[121844] in North American Network Operators' Group
Re: Using /126 for IPv6 router links
daemon@ATHENA.MIT.EDU (David Barak)
Thu Jan 28 10:57:25 2010
Date: Thu, 28 Jan 2010 07:56:49 -0800 (PST)
From: David Barak <thegameiam@yahoo.com>
To: "Dale W. Carder" <dwcarder@wisc.edu>, Igor Gashinsky <igor@gashinsky.net>
In-Reply-To: <01EF79E7-9B7D-40D1-934B-A0BD2A929415@wisc.edu>
Cc: nanog@nanog.org
Errors-To: nanog-bounces+nanog.discuss=bloom-picayune.mit.edu@nanog.org
----- Original Message ----=0AFrom: Dale W. Carder dwcarder@wisc.edu=0AOn J=
an 27, 2010, at 3:19 PM, Igor Gashinsky wrote:=0A> you face 2 major issues =
with not using /127 for=0A> PtP-type circuits:=0A>=0A>> 1) ping-ponging of =
packets on Sonet/SDH links=0A=0A> Following this, IPv4 /30 would have the s=
ame problem vs /31?=0A=0ANo, because IPv4 has the concept of Broadcast, whi=
le IPv6 does not.=A0 Remotely sending packets to an IPv4 broadcast address =
is a "directed broadcast" and that is generally denied by default on modern=
kit.=A0 =0A=0A>> 2) ping sweep of death=0A>=0A>> =A0=A0=A0 Take the same a=
ssumption for addressing as above, and now ping=0A> >=A0=A0=A0 sweep 2001:d=
b8::/64... if the link is ethernet, well, hope you=0A> >=A0=A0=A0 didn't ha=
ve any important arp entries that the router actually=0A> =A0>=A0=A0 needed=
to learn.=0A=0A>Wouldn't this affect *all* /64's configured on a router, n=
ot=0A>just point to point links?=A0 Time for glean rate limiting.=0A=0AThis=
is, of course, one of the reasons why some of us didn't like the ultra-meg=
a-mega ranges used to address handfuls of hosts, but that ship sailed long =
ago.=A0 =0A=0ADavid Barak=0ANeed Geek Rock? Try The Franchise: =0Ahttp://ww=
w.listentothefranchise.com=0A=0A=0A
