Building network automation solutions

9 module online course

Start now!

Recent posts in the same categories

9 comments:

  1. Anonymous 12 September 2015 02:18
    Really? Use /64 everywhere? And make that many neighbor entries possible?! Terrible advice.
    Replies
    1. crzdriver 12 September 2015 03:36
      Yeah, what are they thinking? The next thing you know, they'll be telling us to run BGP across the DC core or to use layer 3 switches. Oh wait, what year is it?
    2. Anonymous 12 September 2015 04:56
      Nice try, fanboy. BGP != 18,446,744,073,709,551,616 potential entries in a finite table, or using massive address spaces because it's "too hard" to subnet.

      This is the stuff of charlatans.
    3. Ivan Pepelnjak 12 September 2015 06:18
      Just because a vendor messed up their hardware so that they do NDP snooping before ingress ACL doesn't mean that "using /64 everywhere" is a bad advice. And BTW, I was writing about that years ago...

      http://blog.ipspace.net/2011/05/ipv6-neighbor-discovery-exhaustion.html

      Not sure whether that particular vendor fixed their bug, but I'm positive this myth will persist for decades.

      Also, if you're that security conscious, why don't you use LLA for non-edge interfaces?
    4. Ivan Pepelnjak 12 September 2015 06:22
      Also, dear Anonymous, do check the /64 table sizes versus LPM table sizes on data center switches. Many of them have interesting limitations for prefixes longer than /64.
  2. Xavier 28 September 2015 11:32
    I'm migrating LAN to IPv6. What happens with address selection if I want to use IPv6 ULA for LAN only and IPv4 for Internet?
    Will it work? Or Windows will prefer ULA for Internet and fail?
    Thanks
    Replies
    1. Ivan Pepelnjak 28 September 2015 17:21
      As soon as the host gets a AAAA response to the DNS query, it will try to reach the IPv6 address of the server.

      Happy Eyeballs should take care of web browsing, everything else will experience various levels of brokenness.

      Long story short: don't do it.
    2. Xavier 29 September 2015 14:21
      Thanks. But with the new OS is almost a necessity to configure IPv6 inside and the ISP doesn't give IPv6 outside yet. So what can we do? Maybe, dual stack inside with ULA, and IPv4 outside with NAT64 and DNS64?
    3. Ivan Pepelnjak 29 September 2015 18:44
      The hosts that desperately need IPv6 (primarily Windows Server) will use either LLA or 6-over-4 (in whatever form).

      Don't claim to have what you don't have.
Add comment
Home
Sidebar