IPV6 DHCP : Active Clients always zero 0

Answered Question
Jun 14th, 2011
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Hello All,


I have configure IPV6 DHCP by using below mentioned configuration, all my LAN PCs are getting IPV6 correctly and internet is also running well.


But if run this command on Router, so it shows Active Clients are always zero 0.


R1# sh ipv6 dhcp pool

DHCPv6 pool: DHCP_POOL

  DNS server: 2001:470:ab::cd

  Domain name: abc.com

  Active clients: 0


R1# sh ipv6 dhcp binding --> also show empty result.


Can anyone please tell me the reason .


MY CONFIGURATION:

ipv6 unicast-routing

ipv6 dhcp pool DHCP_POOL

dns-server 2001:470:ab::cd

domain-name abc.com


interface FastEthernet0/0

no ip address

speed 100

full-duplex

ipv6 address 2400:FC00:ab::/64 eui-64

ipv6 nd prefix 2400:FC00:ab::/64

ipv6 nd other-config-flag

ipv6 dhcp server DHCP_POOL


ipv6 route ::/0 2400:FC00:ab::1


int fa0/0 is directly connected to my LAN Switch.

Regards,

Correct Answer by Phillip Remaker about 6 years 1 month ago

"Managed-config-flag" means that the router manages and controls the IPv6 addresses.  Since it manages and controls, it has "state" because it tracks who has what address.  Hence, it is "stateful DHCPv6."


"Other-config-flag" controls whether or not DHCPv6 hands out informational details, like DNS server information.  Since it merely distributes information but does not track or retain state from the requestors, this is "stateless DHCPv6."

Correct Answer by Phillip Remaker about 6 years 1 month ago

You need to set BOTH, not replace one with the other. Both the Managed and Other bit need to be set.


See also http://blogs.technet.com/b/teamdhcp/archive/2007/01/23/dhcpv6-behaviour-...


Sent from Cisco Technical Support iPhone App

Correct Answer by Phillip Remaker about 6 years 1 month ago

You are using DHCP statelessly, meaning it is only providing configuration information like the DNS server but it is not managing IPv6 addresses.  If you want the router to hand out and manage addresses instead of SLAAC, use


ipv6 nd managed-config-flag


so that the M bit is set in the router advertisements.


For more information, see:

http://blogs.cisco.com/borderless/ipv6-automatic-addressing/

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Correct Answer
Phillip Remaker Tue, 06/14/2011 - 10:17
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  • Cisco Employee,

You are using DHCP statelessly, meaning it is only providing configuration information like the DNS server but it is not managing IPv6 addresses.  If you want the router to hand out and manage addresses instead of SLAAC, use


ipv6 nd managed-config-flag


so that the M bit is set in the router advertisements.


For more information, see:

http://blogs.cisco.com/borderless/ipv6-automatic-addressing/

waqasahmed0 Tue, 06/14/2011 - 21:56
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Ok  i changed my config from 


ipv6 nd other-config-flag   -------->  ipv6 nd managed-config-flag


But still , output of


Show ipv6 dhcp pool shows active clients zero 0


and Show ipv6 dhcp binding is also empty.


My config on interface, now look like this:


interface FastEthernet0/0

no ip address

speed 100

full-duplex

ipv6 address 2400:FC00:ab::/64 eui-64

ipv6 nd prefix 2400:FC00:ab::/64

ipv6 nd managed-config-flag

ipv6 dhcp server DHCP_POOL

end


what i am doing wrong ??


update: One thing more , when i run ipv6 nd managed-config-flag on int fa0/0, DNS address removed from my clients !!!


Regards,

Yash Malvania Fri, 09/13/2013 - 13:36
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Hey i had a similar problem and your solution fixed it. Now where i am stuck is that i want to keep a track of the client mac address and the dhcp assigned address. what command can i use to see that? 

waqasahmed0 Wed, 06/15/2011 - 00:41
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Ok , the problem solved by changing the configuration in this way. Now it is showing Active clients and Bindings.


I will try your method too, to just add ipv6 nd managed-config-flag in my previous config.


But i am still confused which configuratrion is better and which technique to use ?? 

My previous config was stateless , is my new config is stateful ??


My NEW Configuration:


ipv6 unicast-routing

ipv6 cef

ipv6 dhcp pool DHCP_POOL

address prefix 2400:FC00:ab::/64 lifetime infinite infinite

link-address 2400:FC00:ab::2/64

dns-server 2001:470:ab::cd

domain-name abc.com


interface FastEthernet1/0

no ip address

duplex full

speed 100

ipv6 address 2400:FC00:ab::2/64

ipv6 enable

ipv6 nd managed-config-flag

ipv6 dhcp server DHCP_POOL


ipv6 route ::/0 2400:FC00:ab::1

Correct Answer
Phillip Remaker Wed, 06/15/2011 - 09:38
User Badges:
  • Cisco Employee,

"Managed-config-flag" means that the router manages and controls the IPv6 addresses.  Since it manages and controls, it has "state" because it tracks who has what address.  Hence, it is "stateful DHCPv6."


"Other-config-flag" controls whether or not DHCPv6 hands out informational details, like DNS server information.  Since it merely distributes information but does not track or retain state from the requestors, this is "stateless DHCPv6."

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