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1500 questions
17
votes
4 answers
Confusing A, B, C network classes
I'm studying IPv4 addresses and came across this whole thing about classful addressing. I get the idea behind it, bit there is something I find confusing:
There are two "ABC" ranges:
First one:
A: 1.0.0.0 to 126.0.0.0 with /8
B: 128.0.0.0 to…
Axel Kennedal
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17
votes
2 answers
What is the difference between Ethernet II and 802.3 Ethernet?
Can anyone explain to me what is the difference between Ethernet, Ethernet-II and 802.3 Ethernet.
I referred to a lot of books, they are in high level language. Can anyone explain to me in a simple manner?
user2720323
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17
votes
5 answers
How to choose a BGP router ID when using IPv6 only?
Usually, when using BGP, you can choose (or your device chooses four you) a router ID from one of your assigned public IP addresses.
Now, let's admit you only run IPv6. As the router ID is still a 32 bits number, it can not be copied from a…
Benjamin A.
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17
votes
3 answers
On which layer of the OSI Model does the arp protocol belong?
Can anyone explain which layer of the OSI model ARP belongs to and which socket it uses?
I referred to lots of books before asking this question.
In some books, Authors are saying that it belongs to the datalink layer, in some they say it belongs to…
user2720323
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17
votes
2 answers
Why don't we use MAC address instead of IP for having "Internet" or doing communication?
We know MAC address is unique in each devices.So why can't we just send/receive data using MAC address only?
Tanvir Rahman
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17
votes
3 answers
How to verify that a UDP port is open?
I have here a dilemma. I have a device that communicates to another remote device but there is a firewall between them. It's a UDP connection, so TCP utilities don't work to test if the specific port is open. I know that we could get that from the…
JoeliNNaBit
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17
votes
2 answers
Cisco - display ALL routes using a single command
In Junos when you use a show route it displays the routing tables , starting with inet.0 ( global routing table) and then listing each VRF in alphabetic order.
I am after a similar command , for the following reason , new WAN deployment: remote…
DrBru
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17
votes
6 answers
Reason for half-duplex mode in Ethernet?
Half-duplex connections were popular at the time of 10Mbps and 100Mbps Ethernet, and, according to standards, it is allowed also in case of 1Gbps Ethernet.
Am I correct that half-duplex mode support in Ethernet chipsets was crucial in case either a…
Martin
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17
votes
3 answers
Is it possible to remotely influence BGP localpref?
A colleague is attempting to implement active/passive internet multihoming. The design entails sending communities (listed below) to the passive provider to lower the local preference at remote ASes for the advertised routes. The documentation…
Dennis Olvany
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17
votes
5 answers
Why is the U/L bit inversed in EUI64?
This inversion is bijective, so I can't figure out what is it's use.
Silviu
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17
votes
6 answers
What's the difference between an Ethernet cable and a UTP cable?
Is there such a thing as an Ethernet cable or technically no? Are they actually called UTP cables?
From wikipedia
UTP cables are found in many Ethernet networks and telephone systems.
Celeritas
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16
votes
5 answers
Why do we need ports with IPv6?
My understanding is there are 2^32 - 1 possible IPv4 addresses, and 2^16 - 1 possible ports. Which gives ~2^48 addresses.
The additional 2^16 additional ports seem almost insignificant considering the IPv6 address space is 2^80 times larger than the…
Josh
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16
votes
7 answers
What are the differences between VRRP and HSRP?
Are there any significant differences between VRRP and HSRP?
Bulki
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16
votes
12 answers
What would cause high latency anytime there is traffic on WAN?
I have a network that has been experiencing slow internet speeds. After a great deal of troubleshooting, I have determined that any streaming content/downloads will cause the latency of WAN traffic to explode.
For example, under no load, I ping…
Blackjack00
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16
votes
3 answers
How come SFP modules are so incompatible?
In theory I like the SFP concept very much. However what strikes me is the manufacturer restrictions for every switch/card. How come different SFP modules work with different vendors only? Is there a design flaw in the SFP specification? What makes…
Thomas
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