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MATCHING THE WAN TO BUSINESS NEEDS
James Walker, Vice President Managed Network Services WAN Summit 7th October 2015
THE CHANGING WAN
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• The rise and rise of the cloud • Bringing challenges of :
• Integration with legacy systems • Private vs public connectivity • Alignment with internal policies, security requirements, regulatory obligations • Barriers to entry for smaller cloud providers
• Increasing use of hybrid VPNs • Cost reductions • More challenges :
• Load balancing (MP BGP) • Asymmetric routing • Cloud connectivity • Full dual link utilisation
• The arrival of early SDWAN services
So, what’s new?
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Customer requirements
Network-centric Application-centric
• Extensive in-house network expertise • Complex traffic engineering requirements • Deterministic behaviour • High speed core, regional meet-me • Private network • Limited public cloud, little if any SaaS • Tendency to have significant on-premise
applications • Audit, compliance and security
requirements
• Limited internal network expertise • Application performance critical • Hybrid networks, mix of private and public
traffic • Want to increase utilisation levels of the
network • Increasing use of public cloud and SaaS
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Network requirements
Network-centric Application-centric
• Deterministic pathing • Minimise visibility of customer’s routing
table • Predictable network performance • Complex DR scenarios • Possible overlay networks • Generally high speed (1G+) and growing • Challenges around internal cost allocation
and logical separation • Dynamic bandwidth potentially required • Limited sites • Service multiplexing • “TEaaS”
• Managed services • Application visibility and reporting • Performance optimisation • Intelligent load balancing, pathing and use
of network resources • Integration of multiple services (UC,
Internet) • Connectivity to public cloud • A network that dynamically reacts to
application performance and needs • Overlay network requirements • Typically multi-vendor, multi service
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… AND SDWAN HYBRID VPNS
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Let’s start with something very basic
• No contention in the core
• SLA guarantees available
• Premium link
• Unpredictable with potential contention and jitter
• Best effort based
• “Cheap and cheerful” link
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A few more scene-setting thoughts • Last mile connectivity is the biggest cost in a network
• Secondary circuit is hardly used (traffic flows less than 1% of the time)
• Network managers are forced to manage congestion on the primary circuit while the secondary circuit lies idle
• Backup links fail and no-one notices until they’re needed Primary Circuit Secondary Circuit
VPN
• For short term bursts – apply QOS techniques and don’t increase bandwidth
• Long term high link utilization – buy more bandwidth, burst or offload traffic to alternate path
• Frequent path change causes harm
• Always route critical traffic on the best path
Network management best practice
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Now, a little background on SDWAN
This is Cisco IWAN – but most SDWAN solutions have similar concepts • Traffic is hub and spoke • Metrics are measured from the hub to the spokes • Path selection based on metrics • Path abstraction (in IWAN, using DMVPN technology) • Hub Master controller automatically pushes policy to
spokes • Multiple DCs are supported using a concept called a
transit site
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• Questions customers should ask their SDWAN provider • Do all sites need two connections, or can I have single attached sites? • Do all sites have to participate in the overlay?
• What about IaaS sites? • Do I have to migrate everything at once?
• Can I control spoke to spoke traffic? • Can I have different traffic policies at different DCs? • When the primary fails at the DC, does all traffic fail over to the
alternate path (for hybrid sites, this is the Internet…)? • What is the impact on router throughput, are older/smaller routers
supported? • How do I handle local internet breakout at hybrid sites? • Will my load balancing policy cause any issues?
SDWAN – still evolving
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Asymmetric routing
70-80% reduction
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Problem statement Metric based approach – Path Oscillation Problem
Link utilization increases on
last mile
Metric for critical
application (that has the
most stringent requirements)
drops first
Critical applications are offloaded
Offloading causes
metrics to improve
Variable internet
performance impacts
application performance
metrics
Premium applications are offloaded
again. Congestion
reoccurs
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• New applications, cloud and the move to hybrid networking is a very fundamental change • Local internet breakout, connections to cloud (eg O365, Skype) and legacy applications are very
complex to manage efficiently • Managing application prioritisation and failover remains difficult
• Service providers – and the industry – are in a state of flux • Enterprise customers sit on a spectrum with a spread of requirements which become very different at
the two ends • SDN and NFV are not yet here and continue to evolve • Customers have problems now
• Overlay providers are an attractive option for frustrated enterprises • … but can introduce rafts of new issues, and not fix the old ones • There is no silver bullet
• Back to the future? • While supporting SDWAN, we are also investing heavily in innovation using “legacy” protocols • Visibility, efficiency, predictability and control are the objectives
Final thoughts
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