Joshi Rivera: Hello Jeff, regards from Mexico. Just a question, I'm in charge of a small network and the plan is to re-plan a new medium network with remote offices. Do you recommend IPv6 to deploy, and Cisco equipment as core and access equipment?

Jeff_Doyle: A bit like a previous answer, I would ensure that what you deploy is IPv6 capable, but for the present you still need IPv4. You have lots of options at the distribution and access layers beyond Cisco, but I do think what you get there is equipment that most everyone knows how to operate and a strong support network behind it.

BillB28: What will be the thing that most people will be talking about in 2008 regarding routing?

Jeff_Doyle: IPv6, in terms of practical deployment experience and best practices.

Niharika: 2015 and 2020 seems a long time away. I started preparing and reading about IPv6 now to enhance my position. But I think it's too early. Am I wasting my time?

Jeff_Doyle: Depends on whether you are in the enterprise or the service provider space. If you are in a SP, you should have been planning two years or more ago. If you are in the enterprise space, you probably have another five years or so before you need to worry about it, although it certainly helps to be thinking about it now.

BillB28: Whatever happened to IPv5? Why are we jumping from IPv4 to IPv6?

Jeff_Doyle: IPv5 was designated to an experimental protocol that was never deployed. So "6" was the next number on the list of available version labels.

OSPF, routing, switching

Moderator-Keith: PRE-SUBMITTED QUESTION: What kinds of limitations does OSPF have with large hub and spoke networks?

Jeff_Doyle: Adjacencies are the limitation here, but (assuming you have a beefy enough hub router) it only starts to become a limitation when the adjacencies start moving past the many tens into the hundreds. A sane design probably isn't going to do this, plus if it's a straightforward hub-and-spoke topology you can (and probably should) use a lot of static default routes and get away from an IGP on the spokes.

Moderator-Keith: PRE-SUBMITTED QUESTION: You've talked about oddball multi-area OSPF topologies in your blog. In what circumstance is the traditional daisy design problematic?

Jeff_Doyle: The oddball topologies I've talked about are primarily thought exercises, not something you should actually do on a production network. The "daisy" model is something every multi-area OSPF topology should look like; the very nature of the daisy model means areas are being used, so the topology can scale hugely. This assumes, of course, you're not doing anything really dumb like a poorly interconnected area 0 or 50,000 areas with 2 routers each. :-)

RoutetoMe: I am currently managing a network with multiple site-to-site VPN links and we want to do away with a lot of the static routing and incorporate OSPF into the mix... is it wise to think of the remote offices as OSPF areas (the locations are dispersed around the world) and make our main site Area 0?

Jeff_Doyle: Hard to answer without seeing your topology, but I personally am a fan of big single OSPF areas: I've seen too many networks with tons of unnecessary areas, complicating operations. But areas certainly have their place; if you are worldwide, doing areas by region might make sense. How's that for an ambivalent answer?