I work for a cable MSO, meaning that our access network is DOCSIS based. 15
years ago when we had way more IP addresses than customers we had a static IP
allocation scheme wherein we aligned a /24 with each node and reserved the
first 20 or so IPs for static assignment, the rest being left for dynamic
assignment. The primary reason behind this scheme was that as the network grew
and a node moved from one CMTS to another we could pull the /24 with it and
customers wouldn't have to re-address.
As our network has grown, in terms of the number of nodes, as well as the
number of IPs in use we've come to the obvious conclusion that the old scheme
isn't workable into the future. For instance I will soon have more nodes in
service than I have /24s allocated to me.
Instead we are entertaining two basic options as an alternative.
* Create static reservations, as required, within the otherwise dynamic
range.
* Whether or not the customer continues to DHCP or assigns the IP
statically doesn't matter to me.
* Move to having a single subnet, or portion therein, per CMTS. This keeps
the process more or less identical to what we do now.
Both of the schemes above would require the customer to undergo addressing
changes in the event that we move their node between CMTSs in the future.
Can anyone else share what they are doing or otherwise identify if there is a
best practice in this area?
Thanks,
Graham
