Hybrid SD-WAN Internet Breakout for Global SaaS
A manufacturer operates 60 branch sites across North America, Europe, and Asia. Each branch has a 200 Mbps MPLS circuit and a 1 Gbps broadband circuit. The company moved its ERP to a SaaS provider and now measures 480 ms median latency to the SaaS tenant from Asian branches, with 12% packet loss during peak hours. All branch internet traffic currently backhauls to two data centers in Chicago and Frankfurt for security inspection, then exits to the internet. The security team requires TLS inspection and URL filtering, but the CIO wants direct internet breakout at branches to improve SaaS performance. The network team has an SD-WAN overlay with per-application policies, but the underlay MPLS has a 99.99% SLA while broadband has no SLA. The company also has a new AWS workload in ap-southeast-1 that branches must reach privately. Budget allows two regional security stacks and a cloud on-ramp, but not full security appliances at all 60 branches.
1. Recommend an architecture for direct SaaS breakout and private AWS access. Address security inspection and the SLA mismatch.
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Do not place full security appliances at all 60 branches. Use local internet breakout from the SD-WAN edge for known SaaS applications, but steer that traffic through a cloud-delivered secure web gateway or regional security stack via an IPsec tunnel. This keeps TLS inspection and URL filtering centralized while removing the data-center backhaul. For latency-sensitive SaaS, use application-aware routing and measure per-path jitter and loss; send SaaS over broadband when it meets the threshold and fail over to MPLS or LTE when it does not. Keep voice and unknown traffic on MPLS or a stable overlay. For AWS ap-southeast-1, build a cloud on-ramp: an SD-WAN gateway or transit VPC that connects to AWS Transit Gateway over IPsec or Direct Connect. Advertise only the AWS VPC summary to branches. Because broadband has no SLA, use two diverse broadband paths where possible and a cellular backup for critical branches; do not promise MPLS-grade SLA for breakout traffic.
2. How would you segment and route traffic so that SaaS breakout does not expose branch networks to inbound internet threats?
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Use VRFs or segments on the SD-WAN edge: one for PCI or corporate traffic, one for guest, one for IoT, and one for direct internet. Apply a deny-by-default policy between segments. For breakout, use stateful firewalls in the regional security stack or SASE, with NAT and no inbound ports. The branch LAN should never be directly reachable from the internet; only outbound sessions are allowed. Use DNS security and TLS inspection at the regional stack, not at each branch. Route SaaS traffic by application signature or domain-based policies to the breakout VRF. Send all other internet traffic to the regional stack for inspection. Keep AWS private access on a separate VRF and advertise only the required AWS routes. Log flows at the SD-WAN edge and the security stack, and alert on policy denies.
3. What pilot and validation steps would you run before rolling out to all 60 branches?
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Pick five branches with diverse underlays, including one high-loss Asian site. Deploy the breakout policy with the regional security stack and cloud on-ramp. Baseline the current latency, loss, and SaaS response time for two weeks. Then run a controlled pilot for four weeks with synthetic transactions to the SaaS tenant and to AWS. Compare p95 and p99 latency, packet loss, and security inspection rate against the baseline. Use packet captures at the branch and the security stack to confirm the path. Test failover by disabling broadband and confirming MPLS or LTE takes over within the target. Measure helpdesk tickets and security alerts. Define go/no-go criteria such as 30% latency reduction, no increase in missed malware detections, and no more than 0.5% failed transactions. Roll out in waves by region.