On 7 March 2017 at 23:27, Dennis Bohn <bohn@adelphi.edu> wrote:
In addition, IPv6 has link local addresses. This one seemingly insignificant detail causes so much code churn and is probably responsible for 10 years of the IPv6 drag.
AFAICT, Cisco V6 HSRP (mentioning that brand only because it caused me to try to figure something out, a coincidence that this is in reply to Jakob from Cisco but is based on what he wrote) relies on Link Local addresses. I didn't understand why link locals should be there in the first place seemed klugey and have googled, looked at rfcs and tried to understand why link local addresses were baked into V6. The only thing I found was that it enabled interfaces on point to point links to be unaddressed in V6. (To save address space!??) Can anyone point me in a direction to understand the reasoning for link local addressing?
So you can print whilst your Internet connection is down. IPv6 allowed people to rethink IPv4 assumptions, and they realised that a lot of IPv4 things were hacks to work around a lack of functionality in the protocol. NAT has polluted peoples minds when it comes to the distinctions between local and global addressing. Why would you use a global address, with an extra code check to make sure it is on a directly attached interface, to point a route at? "Router 2 on interface B" makes more sense to me than "Router with global address 12345" in this context. I would also have loved it if the all-routers-anycast thing had been better defined rather than deprecated. One of the potential default behaviours could have been fe80:: as a default gateway on every segment, with a logical meaning of "All upstream routers on this interface". - Mike