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Amazon EC2 的可用頻寬提昇

AWSJeff Barr 宣佈了有 ENAEC2 instance 的頻寬提升到 25Gbps:「The Floodgates Are Open – Increased Network Bandwidth for EC2 Instances」。

分成三種,第一種是對 S3 的頻寬提昇:

EC2 to S3 – Traffic to and from Amazon Simple Storage Service (S3) can now take advantage of up to 25 Gbps of bandwidth. Previously, traffic of this type had access to 5 Gbps of bandwidth. This will be of benefit to applications that access large amounts of data in S3 or that make use of S3 for backup and restore.

第二種是 EC2 對 EC2 (內網):

EC2 to EC2 – Traffic to and from EC2 instances in the same or different Availability Zones within a region can now take advantage of up to 5 Gbps of bandwidth for single-flow traffic, or 25 Gbps of bandwidth for multi-flow traffic (a flow represents a single, point-to-point network connection) by using private IPv4 or IPv6 addresses, as described here.

第三種也是 EC2 對 EC2,但是是在同一個 Cluster Placement Group:

EC2 to EC2 (Cluster Placement Group) – Traffic to and from EC2 instances within a cluster placement group can continue to take advantage of up to 10 Gbps of lower-latency bandwidth for single-flow traffic, or 25 Gbps of lower-latency bandwidth for multi-flow traffic.

有 ENA 的有這些,好像沒看到 CentOS

ENA-enabled AMIs are available for Amazon Linux, Ubuntu 14.04 & 16.04, RHEL 7.4, SLES 12, and Windows Server (2008 R2, 2012, 2012 R2, and 2016). The FreeBSD AMI in AWS Marketplace is also ENA-enabled, as is VMware Cloud on AWS.

TP-Link 的 NTP 流量

在「TP-Link repeater firmware squanders 715 MB/month」這邊看到 TP-Link 因為 NTP 的關係而狂吃流量的情況:(這邊是用逗點表示小數點,所以是 715.4 MB/month)

You should probably avoid TP-Link products if you’re on a tight bandwidth budget. By design, TP-Link firmware sends six DNS requests and one NTP query every 5 seconds, for a total of 715,4 MB per month.

如果拿 24 小時都開機的 Windows 相比的話,會發現這數字天差地別:

To put this number in context: an always-on Windows device will use around 1,6 KB per month on NTP.

作者抓出韌體上面的設定,發現裡面寫死了不少伺服器... 那個 aunz 的選擇讓人頗好奇,另外直接把幾個大學的 NTP server 放進去不知道是什麼樣的想法:

TP-Link has hardcoded the following non-configurable NTP servers and server pools in their firmware:

  • time.nist.gov, time-a.nist.gov, time-b.nist.gov, time-nw.nist.gov
  • au.pool.ntp.org, nz.pool.ntp.org

The first sets of servers are operated by the US National Institute of Standards and Technology (NIST). The second is the Australian and New Zealand public NTP project time server pools. The IP addresses are owned by universities in Japan, Colorado; US, and Sweden respectively.

而從行為可以看到沒有遵守這些 NTP service 的規範:

The NTP Pool project asks device manufacturers and vendors to register (and optionally sponsor) their own pools through the service (e.g. tplink.pool.ntp.org), and emphasize that they “must absolutely not use the default pool.ntp.org zone names”. They also request that vendors don’t check more often than every 5 minutes at the most.

而且因為沒有地方可以修改這些設定,唯一的解法是不要買 TP-Link 的產品:

You can avoid buying TP-Link products to avoid this problem.

You can’t turn this behavior off in TP-Link’s web administration interface nor in their management app for mobile. You can’t change the NTP server addresses it targets either.

Amazon S3 的流量,以及 S3 與 Glacier 都推出 Select 功能

Twitter 上看到會場的照片,Amazon S3 單一 region 就有 37 Tb/sec 的量:

在這種量下面對 DDoS 沒什麼感覺 XDDD

另外是 Amazon S3 與 Amazon Glacier 都推出了 Select 功能:「S3 Select and Glacier Select – Retrieving Subsets of Objects」。

看示範的程式碼就可以看出用途了,原文中間那段有 sytax error,我這邊就幫忙修掉了:

handler = PrintingResponseHandler()
s3 = boto3.client('s3')
response = s3.select_object_content(
        'ExpressionType': 'SQL',
        'Expression': 'SELECT s._1 FROM S3Object AS s',
        'InputSerialization': {
            'CompressionType': 'NONE',
            'CSV': {
                'FileHeaderInfo': 'IGNORE',
                'RecordDelimiter': '\n',
                'FieldDelimiter': ',',
        'OutputSerialization': {
            'CSV': {
                'RecordDelimiter': '\n',
                'FieldDelimiter': ',',

這樣可以大幅降低 I/O,節省成本:

Glacier Select 也是類似的想法,不需要整包拉出來再處理,可以在一開始就設定條件。

PS4 下載速度很慢的原因

在「Why PS4 downloads are so slow」這篇作者花了不少力氣找出原因,發現 PS4 下載速度很慢是故意的... 另外討論了在什麼情況下會變慢,以及要怎麼避免的方式。

懶得看的人可以直接看 Conculsions 那段,主要的原因是 PS4 會因為背景程式而調整 TCP window size (就算背景程式在 idle 也會影響到下載的 TCP window size),進而影響速度:

If any applications are running, the PS4 appears to change the settings for PSN store downloads, artificially restricting their speed. Closing the other applications will remove the limit.

用 TCP window size 來調整速度也算是頗有「創意」的方法...


Cloudflare 看這次 815 斷電的網路使用變化

Cloudflare 分析了這次 815 停電對網路造成的影響:「Power outage hits the island of Taiwan. Here’s what we learned.」。

以 Cloudflare 在是方機房的 QPS 來看,停電後反而沒有太大變化:


這點從 HiNet 的使用頻寬也可以看出來,頻寬使用量降了 25% (從光世代與 ADSL/VDSL 換到行動網路上?):

Linode 推出 $5/month 方案,DigitalOcean 推出 load balancer

LinodeDigitalOcean 這兩家有名的 VPS 都推出新的功能:「High-Memory Instances and $5 Linodes」、「Load Balancers: Simplifying High Availability」。

Linode 另外將 $10/month 方案的硬碟空間加大:

And finally, the existing Linode 2GB ($10/mo) plan is receiving a free storage upgrade from 24GiB to 30GiB.

本來對外的速度限制在 125Mbps max 拉到 1000Mbps:(本來的資料可以參考之前的頁面)

And finally finally, we’ve also increased the outbound network speed limit on all plans to be at minimum 1000 Mbits. Existing Linodes will need to reboot to pick up the new value, that’s it!

Google Play Store 將支援 Brotli 壓縮

在「Intern Impact: Brotli compression for Play Store app downloads」這邊介紹了 Google Play Store 引入 Brotli 的情況。

選擇 Brotli 除了是 Google 自家研發出來的東西以外,另外是考量到 Brotli 的壓縮與解壓縮速 (尤其是後者) 不會增加太多,卻可以多出不少壓縮率。維基百科這邊說明的是文字的部份:

Replacing deflate with brotli typically gives an increase of 20% in compression density for text files, while compression and decompression speeds are roughly unchanged.

不過實際在 Google Play Store 上測試 binary 的效果也不錯:

當然,如同之前提到的「Google 再次改善 Android 的 APK 更新,讓下載的量更小」,在去年 12 月時 Google 對於背景更新的下載 File-by-File 的更新來降低流量 (但在手機上會需要大量的 CPU 資源計算,不過因為是背景 idle 時跑而不會影響使用者,所以被採用),透過這兩個改善互相搭配繼續壓低流量。


Brotli compression for app downloads is rolling out now, and users should start to enjoy the benefits over the coming weeks.

Amazon Lightsail:AWS 的 VPS 服務

所以 AWS 決定也跳進來搞 VPS 服務了?推出了 Amazon Lightsail:「Amazon Lightsail – The Power of AWS, the Simplicity of a VPS」。

定價策略就跟 VPS 一樣:

如果你熟悉數字的話,這其實跟 DigitalOcean 的規格與價錢一模一樣 (參考「Pricing on DigitalOcean」這頁),連備份的 USD$0.05/GB/month 也相同。目前雖然只有 us-east-1 有,但看起來複製並不難...

FAQ 裡有提到可以透過 VPC peering 連進 AWS:

You can connect your Lightsail instances to VPC resources in your AWS account privately, by using VPC peering. Just choose Enable VPC peering on your Lightsail account page, and Lightsail does the work for you. Once VPC peering is enabled, you can address other AWS resources in your default AWS VPC by using their private IPs.

有趣的是,這個頻寬費用超級便宜... 目前比較不確定的是 bandwidth 是不是 pool-based (沒用完的流量可以挪到其他機器上用),另外這邊的頻寬計算方式是不是算 us-east-1 內?