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Re: v6 subnet size for DSL & leased line customers
From: Joel Jaeggli <joelja () bogus com>
Date: Sat, 22 Dec 2007 17:14:59 -0800
Randy Bush wrote:
Joel Jaeggli wrote:Randy Bush wrote:the "but what if they want the toaster on a separate subnet from the blender" gives a new depth to 'reaching.' the one case i can think of for firewalling/routing within the home is to keep the bathroom scale from locking the fridge.If ipv6 subnetting is going to be hosed up at this point it's going to be done by people deploying it.unfortunately, 'hosed up' only seems to be understood some years out. smb's point is apt, we always end up too small. but i still have a very hard time understanding what we are gonna do with more than a /56 to a consumer connection.
Leave enough address space for pd to occur? We know that if I hand you the end-user a /64 that the first device that you connect to the network (wireless/ethernet router) will nat because it wants a l3 boundary between the outside and the inside for v6 just like it has for v4. If that device, when it boots and requests pd receives a /64, cool... but what does it do when some device downstream from it asks for address space? So is a /64 ok for an end customer? No because it doesn't meet the criterion of a location where one and only one subnet will be needed. Does it need a whole /48? Probably not. What you need in your provisioning system and how you structure address-space usage for the benefit of your IGP is that downstream devices need to be able to request and receive blocks of a size commiserate with their needs without increasing the footprint of your routing table.
and if i start to go to the left of a /56, where do i stop? there is no obvious detent on the knob.
There is a huge detent at /48, but there's a certain amount of guidance that can only be derived from operational experience. It's not clear to me why /56 would be unacceptable, particularly if you're delegating them to a device that already has a /64. Are one's customers attached via point-to-point links, or do they sit on shared broadcast domain where their cpe is receiving a /128 and requesting pd from the outset? When someone plugs an apple airport into a segment of the corporate lan should it be be able to request pd under those circumstances as well? how is that case different than plugging it in on a residential connection? These are issues providers can and should grapple with. Much as assigning a /32 to a residential customer vs /30 or /28 is a business decision. In many if not most cases we don't currently provide as many v4 addresses as there are devices within the customer premises. Enough addresses isn't going to be an issue in v6, The dynamic creation of topology that was automatically and at least in one direction transparently created by restricted-cone nats is obviously something new.
randy
Current thread:
- Re: v6 subnet size for DSL & leased line customers, (continued)
- Re: v6 subnet size for DSL & leased line customers Chris Adams (Dec 21)
- Message not available
- Re: v6 subnet size for DSL & leased line customers Chris Adams (Dec 21)
- Re: v6 subnet size for DSL & leased line customers Robert E. Seastrom (Dec 21)
- Re: v6 subnet size for DSL & leased line customers Deepak Jain (Dec 21)
- Re: v6 subnet size for DSL & leased line customers Joe Greco (Dec 21)
- Re: v6 subnet size for DSL & leased line customers Owen DeLong (Dec 21)
- Re: v6 subnet size for DSL & leased line customers Joe Greco (Dec 21)
- Re: v6 subnet size for DSL & leased line customers Randy Bush (Dec 21)
- Re: v6 subnet size for DSL & leased line customers Joel Jaeggli (Dec 22)
- Re: v6 subnet size for DSL & leased line customers Randy Bush (Dec 22)
- Re: v6 subnet size for DSL & leased line customers Joel Jaeggli (Dec 22)
- Re: v6 subnet size for DSL & leased line customers Randy Bush (Dec 22)
- Re: v6 subnet size for DSL & leased line customers Joel Jaeggli (Dec 22)
- Re: v6 subnet size for DSL & leased line customers Randy Bush (Dec 22)
- Re: v6 subnet size for DSL & leased line customers Iljitsch van Beijnum (Dec 23)
- Re: v6 subnet size for DSL & leased line customers sthaug (Dec 23)
- Re: v6 subnet size for DSL & leased line customers Christopher Morrow (Dec 23)
- Re: v6 subnet size for DSL & leased line customers Randy Bush (Dec 23)
- Re: v6 subnet size for DSL & leased line customers Christopher Morrow (Dec 23)
- Re: v6 subnet size for DSL & leased line customers Kevin Loch (Dec 24)
- Re: v6 subnet size for DSL & leased line customers Iljitsch van Beijnum (Dec 24)