The Practice Of Deploying Load Balancing To Improve The Response Time Of Vietnam Cn2 Server Cluster

1.

preparation and assessment (context and goals)

before deployment, clarify the goals: reduce the average response time under vietnam's cn2 line, improve concurrent throughput, and ensure failover. collect information: backend node ip/port, operating system (usually ubuntu/centos), whether bgp is enabled on the cn2 dedicated line, bandwidth and concurrency peak estimates, and whether ssl is terminated at the lb end. prepare 1-2 independent load balancing machines (at least two are recommended for redundancy), public ip and corresponding firewall/routing permissions.

2.

choose a load balancing solution

choose based on protocol and performance: it is recommended to use nginx or haproxy for layer seven for http/https, and it is recommended to use haproxy's tcp mode or lvs (ipvs) for layer four for tcp or games/databases. for enterprise level, consider f5 or kemp. if you need high concurrency, low latency and intranet forwarding, lvs+keepalived is the first choice for performance; if you need flexible routing, rewriting, and waf capabilities, use nginx/haproxy.

3.

infrastructure deployment steps

(1) prepare the system: apt/yum update, turn off selinux (depending on requirements), install necessary tools: sudo apt-get update && sudo apt-get install -y haproxy nginx keepalived ipvsadm tcpdump mtr curl; (2) set the port required for the firewall to release lb (80/443/tcp custom port); (3) configure independent users and log directories for haproxy/nginx.

4.

haproxy sample configuration (tcp/http dual mode)

add basic configuration: global/maxconn, defaults timeout in /etc/haproxy/haproxy.cfg. example (simplified): frontend fe_http bind *:80 mode http option http-server-close acl host_www hdr(host) -i example.com use_backend be_www default_backend be_app backend be_app mode tcp option tcp-check balance roundrobin server s1 10.0.0.1:443 check server s2 10.0.0.2:443 check. after uploading the configuration, sudo systemctl restart haproxy. pay attention to enable ssl termination (bind *:443 ssl crt /etc/ssl/...) as needed.

5.

nginx reverse proxy and ssl

if you use nginx as a seven-layer load balancing: the server block listens to 80/443, use proxy_pass to point to the backend; enable keepalive_requests and keepalive_timeout in the upstream block: upstream backend { server 10.0.0.1:8080; server 10.0.0.2:8080; keepalive 32; }, and in location use proxy_set_header, proxy_http_version 1.1 and proxy_set_header connection "" to reuse connections. use certbot to automatically apply for a certificate: sudo certbot --nginx -d example.com.

6.

lvs+keepalived high-performance four-layer solution

suitable for millions of concurrent scenarios. steps: install keepalived and ipvsadm on two lbs; configure /etc/keepalived/keepalived.conf and use vrrp to configure virtual ip (vip); use ipvsadm -a -t vip:port -s rr on the master node and then add the real server ipvsadm -a -t vip:port -r 10.0.0.1:port -m. set up rsync/iptables to synchronize real server status. test failover: disable the main keepalived and observe vip drift to backup.

7.

routing and dns optimization for cn2 lines

cn2 line characteristics: prioritize the use of cn2/ctg exports and ensure that bgp peering settings are loop-free. recommendation: use geodns or smartdns to resolve vietnamese users to vietnamese computer room vip; use low ttl (60-120s) with health detection when deploying in multiple regions; if the supplier supports anycast, placing lb on the anycast network can further reduce rtt.

8.

system kernel and network tuning (key parameters)

add it to /etc/sysctl.conf and take effect (sysctl -p): net.ipv4.tcp_tw_reuse=1 net.ipv4.tcp_fin_timeout=30 net.ipv4.tcp_max_syn_backlog=4096 net.core.somaxconn=65535 net.core.netdev_max_backlog=250000 net.ipv4.tcp_congestion_control=cubic. adjust the file handle: ulimit -n 200000 and write to /etc/security/limits.conf. pay attention to item-by-item verification to avoid blind modification of the production system.

9.

health checks and session consistency

configure active health check (haproxy's http-check or tcp-check, lvs's external script). for applications that require session persistence, use cookie-based stickiness (haproxy: cookie srv insert), or source ip-based hash (balance source). however, session stickiness may reduce the balancing effect, so it is preferable to use shared session storage (redis/db) at the application layer.

10.

monitoring, logging and troubleshooting

deploy prometheus + node_exporter + haproxy/nginx exporter, and the grafana panel monitors response time, number of connections, error rate, and backend delay. use tcpdump/traceroute/mtr to check cross-border packet loss and routing jitter: sudo tcpdump -i eth0 port 80 -w trace.pcap; mtr -r -c 100 xxxx. record baseline and set alarms (delay/packet loss threshold).

11.

online verification and rollback strategy

gradual release: first do a/b testing with real traffic in a grayscale environment, and use ab/jmeter or wrk to simulate concurrency. verification indicators: average rtt, p95 response time, error rate, connection establishment time. if an exception is found, quickly roll back the lb configuration or switch dns to the old vip, and keep the ttl small to shorten the time for the change to take effect.

12.

faq - q: what should i do if there is still high latency after deployment?

answer: first use mtr to determine whether it is link packet loss or last hop delay. if it is a cn2 link problem, contact the bandwidth provider and try to change the exit or peering; at the same time, confirm whether the connection from lb to the backend is congested (look at the number of sockets and queues); check whether inappropriate ssl renegotiation is enabled or there are too many short connections. it is recommended to enable keepalive and connection reuse.

13.

faq - q: how to ensure high availability of lb and no single point?

answer: at least two lbs should be vrrp/keepalived to achieve vip drift, or use the provider's load balancer on the cloud as the front end; cooperate with health checks and automated scripts to revoke vip and switch dns to standby when failure occurs; key configurations and certificates must be managed uniformly through the configuration management tool (ansible).

14.

faq - q: what is the summary of best practices for cn2 nodes in vietnam?

answer: use nearby resolution and low ttl, deploy lb and backend in vietnam to reduce the last mile, prioritize layer 4 forwarding to reduce intermediate processing, fine-tune the system kernel and number of connections, deploy complete monitoring and automated failover, and use anycast or multi-operator bgp backup when necessary.