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

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20 views

ping timeouts with light http traffic on T1 connection

I have a T1 over copper connection and started to notice that if I run ping while loading an http page (http://google.com) I get intermittent timeouts in ping. Is this normal? I expected some ...
1
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0answers
11 views

High latency in urlfetch with google app engine [migrated]

We have a Java application that make use of urlfetch calling an external api. We are having issues with the request time. When we do a request in a local environment we have a mean time of 300ms, ...
2
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1answer
28 views

Windows 2012 Shared Drives Odd Latency Issue

I have a Dell T110 II running ESXi 5.5 with a Windows 2012 R2 instance running with the following roles: ADDS DHCP DNS File/Storage Svcs WSUS I have two shared folders -- Scans and Data -- which ...
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0answers
36 views

Ping RTTs vs UDP Ping Pong RTTs

Network Topology (wired): ServerA - 1Gb - Switch - 10Gb - Firewall - 10Gb - ServerB Pinging ServerB from ServerA shows round trip times (RTTs) of ~1.2 milliseconds. UDP packet 'ping pong' between ...
1
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0answers
32 views

SSH Client sporadically hangs for few seconds

On Ubuntu 14.04 LTS when I use SSH client, it hangs sporadically for few seconds every minute or so. no input is lost is just delayed. SSH -V OpenSSH_6.6.1p1 Ubuntu-2ubuntu2, OpenSSL 1.0.1f 6 Jan ...
0
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1answer
67 views

Ubuntu Trusty: virt-manager performance over WAN… 40+ secs freezes

I'm using the virt-manager GUI 0.9.5-1ubuntu3 on my laptop running Ubuntu 14.04 against a server located some distance away (same OS) and getting rather unpleasant performance. Laptop-server pings ...
7
votes
1answer
12k views

How to troubleshoot latency between 2 linux hosts

The latency between 2 linux hosts is about .23ms. They are connected by one switch. Ping & Wireshark confirm the latency number. But, i dont have any visibility into what is causing this latency. ...
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votes
1answer
70 views

Why the latency increases on highload? [closed]

We have a system built on AWS. We use Beanstalk, we have autoscaling, our database (mysql) is hosted on RDS. We use apache and php. We wanted to test our system on highload. So, we chose large ...
0
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0answers
30 views

Increasingly high connect times for static files with Apache

My client is running a PHP application using Apache 2.4.7 and php-fpm. Apache is configured to use mpm_prefork. I am working on optimising load times. I use FireFox dev tools for profiling, and I ...
-1
votes
1answer
51 views

How to reduce latency? [closed]

I am looking to build something where you can have a workstation/server in one location, and access it remotely using a video stream of the screen to do as you wish. My reason for wanting low latency ...
7
votes
2answers
6k views

Limit incoming and outgoing bandwidth and latency in linux

I realise many similar questions have already been asked, but so far I've yet to find a solution to my problem. I have a virtual linux server (running Debian Squeeze) that I use for testing of ...
3
votes
1answer
105 views

Brocade DCX 8510 inter DC latency - understanding OIDs to find L1 issues

Trying to determine if there is some intermittent inter DC latency on the FC links, but only have access to the OID counters for the DCX 8510. Since it is a L1 link over DWDM there are no stats from ...
35
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7answers
77k views

Why is the response on localhost so slow?

I am working on a tiny little PHP project for a friend of mine, and I have a WAMP environment setup for local development. I remember the days when the response from my local Apache 2.2 was immediate. ...
0
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0answers
96 views

Getting chunks of high ms when pinging local / external IP addresses?

I am having difficulty identifying what a specific problem with one of your vlaned networks. They have a voip phone which regularly cuts out during long phone calls. I have done several ping tests ...
0
votes
1answer
240 views

OpenVPN + Scrambled patch on Amazon EC2

Yesterday I deployed a regular OpenVPN installation on Debian Squeeze / Amazon EC2. The VPN server is in Singapore and I connect to it from China Mainland. Later on, after some tests I had to start ...
3
votes
1answer
193 views

How do I test my internet connection speed via a Microsoft Windows Terminal?

I currently have two production servers. One running Windows Server 2003 and the other Windows Server 2008. When I open the Reliability and Performance Monitor I see a Network section that only goes ...
0
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0answers
89 views

Optimizing Pfsense IPSec VPN for a high latency environment

I have two PFsense routers connecting two networks with high latency between them. What can I adjust to improve file transfers between these two networks?
0
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1answer
203 views

My redis' fork time is slow and impact query performance a little. What should I do to check?

I used redis with RDB option only. It used 2GB of memory. When it forked, it used about 10 seconds to completely save the file. When I check up with redis.io site, I found this latency stat: - Linux ...
0
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2answers
171 views

extreme ping latency in WDS network

I have setup a wireless network at work office with the following config: 192.168.1.1: TP-Link 941 Router, Root AP, connected to internet 192.168.1.2: TP-Link 901 AP, WDS Repeater, connected to ...
5
votes
3answers
3k views

Akamai vs smaller CDN for small/medium-size ecommerce traffic? (caching, latency, NetStorage)

The small/medium sized online retail company I work for uses Akamai as our CDN for static images, but I'm wondering whether it might be hurting rather than helping and, if it's suboptimal, what we ...
2
votes
1answer
287 views

ELB - High latency when enabling cross-zone balancing

I'm working on improve our infrastructure reliability in AWS and one of my tasks is enabling cross-zone balancing on our ELBs. Our ELBs receives around 20K request by second on rush hours as well as ...
0
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1answer
473 views

Lotus Notes Error - “Specified Network name no longer available”

I work for a bank who is using Lotus Notes email and during the transition from Windows XP to Windows 7 the Lotus Notes client was upgraded from Client 8.0.2 to 8.5.3. Given that these were the only ...
3
votes
1answer
920 views

difference between taskset and cpuset

I'm trying to reduce the latency of my linux network application. I've learned that there are two tools for "binding" a program to particular CPU core: taskset and cpuset. Which one should I prefer? ...
1
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1answer
350 views

Why the time taken to fetch results of a query for 10,000 times from a RDS is so uneven? (experiment)

tl;dr : Why the time taken to fetch results of a SELECT statement for 10,000 times from a RDS when requested from an EC2 is so uneven? Updated the question with results of small and medium RDS ...
1
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2answers
205 views

Performance Tuning Linux [closed]

Performance Tuning/ Monitoring/Latency keeping in mind I see following 4 items & in each item they are lot of tools. CPU Memory IO Network What I see following tools we do use. vmstat mpstat ...
3
votes
2answers
478 views

Need ultra-low latency, how to minimize?

I have several Windows Server 2008 R2 machines that act as clients and are connected to another server in the same datacenter. I don't have access to teh server. I need to minimize latency between ...
7
votes
2answers
6k views

Intermittently high ping times to router via Wi-Fi

On my local network there are (among others) 5 machines (running Debian Jessie or Arch) wirelessly connected to a Netgear WNDR4000 router. Below is a graph of the ping times to the router from each of ...
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2answers
127 views

SMB Latency Issue with Multiple Users

We have a program that works by being shared over the network as a normal Windows Mapped Drive. You run the program from the mapped drive and it stores its files in flat file databases in that mapped ...
0
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0answers
104 views

Should I be concerned about AWS inter-zone latency?

I have an app hosted on heroku and I just set up an AWS RDS database. The app and the database are in the same region (US East) but I can't tell whether they are in the same zone or not. Server ...
5
votes
5answers
4k views

finding the best network latency between two countries

I know there are many tools to test for bandwidth and latency, but they all rely on having at least one host from which you can run those tests. I wonder whether there's an online source or some ...
2
votes
4answers
3k views

What kind of latency numbers are reasonable for a corporate network?

I am a software developer and I sometimes want to work from home but to write code over on a VPN is just tortuously slow. I have tried several different things to try and make it more reasonable. On ...
0
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0answers
112 views

Windows Azure VHD Upload Inconsistencies

I'm a little over 2 days deep into a 5 day .vhd upload using the Add-AzureVHD in Windows Azure Powershell and I'm perplexed to the speed (or lack thereof) of this operation. The .vhd is a 300GB file ...
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votes
3answers
558 views

What network performance is required for thin clients?

I am building a network with approx. 1000 thin clients. I intend to run them over VNC. What type of LAN bandwidth and latency are required? What type of hardware will provide that? If, instead of ...
0
votes
1answer
159 views

how to choose right SFP 1000BASE-T transceiver? [closed]

I want to connect SFN7122F network card to 1000BASE-T (1 GB cooper Ethernet). I've found a lot of transceiver and I don't understand how should I choose one: ...
0
votes
2answers
593 views

Why is the latency on one LVM volume consistently higher?

I've got a server with LVM over RAID1. One of the volumes has a consistently higher IO latency (as measured by the diskstats_latency munin plugin) than the other volumes from the same group. As you ...
2
votes
3answers
3k views

Terminal server performance over high latency links

Our datacenter and head office is currently in Brisbane, Australia, and we have a branch office in the UK. We have a private WAN with a 768k link to our UK office and the latency is at about 350ms. ...
2
votes
2answers
3k views

Low latency TCP settings on Ubuntu

There is a server for measurements running on Ubuntu in my lab . And there is C program, which receives data through TCP connection and should as soon as possible send a reply. Network latency when ...
-4
votes
1answer
57 views

multiple domains, one static IP address and latency [closed]

how is latency affected when multiple domains are using one single static IP address ? The scenario is in shared web-hosting By latency meaning the DNS lookup the client has to do. As far as I ...
1
vote
6answers
5k views

MySQL performance over a (local) network much slower than I would expect

MySQL queries in my production environment are taking much longer than I would expect them too. The site in question is a fairly large Drupal site, with many modules installed. The webserver (Nginx) ...
0
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0answers
55 views

Syncing client and server time for latency comparison

I'm struggling to sync my server's time (an EC2 instance in Dublin) with my local machine. I'm using sudo ntpdate ntp.ubuntu.com to sync my server's time with Ubuntu's time server. I'm then using the ...
0
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0answers
142 views

MySQL replication across availability zones in AWS resulting in lag

I have 3 EC2 instances, each running MySQL. 2 are slaves replicating from the master. The master is located in the availability zone eu-west-1b. One of the slaves is in the same zone, and the other ...
-2
votes
1answer
41 views

Users unable to connect due to an unknown plausible reason [closed]

========================= Warning: Long thread; includes a lot of information to give you some basic understanding of my issues. If you rather not read it, then here are my questions: 1) Does Linux ...
0
votes
0answers
57 views

Why is my server so slow to accept connections?

I've noticed that my server seems to be very slow to accept connections - i.e. when analyzing the load time using the Chrome event map, it shows that some tasks can spend multiple seconds waiting for ...
0
votes
1answer
574 views

How do I troubleshoot latency issues with elastic load balancer (ELB) in Amazon AWS?

We have a web app and API hosted at Amazon AWS, with three environments - development (dev), testing/staging (uat), and live. Each environment has a load balancer, two EC2 instances and an RDS ...
5
votes
2answers
104 views

Trans-atlantic VOIP

We're a Canadian business on the east coast and will soon be opening up a new call centre in Australia. This new call centre will be handling our graveyard shift and will be overlapping with the ...
4
votes
1answer
945 views

Hyper-V guests: intermittent latency

I am seeing latency on a Hyper-V host and its guests lately. When I run ping -f from a Linux prompt, I see the dots "pulsate" like a heartbeat indicating 2 successive latency spikes within 1 second ...
1
vote
0answers
1k views

upstream timed out (110: Connection timed out) while connecting to upstream

I have my backend in France and one of my frontend servers is in Japan. This issue doesn't happen with any other of my frontends, only this Japan server, which already has about 2s latency from most ...
0
votes
2answers
410 views

SMB2 over 1GB PTP Link - 10ms latency

Maybe I'm expecting way more from SMB2 than what's realistic. Here is the scenario. Windows 7 Client (Local) A) Win2008R2 Server (LAN -- 1GB, <1ms) B) Win2008R2 Server (WAN -- 1GB, 10ms) ...
1
vote
1answer
802 views

UDP bandwidth calculation based on packet size, request rate and latency [closed]

I need to estimate the bandwidth for a measurement application to be written that uses UDP. I have a good sense of the numbers but am not sure how to put them together. I checked a few throughput ...
1
vote
1answer
176 views

Network ping replies: latency alternates low and high

I'm experiencing some troubles with one machine in my network. When I ping it the ping replies rotates like this : 64 bytes from 10.0.100.10: icmp_seq=156 ttl=62 time=100 ms 64 bytes from ...