Jasmin SMS限流错误咨询：SMPP连接日志异常与Kannel关联原因

Hey there, let’s break down the most likely reasons you’re hitting those frequent rate limiting errors in Jasmin when all your clients are using Kannel servers. I’ve troubleshooted similar SMPP setups plenty of times, so here’s what to check:

• Kannel’s Bursty Traffic Defaults
  Kannel is built to push messages in quick, aggressive batches by default. If your Kannel instances are configured to send high volumes without throttling, they’ll easily exceed Jasmin’s built-in rate limits. Keep an eye on Kannel’s smsc settings like send-smpp-max-pending and send-smpp-window-size—if these are set too high, Kannel will flood Jasmin with PDUs faster than it can process them, triggering the rate limiter.

• Mismatched SMPP Windowing Configs
  SMPP relies on windowing to manage in-flight messages. If Kannel’s smpp-window-size is larger than Jasmin’s configured window_size (found in Jasmin’s smppserver.cfg), Kannel will keep sending new messages before waiting for Jasmin’s acknowledgments. This backlog overwhelms Jasmin, and the rate limiter kicks in to protect the server. Also, if Jasmin is slow to send submit_sm_resp (due to backend delays like a busy database or SMSC issues), Kannel will keep pushing more messages, making the problem worse.

• Overly Strict Rate Limits in Jasmin
  It’s possible Jasmin’s own rate limiting parameters are set too low for your traffic needs. Check your /etc/jasmin/smpp/smppserver.cfg for these key settings:

  • max_throughput: Maximum messages processed per second
  • allowed_pdus_per_second: Total SMPP PDUs (not just messages) allowed per second
  • max_connections: If multiple Kannel instances are connecting, their combined send rate might be hitting the overall connection limit
    If these values are too conservative, you’ll see frequent rate limiting errors even under normal traffic loads.

• Kannel’s Retry Logic Creating a Feedback Loop
  When Kannel hits a rate limit or doesn’t get an immediate response, its retry settings (like smsc-retry-interval and smsc-max-retries) might cause it to resend messages quickly. This creates a loop: Jasmin blocks Kannel, Kannel retries more, Jasmin blocks harder. The result? Even more rate limit errors in your logs from these retries piling up.

• Jasmin Server Resource Constraints
  Sometimes rate limiting errors are a symptom of under-resourcing, not just bad configs. If your Jasmin server is low on CPU, memory, or has slow disk I/O (e.g., an overloaded database), it can’t process incoming SMPP PDUs as fast as Kannel sends them. Jasmin’s rate limiter acts as a safety net to prevent the server from crashing, so check system metrics (CPU usage, memory, disk activity) when the errors occur to rule this out.

内容的提问来源于stack exchange，提问作者Bill Nodes