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

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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 ...
22
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5answers
22k 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 ...
10
votes
4answers
957 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 ...
5
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4answers
16k 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?
5
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2answers
3k 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 ...
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votes
4answers
5k 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 ...
4
votes
1answer
697 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
1k 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 ...
3
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1answer
3k 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 ...
3
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1answer
1k 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
581 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 ...
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1answer
687 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 ...
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2answers
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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, ...
2
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2answers
213 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 ...
2
votes
2answers
269 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
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1answer
314 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
320 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
282 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 ...
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1answer
248 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
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2answers
672 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
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4answers
3k 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
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0answers
256 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 ...
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3answers
607 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 ...
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2answers
108 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
597 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 ...
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1answer
3k 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 ...
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1answer
3k 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 ...
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1answer
902 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 ...
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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 ...
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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 ...
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3answers
232 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
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1answer
216 views

UDP packet loss on Netgear GS110TP

I'm trying to flow data via UDP on two ports of a Netgear GS110TP switch, running the latest available firmware (5.4.2.9). However, I'm experiencing a small amount of packet loss, something like ...
0
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1answer
2k 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 ...
0
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2answers
324 views

Packet loss with all adapters on one PC only on the LAN

I have a Windows 7 64-bit machine that is losing up to 20% of IP packets on both adapters - wireless & LAN. Browser traffic appears to be affected the most, but it is happening to all protocols. ...
0
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1answer
378 views

Packetloss in Juniper SRX with gigether-options loopback enabled

I have run into an interesting problem with a Juniper SRX 240 box. The box is running BGP as a border router, and is announcing a /24. To ensure that the vlan with the network stayed "up" I set the ...
0
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3answers
716 views

Weird Cisco switch problem - minutes with ultimate packetloss

because of dead port were we pushed to replace our Linksys/Cisco SR2016 in datacenter. So we looked to the stock of our supplier and the only interesting switch they had was the Cisco SLM2024 Smart ...
0
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1answer
469 views

Linux TCP stack and network cards performance: packets per minute before drop?

how much TCP packets should come at 100/1000mbit network card (not an embedded Realtek's home solution) before the Linux kernel will become unable to process the NIC's buffer resulting in packet drop? ...
0
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1answer
2k views

ISA Server dropping packets as it believes they are spoofed

We have ISA Server 2004 running on Windows Server 2003 SP2. It has 2 NICs - one internal called LAN on 192.168.16.2, with a subnet of 255.255.255.0, and one external called WAN on 93.x.x.2. The ...
0
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1answer
617 views

fast way to find network user computer on domain hogging all wan bandwidth

i have a network of about 40 domain users and i have huge latency wan issues, like 1400ms for google.com pings. I have noticed that the problem goes away after everyone goes home for the day. I would ...
0
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1answer
29 views

Ubunutu 12.04 Packet loss

I have this Ubuntu Server (12.04.2) which sometimes (thrice a day for 5 minutes) it's unreachable through zabbix and SolarWinds Orion. I logged into to Orion server and Zabbix server and did a ping ...
0
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1answer
52 views

UDP packet loss cause

I have two machines connected to the same LAN and multicasting UDP streams at rate of about 30Mbps. Analyzers often show packet losses on one machine, but never on another. What could be the reasons ...
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0answers
76 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.
0
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1answer
100 views

High ping times and packet loss on Alcatel-Lucent OmniSwitch 9600

We have 2 Alcatel 9600 core switches in a redundant configuration and 2 distribution switches (Alcatel 6850's) on another floor connected by fibre to the core switches. See the diagram below. Pinging ...
0
votes
2answers
71 views

Occasional Delay on Website Resources: Packet Loss Due to Bandwidth Cap?

My website loads more slowly than I think it should, due to a few of the assets taking an absurdly long time to download from the server. I've been trying to track down the cause of this. I'm about ...
0
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0answers
229 views

Packet drop monitoring on vmnic objects

I'm trying to create a script via PowerCLI that can monitor packet drops for vmnic objects. I was able to find online a version of the script that does exactly what I want for host servers, however ...
0
votes
1answer
69 views

Test ethernet port for data loss

We are trying to test the ethernet phy on our linux box for data loss. As of now we just establish a tftp connection to a server to upload and download a file. Whenever a mismatch occurs, it is ...
0
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1answer
108 views

TCP packet filter based on TCP sequence

I need to build a test environment with a very precise packet loss based on specific TCP sequence or, optionally, on payload content. I couldn't figure out how to do it with tc or iptables. What tool ...
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0answers
74 views

Cannot connect to Windows Server 2008 R2 via http, https works

I've been having a problem with my WS2008R2 server ever since I started IIS7 for the first time. I've been managing to work around it so far, because https access works normally. http, however, has ...
0
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1answer
61 views

Network packet loss and major connection issues

We've just swapped isp and have set our network up exactly as it was. We are having really bad connection issues on our network to outside sites. Running Ping Tester we are getting about 13% loss when ...
0
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1answer
405 views

network latency, TCP and UDP packets

Hello recently my network has started to cause me lots of problems. I have a cable modem, connected to a tp-link router (with some port forwarding). Everything was working fine then i started to get ...