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14 votes
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Is there a performance difference between a managed an unmanaged network switch?

Good question. The short answer: No, there's no inherent difference in the speed or latency available to hosts talking to one another on a managed vs. unmanaged switch. In reality though, you'll ...
Ted Quanstrom's user avatar
8 votes
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IPv4 vs IPv6 performance

Based on real-world Internet measurements by large companies, IPv6 has a slight edge in performance. This may be due to several reasons, such as the simplified packet header, or it may be due to other ...
Ron Maupin's user avatar
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8 votes
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100Mbit vs 1Gb/sec transferring 10MB file...speed difference?

The bandwidth is how fast an interface serializes bits onto the wire. Obviously, a 1 Gbps interface serializes bits 10 times faster than a 100 Mbps interface. With everything else equal, a 1 Gbps ...
Ron Maupin's user avatar
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6 votes
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ACL on Nexus 3064PQ performance

That 3K and 9K platforms don't really have a notion of software switching. If it can't be programmed in the forwarding ASIC then it's not forwarded. There are a couple of minor exceptions but for ...
rnxrx's user avatar
  • 6,124
6 votes

how to find the right value of MTU Jumbo frame

Make sure there's a notable performance difference between jumbos and standard frames - without it, there's little reason to dive in. Hardware offloading tends to make jumbos obsolete unless you need ...
Zac67's user avatar
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6 votes
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Why such a large discrepancy between theoretical and real Wifi speeds?

While a rather straightforward question, the answer is quite a bit more convoluted. Simply because there are so many factors that can play into your actual throughput on wireless. Let me start by ...
YLearn's user avatar
  • 27.4k
5 votes

Why such a large discrepancy between theoretical and real Wifi speeds?

The "theoretical maximum" you refer to is the PHY clock rate. That has little to do with throughput, as you have discovered. A better question is why Wi-Fi is slower than Ethernet. There are a ...
Ron Trunk's user avatar
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5 votes
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How can I calculate the network throughput using ping responses?

ICMP has got an overhead of 8 bytes, IPv6 of 40 bytes, (assumed, untagged) Ethernet of 38 bytes. With a payload length of 1388 bytes, the total per packet is 11,792 bits on the wire. Ping doesn't ...
Zac67's user avatar
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5 votes
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How well does 802.11k actually perform on large-scale networks?

We have been running 802.11k (and 802.11v) on our campus network (~9200 AP's) for close to a year. We are using a controller based Wi-Fi infrastructure (Aruba Networks). Our wired network ...
Neil Johnson's user avatar
5 votes
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How do CPU and RAM affect a router's performance?

You are referring to NAT routers. Normal routers (not implementing NAT) require only very little amounts of memory and processing power for routing - they are essentially stateless and pretty much all ...
Zac67's user avatar
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4 votes
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TCP DUP ACKs occurring on a seemingly regular basis

When a link becomes saturated and the queueing depth increases significantly a sudden delay is introduced to the stream. This often causes unnecessary retransmissions because the ACKs for the queued ...
Zac67's user avatar
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4 votes

Is there a performance difference between a managed an unmanaged network switch?

Most switching is performed in hardware at wirespeed, so no, you will not normally see any difference in the speed or latency for standard layer-2 switching. If the managed switch is a layer-3 switch,...
Ron Maupin's user avatar
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3 votes
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Is this a normal TCP retransmission pattern?

Some TCP retransmission is normal, but this looks excessive. Looks like you have packet loss and will have to "walk the line" and check physical connections, cabling, speed/duplex mismatches. Check ...
errdisable's user avatar
3 votes
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Can bad cabling affect the overall network?

A bad link will primarily just affect the communication between the two devices. However, there are some secondary effects that may come into play due to intermittent link loss or loss of important ...
Zac67's user avatar
  • 85.5k
3 votes

High Throughput on BGP Multihomed Network

Yes, it's possible, but you need to fully understand what you're trying to accomplish, and what criteria you will use. Network performance can vary rapidly, and you don't want to overreact to a ...
Ron Trunk's user avatar
  • 67.7k
2 votes

Cisco Aironet performance took a big hit with VLAN

Without knowing what model the switches are, what is the default MTU on the interfaces? Often they default to 1500, and with the addition of the vlan tag you may be surpassing that. This could ...
Derek Poehls's user avatar
2 votes

Cisco Aironet performance took a big hit with VLAN

Have you considered placing your wlc in a different location instead of off of the router in the router. From most of my experience with environments I've worked in we have always placed are wireless ...
Ty Smith's user avatar
  • 533
2 votes
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Cisco ACL performance question?

You always can use wildcards to create your access list, i think with that, you will reduce the matching process of the router The ACL of your example will result like this: access-list 102 permit ...
Orlando Gaetano's user avatar
2 votes
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How to design a wireless network for efficient multicast or broadcast communications?

I haven't found any reliable information on how to make multicast-over-WiFi work better, so what I did in order to work around the problem was write a multicast-simulator-layer that greatly reduces ...
Jeremy Friesner's user avatar
2 votes

How to design a wireless network for efficient multicast or broadcast communications?

The effective bandwidth and reliability of wireless networks (Wi-fi or any other) is highly dependent on the RF environment. In order to have some predictable performance, each installation needs to ...
Ron Trunk's user avatar
  • 67.7k
2 votes

Why such a large discrepancy between theoretical and real Wifi speeds?

The theoretical maximum data rate is subject to several conditions. 802.11 employs several MCS (Modulation and Coding Scheme) indices, that determine the data rate depending on the SNR. This is why ...
V-Red's user avatar
  • 435
2 votes
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What are the concerns other than latency for network tuning?

The tuning concerns that I can think of are: Packet loss - When TCP encounters packet loss, it has to recover - but it starts with a small window and opens it back up again over time. The longer the ...
Yuli Gartner's user avatar
2 votes

What are the concerns other than latency for network tuning?

Good question, Low latency = Healthy network (In my case 200 miles of fiber 4ms round trip) High latency = Hardware failures, Bad network config or bad design In our network we need low latency to ...
Jon Bailey's user avatar
2 votes
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Definition of bandwidth capacity for an internet connection

There are two aspects for bandwidth: The link speed as indicated by the interface presents the upper limit of what that interface can transport. The practical throughput (maximum capacity) you can ...
Zac67's user avatar
  • 85.5k
2 votes

How to Troubleshoot Network Latency Step by Step

Very likely the WAN connection is the major problem. There's little you can do except provide a local server or change the ISP. Additionally, the possibly weak WAN link may be congested and may need ...
Zac67's user avatar
  • 85.5k
2 votes

Random intercontinental TCP streams are slow

One of my clients has traffic between UK, Ireland, and Singapore; frequently there are spectacular slowdowns of the kind you describe. My understanding is that a lot of traffic between Europe and ...
jonathanjo's user avatar
  • 16.3k
2 votes

How can we troubleshoot Wifi problems apart from the basic tips?

I would definitely recommend doing a site survey. There are many resources to do signal strength and interference surveys, but they won't reveal any non-wifi sources of interference that may be around....
Mead-Fi's user avatar
  • 21
2 votes

Intermittent Network Performance Problems

It's been a while since I participated in this question. I believe I located 90% of our problem; we did indeed have a loop. A member of IT had plugged in an additional cable between a switch and a ...
Dominic Hilsbos's user avatar
2 votes

Is it possible to conduct a bandwidth test using iperf between two computers located on different network?

Yes that's possible, provided... both involved computers run iperf, one in "server mode", one in "client" mode. the required TCP (and optionally UDP) communication between "...
Marc 'netztier' Luethi's user avatar

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