Lecture 43: Network I/O credits
- 课程：[NEW] AWS Certified Advanced Networking Specialty 2026
- 视频时长：01:56
- 来源：Udemy Lecture 26073220
- Slide 数量：2
- 画面切换：00:54
扫描说明
按 Udemy Transcript 的 47 个时间点逐一定位并比较视频画面，确认 Network I/O Credits 标题与考试要点共 2 个 Slide。第二页要点逐步出现视为动画构建，截图保留最终稳定状态。
Transcript 来自 Udemy 页面自带的英文自动字幕，没有使用 ASR。下面保留页面原文，包括其中的语法或识别错误。
1. Network I/O Credits
时间范围：00:00–00:54
总结 / Summary
中文
某些 EC2 实例类型会像 T 系列累积 CPU 积分一样累积网络 I/O 积分（Network I/O Credits）。实例长期低于基线带宽运行时积累积分，短时间高峰可消耗积分并突发到高于分配的基线网络性能。
English
Some EC2 instance types accumulate Network I/O Credits in a way analogous to T-family CPU credits. Running below baseline bandwidth builds credits, which can be consumed during short peaks to burst above the allocated baseline network performance.
Transcript
00:00 Hi all and welcome to this lecture.
00:01 This is a very short lecture.
00:03 Maybe, we just talking about
00:05 a one point that you need to remember,
00:08 that's called network I/O credit.
00:10 Now, if you know about how EBS works
00:13 or how easy to T3
00:16 or T family works, right?
00:17 It accumulate the CPU credits.
00:20 What does that mean?
00:21 If you're not using the T3 instance CPU capacity
00:24 for longer time,
00:26 it can burst well beyond the allocated CPU capacity.
00:30 That means it accumulate that credits for the CPU.
00:33 Now, same thing applies for network I/O credits as well
00:38 for certain instance types
00:40 and, then you need to know that
00:42 these instance types will accumulate
00:44 your network I/O credits and when you are required,
00:47 it will go beyond their allocated network bandwidth
00:51 and that's, in short is network I/O credits.
2. Burst Performance and Benchmarking Risk
时间范围：00:54–01:56
总结 / Summary
中文
课程以 R4、C5 等实例家族为例：如果应用一天只短时需要高吞吐，积分突发（Credit-Based Bursting）能提供高于基线的性能。测试时必须先考虑积分余额；刚积累大量积分的实例会在基准测试（Benchmark）中表现很好，但长时间持续负载耗尽积分后会回落到基线，导致选型误判。
English
The lecture uses families such as R4 and C5 as examples: if an application needs high throughput only briefly, credit-based bursting can exceed baseline performance. Benchmarking must account for the credit balance. An instance with accumulated credits may look excellent in a short test but fall back to baseline under sustained load after the credits are exhausted, leading to a poor sizing decision.
Transcript
00:54 So, instance families such as R4 and C5 uses this feature
00:59 and what that means is,
01:01 if there is an application
01:02 which requires a high network throughput
01:04 just for a small amount of time, maybe in a whole day,
01:08 then you can look for this instance type
01:11 which can very well burst beyond
01:13 the allocated network bandwidth.
01:15 So this instance performs
01:16 well above the baseline network performance
01:18 during that peak requirement.
01:20 Now, why it is important to know is because,
01:23 if you are doing some network performance benchmark
01:25 for those instances,
01:27 then make sure that they don't have the accumulated credits,
01:30 otherwise, what would happen during benchmark,
01:33 they are performing really well, then you think that
01:35 these are the appropriate instance types,
01:38 but if you are running those instances for long duration,
01:40 you would see that,
01:41 they are not able to give the same network performance
01:44 because now they don't have that accumulated credits.
01:47 So this is just a point you need to remember,
01:49 and that's it about this lecture.
01:51 So,
01:53 thanks for watching.
整讲总结 / Overall Summary
中文
网络 I/O 积分（Network I/O Credits）适合短时突发，不代表实例可长期维持峰值带宽。评估网络性能时要区分基线（Baseline）、突发（Burst）和测试时的积分余额。
English
Network I/O Credits support short bursts; they do not mean an instance can sustain peak bandwidth indefinitely. Performance evaluation must distinguish baseline, burst behavior, and the credit balance present during testing.
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