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I don't understand why getting rid of DHCP is desirable. DHCP provides a nice central place where you can map MAC addresses to IP addresses instead of configuri

by mort96 3y ago

I don't understand why getting rid of DHCP is desirable. DHCP provides a nice central place where you can map MAC addresses to IP addresses instead of configuring it ad-hoc on every device which needs a static IP address (if you're lucky and the device even supports static IP!). Checking "Does my interface have an IP address?" is also a really really useful and quick analogue for "is the gear related to the LAN pretty much working or is something broken/misconfigured?". As it is, all my interfaces just have these random IPv6 addresses configured which don't work most of the time. I don't get it.

dijit 3y ago
FWIW; SLAAC works by setting the local part to the mac address. So, if you have knowledge of your mac address (which is what you say you are using for DHCP) then you will know the fe80::<> IPv6 IP too, which, while not globally routable is probably what you want based on this comment.
- mort96 3y ago
  Wait SLAACs aren't globally routable? I thought the whole idea behind IPv6 was to not use NAT?
  - dijit 3y ago
    There's an education here that unfortunately I don't have the time to give you. SLAAC is the replacement for DHCP, it provides a local prefix address (fe80::) and optionally (and, crucially: additionally) provides a publicly routable IP if there's a public prefix available. You can think of the subject being split into two components: As a base: You will get a local IP On top: you get DNS/Public routing. Here's a bit more about how it works: https://www.networkacademy.io/ccna/ipv6/stateless-address-autoconfiguration-slaac https://www.networkacademy.io/ccna/ipv6/stateless-address-au...
  - throw0101d 3y ago
    > Wait SLAACs aren't globally routable? It is not the host-component of IPv6 that determines routability, it is the prefix. If you have a link-local prefix (fe80::/10) then it is not global, if it is a private prefix (fc00::/7) then it also may not be global; if it is part of IANA's unicast allocation (2000::/3) it is global (firewall permitting).
throw0101d 3y ago
> I don't understand why getting rid of DHCP is desirable. It's less infrastructure to run, especially with embedded networks. > DHCP provides a nice central place where you can map MAC addresses to IP addresses instead of configuring it ad-hoc on every device which needs a static IP address (if you're lucky and the device even supports static IP!). You are limiting your thinking to macro-scale 'user-managed' devices, as opposed to things like embedded things: * https://en.wikipedia.org/wiki/Matter_(standard) https://en.wikipedia.org/wiki/Matter_(standard)

by mort96 3y ago

dijit 3y ago

FWIW; SLAAC works by setting the local part to the mac address. So, if you have knowledge of your mac address (which is what you say you are using for DHCP) then you will know the fe80::<> IPv6 IP too, which, while not globally routable is probably what you want based on this comment.

mort96 3y ago
Wait SLAACs aren't globally routable? I thought the whole idea behind IPv6 was to not use NAT?
- dijit 3y ago
  There's an education here that unfortunately I don't have the time to give you. SLAAC is the replacement for DHCP, it provides a local prefix address (fe80::) and optionally (and, crucially: additionally) provides a publicly routable IP if there's a public prefix available. You can think of the subject being split into two components: As a base: You will get a local IP On top: you get DNS/Public routing. Here's a bit more about how it works: https://www.networkacademy.io/ccna/ipv6/stateless-address-autoconfiguration-slaac https://www.networkacademy.io/ccna/ipv6/stateless-address-au...
- throw0101d 3y ago
  > Wait SLAACs aren't globally routable? It is not the host-component of IPv6 that determines routability, it is the prefix. If you have a link-local prefix (fe80::/10) then it is not global, if it is a private prefix (fc00::/7) then it also may not be global; if it is part of IANA's unicast allocation (2000::/3) it is global (firewall permitting).

throw0101d 3y ago

> I don't understand why getting rid of DHCP is desirable. It's less infrastructure to run, especially with embedded networks. > DHCP provides a nice central place where you can map MAC addresses to IP addresses instead of configuring it ad-hoc on every device which needs a static IP address (if you're lucky and the device even supports static IP!). You are limiting your thinking to macro-scale 'user-managed' devices, as opposed to things like embedded things: * https://en.wikipedia.org/wiki/Matter_(standard) https://en.wikipedia.org/wiki/Matter_(standard)