Hi Nathalie, > This should be made clear, as I notice in our training courses, a lot of > engineers seem to think that the router ID MUST be an IPv4 address, while it > normally is, it is not mandatory. 0.0.0.1 is a valid router-ID, I believe. In > an IPv6-only network, for example, when you have no IPv4 addresses, you can > just make something 32-bitty up and use that as the router ID.
True, but it has to be unique a least between a router and all its neighbours. So if everybody on an internet exchange starts using 0.0.0.x then there will be trouble :) > On the address assignment: What we see and hear in practice in our courses, > is assign something on 4-bit boundary, big enough to cater for the next 10 > years. > So: a /64 only if you are absolutely sure that the customer will never come > back for one more subnet (not likely). > a /60 (if you are conservative) Don't be :) > a /56 (most common for residential users) > a /52 (we see this in some cases for both residential customers and business > customers) > a /48 (for business customers, or for residential customers if you are > generous, and have a one-size-fits-all-approach) I would phrase this as "a /48 (for business customers, and for residential customers if you are not stingy, and/or have a one-size-fits-all-approach)" But those are minor details. The most common advice is - give a /48 or a /56 to residential customers - give a /48 to business customers - in case of doubt err in the direction of /48 There are not much advantages in giving other sizes to users. Cheers! Sander
