Packet loss occurs when one or more packets of data travelling across a computer network fail to reach their destination.

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36
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5answers
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Why does a hardware router perform better than a Linux router with better specs (RAM & CPU)?

I have a minimal CentOS 6.3, 64 bit acting as gateway with 4 NIC (1 Gbps), each bonded together one for public traffic and other for private, which performs NATing. It has 6 GB RAM and 4 logical cores....
33
votes
5answers
54k views

How passively monitor for tcp packet loss? (Linux)

How can I passively monitor the packet loss on TCP connections to/from my machine? Basically, I'd like a tool that sits in the background and watches TCP ack/nak/re-transmits to generate a report on ...
12
votes
4answers
43k views

How do you diagnose packet loss?

I realise this is very subjective and dependent on a number of variables, but I'm wondering what steps most folks go through when they need to diagnose packet loss on a given system?
10
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4answers
1k views

How common are dropped packets in communications within a data center?

Let's say I have 2 machines in the same data center but not necessarily in the same rack. How common would dropped packets be when sent using UDP between these two machines? I'm asking under the ...
8
votes
3answers
13k views

How to fix corrupt packet error for with rsync for (relatively) large files?

Trying to update files on a server, with the rsync command: rsync -ravq -e "ssh -o ConnectTimeout=2 -o ServerAliveInterval=2 -ServerAliveCountMax=2" --delete ./local_dir user@$SERVER:/dest_dir ...
8
votes
2answers
6k views

Extreme UDP packet loss at 300Mbit (14%), but TCP > 800Mbit w/o retransmits

I have a linux box I use as the iperf3 client, testing 2 identically equipped Windows 2012 R2 server boxes with Broadcom BCM5721, 1Gb adapters (2 ports, but only 1 used for the test). All machines are ...
7
votes
4answers
8k views

Packet loss rate with iperf and tcpdump

I tested a line for its link quality with iperf. The measured speed (UDP port 9005) was 96Mbps, which is fine, because both servers are connected with 100Mbps to the internet. On the other hand the ...
6
votes
2answers
5k views

How to interpret traceroute / output of MTR?

I have been running MTR to/from one of my servers and noticed something that looks odd to me. Because I am not really into this I will give you three outputs: This is from the server to my home ...
5
votes
2answers
11k views

Higher rmem_max value leading to more packet loss

The rmem_max Linux setting defines the size of the buffer that receives UDP packets. When traffic becomes too busy, packet loss starts occurring. I made a graph showing how packet loss increases ...
4
votes
1answer
1k views

Packet loss during TCP handshake

I have to implement a pseudo TCP handshake that leads into a file transfer. I have no problem doing the file transfer: simple send-acknowledge. What I can't wrap my head around is how to do the three ...
4
votes
2answers
5k views

unexplainable packet drops with 5 ethernet NICs and low traffic on Ubuntu

I'm stuck on problem where my machine started to drops packets with no sign of ANY system load or high interrupt usage after an upgrade to Ubuntu 12.04. My server is a network monitoring sensor, ...
4
votes
0answers
2k views

Troubleshooting Packet Loss on pfSense + Ubiquiti UniFi (Wireshark maybe?)

I'm dealing with an annoying situation in a small network in my church, which I'm the primary volunteer IT caretaker, of about 20 PCs, give-or-take. We're in Chattanooga, home of Gigabit internet, so ...
3
votes
2answers
963 views

How to anticipate spanning-tree changes to prevent packet loss during convergence?

We have a LAN with Cisco switches, redundant cabling and spanning tree. If I understand it correctly, when I pull out a redundant cable (that is currently "used" by the spanning tree) it takes several ...
3
votes
2answers
51 views

OSX how to drop packets randomly

I am testing the resilience of one of our streaming applications to handle packet losses. On linux machines I normally use iptables to randomly drop packets like this: iptables -A INPUT -m statistic -...
3
votes
1answer
2k views

huge packet loss and checksum errors

Our 2008 server began to work very slowly within 2 weeks. Our web sites (iis 7.5) are loading very slowly and sometimes its freezing. We began testing with wireshark and saw that our packets are ...
3
votes
1answer
874 views

debian tcp - optimize for clients with packet loss

I have a debian server with a bandwidth of 100 Mbps. My clients are mostly connected using 3G networks, for a duration of 30 mn in average. A lot of them have packet loss, rarely, but each time a ...
3
votes
1answer
2k views

Analysing incoming TCP packet discards on GNU/Linux

I use Ubntu 12.04 Server as a gateway/router. The server has two NetXtreme BCM5721 Gigabit Ethernet PCI Express cards for LAN and WAN interfaces. Opennms monitoring software shows incoming packet ...
3
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0answers
538 views

Forward Error Correction for WAN optimization

Anyone know of user-space tools providing forward error correction with/for tunnelling a stream over UDP on Linux? I found Trafficsqueezer, utunnel and toutunnel which implement TCP over UDP, but ...
2
votes
2answers
1k views

Unexplained 0.1% packets time out when pinging from router

I'm troubleshooting a customer who requires the ability to send 5000 pings from the router to their remote site over a satellite link with zero timeouts, yet they keep experiencing one to five packets ...
2
votes
1answer
415 views

PIX Firewall Causing Packet Loss

I am currently in the process of modifying how internet reaches my front end servers and I am having a strange issue with one of the existing stacks. There is one physical firewall which is above the ...
2
votes
1answer
257 views

Track Source IP of dropped packets

I've got a Linux server running CentOS 7, and I've been facing an issue where the RX dropped packet count keeps increasing. I believe it may be caused by a faulty cable/connector in the network; ...
2
votes
2answers
113 views

Very bizarre Linux-to-Linux but not Windows-to-Linux packet loss over the Internet

I am right now getting additional grey hair fighting a phenomenon concerning packet loss between machines on the Internet. Check the diagram below. Note that whenever I use "SSH" I could use "HTTPS"; ...
2
votes
1answer
572 views

What causes packet loss from Debian server to nearest gateway?

I have a debian Squeeze KVM server hosted with an ISP. The server doesn't have much load (average 0.1) and has sufficient memory, low network traffic, low disk i/o etc etc. It's running standard LAMP ...
2
votes
1answer
370 views

hung up troubleshooting packet discards

My network consists of Cisco switches. I am seeing a significant amount (upwards of millions of packets per day) transmit drops between two switches. One being a 3750 and the other a 3560. The peak ...
2
votes
1answer
486 views

Nagios, Cisco switches, lost packets

I use Nagios to monitor about 30 Cisco 2960 switches (check_snmp_load, check_snmp_int). I only check load and one or two backbone interfaces of every switch. I get a lot of false positives caused by ...
2
votes
2answers
1k views

Racoon on Linux - Initial packet loss

I have configured two Linux boxes so they automatically use a transport-level IPSec connection whenever they need to communicate. The configuration is based on Racoon with X509 authentication and the ...
2
votes
3answers
4k views

massive packet loss when servers are brought online

This is a continuation of ubuntu server, ssh, write failed: broken pipe . I'm starting a new question, because I don't believe the issue is isolated to ssh/ubuntu. I've got two brand new servers (...
2
votes
4answers
5k views

What is causing a vm to exhibit packet loss?

We have a pretty nice piece of hardware set up to run multiple virtual machines in vmware and one of the vm's is an instance of Windows Server 2003 running SQL Server 2005. For some reason we ...
2
votes
0answers
56 views

Network sensor for a TCP connection for collecting statistics each second [closed]

I need a Network Sensor capable to gather basic end-to-end statistics (packet loss, jitter and network delay/RTT) of several TCP connections directed to the very same destination (ip-addr:port) on ...
2
votes
1answer
112 views

Fortinet Ascenlink heavy packet loss

I'm working on a company with some Fortinet appliances. One of them is a Load Balancer named AscenLink. The specific model is an AscenLink AL-700. There's a insane problem: a huge packet loss on the ...
1
vote
3answers
994 views

Unix software to continuously monitor packet loss

I'm looking for some software to monitor packet loss or packet retries. Preferably something that continuously monitors vs. a testing approach and preferably free. My server's OS is debian. I'm ...
1
vote
2answers
119 views

Can an internet connection be more robust when connecting through a VPN?

During live streams some viewers experiencing problems with the stream like dropouts and artifacts although they have a 100MBit line what makes me assume the problems are caused by packet loss. ...
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2answers
858 views

Very high packet loss in burst

We sometimes have 90%+ more packet loss on our server, but it does not always appends. Right now it works perfectly, but just half an hour ago, it had just that problem. Our service provider is ...
1
vote
1answer
4k views

How do I interpret packet loss identified by WinMTR

I've been asked to look into a packet loss problem a previous consultant identified at a client. They have two ADSLMax connections, one for data and the other dedicated to VoIP. The packet loss is ...
1
vote
2answers
84 views

How does ifconfig calculate packet loss?

Does the dropped packets output of ifconfig refer to the number of frames lost on the local subnet (i.e. datalink layer) or the number of lost IP datagrams at the IP layer or is it TCP retransmission ...
1
vote
1answer
5k views

What causes the issue (possibly packet loss) in this scenario

I'm trying to diagnose a network related problem - please understand these points before suggesting an answer (apologies if more information is required, I will add anything people ask). We have a ...
1
vote
3answers
2k views

Light packet loss through router

I just recently got a fiber line installed into my office, and with the exception of an odd bit of trouble that we're having, things are working good, and the network response is really amazing. The ...
1
vote
1answer
79 views

VMWare vSphere packet loss

I have a Dell Blade Enclosure with 14 blades and ESXi 5.5 on it. On blade 7 and 14 I have round about 65 % packet loss when I ping the ESXi Management interface. On all other blades there ist no ...
1
vote
1answer
1k views

Packet loss between Broadcom NetXreme NIC's on different hosts

I've got any interesting problem where I am getting packet loss between multiple servers in the same network. This is happening to about 15 hosts but I'll condense it to just three below. Firstly ...
1
vote
2answers
1k views

Why Packet Loss AFTER tcpdump has logged the packet?

We encounter some strange packet loss and want to know the reason for this. We have an imageserver and a server for stressing the imageserver. Both are located in the same datacenter First we run a ...
1
vote
2answers
60 views

Can't ping between two VMs

I have two VMs that, up until yesterday, have been able to talk to each other just fine. Now they don't. I've been trying to get this fixed for several hours now, but haven't been able to figure ...
1
vote
0answers
120 views

Server error 500 and packet loss [closed]

Is there any dependence between packet loss and server error 500? I have checked Apache (running on CentOS + WHM/cPanel) access logs for 500s and it looks like random occurrence without any major ...
1
vote
0answers
60 views

packet loss rate and netem

I am emulating a network with netem. I wrote a script that changes the network delay according to a linear function from 1 to 50ms every 15 seconds (with a normal variance = 5%). The packet loss is 1%....
1
vote
0answers
49 views

Corrupted files when downloading with HTTP

With my UMTS connection most archives > 50 MB are corrupted when downloading them via HTTP. If I switch to HTTPS the problem is gone. The problem should not reside in my network, because I have an ...
1
vote
0answers
48 views

burnt Switches connected directly to the internet

We got a setup with a switch between the cable modem/bridge and the two router ports. We burn this switch every 6 months, and it has to be replaced. Symptoms are heavy packet loss or in general very ...
1
vote
0answers
261 views

TCP High Send-q coupled with FIN_WAIT1 status

I'm having a problem with one of my webservers, which is taking minutes to completely render a web page. I had a look at the TCP connection and noticed that I have a very high value in the send-q ...
1
vote
0answers
136 views

Failover pacemaker cluster, packet loss monitor

It's issue is continued from this. So, i have two test servers in one vlan. srv1 eth1 10.10.10.11 eth2 10.20.10.11 srv2 eth1 10.10.10.12 eth2 10.20.10.12 Cluster VIP - 10.10.10.100 ...
0
votes
3answers
630 views

Can high packet loss mean users cannot access my website

A quick question. I tested my domain using the following site http://cloudmonitor.ca.com/en/ping.php It showed high packet loss in all countries. Packet loss of 70-100% Does this mean my site is ...
0
votes
1answer
58 views

Troubleshooting packetloss

I currently own a couple of CS:GO gameservers which are hosted in Germany (hetzner). Recently (for the past weeks) some people have been getting weird lags (getting slightly teleported back, some of ...
0
votes
1answer
529 views

iperf udp sequence number wireshark

I'm using iperf for generating udp traffic and my objective is to measure paquet loss. I wanted to know if the first 4 Bytes of Iperf Data are currently the sequence number.