14
votes
Accepted
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 ...
- 2,122
8
votes
Accepted
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 ...
- 101k
7
votes
Accepted
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 ...
- 88.1k
6
votes
Accepted
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 ...
- 6,152
6
votes
Accepted
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 ...
- 27.4k
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 ...
- 88.1k
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 ...
- 68.1k
5
votes
Accepted
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 ...
- 323
5
votes
Accepted
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 ...
- 88.1k
4
votes
Accepted
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 ...
- 88.1k
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,...
- 101k
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 ...
- 68.1k
3
votes
Accepted
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 ...
- 68
3
votes
Accepted
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 ...
- 88.1k
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 ...
- 21
2
votes
Accepted
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 ...
- 135
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 ...
- 21
2
votes
Accepted
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 ...
- 141
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 ...
- 68.1k
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 ...
- 435
2
votes
Accepted
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 ...
- 88.1k
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....
- 21
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 ...
- 88.1k
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 ...
- 16.4k
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 ...
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
"...
- 8,876
2
votes
100Mbit vs 1Gb/sec transferring 10MB file...speed difference?
There are a very large number of variables, in terms of the internals of the PC at each end, the software used to control the transfer, and the lower level protocols used.
Achieving a reliable ...
- 29
1
vote
Is there a performance difference between a managed an unmanaged network switch?
An unmanaged switch comes w/ a fixed configuration, which means that there's no way to reduce network overhead, whereas a managed switch will allow for traffic prioritization through the use of SNMP, ...
- 11
1
vote
How can we troubleshoot Wifi problems apart from the basic tips?
The basic tips are exactly what you need:
survey your wireless location for neighbor SSIDs, their channels and traffic
survey your location for other sources of EM radiation in the 2.4 GHz band (5 ...
- 88.1k
Only top scored, non community-wiki answers of a minimum length are eligible