Questions tagged [performance]

For questions about network performance, where factors like Bandwidth, Throughput, Latency, Jitter and Error rate are all often considered important.

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What is the difference between server-side and client-side data transfer rates in a speed test?

I am using CNLab's UX desktop app to test my internet connection's consistency as shown below for the upload. What is the difference between server-side and client-side data transfer rates. For VOIP/...
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TRex Warning : number of rx packets exceeds 101% of tx packets!

+------------+ | | +------------| tester |<-------------+ | | | | | ...
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iperf between two computers on different networks [closed]

Is it possible to check bandwidth using iperf between two computers on different networks(i.e geographically apart)?. I researched a lot and every answer on stack exchanges or any other website ...
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Does propagation delay of a packet sent across a link depend on the link transmission rate? [duplicate]

I was doing the exercises at the end of chapter 1 of Computer Networking: A Top-down Approach by Jim Kurose and came across the following problem; How long does it take a packet of length 1,000 bytes ...
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Intermittent Network Performance Problems

I've been dealing with an intermittent issue in my network for several weeks now. Symptoms: Periodic "Destination host unreachable.", and similar errors when pinging. The following is ...
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3 answers
508 views

Routing in layer 3 switch vs old modem/router?

I believe what I am about to ask is on-topic. I have Cisco DPC3828S (wireless router/modem) from ISP, which I cannot turn into bridge. So, it does routing. I have layer 3 switch, Cisco SG350-10. ...
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Is performance worse routing between two vlans on one interface than routing between two NICs with no vlans?

I have a Linux router with one interface that is connected to a switch in port 2. Port 2 on the switch is a member of vlan2(ISP) and vlan3 (office devices). My router is currently routing between ...
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How do CPU and RAM affect a router's performance?

I've seen a lot of circumstances when there are 50-100 users in the net cafes -- under normal gaming and web browsing activities with no heavy downloads -- causes the router to drop packets (leads to ...
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High Throughput on BGP Multihomed Network

I've One site connected to my server location via BGP over MPLS and at my server location 2 edge routers cater these WAN links, and are further connected to Servers via switches. Now, Is it possible ...
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How can we troubleshoot Wifi problems apart from the basic tips?

We have a Zyxel Wifi with an NXC2500 and two WAC6503D-S access points in our office. Around 30 devices are connected. We have both a 2,4GHz and a 5GHz radio active, both on channels without known ...
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Measurable performance impact of port mirroring on a firewall\security device?

I am setting up a network monitoring device which recommends that I create a mirror interface on my firewall/security appliance and send all packets to the monitor for sniffing, logging, and ...
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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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Random intercontinental TCP streams are slow

I have a home server in New Zealand and a remote server in Amsterdam of the following configuration: I have a simple test script: #!/bin/bash for i in `seq 1 20`; do scp root@remoteserver:~/...
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Is there a performance difference between a managed an unmanaged network switch?

Is there a tangible difference in speed/latency between a managed and unmanaged network switch?
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2 votes
1 answer
216 views

Definition of bandwidth capacity for an internet connection

First, I want to test the data rate of a fibre-optic internet connection, but I understand that results are affected by the circumstances of the test, like number of hops between the CPE and the other ...
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1 answer
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Is this a normal TCP retransmission pattern?

Our organisation's desktop computers have been performing not satisfactorily during their accessing of network resources. Out of suspicion, I perform a TCP retransmission statistics. Below picture is ...
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Can bad cabling affect the overall network?

TLDR: Can a handful of problematic lines negatively impact the performance of the network as a whole? ... or would any problems stop once it reaches the switch? Longer Version (background): A ...
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TCP DUP ACKs occurring on a seemingly regular basis

I noticed this while checking the performance of our Teamviewer connections. If i start a download test, the following pattern can be observed in the TCP stream graph provided by Wireshark: The red ...
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How can I calculate the network throughput using ping responses?

I have the tcpdump data for the below mentioned command.This is to perform a test on the network to derive the bits per second. Is it possible? sudo ping6 fd9c:b4f9:3108:1045:213:5003:59:324e -c 10 -...
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6 votes
2 answers
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how to find the right value of MTU Jumbo frame

we take the decision to set jumbo frame on all our linux machines we have hadoop cluster with master machines , workers machines and kafka machines our switches ( Cisco ) are suitable to Jumbo frame ...
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PPPoE Performance Test [closed]

I'm looking for some tool or a way to execute performance test with pppoe account. simulate PPPoE sessions and traffic. Example: I have a PowerEdge R420 running a VYOS, I was wondering, how is the ...
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5 votes
2 answers
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Cisco ISR 4000 Performance Levels, router shaper

I am trying to understand Cisco ISR 4000 Performance Levels. In the document ISR 4000, one can read the following paragraph: It's actually quite simple. The router shaper applies only to traffic ...
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2 votes
1 answer
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ACL on Nexus 3064PQ performance

We are using this switch as L3 and planning to run some ACL to stop bad traffic. I never run ACL on switches so wondering is there any performance impact or how bad it will be? if anyone has any ...
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1 vote
2 answers
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Cisco performance issues C890 series

I'm working on a complex project that includes Linux and Cisco routers. I am fairly new to networking and i'm using cisco command lines for the first time, so please be nice and don't hesitate to ...
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3 answers
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Why such a large discrepancy between theoretical and real Wifi speeds?

I am testing the actual speed of transferring a file from a network share. Over my 1 Gigabit Ethernet I get about 120 MB/s - that's 96% of the theoretical maximum. Over my old Wireless G I get about ...
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2 votes
2 answers
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How to design a wireless network for efficient multicast or broadcast communications?

First, a little bit of background information: I'm working on some custom software that allows a group of computers on the same LAN to co-operate on a real-time task in a distributed, fault-tolerant ...
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2 votes
8 answers
321 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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How to make a web application run as fast as when I run it directly through the server? [closed]

I have a web application that run from a local server. When I run the application from the server using remote desktop connection, the application performance is smooth and fast. For example, ...
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3 votes
3 answers
194 views

Cisco Aironet performance took a big hit with VLAN

I manage a wireless network of 50 Aironet 1130AG access points spread across 8 Catalyst switches. This ran very smoothly until I had to employ VLAN tagging. There is now the passwordless Default (1) ...
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1 vote
1 answer
226 views

Cisco ACL performance question?

We have ASR1006 Router and we are running ACL on it to allow specific port to specific server. Question is there any ACL performance impact on individual IP vs full subnet. like following example. ...
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4 votes
1 answer
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IPv4 vs IPv6 performance

What are the differences in performance for IPv4 and IPv6? Is there much of a difference in speed? and what are some of the methods that could be used to test this?
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2 votes
1 answer
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What is the N½ value of a network?

In the context of HPC interconnect networks (Infiniband, OmniPath, ...), I've come across the notion of the N½ value of the network, which is supposedly some performance number. What is this number? ...
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1 vote
1 answer
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General best practice for VLANs and domains

I recently took a job at a school. This is only my second position as an IT professional. My only experience with corporate networks is in a large school district at another school. They used VLANs to ...
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1 answer
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GNS3: performance tests using iperf3? [duplicate]

I'm running some performance tests on GNS3 (I know I shouldn't, but it is not until Friday that I will have the college lab available), and I'm trying to compare real BW or "speed" and ...
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1 vote
1 answer
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NIC speed and PCI bus speed to be synchronized?

Is there any advantage point of having a Gigabit Ethernet if the PCI bus connecting NIC to Memory is a lot slower than that say just 80 MBps? In other words, I am trying to conclude that it makes ...
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2 votes
2 answers
155 views

Effects of local switch time on network performance

Given a collection of switches all communicating together, will the local time on the switching equipment configuration have any bearing on performance, or just a common reference point when ...
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4 votes
2 answers
286 views

Measuring route processing time

I want to feed a Juniper router a set of routes via BGP and measure how long it takes the router to process them, including time spent on prefix filters and RPKI origin validation. Cisco IOS XR ...
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1 answer
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Simple way to monitor network performance w/o access to network infrastructure?

I work for a large organization where the network team is in some disarray (key people left/fired, etc.). My team is responsible for the performance of various client/server applications which of ...
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2 votes
2 answers
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 ...
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1 vote
0 answers
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CDN performance degrading during load testing [closed]

While load testing our website through Soasta we found that the API calls were performing consistently without any degrade in performance (thanks to larger Ec2's serving them and the Elastic Load ...
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4 votes
1 answer
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How well does 802.11k actually perform on large-scale networks?

As a student employee I've done some research on 802.11k and I understand that it's intended to help with devices roaming and also helping the client decide on the best (B)SSID to join. In practice ...
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3 votes
1 answer
1k views

Performance differences of logging session-init and session-close invididually compared to through apply-groups

Assumption: Your interest lies in logging each and every session Approach 1 You configure the session logging within each and every policy, for example: set security policies from-zone trust to-...
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6 votes
2 answers
15k views

How to "size" a Router for a Given Uplink

I'm the tech guy for a small business. (15 office computers, ~15 staff BOYD's, ~30 guest devices.) I'm looking to replace our Asus RT-N53 with a business class router and two access points each ...
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3 votes
1 answer
773 views

Firewall Benchmark- Concurrent connection metrics

I intend to perform a Firewall Benchmark. I have reviewed related research papers and RFCs to create a suitable methodology. I have also examined open-source tools useful for the project (iperf, ...
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5 votes
1 answer
1k views

ACL on entry of Core Switch - Performance doubt

We are an ISP and I would like to implement ACL to protect our core network (Infrastructure) and implement some filtering on public subnet inside. As border device we have a cisco WS-C4500X-32 4500x ...
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3 votes
1 answer
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standard results for gigabit ethernet iperf

I can't achieve good transfer rate through scp and I wonder if the network configuration isn't tuned up correctly. I've noticed some differences when running iperf through tcp vs udp. Are these ...
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9 votes
2 answers
510 views

How to handle performance degradation deep in your provider's network?

What are some possible ways to detect packet loss deep in a provider's network that is several hops away? With multiple providers peered over BGP on our Internet edge routers, I need to be able to ...
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4 votes
2 answers
3k views

OSPF LSA Refresh Time

Is there a Cisco command that would allow one to modify the default value of 1800 seconds (30 min) for the OSPF LSA refresh rate?
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18 votes
3 answers
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How do you know if a Cisco switch is handling traffic well?

I have just read Jeremy's question about 2960-S and iSCSI traffic handling, which drove me to ask this question: We all have lots of switches deployed in distinct infrastructures, how can you know ...
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