White Paper: Failsafe Software Defined WANs

Executive Summary

The cloud – the union of cloud computing, the Internet and Software-as-a-Service (SaaS) – is rapidly changing enterprise IT. The traditional enterprise WAN solution of the last decade – MPLS, often augmented by WAN Optimization technology – no longer cuts it. A new technology, Software Defined WANs (SD-WANs), offers enterprises tremendous opportunity for cost savings, flexibility, bandwidth, manageability and superior cloud access. But SD-WAN implementations, while sharing a few common traits and tending to sound alike, vary significantly.

MPLS is still a $15B+ worldwide market – despite the enormous price/bit gap versus Internet connectivity – because MPLS offers failsafe WANs. “Failsafe” here means the union of high availability and reliable, predictable network performance and application Quality of Experience (QoE). Only a few companies have developed failsafe SD-WAN technology. Talari does “failsafe” better than anyone.

MPLS doesn’t offer connectivity to public cloud computing and SaaS. MPLS locks IT into a single service provider, and is incredibly expensive, as it costs literally 50x – 150x more per Mbps for smaller sites, and can be 10x – 50x more per Mbps at data centers. Meanwhile, traditional WAN Optimization technology offers relatively little benefit over high bandwidth but unpredictable Internet WAN links.

Most SD-WAN implementations do share some things in common: a flexible virtual WAN overlay fabric supporting multiple WAN links, including lower-cost Internet links; centralized controllers with centralized management, reporting and policy control; a choice of physical or virtual appliances.

But vendor SD-WAN implementations differ widely. Some focus on the needs of telecom service providers. Some focus primarily on “router replacement” (the cost of owning/maintaining the routers), rather than the issues surrounding the unpredictability of Internet connectivity, cloud access and the costs of WAN service. Some focus on offering a fully managed service over the public Internet. While this last approach can work for some smaller enterprises who have never had MPLS, nor likely any centralized security architecture, they can be of limited value for larger enterprises with greater control and security concerns, or who do not wish to make an abrupt wholesale cut over of their WAN infrastructure. Few SD-WAN implementations have focused on failsafe WANs. None do failsafe WANs as well as Talari.

Why failsafe SD-WANs? Failsafe WANs means both high network availability and reliable, predictable application QoE. The tantalizing benefits the cloud and SD-WANs might promise notwithstanding, enterprise IT disdains “two steps forward, one step back” solutions for good reason. Even the most aggressive, leading-edge enterprises want failsafe WANs, given the high cost of downtime, limited IT resources available at most remote locations, and limited visibility into the WAN.

Talari’s patented SD-WAN technology has some unique capabilities that enable it to deliver failsafe WANs, including: continuous unidirectional measurement of packet loss, latency, jitter and bandwidth utilization, enabling unprecedented WAN visibility and sub-second response to adapt to network issues; end-to-end QoS and inbound congestion avoidance, providing 90% - 97% sustained utilization on shared links without negatively impacting QoE; the ability to use all bandwidth across multiple links, even for a single high-bandwidth flow when doing link aggregation; optional packet replication for realtime traffic, delivering platinum quality real-time support; centralized management via Talari Aware; high QoE cloud access, especially in combination with carrier neutral colocation facilities close to the core of the Internet; the ability to scale to large WANs (not trivial to deliver when offering true sub-second response).

What can enterprises expect from a failsafe SD-WAN? Benefits include, but are not limited to:

  • 50x - 150x bandwidth per dollar versus MPLS
  • Monthly WAN costs reduced by 40% - 80%
  • Greater network reliability and application QoE than any single MPLS network
  • Radically reduced WAN troubleshooting costs, via a smart, self-correcting, highly fault-tolerant WAN that not only detects problems but fixes them, sub-second
  • Agile, non-disruptive deployment with existing MPLS and WAN Optimization solutions
  • Superior support for real-time apps like UCaaS and video conferencing
  • Excellent support for centralized Internet access and network security architectures
  • Reliable, high QoE access to Saas and public/hybrid cloud computing
  • A long term way to cost-effectively scale the WAN while supporting the migration to cloud-based applications at whatever pace the computing side of the house decides to go

SD-WANs offer enormous potential and benefits – if delivered in a failsafe manner. Talari Networks – unmatched failsafe SD-WANs.


The cloud – the union of cloud computing, the Internet and Software-as-a-Service (SaaS) – is rapidly changing enterprise IT, including the network and the associated IT “plumbing”. Cloud computing, while offering exciting agility and flexibility in application deployment, is particularly challenging for the network team tasked with making it all work with the same reliability and manageability of the purely private networks enterprises have learned to manage over the years. Storage, LANs, application delivery, etc. are all deeply affected by the location of applications and services in “the cloud”. But perhaps the greatest cause for IT concern, and certainly for WAN managers, is the tremendous pressure this change puts on the Enterprise WAN.

In fact, enterprise WANs have changed very little in the last 15 years. While price/bit for the Enterprise WAN has improved somewhat over the past decade, it hasn’t increased with Moore’s Law as have computing, storage, Internet access, LAN switching, etc. – pretty much everything else associated with IT. But while Internet connections have followed along with Moore’s Law delivering quantum improvements in price/bit, the unaided public Internet is still not reliable enough to deliver business-class quality of service (QoS) and application Quality of Experience (QoE). This is the primary reason why the overwhelming majority of enterprise WANs are based not on IPsec VPNs over the Internet, but instead on private MPLS services from telecom service providers like AT&T, Verizon and BT.

That said, IT and WAN budgets are not growing as fast as the demand for additional WAN bandwidth – if those budgets are growing at all. Yet next-generation, bandwidth-hungry applications and real-time applications are placing additional burdens on the WAN. As more and more application traffic goes to SaaS and public cloud-based services, even the best performing, WAN Optimization-enhanced MPLS networks simply aren’t agile enough for the age of the cloud. Left unaddressed, the WAN is likely to be the number one inhibitor to the demands CIOs and CEOs are making on IT to take advantage of the benefits cloud computing promises.

The Traditional Solution No Longer Cuts It

The state of the Enterprise WAN until very recently: expensive but reliable MPLS connections with relatively little bandwidth at remote sites, frequently with WAN Optimization to help squeeze more capacity and performance from those MPLS links, coupled with cheap and getting cheaper but “unreliable” Internet connections at data centers and larger sites (and sometimes branches) for IPsec VPN backup connections, generic Internet access and remote user connectivity. While a reliable solution for the past decade, this approach is on its last legs.


MPLS, of course, is the dominant enterprise private WAN service worldwide. Besides generally locking IT into a single service provider, MPLS bandwidth is very expensive compared to Internet bandwidth. And MPLS offers no practical solution for cloud access. So while MPLS is reliable and can support centralized security, the expense, the limited resulting bandwidth, and the frequent difficulty in expanding bandwidth at many smaller locations all are limiting factors going forward.

Because MPLS is so expensive, users at most smaller locations have more bandwidth at home than they do in the office – frequently a lot more. Some even have more network bandwidth on their LTE smartphone or tablet devices than they do on the office WAN!

While most anyone interested in SD-WANs is generally aware that MPLS bandwidth is expensive compared to Internet connectivity, few people realize exactly how enormous the difference is.

While MPLS prices have come down about 15%- 20% each year for the last several years, this doesn’t come close to the roughly 40% annual reductions in the price of Internet bandwidth. So the price/bit gap between Internet and MPLS connections has been widening, not shrinking. Let’s look at the numbers.

A few years ago MPLS typically cost $300 - $600 per Mbps per month for the copper connectivity (i.e. n x T1/E1) typically deployed at all but the largest enterprise locations, while today in most of North America and much of Europe a more typical range is $100 - $300 per Mbps per month. Over this same period, the monthly price of broadband connectivity like FIOS, cable or xDSL has dropped from the $5 - $15 per Mbps per month range to $1 - $2 per Mbps per month.

For example, high bandwidth cable modem-based Internet connections are available from Comcast Business Internet for $1.67 - $4 per Mbps per month, while business pricing for Verizon FiOS is $0.73 - $2 per Mbps per month. Even using the lower-end estimate of $100 per Mbps per month for MPLS compared to Verizon’s best bandwidth pricing is a factor of 137x. Compared to the higher-end $300 figure, this factor of over 400x!

Most enterprises will see a range of ~50x-150x as the price/bit advantage for Internet connectivity compared to MPLS. There are very few areas in technology where IT sees order-of-magnitude gains, yet with a proper SD-WAN solution, enterprises can get two order-of-magnitude benefits by leveraging Internet connections.

The newer area of price/bit benefits from SD-WANs and Internet connectivity is at the data center. This refers primarily to leveraging data centers located at carrier-neutral colocation (colo) facilities run by companies like Equinix, Interxion, and Telehouse.

Pricing for fiber-based connectivity at customer premises, for both MPLS and Internet connections varies widely depending on location and fiber access to the building, and the local competitive structure of service providers, and is fairly opaque. At customer premise-based data centers, traditional Internet connectivity might only offer a 2x - 4x price/bit benefit over MPLS, with prices for many connections being in the ~$10 - ~$60 per Mbps per month range

At colo facilities, while MPLS pricing tends to be similar to what enterprises can obtain at their private data centers, Internet monthly pricing is usually below $1 per Mbps for high bandwidth connections, delivering a price/bit benefit in the 10x - 50x range. This order-of-magnitude advantage is substantial, and can be important when aggregating connectivity from a large number of branch sites that may now have much more bandwidth than they did when they only used thin MPLS connections.

While relatively few enterprises have moved data centers to such colocation facilities to-date, they offer substantial benefits to those enterprises planning to retain centralized network security and/or migrate to more SaaS and hybrid/public cloud computing. For cloud-based applications and other Internet access, colocation facilities together with the right SD-WAN solution can deliver improved end user QoE in addition to their advantages in bandwidth availability, diversity and cost/bit.

WAN Optimization

The data center consolidation trend of the last decade began because of the benefits on the computing and OpEx side of the house, rather than the network. In fact, this trend put even more pressure on the enterprise WAN. The deployment of WAN Optimization appliances proved to be an excellent answer for a one-time bandwidth upgrade (thanks to data deduplication technology) and to improve performance for certain applications, most notably Microsoft CIFS file service – the one application that performs particularly poorly over the wide area network, especially in the face of any noticeable packet loss.

But traditional WAN Optimization technology offers relatively little benefit over high bandwidth but unpredictable Internet WAN connections, especially as less and less traffic is Microsoft file service. Traditional WAN Optimization technology often runs poorly over Internet links. It doesn’t address longer term bandwidth scaling, offers limited-to-no benefit for cloud access, and does not address critical reliability and QoE concerns for cloud access. So while in the era of predominantly thin MPLS pipes at the branch, the approximately 2x effective price/bit benefits combined with the substantial acceleration benefits for CIFS that WAN Optimization solutions offer was a pretty big deal, WAN Optimization technology is simply not the answer moving forward.

SD-WAN Technology Offers Tremendous Opportunity and Promise

A new technology, Software Defined WANs (SD-WANs), offers enterprises tremendous opportunity for cost savings, flexibility, bandwidth, manageability and superior cloud access. It has the potential to deliver a revolution in price/performance and agility to costeffectively support the next wave of applications and the transition to cloud computing.

SD-WAN technology can be seen as an extension of software defined networking (SDN). Similar to SDN, SD-WAN decouples the network configuration from individual wide area networks, links and hardware components, and instead utilizes software and virtual network overlays to take advantage of available WAN connections while centralizing control of and visibility into the entire WAN fabric. SD-WANs enable greater WAN capacity, lower WAN costs and more flexible management capabilities.

Figure 1: SD-WAN Hybrid WAN deployment scenario
SD-WAN hybrid WAN deployment scenario

SD-WAN implementations from Talari as well as almost all other SD-WAN vendors usually share several things in common:

  • A Secure Virtual WAN Overlay Network Fabric
    This flexible, virtual abstraction of the WAN overlay not tied to any single telecom service providers’ WAN is sometimes also referred to as a hybrid WAN (especially if used with a mix of Internet and MPLS connections), and sometimes as WAN Virtualization. The network traffic across the overlay is encrypted using secure virtual private network connections to ensure data security even over public networks.
  • Leverage of Internet Links
    All SD-WAN implementations support using Internet links, and therefore benefit from Internet economics, bandwidth scalability and fast deployment. No organization’s WAN budget is growing as fast as the data growth on their networks, and much future application traffic growth will be in SaaS and public cloud-based services, so leveraging Internet links simply makes sense.
  • Support for Multiple WAN Links
    All SD-WAN implementations support using multiple links. Many support a combination of Internet links and private MPLS links (a.k.a. hybrid WANs), while some, especially those provided as fully managed, so-called “cloud-based” services, can only effectively use Internet links. Some implementations support only 2 active links per location, while others can support 4, 6 or 8 per location. While many people might think that two links per location is sufficient, there are reasons why a well-architected SD-WAN design might want more. At data centers, to maximize high network availability, IT will want the ability to support 3 or even 4 (if one of them is MPLS) high bandwidth connections. At small locations, while two links may well be sufficient if two different high bandwidth, low cost options like FiOS and cable are available, where they are not, the ability to aggregate multiple inexpensive but only moderate bandwidth connections like ADSL can be very valuable.
  • Centralized Controller Plus Centralized Management, Visibility, Reporting and Policy Control
    SD-WAN implementations replace traditional device-based, command-line interface configuration with a centralized controller. The controller offers automated, networkwide control and orchestration for ease of management. Centralized management provides central device configuration, software upgrades and policy control for WAN traffic flow classification, prioritization and QoS. It is a central place for WAN reporting, monitoring, visibility and analytics, as well as the way to tie into overall network and system management platforms. The centralized controller may run on one of the forwarding devices, on standard x86 hardware, or even in the cloud.
  • Choice of Physical or Virtual Appliances
    Just as SD-WANs eliminate ties to any single service provider, most SD-WAN implementations can use either vendor-supplied appliances or standard x86 hardware.

In addition, many SD-WAN implementations help enable branch simplification, combining multiple functions like firewall, NAT, DHCP, routing and VPN on a single device – whether on a vendor-supplied physical appliance or as Network Function Virtualization (NFV) on x86 hardware.

But vendor SD-WAN Implementations Differ Widely

SD-WAN implementations, while sharing a few common traits and tending to sound alike on their surface descriptions vary widely.

Some vendor SD-WAN implementations focus on the needs of telecom service providers. These service providers have their own wide area network assets, and usually offer high priced, high margin MPLS services to enterprise customers. The needs of these service providers are quite different from those of enterprise customers looking to leverage and tame inexpensive public Internet connections.

Some vendor implementations focus primarily on “router replacement”; in other words, the cost of owning and maintaining their WAN (usually Cisco) routers, rather than the issues surrounding the unpredictability of Internet connectivity, cloud access and the costs of WAN service. While having some overlap with other SD-WAN solutions targeted at enterprise customers, these solutions have a quite different focus (unseating the Cisco WAN edge router) and so design point and associated customer benefits.

Some SD-WAN vendors focus on providing a fully managed (sometimes called “clouddelivered”) service over the public Internet. Some of these offerings can be appropriate for a segment of the enterprise market, especially smaller enterprises and those who have never had MPLS, nor likely any kind of centralized security architecture. However, this approach to SD-WANs can be of limited value for larger enterprises, those enterprises with greater control and security concerns, or those who do not wish to make an abrupt wholesale cutover of their WAN infrastructure.

Only a few SD-WAN vendors have focused on developing failsafe SD-WAN technology. Talari has had this at the core of our philosophy – and our patented technology – from the start. Recently, we are seeing the beginnings of failsafe SD-WAN technology development from Silver Peak Systems and VeloCloud Networks. No one delivers failsafe WANs as well as Talari, but these recent vendor entries recognize and reinforce that success with most enterprises will require failsafe SD-WANs.

Why Failsafe SD-WANs

Why failsafe SD-WANs? Failsafe WANs means both high network availability and reliable, predictable application QoE. The tantalizing benefits the cloud and SD-WANs offer notwithstanding, enterprise IT folks disdain “two steps forward, one step back” solutions for good reason. Even the most aggressive, leading-edge enterprises want failsafe WANs if they are going to augment or replace their time-tested MPLS-based solution, given the high cost of downtime, limited IT resources available at most remote locations, and limited enterprise visibility into the WAN.

While there is no doubt that centralized SD-WAN technology makes it a lot easier to configure and maintain a multi-network WAN using encrypted connections over the public Internet, it is foolhardy to believe that, given the enormous gap in bandwidth availability and cost/bit between MPLS and Internet connections, this easier configuration of public Internet VPN tunnels is the only, or even primary, reason that MPLS has been and remains to this day the mainstay of the enterprise WAN and a worldwide market of more than $15B annually. In fact, the key reason behind the ongoing success of MPLS is that it provides enterprise customers a failsafe WAN.

A little history is in order here. IPsec VPNs, introduced in the mid-1990s, made site-site connections over the Internet secure. But despite the price advantages of Internet links, and despite the fact that the Internet in the last 15 years has revolutionized just about everything else that touches IT, very few large enterprises today use the public Internet for their primary site site intranet connectivity. Of course, almost all enterprises do use it for individual user home and mobile access, and many use it for backup connectivity when the primary MPLS link fails. For most large enterprises, individual user access and mobile security, etc. over the Internet is centrally managed, and has been for years.

But on the Internet, there is no single service provider guaranteeing end-end performance – end-end SLAs over the public Internet are simply not offered. The business model of peering points – the places where the network-of networks that is the Internet connect different Internet Service Providers (ISPs) to each other – precludes the ability to deliver any such SLA. Enterprises simply can’t get meaningful QoS over a single Internet connection, both because of the peering point issue and the difficulty of doing the accounting or billing even if there were service providers who wanted to try.

These issues all exist even when the last mile is a dedicated TDM connection such as T1/ E1 or T3/E3. With inexpensive broadband links, there are the additional problems of lack of sufficient upstream bandwidth on ADSL, and the lower MTBF and much higher MTTR associated with broadband connections.

The resulting “two nines” (99%) reliability plus associated performance predictability for the unaided public Internet doesn’t stack up to the “four nines” (~99.95% - 99.99%) reliability MPLS delivers in practice, and that IT and users have come to expect.

So while standard Internet VPNs – and SD-WAN implementations lacking failsafe capabilities – are an excellent choice as backup connectivity, and may be sufficient for some smaller enterprise locations, such “works pretty well most of the time” solutions over unaided public Internet connections simply don’t deliver the enterprise-grade reliability and predictable application QoE that MPLS does.

Absent proper failsafe SD-WAN technology, enterprise WAN managers have done exactly the right thing being conservative with their WANs for all these years, despite the Internet’s vastly superior economics.

So why is it that some vendors seem to think that even though the public Internet hasn’t been good enough all along for the enterprise WAN, it will somehow be reliable enough for enterprise use, just because they say the magic phrase “SD-WAN” and perhaps add easy-to-use, pretty centralized configuration? The answer, of course, is that it won’t.

On the other hand, putting an MPLS connection at every service location accessing a public cloud service is utterly impractical, as it would not only be very expensive, but also incredibly difficult to manage. Yet as user WAN bandwidth demands continue to grow every year, sticking with MPLS alone “forever” clearly isn’t the answer, either.

The bottom line:MPLS is still a $15B+ worldwide market – despite the enormous price/ bit gap versus Internet connectivity – because MPLS offers failsafe WANs. Only a few vendors have actually developed failsafe SD-WAN technology.

Talari does failsafe WANs better than anyone. With Talari, enterprises need not sacrifice failsafe to gain the benefits that SD-WAN technology promises.

Figure 2: Talari failsafe SD-WAN connectivity
Talari failsafe SD-WAN connectivity

Talari's Failsafe SD-WAN Technology

So how exactly does Talari's Adaptive Private Network (APN) technology make failsafe SD-WANs a reality?

The two most critical capabilities of Talari's failsafe SD-WAN technology are:

  • Continuous unidirectional measurement of packet loss, latency, jitter and bandwidth utilization for all paths between any pair of locations
  • Per-packet forwarding decisions, enabling sub -second response to adapt to network issues on any path

This ability to react in real-time, sub-second, made possible by precise, real-time measurement, is the key element in delivering a failsafe SD-WAN.

In addition to the two noted above, other key capabilities of Talari's failsafe SD-WAN technology include:

  • End-to-end QoS and inbound congestion avoidance delivering highly efficient (90% - 97% sustained) bandwidth utilization on shared inbound and outbound links without negatively impacting QoE
  • The ability to use all bandwidth across multiple links, even for a single high-bandwidth flow when doing link aggregation
  • Optional packet replication for real-time traffic, providing platinum quality real-time application support
  • Centralized management with Talari Aware, offering unprecedented WAN visibility
  • High QoE cloud access, especially in combination with carrier neutral colocation facilities close to the core of the Internet
  • The ability to scale to hundreds of locations and thousands of WAN links

Now let’s look at the “big picture” idea behind Talari APN’s architecture, go over the two most critical capabilities in some detail, and also cover the other key capabilities of Talari’s failsafe SD-WAN technology.

The Big Picture

As described above, Talari’s APN technology for SD-WANs creates a secure virtual WAN overlay network fabric utilizing diverse WAN connections, and is focused on providing the critical network reliability and performance predictability to make failsafe WANs leveraging public Internet connections a reality. It wraps a layer of software intelligence around multiple public and/or private WAN connections in much the same way RAID wrapped intelligence around cheap PC hard disk technology and revolutionized storage over twenty-five years ago.

The basic idea behind Talari failsafe SD-WAN technology is to combine two or more disparate sources of IP bandwidth at each network location and use them in a way that delivers reliability that meets or exceeds that offered by any single vendor MPLS network. These bandwidth sources can be high-speed T3/E3, OC-3, Fast Ethernet or Gigabit Ethernet links at larger sites, as well as any Internet connectivity such as DSL, cable, FiOS, T1/E1, Metro Ethernet, etc. at remote locations. Existing private WAN connections such as MPLS can also be leveraged.

Figure 3.
99% reliability from Talari failsafe SD-WAN

With connectivity between locations possible over at least two paths from different network sources, there is redundancy because of the diversity at the physical and the IP network levels. The probability of timely packet delivery from one location to another across at least one of these networks is very high. Even if each network has a reliability of only 98%, then the reliability of the two networks when combined properly using Talari SD-WAN technology will be 1-((1-0.98) * (1-0.98)) = 99.96%.

Similarly, two diverse Internet connections that are each 99% reliable – which is the approximate general expectation for domestic Internet connections – can be made 1-((1- .99) * (1-.99) = 99.99% reliable. Because Talari’s offering usually uses multiple paths over each available Internet link, rather than just one, it can actually achieve still more reliability when we have multiple diverse public connections at each end.

While there have been WAN link aggregation technologies for a long time now – MLPPP, for example, has been around forever – all of them before Talari APN technology had
fundamental limitations on their usefulness. They were either like MLPPP and required WAN links that were uniform in type and bandwidth and had extremely low loss and jitter characteristics, or they would not deliver reliability in the face of network problems. Most other than MLPPP (and for that matter, most other SD-WAN implementations on the market today) require that each TCP flow use only a single WAN connection. If not, they would actually make application performance worse when there are congestion issues on any of the network connections or links. None have had the ability to move flows off of a bad network path in the face of packet loss or excessive latency/jitter without breaking the connection.

A Talari SD-WAN- addresses all of those limitations of prior aggregation technologies and then some.

Figure 4.
Continuous Unidirectional Measurement

The linchpin technology that enables the delivery of failsafe SD-WANs is the continuous unidirectional measurement of packet loss, latency, jitter and bandwidth utilization for all network paths between any pair of locations.

APN performs continuous measurement of each packet on the WAN, as opposed to measurement via occasional round-trip test packets. The measurements are unidirectional, not simply round-trip, since just as on roads and highways, traffic jams are usually in one direction but not the other, and since unidirectional information is essential for real-time traffic. The measurements are done across all paths, since given m Internet links at one location and n at the other, there are m x n possible network paths that can be used across the network-of-networks that is the Internet, substantially increasing reliability and QoE. In the figure above, given two Internet links at each site, plus a private MPLS connection, there are 2 x 2 + 1 = 5 different possible network paths between the two locations shown. APN supports up to 8 WAN links per location.

The measurements are done on each and every packet sent between the two locations, not simply using sporadic test packets – though multiple test packets per second are sent when there is no actual network traffic for any given path, to ensure constantly up-to-date measurement data.

Per-Packet Forwarding Decisions, and Sub-Second Response

This precise, real-time measurement enables unprecedented WAN visibility and subsecond response to adapt to network issues, both hard link/device failures as well as “soft outages” from network congestion-based packet loss and jitter. It is this sub-second response that is the critical component to delivering a truly failsafe SD-WAN.

End-to-end algorithms match the state of the network with the needs of different traffic types and adapt using real-time, per-packet traffic engineering. Even though packets can follow any number of paths to the destination, the connection between two locations appears as a single highly reliable link. This delivers predictable IP session performance throughout, regardless of transient congestion or network outages. To TCP/IP-based applications, the resulting WAN connectivity looks like a zero-loss network with occasional bouts of high jitter.

The sub-second response delivered by Talari APN technology is more than fast enough
to handle any application that can run on an MPLS WAN. Consequently, it delivers as good—and usually better — reliability and predictable application QoE as an enterprise can achieve with a single-vendor MPLS WAN.

End-to-end QoS and inbound Congestion Avoidance

Like all good intermediate networking devices, APN appliances implement QoS and use the class of service information and any other configured policy rules associated with each flow as part of the path selection criteria. Unlike other offerings that implement QoS and can only prioritize which traffic goes out on the local link first, APN technology uses this QoS information to choose the path that gets the packet to the destination at the other end of the WAN in the shortest possible time – which is ultimately what matters most for delivering application QoE. This end-to-end QoS is only possible because of the
detailed unidirectional measurement information.

Network administrators don’t have to associate certain flows with certain network connections, just because those flows are higher priority or that network connection usually has better jitter and loss characteristics. Network paths that are currently working well get traffic, and traffic is diverted, sub-second, away from network paths experiencing problems. An organization’s most important traffic gets to the other end of the WAN as quickly as possible, and all of the traffic gets to the other end of the WAN quickly and reliably.

Further, APN technology leverages the latency and bandwidth utilization information it gathers to ensure that even inbound links are used efficiently and not congested. This ability to both inform and then negotiate with far side edge devices about available access to their last mile interface is sometimes referred to as bandwidth reservation, but the technology is more sophisticated than prior bandwidth reservation technologies for packet-based networks.

APN’s patented technology is able to provide highly efficient bandwidth utilization – delivering 90% - 97% sustained utilization on shared outbound and inbound links without negatively impacting QoE (i.e. minimizing latency increases on last mile links). All reputable basic QoS solutions have been able to do this for outbound links for years; doing this for inbound traffic is much more difficult; in fact, the rule of thumb for inbound or core network links is that above 40% sustained utilization, more bandwidth is necessary to avoid jitter/latency/loss issues that can materially impact QoE.

Use All Bandwidth Across Multiple Links, Even for a Single Flow

Because Talari APN technology can make per-packet, rather than simply per-flow, forwarding decisions, it can deliver far better link aggregation capabilities than competing approaches. It is able to use all available bandwidth at any location, across even widely disparate links, even for a single large flow – something not possible to do in a reliable, predictable fashion with other technologies when leveraging multiple WAN connections with differing latencies and varying loss and jitter characteristics.

With a Talari SD-WAN, IT gets to use all of the bandwidth almost all of the time, and do so in an automatic, failsafe manner.

Packet Replication for "Platinum Quality" Real-time Support

For real-time applications like VoIP and videoconferencing, Talari’s failsafe SD-WAN technology can deliver ultra-reliable, cost-effective support, choosing network paths with the least packet loss and lowest jitter for such high-priority traffic, and switching subsecond to a better path in the face of high loss or jitter.

Where sufficient bandwidth is available, it can provide still greater flow reliability by optionally replicating real-time traffic flows along a second path, suppressing duplicates at the receiving end, and so delivering “perfect” platinum-quality sound and voice quality even in the face of failures or massive congestion on one of the connections.

Competing Forward Error Correction (FEC) technologies purport to provide similar benefits, but while they provide benefit when used with links that have relatively uniform loss (as, e.g. some wireless connections), given that by definition they send the traffic over the very network path having issues, they are of little benefit when dealing with the occasional bouts of high loss and high jitter that occur on shared networks like the public Internet, and of essentially no benefit in these instances to real-time applications like VoIP or videoconferencing.

Figure 5.
Centralized Management, Unprecedented WAN Visibility

Centralized Management, Unprecedented WAN Visibility

Talari’s APN Aware is a centralized management system that gives IT staff the ability to configure, monitor, and analyze a Talari SD-WAN. Aware reduces network device configuration time, and provides access to detailed performance data and events correlated across the WAN. This results in an easy to manage network with unprecedented WAN and application performance visibility.

Talari Aware Highlights

  • Intuitive, centralized management system for Talari appliances
  • Single point configuration with comprehensive network-wide audits
  • Simplifies monitoring and analyzing a Talari SD-WAN
  • Fully customizable reports and graphs for easy network and application performance management

High QoE Cloud Access

In addition to offering virtual appliances in the cloud, Talari’s powerful SD-WAN technology in combination with carrier neutral colocation facilities offers Internet economics for data centers, cost effective maintenance of existing centralized enterprise security architectures, a smooth path to efficient hybrid cloud computing and reliable, predictable QoE for SaaS and public cloud computing services.

With virtual appliances for AWS (Amazon Web Services) and Microsoft Azure, Talari extends the reach of the corporate WAN into the Amazon or Microsoft clouds, making it possible to control, manage and have visibility into the connection to the cloud. It uses the same Talari SD-WAN technology that enterprise locations do, and so ensures that applications and content are always available regardless of any single network failure.

In addition, Talari SD-WAN technology can be used to add one or more locations on the customer’s WAN at colocation facilities. Deployment at a colo facility is similar to deployment at a private data center, though some customers will prefer virtual appliance deployments at a colo even when choosing physical appliances at private locations.

Using Talari’s failsafe SD-WAN technology, especially in conjunction with colocation, allows IT to centralize the complexity in the network at locations where diverse bandwidth is cheap and plentiful, and which provide excellent connectivity to “the core of the Internet” and so to public cloud-based cloud computing services and SaaS. Backhauling Internet traffic to a colo facility – where the enterprise’s centralized security technology is deployed – rather than to private data centers now makes tremendous sense. Such deployments are the key to enabling a smooth migration to cloud services.

Scaling the SD-WAN

Scaling failsafe SD-WAN technology to support hundreds of locations and thousands of WAN links is no easy task, but Talari APN technology does exactly that.

Note that scaling SD-WAN technology is relatively straightforward if not doing fail-safe WANs – and the continuous measurement and sub-second response that goes along with it – but not at all trivial to deliver when performing real-time measurements on all network paths and offering sub-second response to network issues.

Be wary of vendors who try to conflate scaling of network management and device configuration with the much harder task of scaling the technology of continuous measurement and failsafe forwarding decisions with sub-second response. Of course, it’s true that SD-WAN vendors that don’t offer such failsafe SD-WAN technology don’t have to deal with such challenging scaling issues.

Complementary to WAN Optimization

WAN Optimization, another two-ended technology from companies like Riverbed, Silver Peak and Citrix, was built on the longstanding assumption that the existing enterprise WAN is as reliable as needed, but bits are expensive – and the need, therefore, is to squeeze as much out of those thin pipes as possible. The insight behind Talari’s SD-WAN offering is that there are lots of cheap bits out there, thanks to the Internet – they just need to be made reliable enough to be business quality.

Where WAN Optimization focuses on optimizing each application for the network, Talari failsafe SD-WAN technology optimizes a more-affordable, higher-bandwidth network fabric for all applications. Talari’s SD-WAN solution is highly complementary to WAN Optimization; many of our customer deployments are in conjunction with existing WAN Optimization appliances.

Talari failsafe SD-WAN technology, thanks to its ability to aggregate bandwidth across disparate links, deal with the effects of packet loss, and quickly react to jitter and latency caused by network congestion, has capabilities that help real-time and highly interactive applications in ways that WAN Optimization simply cannot. It offers better performance for first-time data transfers, improved QoE and reliability for real-time apps like VoIP and time-sensitive interactive applications like VDI, and offers more predictable performance for all applications even in the face of network “brownouts” which stymie other network reliability or application acceleration technologies.

Benefits of a Failsafe SD-WAN

What can enterprises expect from a failsafe SD-WAN? The benefits are substantial, both short term tactically and longer term strategically, for both the network itself and “beyond the network”.

For the Network

Far Greater WAN Bandwidth

As noted, Internet bits are simply far less expensive than those from the oligopoly MPLS providers, offering 50x – 150x bandwidth per dollar compared to MPLS at branch locations, and can be 10x – 50x for data center locations, especially at carrier-neutral colocation facilities. Talari’s failsafe SD-WAN technology allows enterprises to use inexpensive Internet bandwidth to augment or replace expensive MPLS links.

It also enables much more bandwidth per enterprise location, because of its ability to aggregate multiple, disparate links and use the combination in a failsafe manner as if it were a single connection. Talari’s bandwidth aggregation capabilities enable enterprises to take advantage of the asymmetric bandwidth offered by some broadband connections. The asymmetry reflects the way that most traffic flows (from data center to branch). But while a single ADSL connection alone might not have sufficient upstream bandwidth to satisfy some corporate uses, by aggregating multiple connections, sufficient upstream bandwidth is available even for enterprises that choose to eliminate a T1/E1 MPLS link.

Lower WAN Costs

Since Internet bandwidth costs far less than MPLS, monthly WAN costs can be reduced by 40% - 80% (even as IT adds bandwidth to the WAN) as Talari’s failsafe SD-WAN technology enables that Internet bandwidth to be business quality. Consequently, spending on MPLS can be capped and, if desired, eventually eliminated altogether for maximum cost savings.

Talari’s SD-WAN solution makes it easy to take advantage of small amounts of expensive private bandwidth combined with larger amounts of cheap Internet bandwidth for the best of both worlds. If they wish, enterprises can continue to keep spending, say, 60% of their WAN budget on the 10% of really expensive private (read: MPLS) bits while spending the other 40% on the 90% of cheap Internet bits. Thanks to Talari’s failsafe SD-WAN technology, enterprises will not only have more bandwidth and lower cost per bit, but they also will have lower overall monthly WAN spend, and greater reliability, than they would by putting all their eggs in the AT&T/Verizon/BT basket.

Greater Network Reliability and Application QoE than any Single MPLS Network

The reliability technology at the core of Talari’s SD-WAN solution making it all possible is, of course, a great benefit in its own right. With Talari failsafe SD-WAN technology, the wide area network is now more fault tolerant even to errors users or IT might inadvertently introduce (software upgrades, taking connections down for maintenance, etc.), thanks to the multi-path reliability combined with the fact that most Talari SD-WAN implementations are overlays – software-defined networks that sit on top of the routed network infrastructure rather than replacing or actively modifying its construction. Talari SD-WAN technology
greatly enhances network reliability, and in particular application QoE, by eliminating single points of failure from even temporarily taking out the network and causing application sessions to be broken.

Radically Reduced Troubleshooting costs

WAN managers also need to do far less troubleshooting of that portion of the network – the external WAN – where they have historically had both the least visibility and the least control. A Talari SD-WAN is not just a visibility tool to inform IT of network problems or help track down the specific cause of a problem after it happened; it fixes the problems in real time before users even notice them, virtually eliminating MTTR issues. Lower troubleshooting costs translate into lower WAN OpEx.

Unprecedented WAN Visibility

Of course, the continuous unidirectional monitoring technology enables rich, detailed visibility reporting into WAN performance, to help track down those problems which are not simply transient at your leisure, without impacting users. It can enable IT to document and get money back from SLAs missed by their service providers.

Agile, Non-disruptive Deployment - No "Forklift Upgrades"

Despite the revolutionary benefits it offers, Talari’s SD-WAN solution was designed to be deployed in a non-disruptive fashion, augmenting existing MPLS networks and WAN Optimization equipment. It enables incremental, IT-controlled evolution of the WAN, rather than requiring periodic “forklift upgrades”. Older WAN connections need not be ripped out. If desired, enterprises can augment and keep older, expensive private WAN connections indefinitely, or let them eventually wither away when they are no longer cost-effective, and sufficient total network reliability has been demonstrated.

Talari’s SD-WAN offering also allows for easy, cost-effective bandwidth scalability. Bandwidth additions can now be incremental and done in days, rather than the weeks or months it can sometimes take to get an additional MPLS circuit deployed, or the months or years it can take to get fiber to some locations – and can be done without sacrificing reliability or application QoE.

"Beyond the Network" Benefits

Superior Support for Next-generation Apps, and Real-time Apps like UCaas and Videoconferencing

Applications run better, with greater QoE and more predictable performance, with Talari failsafe SD-WAN technology. A Talari SD-WAN enables the cost-effective deployment of applications that are otherwise difficult to deploy and support over a farflung WAN.

Talari failsafe technology can improve latency-sensitive VDI (a.k.a. Desktop Virtualization) flows in ways that WAN Optimization technology cannot, via sub-second path switching in the face of network congestion and even replication of flows. For some interactive or real-time applications that are very sensitive to latency or packet loss, a Talari failsafe SDWAN may be the difference between implementation success and failure, especially given the realities of today’s IT budget constraints.

For example, UC solutions hosted in the cloud to augment or replace purely internal VoIP, videoconferencing or UC deployments will also be made much easier with a Talari SD-WAN solution. In the case of videoconferencing, for many enterprises, Talari failsafe SD-WAN technology enables the necessary additional bandwidth and QoE allowing enterprise-wide deployments even to be possible, as running HD videoconferencing over thin T1/E1 circuits along with existing application traffic can be a nonstarter.

Excellent Support for Centralizing Network Security and Internet Access

Despite the more distributed nature of the cloud when it comes to the location of application and services, and despite the claims of some that using SaaS and cloud computing effectively requires fully distributed Internet access, a Talari failsafe SD-WAN solution facilitates the centralization of network and IT complexity, e.g. for Internet access/ Internet security and remote site backup. With proper WAN design, centralizing network and IT complexity can save time and money while simultaneously improving application QoE.

A Talari failsafe SD-WAN, especially in conjunction with colocation, allows IT to centralize the complexity in the network. As we know already from server consolidation, there are computing and security benefits to centralizing complexity in a small handful of locations. For the network, a Talari SD-WAN enables the centralization of network complexity and policy at a tiny number of data centers and colocation facilities, even for a large worldwide WAN with hundreds or thousands of locations, without sacrificing performance, security or application QoE, and doing so in a low cost way that will scale.

A Talari SD-WAN enables scalable, compromise-free Internet backhaul. In conjunction with carrier-neutral colocation, Talari’s failsafe SD-WAN technology allows enterprises to have all the security and simplicity benefits of network backhaul using a partial mesh hub-and-spokes design, with the higher performance and lower average latencies benefit of distributed Internet connectivity, in a manner which is lower cost and more scalable than either. Expensive, complex IPS and next-generation firewall technologies can be limited to only a few carefully chosen colocation sites and data centers, maintaining security and allowing easier upgrades to and lower management costs for security solutions, while central site bandwidth is far lower cost and more scalable as well.

Reliable, High QoE Access to SaaS and Public/Hybrid Cloud Computing

Building on the above, and even more important from the perspective of using SaaS and public cloud computing services for mission critical user access, access from the branch into the Internet core is now as reliable as site-to-site internal WAN connectivity.

A Talari SD-WAN implementation leveraging colocation facilities improves network reliability and application QoE for not only Internet access in general, but can enable “on-net” reliability to cloud services located at the same colocation facility. It also offers IT the next best thing - “3 ½ nines” – even for SaaS and cloud services not immediately near the colo facility. The problems with Internet performance – at least within North America and within Western Europe – are rarely in the Internet core, but rather on first mile/last mile links, or the peering points connecting first mile/last mile to the Internet core; Talari’s failsafe SD-WAN solution addresses all the key problem points.

This is critical to allowing enterprises to leverage cloud computing – public, private or hybrid – in an incremental, secure and reliable way. Without reliability and predictable application QoE, most Application IT teams simply will not be willing to move mission-critical applications to a private cloud, to say nothing of hybrid or public clouds. Having a private cloud at a carrierneutral colo facility connected by a predictable, reliable WAN under enterprise control is the way that the vast bulk of enterprise applications can be safely and securely migrated to take advantage of public cloud services, at a pace that makes sense for each enterprise’s computing department, without blowing the budget or causing users to complain about unusable applications.

With a Talari failsafe SD-WAN, enterprise WAN managers can prepare and enable their WAN for the move to private or public cloud computing, at whatever pace the computing side of the organizations wants to go, without sacrificing the network reliability, network security and predictable application QoE they have today.

Leverage over telecom service providers

One of the most beautiful points about a Talari SD-WAN solution is that most or all of the next generation network upgrade can pay for itself out of the WAN OpEx budget. It also provides a long-term way to leverage Internet economics and Moore’s Law, giving enterprises a failsafe way to cost-effectively scale their WANs and leverage new WAN technologies, even consumeroriented ones, as they appear. It gives enterprises leverage for the first time with their telecom service providers.

Source of funds for other WAN and cloud projects

While not something that an AT&T or Verizon salesperson wants to hear, enterprises now have a new source of funds for projects: the private WAN OpEx budget. In the same way that PCs, LANs, WANs and client-server computing spending grew much faster annually than IT budgets overall in the 1980s and 1990s by stealing from the mainframe/minicomputer budget, a Talari failsafe SD-WAN enables enterprises to first cap, and then tap, their expensive spending on MPLS, and over time use that budget as a source of funds for not just adding bandwidth, but even other priorities like enabling videoconferencing or migrating to cloud computing.

A Talari SD-WAN gives enterprise WAN managers a long term way to cost-effectively scale the WAN while supporting the migration to cloud-based applications. Thanks to Talari failsafe SD-WAN technology, Wide Area Network design, for the first time in a long time, is strategic. A Talari SD-WAN helps lower overall IT CapEx and OpEx.


The cloud is changing everything, and the traditional solution of MPLS, even augmented with WAN Optimization, simply won’t cut it. SD-WANs offer enterprises enormous potential and benefits – if delivered in a failsafe manner. A failsafe SD-WAN solution provides enterprise WAN managers a safe, evolutionary, cost-effective way to deliver predictable QoE while meeting application demands in the age of the cloud. Few vendor SD-WAN solutions actually deliver failsafe enterprise WANs. Make sure to source your SD-WAN from a vendor that does.