On 08-03-2017 00:27, Dennis Bohn 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?
dennis
Many features of IPv6 depends on link local. Take a look at the routing table of your computer - you will find that most routes have a next hop with a link local address. Many buildin protocols, such as RA and DHCPv6, use link local to communicate without depending on any configuration. Many protocols with automatic discovery will use link local - why would you want your printer or local NAS server to use a public IP when link local works? In fact, you may prefer the printer to be only on link local so it can not be accessed from outside. The public IP is something your ISP assigns to you, so using that unnecessary only makes your setup vulnerable to problems if the internet is down. You could assign an ULA prefix https://en.wikipedia.org/wiki/Unique_local_address for your network but most people wont. Regards, Baldur