Questions tagged [latency]

For questions about network latency. For instance: the propagation of your network traffic, where the transmission medium can be defect or the processing of packets by a network device has slowed down.

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29 views

Transmission and propagation delays

I am now working through book "Computer Networking - A Top Down Approach", and there is one question among others after the first chapter: "Consider two hosts, A and B, connected by a ...
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Reducing Wi-Fi Latency [closed]

I've got a good wi-fi connection with only 4ms ping time to my router: PS C:\Users\bobuhito> ping 10.0.0.1 Pinging 10.0.0.1 with 32 bytes of data: Reply from 10.0.0.1: bytes=32 time=4ms TTL=64 ...
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How to calculate the latency in vehicular network?

I need to calculate the delay in vehicular network V2V and V2I and I define it as the following: Where L [Bit] the length of data and the transmission rate where is the distance between vehicle i ...
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6answers
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Network latencies between opposite ends of the Earth

This is just out of curiosity. when I pinged domains such as bbc.co.uk and google.com (in California), I get latencies of around 5ms as below: 64 bytes from xx: icmp_seq=0 ttl=55 time=2.940 ms 64 ...
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2answers
28 views

Will TCP packets smaller than the full bandwidth of its link travel at the same speed?

If I send 5bytes over a 1mbps connection will that travel faster than 500bytes. Or is the latency after propagation going to be constant since the packet is under 1mb? If you downvote because you ...
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How can the latency value be so low from Singapore to USA (~2ms)?

Here's the ping output from Singapore: 64 bytes from 8.8.8.8: icmp_seq=1 ttl=50 time=1.96 ms Singapore to 8.8.8.8 = ~2ms Another ping output: 64 bytes from 23.59.8.146: icmp_seq=81 ttl=44 time=66....
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124 views

Copper or Glass for Low Latency?

I'd like to preface the main content of this post with the following: I understand this question may be equally suited to the Physics Stack Exchange, and so I have posted on there as well, but maybe a ...
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1answer
55 views

TCP Bandwidth and delay guarantees

I was wondering if TCP can provide bandwidth and delay guarantees? Or does it have to implemented on the application layer?
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55 views

network slowness troubleshoot

I want some suggestion regarding our network issue: From our office location to our DC ==> it's ~270msc(office and DC lies in different countries). As, you can already see here latency is the major ...
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2answers
66 views

Best way to Fast Reconnect TCP with dynamic IP

I am aware of TCP Fast Open, all though, I'm pretty sure it doesn't apply when the IP of the server changes dynamically. Getting the IP of the server quickly isn't the problem. The problem is that I ...
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2answers
4k views

Switch Buffer Sizing

What is the relationship between a switches buffer size and the effect it has on latency? I am aware of the bufferbloat issue and understand that buffers that are too large in networks of slower BW (i....
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3answers
96 views

Estimate latency between two IP addresses

I would like to estimate what is the latency in sending a packet between two IP addresses. Let's assume that I have two IP addresses: ip1 and ip2. I can easily ping both ip1 and ip2, and the ping ...
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latency in the network layer and transport layer [duplicate]

We have several way to measure latency (ping command (ICMP packets), hping(TCP SYN), iperf..).What is the difference between measuring the latency in the network layer and measuring in the transport ...
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95 views

Response time of TCP congestion control

I would like to know about the overall latency of the TCP congestion control for adapting to varying network conditions. Specifically, my questions are: How fast can the system react after a change ...
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2answers
90 views

Delay, Packet length and transmission rate

Why does the delay in sending a packet from source to destination doesn't depend upon the transmission rate and the packet length? If we look at the delay formula then it is, L/R + D/V.
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4answers
2k views

Measuring per-link latency/jitter/packet-loss

I need to measure the latency, jitter and packet-loss per link in a network, as opposed to end-to-end, e.g. like this: s1-eth0 <--> s2-eth0 (~ 20µs avg. latency, standard derivation 10µs, 57 % ...
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1answer
30 views

Can clock synchronization ever be more than guesswork within a certain interval?

Assuming consistent spacial interference, e.g. The time for packet Z to get from point A to point B will always be constant. The time for packet Z to get from point B to point A will always be ...
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12answers
35k views

What would cause high latency anytime there is traffic on WAN?

I have a network that has been experiencing slow internet speeds. After a great deal of troubleshooting, I have determined that any streaming content/downloads will cause the latency of WAN traffic to ...
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64 views

Estimating bandwidth requirements and productivity gain from traffic data

My small office has a 30Mbit/s internet connection, on which two or three people work. We could get twice the bandwidth at a substantial cost. I imagine a bandwidth upgrade would slightly improve ...
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1answer
843 views

How to Troubleshoot Network Latency Step by Step

Does anyone have an idea of how to troubleshoot high network latency step by step? For example, let's say we have a remote office. And all users are from that office are having high latency accessing ...
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2answers
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Serialization and serialization times in 40G/10G and 100G/25G Ethernet

I've recently been involved in discussions about lowest-latency requirements for a Leaf/Spine (or CLOS) network to host an OpenStack platform. System architects are striving for the lowest possible ...
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2answers
2k views

Does bridging add delay?

If I use a bridge to perform traffic sniffing like man in the middle will the bridge add a delay? And what word should I use delay or latency?
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2answers
402 views

Dynamically generate OSPF/BGP routes based on Internet latency

Scenario Three Offices with 2 ISPs each - utilizing static routing to the ISP. Each office has a VPN and leased point-to-point circuits connecting the offices in a ring. A VPN is also connecting the ...
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2answers
296 views

How to measure time a request takes between two machines?

I need to calculate the time it takes between: a request sent from a machine the request is received at another machine I can do it by logging, but the clocks at these 2 machines are possible have a ...
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3answers
11k views

What causes packet loss when using full bandwidth from ISP?

We have a small, local ISP that is having some networking issues and I'm trying to understand the cause to better communicate with their network guys. I work with a number of companies with different ...
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4answers
3k views

High latency during downloads

I am having the same issue on my business connection 5Mbps as in another posting on this site. As soon as any computer starts a download the latency on the first hop past our DFG provided by our ISP (...
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1answer
3k views

What is the value of EstimatedRTT at first time?

Although this question might be marked as duplicated! I'm asking again because other question's answers like this couldn't help me. So please consider the case and don't mark it as duplicate and ...
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4answers
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What's the difference between `Latency` and `Round Trip Time`?

Golang community provide a HTTP/2 demo website to compare the performance between HTTP 1.1 and HTTP/2. We can choose different latency, e.g. 0s latency, 30 ms latency, 200ms latency. Is latency a ...
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3answers
4k views

Why can insufficient bandwidth reduce latency?

In this article, it is stated that latency does not affect bandwidth, but insufficient bandwidth can reduce latency. Can someone explain me the latter part of the statement? How would insufficient ...
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1answer
113 views

Weird packet lost. Looking for some input

Like me start by saying I'm not an network expert but this situation got me scratching my head and you guys might be able to help. The infrastructure is 4 switches (Dell 2848). 2 For the LAN and 2 ...
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1answer
715 views

What is the relationship between throughput and latency

Looking at the structure of a TCP packet, such as discussed here: What is the internal structure of a mobile phone call packet/datagram?, this indicates that a TCP packet size is 192 bytes excluding ...
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2answers
1k views

What are the differences between TCP iRTT and ICMP Ping?

I’m attempting to estimate latency between my PC and any servers/clients it interacts with. I don’t want to use Ping for various reasons (requires both ends to allow it, would require additional ...
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2answers
264 views

How fast can information travel through various media?

I'm working on compiling some information about network latency and designing tests to help our support folks troubleshoot problems. In order to do this, I need some basic information that I don't ...
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1answer
2k views

What is the latency of IP over Infiniband compare with 10Gbps fibre network?

What is the latency of IP over Infiniband compare with 10Gbps fibre network? 10Gbps network is something like a Solarflare low latency NIC card. How well does IP over IB perform not just throughput ...
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2answers
654 views

High Jitter and Data Loss on Cisco Meraki Z1

Our office is running a Cisco Meraki Z1 Security Appliance and recently (March 5th) the internet has been dropping out intermittently. The appliance remains online but the internet either doesn't work ...
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1answer
2k views

IPTV Cisco configuration for C2960

I have attached a network diagram explaining IPTV network , i have below queries to understand & configure IPTV . All ports on edge switches are configured as access ports in VLAN 101. On Core &...
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2answers
72 views

are the RTTs additive?

By using the ping, I calculate the RTT between A and B. I calculate the RTT between A and C. I calculate the RTT between C and B. Is it possible to compare the RTT of topological link A->B with the ...
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2answers
1k views

does the DSL distance really add more latency

I've been using dsl internet for quite a while and having a ping from Algeria to France of about 90 ms , after trying to ping some locations in Algeria , i am getting about 50 ms, ping to my gateway ...
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1answer
330 views

Latency in P2P Circuit

I have one P2P Circuit from our HQ to a secondary office. the distance between them is approx 2kms. Earlier when the Circuit was delivered at that time we were having an RTT of 3-4ms. It is a 10Mbps ...
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1answer
919 views

Cisco C891F-K9 ISR latency?

What is the multicast routing latency of Cisco C891F-K9 ISR? Please cite references for your answer. I think it's store-forward type and isn't one of the fastest models (given its price!). I've ...
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2answers
703 views

On a Layer 3 switch, what part does the CPU play in forwarding packets?

I am a Systems Administrator at a small firm. We are latency sensitive. When forwarding packets, what protocols use the CPU and which use the ASICs? We have mostly Arista 7124's (for the most latency ...
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3answers
702 views

Measure latency and other statistics by comparing PCAPs

I need to measure certain statistics, such as latency, packet delay, and jitter. Would it be possible to measure these statistics between 2 nodes by sniffing traffic on both ends and then comparing ...
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2answers
962 views

POST duration over https vs ping time? [closed]

I'm trying to get a first-order evaluation of how network latency / Round Trip Time (RTT) T, as characterized by ping time, will affect the duration of consecutive sequential POST requests over an ...
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1answer
503 views

How to measure latency and udp-jitter from the end-server [closed]

Is there anyway to monitor a latency and jitter from SLA Router to EndClient(Linux Server). I have tried to use IP SLA with UDP Jitter but it didn't work. Diagram SLA-Router -------> Linux ...
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4answers
59k views

How to find the source of increased latency?

I've got monitoring setup on several devices in our office. The ping response time to small access switches is commonly 1-4ms... As of 3AM this morning, this has sky-rocketed to 300ms on average. ...
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1answer
2k views

Is RTT the same as round-trip propagation time?

As far as I know: (1) Latency (τ) = transmission delay + propagation delay + queuing delay + processing delay (2) Round-trip time (RTT) is two times the latency (assuming the same latency both ways) ...
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2answers
163 views

Cisco VLAN configurations with WAP - Poor performance

We've recently applied a new modification to our network config. Separating two SSIDs into a guest \ corporate split config. All of the VLAN and DHCP scopes are functioning in the way it was designed ...
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8answers
282 views

What are the concerns other than latency for network tuning?

Everywhere I keep finding "to achieve low latency" or "latency is of concern", do this! So, I don't really get what are the other concerns other than latency. I mean who doesn't want low latency? Or ...
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4answers
9k views

Does physical distance affect download speed?

I just had an argument with a colleague of mine and thought I'd just reach out to the experts on this. Here's the scenario. We were using a website that measures your connection's speed. We tested ...
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2answers
2k views

Difference in latency between public and internal IP addresses

Should there be a difference in latency when accessing resources by their public IP address versus their private, internal IP address? And if there is, would (mis)configuration be to blame? My ...