IPv6 network boundaries vs. IPv4

Jason LeBlanc jml at packetpimp.org
Mon Aug 27 11:12:54 UTC 2007

OT: He probably meant MOP and LAT are not routable, man that brings back 

Kevin Oberman wrote:
>> Date: Sat, 25 Aug 2007 23:56:29 -0600
>> From: John Osmon <josmon at rigozsaurus.com>
>> Sender: owner-nanog at merit.edu
>> Is anyone out there setting up routing boundaries differently for
>> IPv4 and IPv6?  I'm setting up a network where it seems to make
>> sense to route IPv4, while bridging IPv6 -- but I can be talked
>> out of it rather easily.
>> Years ago, I worked on a academic network where we had a mix
>> of IPX, DECnet, Appletalk, and IP(v4).  Not all of the routers
>> actually routed each protocol -- DECnet wasn't routable, and I recall
>> some routers that routed IPX, while bridging IP...
> DECnet not routable? Not even close to true. At one time DECnet was
> technically well ahead of IP networking and far more commonly used. It
> was not until about 1993 that IP traffic passed DECnet as the dominate
> protocol and ESnet continued to route DECnet, mostly to support the High
> Energy Physics community. When the Hinsdale fire segmented tie IP
> Internet in 1988, the global DECnet Internet survived, albeit with limits
> bandwidth between the coasts.
> DECnet was far from perfect and, over time, IP surpassed it in terms of
> both performance and robustness, but it was not only routable, but
> globally routed long ago.
>> This all made sense at the time -- there were IPX networks that needed
>> to be split, while IP didn't need to be.  DECnet was... DECnet -- and 
>> Appletalk was chatty, but useful. 
> AppleTalk was a royal pain! Gator boxes and FastPaths would go insane
> and saturate the network with broadcasts. But AppleTalk did have some
> really neat features.
>> I keep hearing the mantra in my head of: "I want my routers to route, and 
>> my switches to switch."  I agree wholeheartedly if there is only one 
>> protocol -- but with the mix of IPv4 and IPv6, are there any folks
>> doing things differently?  With a new protocol in the mix are the
>> lessons of the last 10 (or so) years not as clear-cut?
> Most routers are a blend of router and switch. The Cisco 6500 and 7600
> boxes are probably the most popular large router in the world, but the
> heart of each is a Catalyst switch. So, the switch switches and the
> router routes, but they are both the same box.
> At a major networking show we would switch the IPv6 back to the core
> routers because of bugs in the IPv6 implementations on many systems.
> You do what works best for your network. If it means switching IPv6, so
> be it. This is probably especially true when the router is from a
> company that charges substantially extra for IPv6 software licenses. If
> the is only limited IPv6 traffic, switching to a central router might
> not only be technically the best solution, but the most reasonable
> fiscal approach.

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