Questions tagged [latency]

Latency is the time period between a signal being sent and a signal being received

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Using SSH over high-latency connection (satellite)

Our only available ISP is satellite where we live. We're currently on HughesNet and waiting (very impatiently) for Starlink's beta to send us our invite. In the meantime, I still need to get into my ...
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77 views

How to adjust TCP Window Size?

I asked a similar question before, but I believe I was not clear with the details. I'm basically having some problems with my server related to high latency between the server and the clients due to ...
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Which one is faster, USA based AWS Servers vs local servers in Malaysia?

I have been tasked to create a local university database for a Malaysian Client. The client is requesting us to use Amazon Web Services as they bought into the marketing hype. I told them that AWS' ...
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27 views

How can I easily (e.g. as easy as rsync or SCP) do a high speed (1gpbs) file upload over an Internet-latency link?

I recently asked a similar question about how to transfer large (many gigabyte to many tens of gigaytes) files over the Internet when latency is high. I got a great answer, but only for downloads. ...
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Intermittent Network Across EC2 in Public Subnet / VPC. Tool to determine cause?

we have a fairly complex set-up of g4dn instance types running vMix with NDI, TeamViewer, and other streaming protocols to operate a live stream. We've had a several occasions in which TeamViewer ...
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1answer
110 views

Minimising latency: AWS and a third-party datacentre

I have a VPS (an EC2 instance) running on AWS-Ireland. I would like to minimise the latency of traffic between this instance and a service provider that has their servers at a third-party data centres ...
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2answers
84 views

Network Latency (mathematical) relation to bandwidth?

Let's say I have a 1Gbps bandwidth NIC. Can I mathematically derive what would my network latency be just from the bandwidth number?
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Can someone help interpreting high latency / low throughput on a ESXi host (Direct-attached storage)

as a disclaimer - I am not a storage guy, so ELI5 ;) I am looking at a ESXi with direct-attached storage (SAS SSDs and HDDs in a RAID1, different datastores). System X shown on the graphics is on the ...
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Unable to see pending queue latency for App Engine application

I have a nodejs application on App Engine Flexible environment with auto-scaling enabled. According to documentation, the max_pending_latency autoscaling parameter has a default value of 30ms. https://...
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1answer
75 views

Approximate speed-up from TLS 1.2 to TLS 1.3

We're using AWS API Gateway in a single region, which users from all over the world interact with. We've not yet had a chance to do multi-region deployments so some users experience a lot of latency ...
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Why HFSC does not provide the expected results regarding latency?

Linux scheduling algorithm HFSC is poorly documented and it is difficult to find complete configuration examples, fortunately there is this nice tutorial I tried to follow in order to create this ...
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152 views

Troubleshooting low TCP transfer rate behind a router

I’m trying to debug a low tcp transfer rate on a host (“lowHost”). As a reference, i’m comparing it against a second host (“highHost”). I’m making two rate measurements: Downloading a big file using ...
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1answer
163 views

How to priorize Zoom meetings on a fritz.box?

is there a way to configure the fritz box to priorize zoom calls? Of course I could configure the IP to have higher prio, but this is not solving the issue, that I want to have Zoom only to have real ...
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109 views

Linux machine unable to send IPv6 packets for five minutes about once per day [closed]

I am operating a router based on a Linux server running Debian stable (Buster). It uses Quagga to speak BGP4 to four peers (one of which sends the entire Internet routing table for IPv4 and IPv6, the ...
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1answer
464 views

High ping latency over direct Gigabit Ethernet link on Enterprise-class hardware

FINAL EDIT 7/7 Multiple cable, port, and device substitutions have narrowed this to the Comcast modem, and on all 8 of its Ethernet ports. Given, as the comments say, this is a closed device, and ...
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Monitor performance of IIS UrlRewrite Extensibility Sample SQL Custom Rewrite Provider

I've implemented the SQL provider from IIS UrlRewrite Extensibility Samples and it seems to work well, but I'm wondering about the performance impact of IIS calling a stored procedure on an Azure SQL ...
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Add latency to domain

I have a question. Is it somehow possible to add latency to a Ubuntu server when it hits a specific domain? For example it should add 50 ms for google.com And add 20ms for Facebook.com
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45 views

Measure packet latency / drop between ingress and egress interface of a rate-limiting pass-through host

Somewhere between my sender and receiver, there is host explicitly limiting my transfer rate. I know it's a Linux host. The ingress interface for my traffic is eth0 and the egress interface is eth1. ...
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37 views

“Correlate” two pcap files to measure packet latency / drop rates

Imagine I have two pcap files, recorded at ingress (eth0) and egress (eth1) interfaces of a rate-limiting, packet-forwarding host. Both pcaps contain the same TCP flows, and the time base in both ...
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1answer
30 views

CL latency of unbuffered and registered RAM

So AFAIK, registered ram generally has a bit higher latency as going through the registers adds (usually one?) cycle. If I have two dimms of ecc ram, one registered and one unbuffered, and both say ...
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iptables tool to measure latency instead of bandwidth

I'm trying to measure the latency of having a lot of iptables rules. I tried to use iperf but I think that bandwidth is not what i want. Any help with this?
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29 views

Azure App Service Http Request Latency

We are hosing a web api on an Azure App Service resource. We are experiencing issues where a request is made to an endpoint but isn't handled by the api until 30-60+ seconds later. Through many days ...
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47 views

tc - Simulating Network Latency of Internal Ports (LAN)

I am doing some network simulations on an Ubuntu VM. I am trying to add some latency to all packets being sent to and from specific ports without affecting the whole adapter. The traffic never leaves ...
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1answer
197 views

How can I easily (e.g. as easy as rsync or SCP) do a high speed (1gpbs) file transfer over an Internet-latency link?

A few times per year, I need to transfer massive files (20+GBs) over the Internet (latency 20-100ms), but with reasonably fast connections on the order of 1gbps between servers. Unfortunately, when I ...
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82 views

Strongswan high latency on LTE

Allow me to ask for help to solve the following problem with latency. I have a network which is on one side the Strongswan server and on the opposite side are terminals connected through DSL, cable or ...
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1answer
23 views

Determining on which machine a packet/update arrived first

I have two separate AWS Virtual Machines set up within a region (different availability zones) both are connected via WebSocket (in Python) to a different load balancer (Cloudfront) of the same host ...
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VNET Peering Latency

I’m running a mission critical global three-tier-application (App, IIS & SQL Virtual machines) on same region (Central US), right now, some of the European users are suffering poor performance. I’...
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1answer
296 views

Using tc to decrease bandwidth to a specific destination address

I am trying to find the shortest path between two hosts H1 and H2 using Dijkstra code. Setting a condition in one of the switches on that path. the condition is: if the packet sending to H2 then ...
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2answers
27 views

If my database has to stay in one region, is there much point distributing my API across several?

We currently have an API and database in Australia, and are attempting to reduce latency in other countries. Coming to grips with the CAP theorem for synchronized databases is probably a little out-...
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1answer
298 views

App Engine high latency

Hi we have an static web page using Smarty, we want to migrate it from our private web server on Compute Engine to App Engine. We did made the migration but on App Engine we got a latency of 3 sec to ...
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123 views

Delay on NFS mounts

My setup: 3 machines, 2 client, 1 server. The server is redhat 7.6, the clients are ubuntu server 18.04.2. The mount is a few dozen TB, the files placed on the clients are a few 100Gigs each. The ...
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Azure App Service / Postgresql high latency

We have an very simple Azure App Service application using Django (Python) running in West EU Region. The Service Plan for this Service is P1v2 (production plan). The Postgresql is configure with ...
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336 views

Hyper-V inconsistent/high latency between two VMs on the same vSwitch

This is a clean installation of Windows 10 1903 with Hyper-V, though I've experienced this in previous versions of Windows 10. Add a private vSwitch (so, not tied to any physical network adapter). ...
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1answer
33 views

What is the fastest posible way to comunicate to a server on Amazon EC2?

I need to communicate via WebSockes and normal HTTP. I am trying to save some microseconds. I have already done: I got an instance at the same Amazon EC2 zone. The ping is 1 millisecond. I have ...
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52 views

Latency jumps in first, middle and last mile of path

I work for SD-WAN company providing an all in one solution edge router(Like FORTINET but not FORTINET). We have one customer in particular that has such a hard time with our services i.e. gift card ...
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185 views

NPing gives significantly less time on `TCP Connect` than `TCP`

I'm using NPing (NMap's pinging tool) to measure latency on specific servers that may not respond to ICMP. Also, servers do not usually run HTTP(S) and I only check latency on a specific TCP port ...
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1answer
46 views

One machine's network usage can increase latency for everyone sharing the same ethernet switch

I'm managing an office network of about 20 computers, which all share a common ethernet switch (unmanaged), which is then connected to the ISP's cable modem/router combo. Every now and then someone ...
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997 views

Adding some delay to a specific port on localhost using tc and netem

I'm going to simulate a network latency on three different ports of local host by using tc (traffic control for Linux) commands. I run the following code: !/bin/bash tc qdisc add dev lo root handle 1:...
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1answer
407 views

Why may AWS t3.micro in Singapore respond slower than t2.nano in N. Virginia from Bangladesh?

I have a t2.nano instance running in North-Virginia availability zone (us-east-1) for almost 1 year. In hope of reducing latency, I just have deployed the created AMI of that instance to a t3.micro ...
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451 views

What is a “normal” latency/performance of inserts on mariadb or mysql?

Hadn't used MySQL family for years. Now need to move from OracleDB to either MariaDB or PostgreSQL. So on a similar "hardware" (Openstack VM: RHEL 7.3, 4HT cores of 2.5GHz Xeon E312xx, "local" SAN &...
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3answers
239 views

Is RTT theoretically the same regardless of ping origination?

Let's say you send a ping from device 1 to device 2. The result would give you the RTT. Theoretically speaking (because many variables are realistically in play), would the RTT be the same by ...
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195 views

~1300ms latency touching file on nfs mount

I have an NFS mount where the server is on the same subnet as the client. When I time touch testempty from the client, I get: touch testempty 0.00s user 0.00s system 0% cpu 1.325 total The time ...
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1answer
46 views

Building reliable internet speed test tools

I'm interested in building a command-line speed test tool similar to the one used here. I started using it in a cron job to automatically check and record speeds at different times when we started ...
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1answer
354 views

How to control AWS Elastic Beanstalk auto scaling based on average response times if one endpoint is expected to take circa 60 seconds

We auto-scale our Elastic Beanstalk Java Application based on the average response times exceeding 3 seconds. When this happens we add 2 instances to our environment. Once we are back within 1.5 ...
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2answers
189 views

ICMP maximum delay between echo request and reply sustained by a router NAT

I was trying to slow down network on my server (arch linux vm) with netem sudo tc qdisc add dev eth0 root netem delay 1600ms With 1600ms delay client doesn't receive the echo reply packet though the ...
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740 views

Linux TCP/IP tuning for low throughput network?

I have two linux machines connected by a radio modem. The bandwidth is about 2kbps, with ping times of around 400ms (5% packet loss). Currently, ssh sessions have a delay in the order of 5 seconds, ...
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137 views

vCenter to vCenter transfers slow over 10Gbps 80ms link

We have two datacentres either side of the Atlantic with a 10Gb VPLS connection between sites with 80ms latency and better than 0.0000001% packet loss. When moving VMs between datastores on either ...
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1answer
69 views

Should things like database performance be included in a healthcheck

I manage a webservice and it is very important for my company to detect and notify if any of the services is down, and also if any of the operations it does is taking too long to respond. Until now ...
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1k views

Ping latency between 2 directly connected PCs

I have a lot of experience with PCIe, some with USB, and little with Ethernet, so the following has got me confused: I'm evaluating the performance of a USB-to-Ethernet controller, vs a PCIE-to-...
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1answer
873 views

Multi-host VM/Docker network communication is SLOW, any best practice?

VM-1 on host-1 <[cable]> network router <[cable]> host-2 with VM-2 If I understand correctly, in case of file transfer from application on VM-1 to same application on VM-2 the data will ...

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