hi,


the introduction of IPv6 allows us to act as a greeenfield site regarding
address allocation and routing - therefore, rather than have everything fragmented
all over the place (....over 2k of routes once seen on internal routers!) we
use the SLA-ID to identity the network as follows

XYYY

where X is the VTP domain/campus park and YYY is the VLAN  (we kept in 3 digit
VLAN territory) 

by using the X designator, a section of the IPv6 space at that boundary cannot
suddenly be in another routed domain...

i did look at doing it 'properly' with the VLAN etc being hex-encoded - ie non
human readable (*) but there were complaints that IPv6 was already difficult
enough..... by using trhe human-readable, our less techy people can read the
address (yes yes) and see what VLAN they are on..or the system is on etc

alan
* of course, some people can do on the fly xlation in their h34ds ;-)

PS as others have said - feel free to follow your own dreams...but I would
say dont let your IPv6 space get fragged to death across the network.

PPS I would also point you to these masterpieces:
http://www.surfnet.nl/Documents/rapport_201104_IPv6_Deployment_In_Local_Area_Networks.pdf
https://www.ripe.net/lir-services/training/material/IPv6-for-LIRs-Training-Course/IPv6_addr_plan4.pdf