Tag Archives: IPv6

10 Sep

/29 IPv6 allocation is now possible (RIPE-552)

You can now get /29 IPv6 subnet instead of default /32 from RIPE, when you’re getting new address allocation. RIPE-552 document has been updated in point 5.1.2 and now not only /32 is default allocation size for new IPv6 subnets. Of course any allocation between /29 and /32 is possible without providing additional documentation.

It’s possible to extend current /32 allocation to /29. The subnets were allocated in schema that if you requested initial /32 subnet, next /32 were reserved not straight after that, but space for extending to /29 were left.

Look to Jan Zorz’s presentations or check RIPE webpage for more details.

10 Aug

Deleting a subinterface that has IPv6 EIGRP running on it and crashing IOS XE

In some cases router running IOS XE might crash or produce traceback if we try to delete logical interface (like ie. port-channel) or subinterface that runs IPv6 EIGRP. This can occur mostly on XNE or older releaseses, has been fixed in new ones. Cisco have internal bug CSCtd63242 describing this problem (might be released into public).
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20 Mar

IPv6 only segments not really working (mostly)

I’ve been playing a little with IPv6 when I was preparing WLAN infrastructure for PLNOG 6 conference in Warsaw last week. Here are few discoveries:
1) Most operating systems (including latest Windows and MacOS X) does not like when network is IPv6-only. All of the systems reported limited network access, even tho they had Internet access via IPv6 network.
2) Most operating system were having problems acquiring DNS server information via DHCPv6. MacOS X does not support DHCPv6 at all, Windows, especially when additional antivirus or firewall software were present, wouldn’t work with DHCPv6 either.
3) We really need statefull NAT64 on routers. On ASR1000 stateless NAT64 is available, but it does not solve lack of IPv4 addresses problem. Statefull NAT64 is expected in Q2 or Q3 this year. NAT-PT on ISR routers is not really a solution because you have to disable CEF for IPv6 to make it work.

06 Apr

DHCPv6 service

On IOS routers you can disable built-in DHCP server issuing command 

no service dhcp

you should expect that it will disable whole DHCP service no matter what protocol it’s going to service. Wellm you are wrong. It disable only IPv4 DHCP service leaving IPv6 one still running. Therefor following configuration

ipv6 dhcp pool IPv6
 dns-server FC00:2::D911:220A
!
interface GigabitEthernet0/0
  ipv6 address FC00:3::1/64
  ipv6 nd other-config-flag
  ipv6 dhcp server IPv6

will still work and built-in DHCP server will assign DNS information to requesting IPv6 host.