Questions tagged [hardware]

For questions about network hardware. For instance, switches, routers, firewalls, bridges, IP phones, Wireless lan controllers, Access points etc.

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35 views

Port mirroring question

I've got some questions about my port mirroring configuration. I'm working with alcatel omniswitch. After configuring port mirroring my destination port is loosing network connection and it can't ...
2
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1answer
31 views

What is a “gearbox”?

What is a "gearbox" in the context of networking chips? The term often comes up in conjunction with SERDES (serializer / de-serializer).
1
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1answer
75 views

Can't install OS on S6000-ON

I have a Dell Networking S6000-ON. I'm trying to install an OS with ONIE but am running into an issue with the EEROM TLV info. Using some of the onie-syseeprom commands came back with this: ONIE-...
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1answer
73 views

Is there a MTBF related to port linking?

During a firmware upgrade, I've noticed one problem: An equipment keeps linking/unlinking on a specific port of a PowerConnect 3548(stp portfast, switchport access mode). I've contacted the local ...
5
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1answer
2k views

Does it make sense to generally “Disable TCP Checksum Offload”?

In a work sheet for PCs that we deliver to customers, I found instructions to always "Disable TCP Checksum Offload" on the NICs. Via those NICs, the PCs are connected to the customer's LAN, and it is ...
3
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1answer
62 views

Is temperature sensor on zero enough to prove PoE Control Module is failed?

I'm probing an issue where 4 PoE cameras can't get powered on. Switch model Dell N2048P Series. The "P" at the end of the model stands for "PoE Enabled" so, this feature is/should be available. The ...
1
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1answer
56 views

Cisco router boot error

When I start my Cisco router it shows me the attached error. What is the problem with the NVRAM of the router and how do I fix it? Thanks.
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1answer
157 views

SG500 powers on, but won't boot, won't reset

I have a Cisco SG500-52 switch. On boot the Fan light comes on green, and the System light starts blinking green. No other lights show (no port lights at all). I tried rebooting or resetting the ...
2
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1answer
559 views

Load-balancing one VPN-connection over multiple WANs

My internet connection will be provided by 4 different WANs (each 250 Mbit down, 100 Mbit up), which should be load-balanced to one 1 Gbit connection (full duplex, most likely ethernet (should be ...
0
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1answer
44 views

What are the major factors influencing the variance in time packets need to be transferred? [closed]

It's pretty easy to see that packets transferred via internet take not a constant amount of time, even if the two communication partners don't change the location and the route in between likely doesn'...
4
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3answers
732 views

Is there any reason to use a hub over a switch?

Given that hubs are essentially the same as switches, as far as I know, except they share bandwidth between all connected devices, while switches do not, resulting in faster connections. I am simply ...
3
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2answers
883 views

What advances in hardware allowed DPDK to increase performance on packet processing?

I've heard that DPDK library will allow us to use more Software-switches/routers (and maybe even to replace them completely), because somehow it helps dramatically increase performance on processing ...
2
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2answers
82 views

How to debug an unstable connection in a P2P configuration

I have a setup where I have two computers connected to each other (C1 and C2). Both have a static IP and they know each others IP. C2 sends UDP packets to C1 and C1 receives and logs them. Seems ...
4
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1answer
67 views

Cisco 6500 chassis modules color edge

The modules for the Cisco 6500-series switches have a color band on the right edge. The most common I've seen are magenta (or an occasional purple) on Ethernet modules and aqua on supervisors. Are ...
3
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0answers
182 views

HP 5500 JD374A Port naming convention

Hi to all :) To most of you it'll prolly sound like a very silly question to ask, however to me as a fresh network trainee the answer is unfortunately not so obvious. So, the question is whether the ...
0
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1answer
46 views

Is the auto-correlation of a frame transient based on the physical characteristics of a device?

I am currently studying ways to fingerprint Wi-Fi devices based on their physical characteristics and I was struck by a question after reading Section B of this paper http://www.ccs-labs.org/bib/...
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2answers
208 views

Hardware Implementation of Ports

What is the hardware implementation of a port and/or network socket? I understand that, at the lowest level, x86 uses opcodes such as IN and OUT when the data resulting from the instruction execution ...
5
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1answer
2k views

Why does 10Gbps ethernet claim PAM16 encoding then use a squared DSQ128 constellation?

I've been looking into the way that 10 Gbps Ethernet encodes its data and I'm a little confused by the nomenclature. I have gathered, e.g. from here http://www.ikn.no/download/Whitepaper-10G-...
1
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1answer
924 views

Cisco 3850 Model Naming Convention?

I am having some trouble identifying a switch model via the CLI, and also understanding the differences between a few different models. The models in question are : 3850-48P-S 3850-48P-L 3850-48P-E ...
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5answers
111 views

Is it possible to create a collaborative network?

My problem, I have a hotel in a remote area, with many guests and a lot of Internet use. Is there a way to use Internet from different sources and combine it to increase the total network speed? ...
4
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2answers
2k views

Software Switches vs Hardware Switches [closed]

My main question is why service providers don't move to all software switches? I know the answer must be the rates, capacity and port density of the hardware switches. So what are the difference ...
7
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2answers
477 views

What certifications are there for Fiber Optic termination and splicing?

As a knowledgeable person in computer networks I have always had an itch for learning how to create custom-length fiber optic cables. So, as a personal goal, I want to get trained and certified in ...
2
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1answer
1k views

How to determine if a port is physically(hardware) bad

We are using a 48 port 3com baseline switch and recently ports have started dropping, completely shutting off(no connection light) and have switched to another open port and moved on our merry way. ...
2
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2answers
49 views

Is it possible to design a network switch that could work only with combinational or sequential logic circuits without a software?

And if it is possible are there any companies that are building these type of switches ? Are they/would they be much more expensive than a regular switch which has a more 'standard' processor and is ...
1
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1answer
477 views

How “show inventory” displays SX SFP?

I've a Cisco 3925 and it's not quite clear why an "1000BASE-SX SFP" entry is visible in the inventory. Is it only visible when the SX SFP is in use? (I've no chance to modify it.) NAME: "CISCO3925-...
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1answer
40 views

Hard drive array usage [closed]

I recently bought this EMC server rack, it's got a bunch of hard drive arrays which came with it. How do I use these? Seems a shame to throw them away. Are these just a sort of NAS that I could ...
2
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1answer
2k views

How to hard reset an Allied Telesis x510?

I have a newly opened from the box Allied Telesis Port. After some configuration, I was locked out due to timed out. I have already setup the Login with correct login and managed to login before. ...
8
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2answers
18k views

What is the purpose of an Ethernet magnetic transformer, and how are they used?

I have been told that Ethernet magnetic transformers are used for base-t Ethernet when transmission is sent over a lengthy cable. What is the purpose of the transformer? (is it for signal filtering or ...
5
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1answer
178 views

What happens at the hardware level of a router when a packet is received and eventually triggers a process like ARP?

Please let me know where the gaps in my understanding are. There are many gaps, so please do not hesitate to fill them in or correct them. To my knowledge, what happens on the hardware level when ...
5
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1answer
12k views

How do hardware timestamps (hardstamps) work

I am currently diving into topics like PTP (IEEE 1588) and precise timestamping for capturing network traffic. Many resources on the Internet name hardstamps as a feature of network cards, allowing ...
6
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2answers
4k views

How to check if a NIC supports hardware timestamps [closed]

I want to capture packets using tcpdump and get as precise timestamps as possible. The latest version of tcpdump has the -j adapter command-line option, which can be used for this. I tested the ...
0
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1answer
120 views

what's the meaning of this formula “cutoff frequency / (b/8)”

I am not sure whether my question is suit for this place. I am a newbie in computer networks. And I choose Andrew S. Tanenbaum's Computer Networks for my textbook. In the second chapter: Given a ...
2
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2answers
17k views

How do i factory reset a Allied Telesyn AT-9924t?

I have connected to the switch from my Win7 computer with the following equipment. (the blue cable isnt the exact one, but nearly the same) When i restart the switch while connected with Putty or ...
0
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3answers
2k views

Cisco 3925 not booting/outputing to console

This started after trying to enter password recovery mode and rebooting. It rebooted the one time and started to load the ios but had some sort of TraceBack/Exception on the screen. I reset the power ...
1
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3answers
6k views

Checklist for replacing failed ASA hardware

I have a failing Cisco ASA that is being replaced under a support contract. It is a single-point-of-failure in production at a branch office that can tolerate downtime. I will physically replace the ...
5
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4answers
6k views

DLink switch loses configuration on power off!

We just bought a DGS-1210-28P smart switch, it is my first experience with a business class switch, however I found a pretty weird behavior. The switch loses all of its configurations, even management ...
0
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3answers
122 views

How is a single physical packet of data kept together?

E.g. is there some scheduling going on at the hardware level that sends whole packets one after another in bit-streams to prevent individual ones being broken up, or if they are split up while being ...
5
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3answers
8k views

How is it possible to run VoIP on CAT3. Do you not need CAT5 for the voice data?

So I never knew this till today but I thought you needed CAT5 for VoIP but this business is running VoIP on CAT3. Don't you need the extra wires for the voice, data and power?
6
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3answers
2k views

Cumulus Linux and Whitebox switch hardware?

I'm on a consulting engagement with a new client whose network infrastructure is comprised of slightly non-standard equipment. During discovery, I inquired about the switching equipment and network ...
2
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1answer
616 views

Why does a sever's host automatically broadcast an ARP request after a server attempts to reply to a BOOTP request?

I realise BOOTP is a legacy system, but this is for my reading for my studies. Consider a client, C, that is bootstrapping itself. It sends a BOOTP request to the server—obviously because it does not ...
6
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4answers
10k views

Toggle Switch for an Ethernet Cable

Is it possible to place a switch in one of the four/five wires of an Ethernet cable that will disable it? For my hardware project I would like the user to be able to disable the internet connection ...
2
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1answer
509 views

HW State: DEAD - Cisco 3925

I received an alert stating that a crypto engine was 'dead'. I did a bit of digging and was able to find some output to validate this: #sh crypto eng config crypto engine name: Virtual Private ...
3
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2answers
391 views

Frost prevention for indoor router and cable modem

I'm working on a community wifi project for an impoverished settlement. We have a router and a cable modem installed in a container house, sometimes without heating for days. Both are designed for ...
6
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3answers
3k views

Is there a way to identify a Tri-Rate Copper SFP in a Juniper MX device

Juniper has two kinds of Copper SFPs. One (SFP-1GE-T) only does Gigabit. The other one (SFP-1GE-FE-E-T) can also run at 100M and 10M respectively. The problem is, in the chassis inventory both are ...
1
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0answers
109 views

How do Wi-Fi access points discard frames on adjacent channels?

Naturally, Wi-Fi devices (access points, client adapters) receive frames that were sent on an adjacent channel as these overlap, i.e., they 'see' frames that were sent on a channel that the device ...
4
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1answer
626 views

Can I Use Different Versions of CME and CUE

I am running CME 8.6 on a Cisco 2811. I would like to install NM-CUE and run CUE 7 with this. It this possible, even with a version mismatch?
5
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2answers
1k views

Building a 3 port network tap (100mbps half-duplex)

I've tried building a network tap with only three ports: the two communicating parties and a tap side. I knew this would force the communicating sides to use at most half-duplex 100mbps, but detection ...
2
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1answer
429 views

Improving Network Flow Documentation in 3G->4G upgrade project

I just started on an upgrade project, 3G-> 4G, with network flow documentation in PNG, BMP and Visio files (500+ flows). The HLD and LLD documents have been written however it appears from reading ...
2
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2answers
345 views

Line Sync when there is supposed to be no ADSL codes on the line? [closed]

I have a client who had ADSL (1500/256), and in an attempt to get her a faster connection, she tried to churn to a different provider. Long story short, the other provider will not supply adsl ...
17
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4answers
7k views

MAC address recycling?

Something I've always wondered about is MAC address exhaustion. Do hardware vendors keep track of MAC address allocation to their platforms, and then subsequently "reclaim" MAC addresses when a ...