Deployment Recommendations: Avoid Cn2 To The United States And Bypass Singapore In A Multi-exit Environment. Summary Of Best Practices

This article outlines how to reduce the risk of path anomalies and performance degradation caused by operator transit (especially involving Asian transit points) through detection, routing policies, traffic engineering and other means when operating a multi-exit network, helping the engineering team optimize traffic to the United States while ensuring compliance and stability.

How many exits can significantly reduce the risk of cn2 to the United States bypassing Singapore?

More exports are not better, the key lies in diversity and independence. It is generally recommended to configure at least three physical or logical exits: a direct international backbone (preferring BGP directly connected backbones/partners), a secondary operator via regional interconnection, and a cross-border interconnection as a backup. This enables controlled policy switching when a single path is affected, reducing the probability of passively heading to Singapore or other undesired transit points.

Which exit or operator is better to avoid detouring around Singapore?

When selecting an operator, you should focus on its direct connection capabilities to the United States, whether it has dedicated line products such as CN2, and backbone interconnection relationships. Prioritize ISPs with direct access to US PoPs or high-quality North American direct partners to avoid relying on regional relay providers that transit international traffic through Singapore. Also evaluate the routing announcement policy and community label support of the peer AS.

How to avoid undesired transit paths through routing policy control?

At the BGP level, local-preference, AS-path filtering, community tags, and MED are used to implement refined traffic engineering. Set a lower priority or direct filtering on paths that may pass through Singapore, and configure prefix precision and longest matching policies on the egress router to ensure that traffic to the United States preferentially takes direct connections or paths through trusted partners.

Where should monitoring points be deployed to detect detours to Singapore in a timely manner?

Monitoring should be deployed in layers: first, deploy real-time BGP monitoring and routing table snapshots on egress devices; second, place active detection probes at the edge and core (such as TCP/ICMP/HTTP speed measurement for major US servers); third, deploy passive traffic sampling (NetFlow/sFlow) in the cloud or peer PoP for long-term trend analysis. Focus on monitoring round-trip latency, packet loss, and AS path changes.

Why does it happen that cn2 goes to the United States and bypasses Singapore?

Common reasons include the operator's transmission strategy (cost and link capacity optimization), peer relationship adjustment, temporary detour due to link failure, and improper BGP policy. In order to reduce local relay costs, some regions will aggregate some traffic through regional hubs (such as Singapore) and then send it overseas. This is especially likely to happen in an environment with multiple exits but lack of traffic engineering control.

How to detect and respond quickly to path anomalies to avoid affecting business?

Establish an automated alarm and fallback mechanism: when RTT, packet loss, or abnormal changes in AS-path to the United States are detected, a script is triggered to adjust the local priority or activate an alternate exit. Cooperate with the grayscale release and alarm suppression strategies for change approval to ensure human control and rapid recovery. Regularly practice failover and switchover regression processes to ensure smooth switchover.

How much cost and compliance factors need to be considered when deploying?

Avoiding detours often requires establishing direct connections or interconnection relationships with more ISPs, which means additional link and peering costs. When evaluating, operational costs, latency benefits, and compliance audits (such as data sovereignty and export reviews) should be quantified along with SLA requirements. For sensitive services, encrypted tunnels or MPLS L3VPN can be used to meet compliance and privacy requirements.

How to balance multiple exits with security and reliability in implementation?

In practice, routing security (RPKI/ROA, maximum prefix limit), DDoS protection and multi-path strategy should be combined in the design. Use routing policy whitelist, AS-path verification and community labels to avoid misrouting; at the same time, configure traffic mirroring and rate limiting on the egress side, and cooperate with DDoS scrubber or cloud protection to ensure that no security risks are introduced when switching egresses.

Where can I obtain and verify the path quality claimed by the operator?

In addition to the SLA documents provided by the ISP, end-to-end data should be obtained through third-party measurement platforms (such as RIPE Atlas, ThousandEyes) and self-built probes. Compare BGP routing views (such as RouteViews, RIS) with active measurement results to confirm whether the direct connection to the United States announced by the operator is true and stable, and avoid making decisions based solely on quotations or publicity.

How to turn these suggestions into an executable deployment checklist?

Make a phased implementation list: evaluation period (select ISP and collect baseline data), configuration period (deploy BGP policies, communities and route filtering), verification period (active monitoring and drills), and operation period (continuous monitoring and regular audits). Designate the responsible person, rollback plan and SLA indicators for each item to ensure that we can quickly locate and handle the situation when encountering cn2 to the United States around Singapore.