Running IPv6 (2006)
by Iljitsch van Beijnum
Site-Local Addresses⏎ In IPv4, it's common to use RFC 1918 private address ranges (10.0.0.0/8, 172.16.0.0/12, and 192.168.0.0/16) for internal communication. The idea was to take private addresses to the next level in IPv6 by introducing the "scope" mechanism. We've already discussed addresses with link-local scope. Because those are only valid on an individual subnet, they can be reused on other subnets without real problems. Site-local addresses are supposed to work in a similar vein: they are only used within an individual "site" so that other sites can reuse the same address range. But can router vendors make that a router that connects to two different sites, manages to keep packets from site A in site A, and packets from site B in site B, even though both sites use the same addresses? This would require hacks such as using different routing tables, depending on the interface a packet was received on. For link-local addresses, this isn't a problem, because packets with those addresses are never forwarded by a router: they flow directly from the source to the destination over the local link; so there is never any real ambiguity. Experience with RFC 1918 addresses has also uncovered other problems, such as packets with private addresses leaking into the global network, where they can't be traced back to the source (to fix the leak) because of their ambiguity. And, when two large organizations that both use private addresses merge, their addresses plans often clash, requiring inconvenient renumbering efforts.🏁
Global Leaderboard
| # | Player | Time | Duration | Accuracy | WPM | pp | ||
|---|---|---|---|---|---|---|---|---|
| 1 | ||||||||
| 2 | ||||||||
| 3 | ||||||||
| 4 | ||||||||
| 5 | ||||||||
| 6 | ||||||||
| 7 | ||||||||
| 8 | ||||||||
| 9 | ||||||||
| 10 |
Site-Local Addresses⏎ In IPv4, it's common to use RFC 1918 private address ranges (10.0.0.0/8, 172.16.0.0/12, and 192.168.0.0/16) for internal communication. The idea was to take private addresses to the next level in IPv6 by introducing the "scope" mechanism. We've already discussed addresses with link-local scope. Because those are only valid on an individual subnet, they can be reused on other subnets without real problems. Site-local addresses are supposed to work in a similar vein: they are only used within an individual "site" so that other sites can reuse the same address range. But can router vendors make that a router that connects to two different sites, manages to keep packets from site A in site A, and packets from site B in site B, even though both sites use the same addresses? This would require hacks such as using different routing tables, depending on the interface a packet was received on. For link-local addresses, this isn't a problem, because packets with those addresses are never forwarded by a router: they flow directly from the source to the destination over the local link; so there is never any real ambiguity. Experience with RFC 1918 addresses has also uncovered other problems, such as packets with private addresses leaking into the global network, where they can't be traced back to the source (to fix the leak) because of their ambiguity. And, when two large organizations that both use private addresses merge, their addresses plans often clash, requiring inconvenient renumbering efforts.🏁