nanog mailing list archives
Re: IPv6 filtering (was Re: IPv6 internet broken, cogent/telia/hurricane not peering)
From: Seth Mattinen <sethm () rollernet us>
Date: Tue, 13 Oct 2009 11:52:36 -0700
Matthew Petach wrote:
As I understand it, (and Cisco's documentation seems to support this, http://www.cisco.com/en/US/docs/switches/lan/catalyst6500/ios/12.2ZY/command/reference/M1.html#wpxref54198 as an example), if you put a /128 in an ACL, you cannot specify any L4 port information for the address due to the limited width of the TCAM; in order to specify L4 information for the ACL, Cisco stuffs it into bits 24 through 39, losing what information was originally stored in those bits. It just so happens those are the fixed FFFE bits in an EUI-64 address, so if you're using EUI-64, no "real" information is lost. You can do your own non-EUI-64 addressing and still use ACLs with layer 4 port information as long as you don't put any addressing information into bits 24 through 39.
Interesting; makes sense though. Thanks for the explanation. ~Seth
Current thread:
- Re: IPv6 internet broken, cogent/telia/hurricane not peering, (continued)
- Re: IPv6 internet broken, cogent/telia/hurricane not peering Michael Peddemors (Oct 12)
- Re: IPv6 internet broken, cogent/telia/hurricane not peering Joel Jaeggli (Oct 12)
- Re: IPv6 internet broken, cogent/telia/hurricane not peering Dan White (Oct 12)
- Re: IPv6 internet broken, cogent/telia/hurricane not peering Jack Bates (Oct 12)
- IPv6 filtering (was Re: IPv6 internet broken, cogent/telia/hurricane not peering) Marco Hogewoning (Oct 12)
- Re: IPv6 filtering (was Re: IPv6 internet broken, cogent/telia/hurricane not peering) Jeroen Massar (Oct 12)
- Re: IPv6 filtering (was Re: IPv6 internet broken, cogent/telia/hurricane not peering) Marco Hogewoning (Oct 12)
- Re: IPv6 filtering (was Re: IPv6 internet broken, cogent/telia/hurricane not peering) Jeroen Massar (Oct 12)
- Re: IPv6 filtering (was Re: IPv6 internet broken, cogent/telia/hurricane not peering) Seth Mattinen (Oct 12)
- Re: IPv6 filtering (was Re: IPv6 internet broken, cogent/telia/hurricane not peering) Matthew Petach (Oct 13)
- Re: IPv6 filtering (was Re: IPv6 internet broken, cogent/telia/hurricane not peering) Seth Mattinen (Oct 13)
- Re: IPv6 internet broken, cogent/telia/hurricane not peering Michael Peddemors (Oct 12)