Monday, October 10, 2011

Tweet forwarded by @russruns

cmross: Will seek this out later today.  Steve Jobs banner in the Windy City a nice tribute http://t.co/UjlQ2eG0 via @zite
Original Tweet: http://twitter.com/cmross/status/123434197460324352
Sent via TweetDeck (www.tweetdeck.com)

Tuesday, October 4, 2011

F5 LTM GTM IPv6 quick hit

Just quick note, F5 products LTM and GTM work just great with IPv6.  But IPv6 address shortening (double-colons '::') is not permitted in the GUI or tmsh.
LTM and GTM are Linux based systems, so if you are using BASH, the standard rules apply.
But if you are using the GUI or tmsh, IPv6 addresses must be fully completed.
This:
fe80:0:0:0:201:d7ff:fed4:d041
Not this:
fe80::201:d7ff:fed4:d041     ^^  Cannot have a double colon.

Wednesday, September 28, 2011

IPv6 SLAAC(er)

Promoted as a feature of IPv6, allows a device to connect to a network and receive an addresses without the administrative overhead of managing a DHCP.

But there are a few limitations that limit its usefulness in an enterprise environment:

  • SLAAC only works with /64 subnets. No more, no less.
  • SLAAC does not hand out DNS information (or any Windows domain specific info).

You get an address, a fixed subnet, and a default gateway. Period. This doesn't make it entirely useless, but definitely SLAAC is not a DHCP killer.

To enable a Cisco router to being making SLAAC announcements, all you need to do is configure an interface with an IPv6 address and a /64 subnet:

interface GigabitEthernet0/2
no ip address
duplex auto
speed auto
ipv6 address 2001:1890:1208:240::1/64

This line:

ipv6 address 2001:1890:1208:240::1/64

causes the router to begin making ND announcements which permit other devices to SLAAC themselves. We can verify announcements with a show ipv6 interface:


V6-R1-2911#sh ipv6 int gi0/1
GigabitEthernet0/1 is up, line protocol is up
IPv6 is enabled, link-local address is FE80::xxxx:xxxx:xxxx:xxxx
No Virtual link-local address(es):
Global unicast address(es):
   2001:xxxx:xxxx:xxxx::1, subnet is 2001:xxxx:xxxx:xxxx::/58
Joined group address(es):
   FF02::1
   FF02::2
   FF02::1:FF00:1
   FF02::1:FFFD:CCC1
MTU is 1500 bytes
ICMP error messages limited to one every 100 milliseconds
ICMP redirects are enabled
ICMP unreachables are sent
ND DAD is enabled, number of DAD attempts: 1
ND reachable time is 30000 milliseconds (using 30000)
ND advertised reachable time is 0 (unspecified)
ND advertised retransmit interval is 0 (unspecified)
ND router advertisements are sent every 200 seconds
ND router advertisements live for 1800 seconds
ND advertised default router preference is Medium
Hosts use stateless autoconfig for addresses.
V6-R1-2911#

Tuesday, September 13, 2011

So you've got IPv6...

...now what?

This site contains a list of websites with verified IPv6 connectivity. Regularly updated and tested. Also provides the resolved IPv6 address so you can perform basic ping testing in case your DNS is flaky (anyone else have this problem?).

Global IPv6 Deployment Progress Report

Haven't ruled out a problem on the local end, but we do get better (but not 100%) responses from:

Public DNS servers:

  IPv6 IPv4
Open DNS 2620:0:ccc::2
2620:0:ccd::2
208.67.222.222
208.67.220.220
Google Public DNS 2001:4860:4860::8888
2001:4860:4860::8844
8.8.8.8
8.8.4.4