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1500 questions
25
votes
7 answers

Does CIDR really "do away" with IP address classes?

I am still struggling to understand to what extent CIDR really renders IP address classes obsolete. Here's what I understood so far: It's ridiculously inefficient (and impossible, too) to assign every organization that needs to address more than…
user15544
25
votes
5 answers

Accidentally Removed Allowed VLANs from Cisco Switch Dot1Q Trunk

I am adding a new VLAN to an existing trunk port between two Cisco Catalyst switches (3750's). In the process of adding the new VLAN, it appears that I've removed the existing allowed VLANs on the trunk... How is this possible? Existing trunk port…
Brett Lykins
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25
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8 answers

What is the purpose of network address?

What is the purpose of network address? (aka subnet address, starting address of each subnet) For example in this network: 192.168.1.0/24 Why we should leave 192.168.1.0 address free?
Microsoft Linux TM
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24
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5 answers

Usage of 192.168.xxx, 172.xxx and 10.xxx in private networks

I know that the organization that distributes IP addresses decided to assign 192.168.xxx, 172.xxx and 10.xxx to private networks. However, I thought that private networks have their own address space so shouldn't a private network be able to assign…
coderhk
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24
votes
3 answers

Why is broadcast used at the DHCPREQUEST step?

This is the process of DHCP operation, My question is at the 3rd step why does the Client send a Broadcast and not a Unicast as after the previous two operations the address of the DHCP server / Relay server should be known?
arif
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24
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7 answers

Why use iBGP inside an Autonomous System, if IGP protocols fulfill the need for internal communication

Can anyone explain why we need iBGP for the routes when we have the IGP protocols (OSPF, RIP) for internal communication within the AS? I have read a lot of articles and books, but I could not find the answer.
user2720323
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24
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2 answers

Emulate Ethernet frame loss for testing purposes

Maybe I am missing something rather basic, but I don't know so I figured I would ask. In terms of testing, how sensitive various TDMoE are to BER and packet delay, I am looking into how to simulate delay and random packet dropping at the ethernet…
Chris Travers
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24
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8 answers

How can I force VTP clients to update their VLAN database from the VTP server, on Cisco devices?

I was doing some cisco exercises on configuring a vtp server and client, something I can't figure out is : I setup a vtp server, added my VLAN's I then took another switch that was attached to this vtp server and set it to client Now my VTP client…
Lucas Kauffman
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24
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4 answers

Can I use a Catalyst 2960-S for iSCSI?

I need to set up a modest iSCSI SAN with a few ESX hosts and one storage array. Can I get by using a Catalyst 2960-S or do I need to upgrade? Are there any special tweaks I need to make to the switch in order to handle iSCSI? The switch will be…
Jeremy Stretch
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24
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4 answers

What is the difference between netFlow and sFlow?

How is sFlow different from netFlow, and how is each supported by different vendors ?
Benjamin A.
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23
votes
7 answers

Difference between access list and prefix list?

Can someone explain with an example whats the difference between an access list and prefix list.
NAVEEN GEORGE
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23
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4 answers

NACK vs. ACK? When to use one over the other one?

Personally I don't even feel that there is a need for ACK. It's faster if we just send NACK(n) for the lost packets instead of sending an ACK for each received packet. So when/which situations would one use ACK over NACK and viceversa?
nFu9DT
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23
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3 answers

What is "industrial ethernet"?

When a teacher introduced it to us he gave the impression that it specifically covers some Siemens technology; that it's even a Siemens trademark. I believe the term covers something more general, but I haven't been able to find a useful definition…
Mads Skjern
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23
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6 answers

What stops someone from configuring their network with IP addresses they do not own?

Here's the scenario. I was picturing a university that bought a range of IP addresses. I think their network would still be connected to an ISP (right?), but they'd have freedom to configure stuff the way they wanted. What stops them from assigning…
Tiago Oliveira
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23
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4 answers

What's the difference between `Latency` and `Round Trip Time`?

Golang community provide a HTTP/2 demo website to compare the performance between HTTP 1.1 and HTTP/2. We can choose different latency, e.g. 0s latency, 30 ms latency, 200ms latency. Is latency a terminology of computer science? What does that…
Ryan Lyu
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