dhcp ipv6 unexpected subnetmask /128

MAYER Hans mayer at iiasa.ac.at
Wed May 2 12:33:41 UTC 2012

Dear all

I am running DHCP Server 4.1-ESV-R4 on a Solaris 11 machine. In the same network also a Windows 7 client is connected, all within GNS3. 

This is my simple configuration: ( maybe too simple )  /etc/inet/dhcpd6.conf

# dhcpd.conf
# Sample configuration file for ISC dhcpd
default-lease-time 600;
max-lease-time 7200;
allow leasequery;
log-facility local7;
shared-network LAN {
  subnet6 2001:628:21f0:1::/64 {
	range6 2001:628:21f0:1::100 2001:628:21f0:1::1ff ;
	option dhcp6.name-servers 2001:628:21f0:1::1 ;
	option dhcp6.domain-search "iiasa.ac.at" ; 

Within Solaris I have the following fixed IP configured: 
e1000g1:3: flags=20002000941<UP,RUNNING,PROMISC,MULTICAST,IPv6> mtu 1500 index 9
	inet6 2001:628:21f0:1::1/64

I start the dhcpd with the following command in the foreground:
/usr/lib/inet/dhcpd -6  -d -cf /etc/inet/dhcpd6.conf -lf /var/db/isc-dhcp/dhcpd6.leases

After a while I see on Solaris 11 the following interface:
e1000g1:2: flags=20002004941<UP,RUNNING,PROMISC,MULTICAST,DHCP,IPv6> mtu 1500 index 9
	inet6 2001:628:21f0:1::160/128

To check on Windwos I do: netsh interface ipv6 show  route
And I see:
No       Manual    256  2001:628:21f0:1::1ba/128   15  Local Area Connection 2

In both cases a /128 subnet mask. 
Why /128 ? 

I can ping the link-local address of the other site in each case but I cannot ping the official 2001:... address. I can ping the own IPv6 address but not the other as it is /128 and therefore not accessible within the network. I would expect that the dhcp daemon gives a /64 address as defined in the 'subnet6' declaration. 

Some ideas what I did wrong ? 

Kind regards


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