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1500 questions
53
votes
2 answers
Why do I see a RST, ACK packet instead of a RST packet?
Looking in Wireshark, I often see TCP Streams end with a RST, ACK packet instead of a RST packet. Anyone know why this is?
An example of what I see:
SYN
SYN, ACK
...data...
RST, ACK
Wireshark is not picking up a RST packet prior to the RST, ACK…
packetwrassler
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51
votes
14 answers
Does having a longer Ethernet cable slow your connection?
As the title suggests, Does a longer Ethernet cable slow your connection down?
SidS
- 613
- 1
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- 8
49
votes
6 answers
Difference between control plane, data plane and management plane?
I think I understand these concepts, but I'm a little rusty. Can someone give a concise, easy-to-understand explanation of these concepts? The planes are logical concepts, aren't they? Is this a Cisco only thing?
stets
- 1,000
- 3
- 8
- 17
48
votes
24 answers
How can I see which switchports are not in use?
On a large Cisco Catalyst switch stack, almost all switchports are patched. I need to identify the ports, which are not in use, for connecting further devices.
Following switchports, cabling, patch fields and sockets to possible end devices is…
Stefan
- 3,374
- 6
- 32
- 49
47
votes
5 answers
Is Ethernet port blinking really useful?
This question may not look as an important one and in fact it is just out of curiosity.
But to the point:
Is Ethernet port blinking really useful?
Ethernet ports usually have two light indicators of activity (blinking leds). Yes, I know that they…
Stanowczo
- 581
- 1
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- 8
46
votes
8 answers
Network Neutrality, how does it actually work, technically speaking?
In this NPR article there is mentioned 'network neutrality' with very little details on what it actually is or how it actually works. I tried researching it on my own but I get a lot of non-technical explanations of what it is fighting against…
Matthew Peters
- 559
- 4
- 9
46
votes
5 answers
Why do we need IPv6?
This will be a kind of newbie question but I am not quite sure why we really need IPv6. AFAIK, the story is as follows:
In the olden days, when computers were not plentiful, 32 bit IP addresses were enough for everybody. At these times, the subnet…
Utku
- 734
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- 11
45
votes
3 answers
What is the difference between MSS and MTU?
I'm confused as to the difference between maximum segment size and a maximum transmission unit.
Can someone please explain in relation to layers 2 and 3?
If I had a packet of 800 bytes in the payload. Would it be correct to say that the MSS would be…
NetworkNinja
- 631
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- 9
44
votes
7 answers
Does UDP do anything at all?
It's my understanding that TCP has logic for ensuring reliable communication, but UDP just naively sends information along the channel set up for it using IP and things in lower layers.
Does UDP actually do anything?
I'm kind of confused by why it…
JacKeown
- 559
- 1
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- 7
44
votes
1 answer
Why is such a large IPv4 range assigned to localhost?
Why is so large a range of IPv4 addresses assigned to localhost, (127.0.0.0 through 127.255.255.255)?
user2677679
- 727
- 2
- 7
- 10
44
votes
4 answers
Why is fe80::/10 reserved for link local addresses when fe80::/64 is actually used?
I understand that IPv6 reserves the fe80::/10 prefix for link local addresses, and that hosts select an address with a /64 prefix.
Why is the reserved space so much larger than what is actually used for link local?
Craig Constantine
- 4,972
- 5
- 36
- 53
43
votes
3 answers
Why 192.168.*.* for local addresses?
The standard I've seen so far is to use 192.168.*.* IP addresses for devices on the local network.
Why this combination? If it were me, I would have chosen something simpler, like 1.0.*.*. What's the historical reason?
Undo
- 542
- 1
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43
votes
15 answers
How can I diagnose a bridging (ethernet) loop?
Given that spanning tree has failed (or you don't have any spanning tree) and get an ethernet loop, what's the best way to diagnose where the problem is?
Which switch?, which cable? and so on.
nos
- 763
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- 14
42
votes
13 answers
Difference between Subnet and VLAN?
You often hear the terms Subnet and VLAN used interchangeably. With the ubiquitous nature of IP these days, when are the two not considered roughly the same from a high-level, understanding that VLANs are L2 and Subnets are L3. In other words,…
generalnetworkerror
- 7,094
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- 65
41
votes
3 answers
How does gratuitous ARP work?
Does gratuitous ARP work like a normal ARP request?
Why is gratuitous ARP used for HSRP?
Trojan
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