What are the properties usually associated with Internet Protocol 6? Multi-cast? A huge address space? A cleaner implementation with more packet throughput? Whatever.
Internet Protocol 6 has 128 bit addresses. That's more addresses than atoms in the visible universe. However, there are edge cases where that's insufficient. Internet Protocol 4 has 32 bit addresses (by default) and that was considered vast when it was devised. That was especially true when total human population was less than 2^32 people. Superficially, it was possible to give every person a network address.
Several address extension schemes have been devised. The best is RFC1365 which uses option blocks to optionally extend source and destination fields in a manner which is downwardly compatible. So, what size is an Internet Protocol 4 address? 32 or more bits, as defined by RFC1365.
Header Size
Internet Protocol 4 is often described as having a 20 byte (or larger) header while Internet Protocol 6 is often described as having a header which is exactly 40 bytes. This is false. IPv6 has option blocksjust like IPv4 and therefore both have variable length headers. The difference is that IPv6 headers are usually 20 bytes larger.
Packet Size
IPv4 typically supports a PMTU of 4KB or more. Admittedly, there are no guarantees but Ethernet without packet fragmentation provides about 1500 bytes. With PPPoA or PPPoE over AAL5 over ATM, 9KB payloads only fragment over the last hop. This is ideal for video delivery. IPv6 only guarantees 1280 bytes. How common is this? Numerous variants of micro-controller networking only support 1280 buffers. This is especially true for IPv6 over IEEE802.15.4 implementations. This is especially bad for video.
Packet Fragmentation
IPv6 has no packet fragmentation. IPv6 packets which exceed MTU always disappear.
Packet Throughput
Compared to IPv4, IPv6 generally has longer headers, longer addresses and shorter payloads. On this basis, how would you expect packet throughput of IPv6 to match or exceed IPv4?
Summary
The introduction of IPv6 provides no particular benefit to end-users. IPv6 is detrimental payload size and this is particularly detrimental to video delivery.
Benefits Of Internet Protocol 6 Greatly Over-Stated
(This is the fifth of many promised articles which explain an idea in isolation. It is hoped that ideas may be adapted, linked together and implemented.)
What are the properties usually associated with Internet Protocol 6? Multi-cast? A huge address space? A cleaner implementation with more packet throughput? Whatever.
Multi-Cast
Internet Protocol 4 addresses from 224.0.0.0 to 239.255.255.255 are for multi-cast, as defined in RFC1112. Unfortunately, multi-cast is incompatible with TCP, so that's 2^26 Internet Protocol 4 addresses and 2^120 Internet Protocol 6 addresses which don't work with YouTube or QuickTime.
Address Space
Internet Protocol 6 has 128 bit addresses. That's more addresses than atoms in the visible universe. However, there are edge cases where that's insufficient. Internet Protocol 4 has 32 bit addresses (by default) and that was considered vast when it was devised. That was especially true when total human population was less than 2^32 people. Superficially, it was possible to give every person a network address.
Several address extension schemes have been devised. The best is RFC1365 which uses option blocks to optionally extend source and destination fields in a manner which is downwardly compatible. So, what size is an Internet Protocol 4 address? 32 or more bits, as defined by RFC1365.
Header Size
Internet Protocol 4 is often described as having a 20 byte (or larger) header while Internet Protocol 6 is often described as having a header which is exactly 40 bytes. This is false. IPv6 has option blocks just like IPv4 and therefore both have variable length headers. The difference is that IPv6 headers are usually 20 bytes larger.
Packet Size
IPv4 typically supports a PMTU of 4KB or more. Admittedly, there are no guarantees but Ethernet without packet fragmentation provides about 1500 bytes. With PPPoA or PPPoE over AAL5 over ATM, 9KB payloads only fragment over the last hop. This is ideal for video delivery. IPv6 only guarantees 1280 bytes. How common is this? Numerous variants of micro-controller networking only support 1280 buffers. This is especially true for IPv6 over IEEE802.15.4 implementations. This is especially bad for video.
Packet Fragmentation
IPv6 has no packet fragmentation. IPv6 packets which exceed MTU always disappear.
Packet Throughput
Compared to IPv4, IPv6 generally has longer headers, longer addresses and shorter payloads. On this basis, how would you expect packet throughput of IPv6 to match or exceed IPv4?
Summary
The introduction of IPv6 provides no particular benefit to end-users. IPv6 is detrimental payload size and this is particularly detrimental to video delivery.
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