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86 votes
Accepted

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 ...
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  • 15.6k
27 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 ...
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  • 93k
27 votes

What is the practical use of a /31 CIDR or 255.255.255.254?

A /31 network actually has two usable hosts for a point-to-point link. See the Standards Track RFC 3021, Using 31-Bit Prefixes on IPv4 Point-to-Point Links (published in December 2000): Abstract With ...
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  • 93k
24 votes
Accepted

acknowledgment by TCP does not guarantee that the data has been delivered

This part of the RFC is about passing responsibility over to the operating system or whatever is the next stage of the process. It's fundamentally concerned with the separation of layers. An ...
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  • 15.9k
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 ...
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  • 4,417
19 votes
Accepted

Why are there 3 ranges of private IPv4 addresses?

Back when the RFC for private addressing was proposed, classful addressing was still common. The reasons for the three address ranges are found in RFC 1918, Address Allocation for Private Internets: ...
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  • 93k
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 ...
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  • 69.7k
18 votes
Accepted

IPv4 Segment 100.64.0.0/10

The 100.64.0.0/10 address block is not private address space; it is shared address space. This is spelled out in RFC 6598, IANA-Reserved IPv4 Prefix for Shared Address Space (I highlighted the ...
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  • 93k
15 votes
Accepted

How broadcasting works on different networks?

How Routers Handle Limited and Directed Broadcasts The first thing to understand to answer your questions is that limited broadcast frames are not routed. By default when a router receives a frame ...
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  • 363
12 votes
Accepted

How is BGP "AS_SET" used?

My question then is, what would the purpose be of sending an unordered list? In what cases would you be better off sending an unordered list as opposed to an ordered list? as-set is commonly used ...
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11 votes

How OSPF decides a network to be a stub network?

A Tale of Three Stubs... When using Cisco equipment, OSPF calls several things a "stub"... it gets a bit confusing.... Stub Host Stub Network Stub Area The meanings are very different for ...
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11 votes
Accepted

Where can I use the IPv6 documentation prefix

If your test environment is separated from your local network you hypothetically could use any IPv6 addresses which are not reserved for special uses. However, if you are looking for an equivalent of ...
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11 votes
Accepted

Where are 0 TCP/UDP ports banned?

IANA has reserved both TCP and UDP port 0. See the IANA Service Name and Transport Protocol Port Number Registry. IANA is the Internet Assigned Numbers Authority, so all internet numbers, including ...
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  • 93k
10 votes

Why is the IP layer aware of higher layers in the network stack?

Every "header" has some sort of "Next Protocol" identification field. This is necessary because on the wire, the data is nothing but a string of 1's and 0's. The receiving endpoint must have a way ...
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  • 13.9k
10 votes
Accepted

What is the proper name for hexadecimal like standard notation of an IPv6 address?

RFC 5952 gives you the canonical IPv6 format. That is explained in the RFC itself: This document defines a canonical textual representation format. and 4. A Recommendation for IPv6 Text ...
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  • 93k
10 votes
Accepted

Should a router use SLAAC for IPv6 address assignment?

In RFC 7084, it also states: W-1: When the router is attached to the WAN interface link, it MUST act as an IPv6 host for the purposes of stateless [RFC4862] or stateful [RFC3315] interface address ...
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10 votes

acknowledgment by TCP does not guarantee that the data has been delivered

From the RFC perspective, the "end user" is the application. There's no guarantee that the application got the data, just that the TCP process received it. From your NOC perspective, the network is ...
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  • 62.1k
9 votes
Accepted

IP Traceroute RFC 1393

The new ICMP message type as defined in this RFC actually was added to the ICMP standard - though it's currently listed as Historic in RFC 6918: 2.6. Traceroute (Type 30) This message type is ...
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  • 178
9 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 ...
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  • 91
9 votes

Where are 0 TCP/UDP ports banned?

TL;DR: RFC870 Port zero has been included in the "Network Wide Standard Functions" range since RFC433 in 1972, but has never been assigned. https://www.rfc-editor.org/rfc/rfc433.html Here ...
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  • 191
8 votes
Accepted

How is the OSPF Opaque LSA Option used?

Opaque LSA's are used to extend the capabilities of OSPF, and to allow for transmission of arbitrary data that OSPF does not necessarily need to care about. For example, if you were writing an ...
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  • 8,847
8 votes
Accepted

VXLAN: how receiver knows that the received packet is VXLAN-encapsulated?

The destination UDP port in the outer UDP header is specified in the VXLAN specification (Port 4789). This means it is a well-known service. So an UDP packet that arrives on Port 4789 is expected to ...
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8 votes
Accepted

ipv6 Aggregatable global unicast addresses

TLA/NLA structure for IPv6 addresses The TLA/NLA allocation structure has been deprecated in RFC 3587, August 2003: 2. TLA/NLA Made Historic The TLA/NLA scheme has been replaced by a ...
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  • 234
8 votes

IPv4 Segment 100.64.0.0/10

Officially RFC 6598 says Devices MUST be capable of performing address translation when identical Shared Address Space ranges are used on two different interfaces. Most NAT ...
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  • 11.6k
8 votes

Where can I use the IPv6 documentation prefix

Just from the RFC I can't see anything defining that documentation is strictly written text. Do you have any source for this interpretation? According to the IANA IPv6 Special-Purpose Address ...
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  • 93k
8 votes
Accepted

What MAC address do I use to generate a IPv6 Pseudo-Random Global ID

Remember, the purpose of the algorithm is to avoid everyone picking FD00::/48 so they can abbreviate everything with the double colon. (Or other "easy" ones like FDAA:AAAA::/48, etc). The ...
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  • 13.9k
8 votes
Accepted

Class A most significant bits '0' as in RFC1166 or older or '00' as suggested in RFC4632?

It appears to be a typo in that RFC. Notice that the header of the RFC says Errata Exist. It is not uncommon for things like that to happen. That particular error is corrected in the errata. See the ...
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  • 93k
8 votes
Accepted

Why isn't 10.0.0.0/8 used instead of 192.168.0.0/16 for private addresses?

It is merely a necessity constraint and personal preference. If a Network is being built that would only have 10, or 20, or 50, or even 100 hosts, there is no reason not to use a /24 from 192.168.0....
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  • 13.9k
7 votes
Accepted

MLD messages during IPv6 duplicate address detection

Key to answering your question is making a very important distinction: Duplicate Address Detection (DAD) and Multicast Listener Discovery (MLD) are completely separate protocols. Now, that said, I ...
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  • 13.9k
7 votes

Why is the design "intelligence on the edge" better for a computer network?

The Core layer is responsible for fast transportation across a network. The more intelligent routing you try and perform there the more you slow down the rate of packet flow. You don't want to have a ...
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  • 1,669

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