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 ...
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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 ...
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  • 92.7k
7 votes
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How to "size" a Router for a Given Uplink

Apologies for the delay in my response, I just got back from vacation... I'm looking to replace our Asus RT-N53 with a business class router and two access points each servicing a private and a ...
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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 ...
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  • 6,018
6 votes
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ACL on entry of Core Switch - Performance doubt

The peak traffic on downstream is 3Gbps. I follow the guidelines and I've already define the ACL, just left implement them. My doubt now is how will be the throughput performance, if it's ...
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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 ...
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  • 69.5k
5 votes
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GNS3: performance tests using iperf3?

Don't trust GNS3 for throughput tests. As soon as you use a router in your topology you are likely only to get 5mb/sec tops, regardless of whether you use a serial, ethernet or fast ethernet interface ...
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  • 2,317
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 ...
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5 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 ...
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  • 26.7k
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 ...
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  • 69.5k
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 ...
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  • 69.5k
4 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 ...
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  • 62k
4 votes
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Difference in latency between public and internal IP addresses

Technically yes there will be a small difference and notability will depend on your devices/configuration. This is because of the different paths the packets have to take, but like i said, depends on ...
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  • 333
4 votes
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NIC speed and PCI bus speed to be synchronized?

This was a problem when 1 Gb NICs first came out. Servers could only get about 400 Mb of throughput on a 1 Gb network because the server bus wasn't fast enough to get 1 Gb. It was still four times ...
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  • 92.7k
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 ...
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  • 69.5k
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,...
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  • 92.7k
3 votes

Effects of local switch time on network performance

Regarding your first question local time on certain switch or switching equipment won't affect any switching Performance. You may face this problem and in the devices which are multi homed to multiple ...
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  • 3,404
3 votes
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Performance differences of logging session-init and session-close invididually compared to through apply-groups

If we are assuming you want to log every session on your device then the apply-groups statement itself will as you thought only impact the performance of commit's. This is because the system will ...
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3 votes

Firewall Benchmark- Concurrent connection metrics

For metrics you can look in to the reports that NSS labs are publishing, they have pretty solid documentation on how they do firewall testing. You can also google for their reports, sometimes firewall ...
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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 ...
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  • 69.5k
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 ...
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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 ...
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  • 62k
2 votes

General best practice for VLANs and domains

You may consider the following general guidelines when implementing VLANs: Grouping devices by traffic patterns – Devices that communicate extensively between each other are good candidates to be ...
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  • 175
2 votes

Simple way to monitor network performance w/o access to network infrastructure?

Iperf is a great tool for measuring actual TCP or UDP throughput. It is a client server tool so you need access to a machine at both ends of the link to be tested. There is a nice graphical java (...
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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 ...
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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 ...
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  • 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 ...
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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 ...
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