Optimizing Network Performance for Cluster Computing Application
Question
You need the absolute highest possible network performance for a cluster computing application.
You already selected homogeneous instance types supporting 10 gigabit enhanced networking, made sure that your workload was network bound, and put the instances in a placement group.
What is the last optimization you can make?
Answers
Explanations
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A. B. C. D.Answer - A.
Jumbo frames allow more than 1500 bytes of data by increasing the payload size per packet, and thus increasing the percentage of the packet that is not packet overhead.
Fewer packets are needed to send the same amount of usable data.
However, outside of a given AWS region (EC2-Classic), a single VPC, or a VPC peering connection, you will experience a maximum path of 1500 MTU.
VPN connections and traffic sent over an Internet gateway are limited to 1500 MTU.
If packets are over 1500 bytes, they are fragmented, or they are dropped if the Don't Fragment flag is set in the IP header.
For more information on Jumbo Frames, please visit the below URL:
http://docs.aws.amazon.com/AWSEC2/latest/UserGuide/network_mtu.html#jumbo_frame_instancesGiven that the workload is network-bound, homogeneous instances supporting 10 gigabit enhanced networking have been selected, and the instances are placed in a placement group, the last optimization that can be made to achieve the highest possible network performance for a cluster computing application is to use 9001 MTU instead of 1500 for Jumbo Frames.
Jumbo Frames are larger than standard Ethernet frames and can reduce the overhead associated with processing and transmitting packets. This is because the header overhead of Ethernet frames remains constant, regardless of the payload size. Therefore, by increasing the payload size, the packet body to packet overhead ratio increases, which can improve network performance.
The maximum transmission unit (MTU) is the maximum packet size that can be transmitted over a network link. By default, Ethernet networks use an MTU of 1500 bytes. However, some networks and devices can support larger MTU sizes, such as 9001 bytes, which is the maximum MTU size supported by Amazon Web Services (AWS) Enhanced Networking.
Therefore, by using Jumbo Frames with an MTU size of 9001 bytes, the payload size can be increased, which can reduce the number of packets required to transmit the same amount of data. This can reduce the overhead associated with processing and transmitting packets, which can improve network performance and reduce latency.
The other options listed in the answer choices are not optimal for achieving the highest possible network performance for a cluster computing application.
Segregating the instances into different peered VPCs while keeping them all in a placement group, so each one has its own Internet Gateway (option B), can isolate traffic between instances and reduce network congestion, but it may also introduce additional overhead due to inter-VPC traffic.
Baking an Amazon Machine Image (AMI) for the instances and relaunching them (option C) may ensure that the instances are fresh and do not have noisy neighbors, but it does not address network performance directly.
Turning off SYN/ACK on your TCP stack or beginning to use UDP for higher throughput (option D) may improve network performance, but it may also introduce reliability and consistency issues that can impact the cluster computing application.
