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152

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 public Internet was never envisioned. The IP paradigm was that each connected device would have a unique IP address (all packets sent between IP devices would be ...


83

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 actual proposal gaining any momentum, especially due to this note: All Internet connected hosts must be IPv10 hosts to be able to communicate regardless the ...


80

Two things are getting confused here: classful addressing vs CIDR Masquerading / NAT Going from classful addressing to Classless Inter Domain Routing (CIDR) was an improvement that made the address distribution to ISPs and organisations more efficient, thereby also increasing the lifetime of IPv4. In classful addressing an organisation would get one of ...


73

The layout that we are using for our rollout is: /48 per customer /56 per customer site (as a subnet of the other /48) /126 for all point-to-point links in the core, these are all subnets of a /48 used for all core links These sizes are mostly taken from the RIPE advisory here.


40

MAC addresses only need to be unique in a local broadcast domain, not globally, so re-use of MAC addresses in different networks usually isn't a problem. The internet isn't one global broadcast domain and thus needs to be divided into many blocks of addresses assigned to different ISP's and each ISP divides his blocks into smaller blocks for different ...


31

I think the link-local scope was set to /10 simply to "fit in" better with the other scopes, e.g. site-local (before it was replaced with unique local). Initially I had thought maybe it was to allow the use of many link-local networks on the same link, but RFC 4291 explicitly states that only fe80::/64 may be used.


31

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 this city would just be on a private network of that city. Then this one city would be able to assign addresses from range 0.0.0.1 to 255.255.255.254. On the face ...


27

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 been renewed by the author several times. It doesn't appear to have much, if any, support, and it doesn't even have a proposed RFC status, e.g. Standards Track. ...


26

The old recommendation was to use /64 everywhere even on P2P links and assign a /48 per site. Using large, empty subnets on point-to-point links can lead to a number of potential security issues, (see RFC6164,) so it's now best practice to use a /127 for P2P links and /128 for loopbacks. It's not necessary to give a small customer a /48 although you would ...


23

IP address and port pair is called, Socket Address Pair of socket addresses (10.0.0.1:123, 192.168.0.1:123) may also be called 4-tuple or 5-tuple if the protocol is specified as well (10.0.0.1:123, 192.168.0.1:123 UDP)


22

I don't have a full strategy, but here's the rough way I did it at $JOB[-1]: Get an IPv6 block, either from your existing carrier, or an RIR You might also want to mark a fc00::/7 (Unique local) block for fully internal subnets if you have an ISP block and may ever need to renumber Decide on your v6 IGP, IS-IS is still a safer option than OSPFv3, but much ...


22

With IPv6 you no longer have to worry about allocating space for a given number of hosts. All subnets (other than P2P links) should be assigned as a /64 which gives you a ridiculous number of host addresses. This frees you to focus on other topics such as good network layout & design. (A /48 would give you 65,536 /64 networks) There are (of course) ...


19

A little precision to earlier responses, based on the RIPE IPv6 training session I had a year ago. Basically their recommendation is to focus on aggregation rather than address space preservation. That is : don't worry to reserve a large amount of IPs for a Point of Presence even if you only have small amount of subnets here (for now). But you should ...


19

TL;DR: If you're a consumer/SOHO nothing needs doing. If you're providing services, start planning now while there's no rush and no deadline. Basically, everything is dual stack these days, meaning it supports IPv4 and IPv6 out of the box. The Internet in general is still operating fully supporting IPv4 as much as possible. At this point, if you're ...


19

These days it's usually at /48, and it's very unlikely to ever be longer. There are still AS' filtering longer than /32 though, but they should all have a default at this point (Verizon were a hold-out, but I believe they've given up). There are also AS' filtering on allocation lengths, so if you got a /32 they might require you advertise it as such (based ...


19

The mechanism is called Address Resolution Protocol (ARP). Every ethernet IPv4 device ARPs to resolve ethernet mac addresses for target IPs. IP to mac mappings are stored in each device's ARP table (the phone book in your analogy). To simplify: In most cases, to resolve the MAC address associated with an IP address, you send a broadcast ARP packet (to all ...


19

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 you are simply out of addresses in that network. Adding any more hosts would require reclaiming unused addresses, expanding the network (may not be possible), ...


19

Is “IPv10” a joke or a serious RFC draft? Both. I guess that bloke is serious and he doesn't get what ridiculous schemes he's proposing. The joke's on him. The Fiber Satellite proposal is even more ludicrous as it neglects required fiber lengths and totally ignores orbital mechanics. IETF should block him for trolling.


19

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 be used in practical networks. There is a "private IP range" of fc00::/7 which should be used for device testing, demos, courses, etc. as per RFC4193 Unicast ...


18

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 successor of IPv4. Internet Steam Protocol is defined by RFC1819 in which you will find in section 1.2: Both ST2 and IP apply the same addressing schemes to ...


18

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 can get a /29 just by asking for it Conclusion: Get a /29 and start using the a /32, save the other /32s for when you deploy to other countries, continents etc. ...


17

IPv4: It will "flap". On the sending host (another host or the gateway/router) there will be an ARP entry for the IP pointing to the MAC address of one of the hosts. Packets will go to one of the hosts, wherever the ARP entry currently points. This will effectively disrupt connectivity for both hosts. IPv6: The neighbor discovery protocol will do a ...


16

Not all types of network interfaces use MAC addresses. MAC addresses are mostly associated with Ethernet, though quite a few other networking standards do use it. However, an IPv6 address can still be assigned to a network interface that doesn't use MAC addresses for Layer 2. Also of note, a MAC address can be converted to an IPv6 host portion through EUI-...


15

RFC 4291 provides instructions on how to create the EUI64 address: Links or Nodes with IEEE 802 48-bit MACs [EUI64] defines a method to create an IEEE EUI-64 identifier from an IEEE 48-bit MAC identifier. This is to insert two octets, with hexadecimal values of 0xFF and 0xFE (see the Note at the end of appendix), in the middle of the 48-bit MAC (between ...


15

The Internet Protocol (IP) was designed to provide end-to-end connectivity. The 32 bits of an IPv4 address only allow for about 4.3 billion unique addresses. Then you must subtract a bunch of addresses for things like multicast, and there is a lot of math showing that you can never use the full capacity of a subnet, so there are a lot of wasted addresses. ...


15

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 the OUI (Organizationally Unique Identifier, which are the most-significant 24-bits) part of the MAC address: The least-significant bit is the I/G (Individual/...


14

Well technically fragmentation can happen in IPv6; This is the wikipedia article on it. This Juniper page is a bit old but it shows that you can clamp an MSS for TCP over IPv6 on Junos the same as you would in IPv4 using the same command, tcp mss. The same is shown in this article for Cisco IOS 15, using the traditional ip tcp adjust-mss command. So you ...


14

You can indeed request a Provider Independent (PI) assignment from the local RIR through an LIR. Routing a block of IPv6 address space is done with BGP in the same way as a block of IPv4 address space. The block is only a bit bigger :-) For IPv4 it is common that a block smaller than a /24 (so a /25 or longer prefix) will not be commonly routed by ISPs. In ...


14

Many of us do use /126's on PTP links. I personally like being able to identify something as a network infrastructure PTP link just based on the first 64 bits of the address, so I reserve a /64 to pull the /126's from. Different people have different opinions on what's important, so...shrug Incidentally (#1), because IPv6 doesn't have the concept of a ...


14

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 required via the private link. Second option depends on available connectivity options, you might be able to acquire a Layer2 (switched) link between both DCs and ...


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