EC2 Instance Network Throttled?

Question

Hello,

Have a t3.micro instance that I'm using to transfer data to RDS from a remote location. This was initially performing as expected, ranging up to  480Mbs and varying quite a bit. However, after a couple of hours, the transfer rate dropped to 60Mbs and flatlined there and been so for hours. Packet rate was similar, starting variable from 1M/s to 400k/s, then flatlined to 200k/s.

Is there some throttling that is put in place on long term connections with high data rate?

Thanks,
Bill

re:Post Agent · Accepted Answer

Yes, it's possible that you're experiencing network throttling on your t3.micro instance. There are a few factors that could be contributing to this situation:

1. Instance Type Limitations: T3 instances, including t3.micro, use a credit-based system for CPU usage and network performance. These instances have a baseline performance and can burst above that baseline by using CPU credits. Once the credits are exhausted, performance is throttled back to the baseline. For t3.micro, this baseline network performance is relatively low.

2. Connection Tracking: AWS uses connection tracking to maintain information about network traffic states. There's a fixed number of connections (conntrack allowance) allocated to each EC2 instance, with larger and networking-optimized instances having higher allowances. Your t3.micro instance may have exhausted its conntrack allowance due to the high number of simultaneous connections over an extended period.

3. API Request Throttling: If your data transfer involves making numerous API calls, you might be hitting EC2 API request throttling limits. This is especially true for operations related to network interfaces or IP addresses.

4. Bandwidth Allocation: Smaller instance types like t3.micro have limited network bandwidth. The initial high performance you observed might have been due to burst capacity, which then settled to the baseline performance after extended use.

To address this issue, you could consider:

1. Upgrading to a larger instance type with better network performance.
2. If possible, use enhanced networking features for improved performance.
3. Optimize your network usage by adjusting TCP settings or using techniques like connection pooling.
4. If you're making many API calls, consider implementing backoff strategies or requesting a rate limit increase from AWS support.

Remember, the network performance of EC2 instances can vary based on many factors, including instance size, type, and overall usage patterns. For consistent high-performance data transfer, you might need to choose an instance type specifically optimized for networking tasks.  
**Sources**  
[how can I improve the bandwidth? | AWS re:Post](https://repost.aws/questions/QUi6ypAgc5QUyqSbDorChTmg/how-can-i-improve-the-bandwidth)  
[Using connection tracking improvements to increase network performance | Networking & Content Delivery](https://aws.amazon.com/blogs/networking-and-content-delivery/using-connection-tracking-improvements-to-increase-network-performance/)  
[Known Limits and Service Quotas - Amazon EKS](https://docs.aws.amazon.com/eks/latest/best-practices/known_limits_and_service_quotas.html)

EC2 Instance Network Throttled?

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