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174 votes
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Why are IPv4 addresses running out?

The IPv4 Address Shortage According to Vint Cerf (the father of IP), the IPv4 32-bit address size of was chosen arbitrarily. IP was a government/academic collaborative experiment, and the current ...
Ron Maupin's user avatar
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87 votes
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Is "IPv10" a joke or a serious RFC draft?

As Ron said, anyone can write a proposal. I have a hard time taking proposals seriously from someone who suggests interconnecting satellites with optical fiber, though. Also, I can't imagine this ...
Teun Vink's user avatar
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58 votes
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Why does the IPv6 header not include a checksum?

One of the ideas around IPv6 was to speed up packet forwarding. To that end, several decisions were made. For example, the IPv6 header was greatly simplified and is a fixed length, unlike the variable ...
Ron Maupin's user avatar
  • 99.8k
39 votes

Why are IPv4 addresses running out?

Ron Maupin's answer gives a brilliant overview of the IPv4 shortage, but I'd like to address this part of your question: Why can't a city (for example) have just one IP address and all homes in ...
IMSoP's user avatar
  • 490
31 votes
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Will IPv6 make private IP addresses become obsolete?

No, private addressing will not become obsolete. But actually, there are two kinds of private addresses: the Unique Local Addresses (ULAs) and the link-local addresses (LLAs). There will always be a ...
KillianDS's user avatar
  • 1,029
28 votes

Is "IPv10" a joke or a serious RFC draft?

You must remember that anyone can submit proposals to the IETF, and they are taken seriously, until they are either adopted or die due to lack of interest. This particular proposal has expired and ...
Ron Maupin's user avatar
  • 99.8k
27 votes

Why does the IPv6 header not include a checksum?

Because it's redundant. All the common link-layer protocols, like Ethernet or WiFi, have their own error checking and error correction mechanisms, so physical transmission errors are already unlikely....
Philipp's user avatar
  • 370
25 votes
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Why do we need ports with IPv6?

An IP address targets a host on the network layer. Transport layer ports multiplex an L4 protocol within a host (to different processes/services). Both are different things on different layers. ...
Zac67's user avatar
  • 84.8k
22 votes

Difference between :: and ::1

:: is the unspecified address (0:0:0:0:0:0:0:0), and it is only used in packets as the source address of a host that does not yet have an address and is trying to get an address assigned. What you see ...
Ron Maupin's user avatar
  • 99.8k
20 votes

Where can I use the IPv6 documentation prefix

The IPv6 documentation prefix (2001:db8:::/32) must be used ONLY for documentation purposes. It means written examples, diagrams, PPT presentations, Textbook explanations, etc. This range shouldn't ...
jcbermu's user avatar
  • 4,497
20 votes

How does the shortage of IPv4 public IPs influence existing firewalls?

You're late to the game: IPv4 addresses are already exhausted, and have been for a number of years. All the major manufacturers have included IPv6 capability (in varying degrees) in their product ...
Ron Trunk's user avatar
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19 votes
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What happened to IPv5?

The first four bits in the IP header are used to store the Protocol version (4 or 6). The version 5 was assigned to another protocol, the Internet Steam Protocol and so was not available for the ...
JFL's user avatar
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19 votes
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What are common sizes to split a /29 - /32 IPv6 subnet?

Some simple guidelines that work most of the time: Dividing your /29 The standard size of your allocation from RIPE NCC is a /32 A /32 is a well-accepted prefix size in the global routing table You ...
Sander Steffann's user avatar
19 votes
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What happens when a subnet reaches capacity?

A subnet (network) is really just a collection of contiguous addresses within a binary mask. It is simply a logical way to divide address block. If you run out of addresses in a network (subnet), then ...
Ron Maupin's user avatar
  • 99.8k
19 votes

Is "IPv10" a joke or a serious RFC draft?

Is “IPv10” a joke or a serious RFC draft? Both. That draft doesn't solve a single problem but opens a can of new ones. I guess that bloke is serious and he doesn't get what ridiculous schemes he's ...
Zac67's user avatar
  • 84.8k
17 votes
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Why the first octet of a MAC address always end with a binary 0?

You may notice that two least-significant bits of the most-significant byte of a 48-bit MAC address are usually set to 0 (as in all your examples). There are two flags in the most-significant byte of ...
Ron Maupin's user avatar
  • 99.8k
16 votes

Why are IPv4 addresses running out?

Right now, every home has its own IP address. Why can't a city (for example) have just one IP address and all homes in this city would just be on a private network of that city? Exactly this is ...
Martin Rosenau's user avatar
15 votes

Usage of Flow label in IPv6 header?

The above answer isn't really correct. The flow label isn't designed for packet ordering - IP does not care about order, it is an unreliable services whose only goal is delivery on layer3. Better way ...
J M-A's user avatar
  • 151
15 votes
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IPv6 prefix interpretation

From RFC4291 section 2.3: An IPv6 address prefix is represented by the notation: ipv6-address/prefix-length The whole thing is called prefix. First part up to / is called address. Second part ...
manish ma's user avatar
  • 1,624
14 votes
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Using IP subnet at multiple datacenters

Connect the two DCs with a private connection. Then advertise the /24 at both Data Centers. When traffic arrives at one DC for the other, your internal devices route or switch the traffic as ...
Criggie's user avatar
  • 737
14 votes

Could IPv6 make NAT / port numbers redundant?

IPv6 does not have a NAT standard as IPv4 does (NAT breaks the end-to-end premise of IP, and IPv6 was designed to restore that). There is an experimental RFC for IPv6 NAT, but it is a one-to-one NAT ...
Ron Maupin's user avatar
  • 99.8k
13 votes
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IPv6 and online privacy and security

Let's look at a live example. This being from my Linux workstation. (And for simplicity I actually omitted a couple of addresses.) I'll explain each of the addresses in turn: $ ip a s dev br0 3: br0: &...
Michael Hampton's user avatar
13 votes
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Why do IPv6 unique local addresses have to have a /48 prefix?

The requirement exists to prevent collisions. This is a bit more important than most people recognize. Even if you have systems which currently don't communicate with other systems over the internet ...
kasperd's user avatar
  • 764
12 votes

What is Link-local addressing?

Link-local addresses are used for communication between two hosts (which are on the same link) when no other IP address is specified. In simple words, at the time of booting up, the OS tries to ...
Gaurav Kansal's user avatar
12 votes
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Possible (bit) patterns of a netmask

RFC950 states that Since the bits that identify the subnet are specified by a bitmask, they need not be adjacent in the address. However, we recommend that the subnet bits be contiguous and located ...
Filip Haglund's user avatar
12 votes
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Does IP provide QoS or not?

IPv4 has the DSCP (formerly ToS) field, and IPv6 has the Traffic Class field. Those are just fields in the IP headers. IP itself does not have any QoS. QoS is implemented by network devices, often ...
Ron Maupin's user avatar
  • 99.8k
12 votes
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How does router advertisement in IPv6 avoid IP conflict?

A host performs Duplicate Address Detection (DAD) before actually activating the given address on the interface RFC 2462 has to say about this: 5.4. Duplicate Address Detection Duplicate Address ...
Marc 'netztier' Luethi's user avatar
12 votes
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What is the use-case of including the IPv4 address in IPv6 address?

There are some common use cases: ::ffff:192.168.0.1 This is used in software that uses IPv6 sockets even for handling IPv4 connections. That makes it easier to write software because everything ...
Sander Steffann's user avatar
12 votes

Difference between :: and ::1

"::" is the ipv6 "unspecified address" (the equivilent IPv4 address is "0.0.0.0"). When binding a socket* it is used to indicate that the socket will listen on all local ...
Peter Green's user avatar
  • 13.3k
11 votes
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Why are IPv6 addresses so long?

By convention, each device on the LAN under IPv6 gets a /64 subnet, right? No. Each network is almost always a /64 network. Each host still gets one or more addresses on the network, but I don't ...
Ron Maupin's user avatar
  • 99.8k

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