Tag: IPv6

IPv4 free address pool is empty. No reason to panic.

What Happened?

ICANN announced there are no more IPv4 addresses. What they said was IANA have delegated the last blocks to RIR’s. Does it mean you can no longer get a public block of addresses? No. You still can get a brand new block from your local RIR. Or yet unallocated block from your local ISP. Meaning, there is NO reason to panic.

How IP address allocation works?

For ones, who does not know how IP addresses are given out. The process is the following. The original holder of the whole free address space for both IPv4 and IPv6 is IANA. IANA registers and delegates IP address blocks to Regional Internet Registries (RIR’s). RIR’s alocate IP addresses and IP address blocks to end customers. If you want to get an IP address, you have to allocate a block by registering it in your local RIR. Upon successful registration the block is allocated to you and you can do whatever you want with it, including reselling it. Currently most IP blocks are allocated to ISPs and big corporations. End users are mostly getting addresses from their ISPs.

The allocation works as follows:

ICANN (IANA) -> RIR -> Organization (ISP, corporation)  -> End user

What really happened?

What really happened is IANA’s “IPv4 allocation department” is going to be renamed to “IPv6 allocation department”. They’ve done their job with IPv4 – they have delegated all of them to RIR’s, they announced it, they had a fierce party. These are the processes behind allocating the last block.

Currently whole free IPv4 address space (not so big – 16 000 000 managed by each of 5 RIR’s) is managed by RIR’s and ISP’s worldwide. Meaning, IPv4 addresses space is going to be really exhausted soon. Not yet, but it’s approaching. Still there is nothing to fear. Even if it fully exhausts, the only problem of yours is not getting a pretty 4-octet address. Internet will remain running. Moreover, IPv4 addresses are a subset of IPv6 address. Even if whole Internet except you migrates to IPv6, you’ll still be available on an Intenet.

The ICANN’s announcement shall be considered as a last warning and a last call for IPv6 migration.

Frame, packet and segment sizes or TCP/IP without fragmentation

It appeared to be really complicated to find relative information about sizes of transmission units in different levels of TCP/IP stack and completely impossible to find a united chart with their comparison. So, here it is.

Layer Protocol Header Size Recommended size with header included without protocol extensions, ensuring no segmentation on all underlying layers Maximum size of transmission unit with protocol extensions
Transport TCP 20-60B 1480 Bit 1 GB
UDP 8 B 1480 Bit 65535 B
Network IPv4 20 B – 60 B 1500 Bit* 65535 B
IPv6 40 B – infinite 1500 Bit 4 GB
Data link 10/100 Ethernet 18 B 1542 bit 1542 bit
1/10 GB Ethernet 18 B 1542 bit 9000 bit**
10/100 GB Ethernet 18 B 1542 bit 64000 bit***
802.11 (WIFI) 34 B 2312 bit 2312 bit

* Fragmentation is widely used in IP protocols

** Jumbo frames are used on high-rate data link protocols, like Gigabit Ethernet or higher

*** is called Super jumbo frame. Not practically used and may not be profitable on a links lower than 10Gbit Ethernet