can also

execute inbound probing. As an example, by inserting a short javascript code in its

website, BazIt has allowed XCA Edge inbound probing probes. Every web browser

accessing the BazIt website executes a quick request to the XCA Edge device, giving it

more information on inbound transit quality.

Probes can be configured within the probing section, automatically created probes

are available in the Probing / Configure - Control probes tab.

Data collected by probes can be used to evaluate the probed subnets performances.

These performances are displayed in the Probing / Summary or the Probing / History

sections. With the Probing / Toubleshooting tool, these reports can be used to

troubleshoot network issues towards remote subnets.

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Figure 3: Control probes panel

Please refer to the "Optimized IPSec WAN" use case for more information on manual

probes configuration.

2.2. Step 2: Monitored subnets

According to XCA Edge design, a subnet must be monitored to be optimized. Data

collected from probes within each subnet is used to evaluate a representative link

quality to reach this subnet.

For obvious performance reasons, not all prefixes from Internet can be monitored.

The maximum number of subnet monitored by XCA Edge is fixed by the XCA Edge

device contracted license (2000 in a standard licensing).

Let us take the example of QuxMotion. On the one hand we have web browsers

destinations. These subnets are monitored because they generate high traffic load:

probes are automatically created within these subnets. On the other hand, manually

created probes attached to SSPs' subnets also set these subnets as monitored.

Consequently, both web browsers destinations and advertisers subnets will be

monitored, allowing them to be optimized.

XCA Edge provides the user with a set of tools to deeply analyse its network

performances towards monitored subnets. These reports, available in the Traffic /

Destination section, can give him information on the per-subnet distribution of the

traffic.

Moreover, monitored subnets can be configured to raise alarms whenever a problem

occurs. This is also covered by the "Optimized IPSec WAN" use case. The Prefix /

Monitoring - prefixes section (Figure 4) deals with the alarm configuration.

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Figure 4: Prefix / Monitoring - Prefixes tab

2.3. Step 3: Routing optimization activation

Now that the subnets that must be optimized are monitored, the network

administrator can activate the routing optimization. The Routing Decision Engine,

thanks to the data provided by probes, is able to select the best transit to use to

reach remote destinations.

By selected an appropriate routing policy, the network administrator configures how

XCA Edge optimizes the link quality. As BazIt and QuxMotion need the highest speed

at any price, the routing policy should choose the transit with the lowest RTD to route

the traffic. This routing policy is not implemented in XCA Edge 1.1, but might be

according to clients needs.

Once this is done, he can activate both outbound and inbound optimization.

Outbound optimization is simply made by updating BGP routers routing tables, so

that a subnet will be routed through the best available transit. Inbound,

optimization can be made by announcing specific subnets with artificially

prepended AS-paths, so that some subnets appears (to peer routers) further that

they really are. Note that inbound optimization cannot perform a per-subnet

division, but might favour a transit more that another.

For more information on routing optimization configuration, please refer to the

Mixed IPSec / MPLS-VPN network optimization.

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2.4. Step 4: Evaluating the benefits from usingXCA Edge

To evaluate its benefits from using XCA Edge, the network administrator would like

to evaluate the difference between the route chosen by BGP and the one chosen by

XCA Edge. He accesses the Probing / Top Gaps section (Figure 5).

This page provides the network administrator with a list of the subnets that have

taken the most from XCA Edge. By using the top field, he can search for the remote

destinations he is interested in.

The QuxMotion network administrator notices that the RTD from SSP subnets have

been reduced by more that 20ms, which is important according to the 100ms limit

to answer to an auction sale. By sorting the list by volume, he also notices that

several of the top 10 subnet have seen their RTD significantly reduced.

Figure 5: Prefix / Monitoring - Prefixes tab

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3. Conclusion

XCA Edge provides BazIt and QuxMotion with a perfect way to optimize their

transit connections. Thanks to its probing engine, XCA Edge gathers a complete

view of the companies connections towards distant subnet. Then it chooses the

fastest transit towards each destination, allowing these companies to provide their

clients with the fastest possible service.

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