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"Internet Protocol Five Fields - Design Decisions",
Alexey Eromenko, 2016-09-29,
expiration date: 2017-03-29
Intended status: Informational
Internet Protocol "Five Fields": Design Decisions
Goal of IP-FF: provide future growth, without design complexity of
IPv6. This document writes the design decisions behind IP-FF and
explains why they were done.
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1. Overall architecture based on IPv4 (for easy code and network migration,
and easy understanding by developers and network engineers)
1.2. Address space was designed to be big enough for the next several
hundred years *but* _optimized for human memory_, rather than computer
It turned out that 50-bit addresses are very good at it.
(computer memory is cheap nowadays, even if we use a 64-bit data field
for only 50-bits of actual data).
1.3. ARP stays; It's easy to understand and won't require massive
network configuration changes.
1.4. Links are required to support 1280 bytes MTU (I expect physical
networks to be compatible with IPv6 by this time. which mandates this
2. Port numbers stay 16-bit. While I considered 32-bit, I rejected this
2.1. will push carriers towards carrier-grade NATs (CGNs), which is a
2.2. extra overhead of 4 bytes per packet. (0.27% slower for 1500 byte
2.3. I was unable to find major advantages.
3. Ports were moved from Layer 4 to Layer 3 header; which allows for:
3.1. Flow-based routing (via 5-tuple or 6-tuple rule).
3.2. Faster Firewalls
3.3. Simpler fragmentation for FDP
3.4. A bit higher overhead for protocols, that do not use 16-bit ports.
(a minor evil, but still.)
4. UDP protocol length field removal:
4.1. Is not needed, as TCP lacks length field, and does fine.
4.2. Allows for jumbo frames.
4.3. Allows for a stronger checksum.
5.1. needed for faster speeds (1 Terabit or more - I envision for end-user
devices, at Earth distances. Lots of data in mid-air, unacknowledged).
5.2. Ensuring reliability at such speeds requires *much* stronger checksums.
* TCP protocol originally designed to guarantee reliability, and it's
16-bit checksum worked fine in the 80's and 90's with 56 kbit/s WAN speeds,
but is not adequate nowadays at gigabit speeds let alone future-networks at
terabit speeds. A stronger 64-bit checksum restores this original guarantee.
6. Type of Service stays for compatibility reasons
7. TTL/HTL (Hops-to-Live) was extended mostly due to my envision of future
network virtualization, where virtual routers and containers (network
namespaces) speak to each other.
For physical networks TTL of 255 I expect it to be enough for this century.
8. Payload length was reduced to 14-bits, because it's enough to handle
both Ethernet Jumbo frames (9 KB) as well as WiFi frames (8 KB).
8.a. A standard IP-FF extension provided for Jumbograms (4 MiB size
IPFF packets), just-in-case.
9. Compatibility: IP-FF networks are theoretically backwards compatible with
IPv4 networks over a NAT router.
10. Extensions mechanism was completely rewritten for simplicity (of
11. Fragmentation: moved to Layer 4.
* TCP doesn't need a fragmentation, due to sliding windows.
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