Questions tagged [packetloss]

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

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

Packet loss is distinguished as one of the three main error types encountered in digital communications; the other two being bit error and spurious packets caused due to noise.

Packet loss can be caused by a number of factors including signal degradation over the network medium due to multi-path fading, packet drop because of channel congestion, corrupted packets rejected in-transit, faulty networking hardware, faulty network drivers or normal routing routines (such as DSR in ad-hoc networks).

When caused by network problems, lost or dropped packets can result in highly noticeable performance issues or jitter with streaming technologies, voice over IP, online gaming and videoconferencing, and will affect all other network applications to a degree. However, it is important to note that packet loss does not always indicate a problem. If the latency and the packet loss at the destination hop are acceptable then the hops prior to that one don't matter.

Some network transport protocols such as TCP provide for reliable delivery of packets. In the event of packet loss, the receiver asks for retransmission or the sender automatically resends any segments that have not been acknowledged. Although TCP can recover from packet loss, retransmitting missing packets causes the throughput of the connection to decrease. This drop in throughput is due to the sliding window protocols used for acknowledgment of received packets. In certain variants of TCP, if a transmitted packet is lost, it will be re-sent along with every packet that had been sent after it. This retransmission causes the overall throughput of the connection to drop.

Protocols such as UDP provide no recovery for lost packets. Applications that use UDP are expected to define their own mechanisms for handling packet loss.

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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 which peer IP addresses "seem" to be experiencing…
nonot1
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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. We have been using this for the past two years…
Blue Gene
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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?
KushalP
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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 connected via a single 1Gb switch. Testing UDP…
Evgeniy Berezovsky
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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 corrupt packet errors keep getting thrown,…
Juan Carlos Coto
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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 datagram loss rate was shown to be 3.3-3.7%, which…
stefita
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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 assumption that since there are only a few switches…
z8000
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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 depending on the incoming bandwidth. (I use IPerf to…
Nicolas Raoul
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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 location: My traceroute [v0.75] prag341.server4you.de…
The Shurrican
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Linux server dropping RX packets in __netif_receive_skb_core

I have an Ubuntu 18.04 server dropping received packets and I cannot figure out why. Here's a graph of dropped packets from netdata: The server is running multiple docker containers and networks, therefore having several Linux bridges and veth…
Bernhard
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Is it normal to have HTTP 499 errors in 1 out of 4000 requests?

I made a website, behind CloudFlare, and sometimes I get an early terminated (nginx 499) request, which is really hard to work around in the codebase. This happens in about 1 out of 4000 requests. What I would like to ask is if this is normal or…
hyperknot
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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, although this varies. Raw telnet is similar and…
John K
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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 packet is lost, the tcp link is stalled for 30…
Joel
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What is an expected TCP retransmission rate

I have a direct connection setup between my NAS and server with two gigabit links bonded in mode 0. I also have a single gigabit link from my server to my network. I want to test how the bond is performing in mode 0. netstat -s | grep 'segments…
Alec Fenichel
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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 we have plenty of bandwidth (100mb connection).…
David W
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