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New Member

ipv6 dhcpv6 (different subnets)

Hello,
i would like to get some help on how to make a cisco router supplies addresses to different subnets connected to fastinternet interfaces using "dhcpv6"?

here is my attempt, which is not working;

en
conf t

ipv6 unicast-routing

ipv6 local pool VLAN10-pool AAAA:1::/48 64
ipv6 local pool VLAN20-pool AAAA:2::/48 64

ipv6 dhcp pool DHCPv6POOL
prefix-delegation pool VLAN10-pool
prefix-delegation AAAA:1::23F6:33BA/64 00030001000E84244E70
ipv6 dhcp pool DHCPv6POOL2
prefix-delegation pool VLAN20-pool
prefix-delegation AAAA:2::23F6:33BA/64 00030001000E84244E71

interface FastEthernet0/0
no sh
no ip address
ipv6 enable
ipv6 address FE80::1 link-local
ipv6 address AAAA:1::1/64
ipv6 nd other-config-flag
ipv6 dhcp server DHCPv6POOL

interface FastEthernet0/1
no sh
no ip address
ipv6 enable
ipv6 address FE80::2 link-local
ipv6 address AAAA:2::1/64
ipv6 nd other-config-flag
ipv6 dhcp server DHCPv6POOL2
end

Everyone's tags (1)
5 REPLIES
New Member

ipv6 dhcpv6 (different subnets)

Hi Kris,

Prefix delegation feature gives the possibility to centrally control IPv6 addresses used in remote sites using a single DHCP server as shown below :

I guess it is not what you want to do, but just client-server model. Instead try this configuration on the server (IOS > 12.4(24) T) :

ipv6 unicast-routing

!

ipv6 dhcp pool VLAN10-pool

  address prefix AAAA:1::23F6:33BA/64 lifetime   infinite infinite

  dns-server

  domain-name

!

ipv6 dhcp pool VLAN20-pool

  address prefix AAAA:2::23F6:33BA/64 lifetime   infinite infinite

  dns-server

  domain-name


interface FastEthernet0/0

ipv6 address AAAA:1::1/64

ipv6 dhcp server DHCPv6POOL2 rapid-commit

interface FastEthernet0/1

ipv6 address AAAA:2::1/64

ipv6 dhcp server DHCPv6POOL2 rapid-commit

Turn IPv6 DHCP on and observe SOLICIT messages from the client and because it is in rapid-commit mode you should see only REPLY from the router to the client.

New Member

ipv6 dhcpv6 (different subnets)

thanks for replying

but i am simulating this network using the latest packet tracer and i am not seeing the address prefix command.

Router>en

Router#conf t

Enter configuration commands, one per line.  End with CNTL/Z.

Router(config)#ipv

Router(config)#ipv6 un

Router(config)#ipv6 unicast-routing

Router(config)#ipv

Router(config)#ipv6 dh

Router(config)#ipv6 dhcp p

Router(config)#ipv6 dhcp pool VLAN10-pool

Router(config-dhcp)#?

dns-server         DNS servers

domain-name        Domain name to complete unqualified host names

exit               Exit from DHCPv6 configuration mode

no                 Negate a command or set its defaults

prefix-delegation  IPv6 prefix delegation

Router(config-dhcp)#

New Member

Re: ipv6 dhcpv6 (different subnets)

Well, that's another story, packet Tracer do NOT use real IOS but simulates its behavior and in this case IOS 12.4(15)T1

So it works slightly differently, indeed previous versions do not support "address-prefix" command under the dhcp pool, but it works with "prefix-delegation" command :

- Stateful DHCPv6 & ping works (by the way just do ping )

and here is the router configuration :

ipv6 dhcp pool dhcp-pool

prefix-delegation pool client-prefix-pool1 lifetime 1800 600

dns-server 2001:DB8:3000:3000::42

domain-name example.com

!

ipv6 dhcp pool dhcp-pool2

prefix-delegation pool client-prefix-pool2 lifetime 1800 600

dns-server 2001:DB8:3000:4000::42

domain-name example.com

!

ipv6 local pool client-prefix-pool1 2001:DB8:1200::/40 48

ipv6 local pool client-prefix-pool2 2001:DB8:2200::/40 48

!

interface FastEthernet0/0

description downlink to clients

ipv6 address 2001:DB8:1200::1/48

ipv6 dhcp server dhcp-pool

!

interface FastEthernet0/1

description downlink to clients

ipv6 address 2001:DB8:2200::1/48

ipv6 dhcp server dhcp-pool2

Try to do it 1st without assigning specific DUID.

ping


I hope this resolves your issue.

AJN

New Member

Re: ipv6 dhcpv6 (different subnets)

Thanks for the detailed explanation.

However, from the router configuration;

ipv6 dhcp pool dhcp-pool

prefix-delegation pool client-prefix-pool1 lifetime 1800 600

dns-server 2001:DB8:3000:3000::42

domain-name example.com

!

ipv6 dhcp pool dhcp-pool2

prefix-delegation pool client-prefix-pool2 lifetime 1800 600

dns-server 2001:DB8:3000:4000::42

domain-name example.com

!

ipv6 local pool client-prefix-pool1 2001:DB8:1200::/40 48

ipv6 local pool client-prefix-pool2 2001:DB8:2200::/40 48

!

interface FastEthernet0/0

description downlink to clients

ipv6 address 2001:DB8:1200::1/48

ipv6 dhcp server dhcp-pool

!

interface FastEthernet0/1

description downlink to clients

ipv6 address 2001:DB8:2200::1/48

ipv6 dhcp server dhcp-pool2

I assume that a pc connected to fa0/0 should get an ipv6 address starting with 2001:DB8:1200:.......

and  a pc connected to fa0/1 should get an ipv6 address starting with 2001:DB8:2200:.......

But that is not the case when i examined the pc0 and pc2 config ipv6 address displayed on the snapshots where trey both start with 2001:DB8:1200: ?

Moreover when i simulated the network with the given configuration, i not only got the same problem but both pcs also got the same dns server ?

New Member

Re: ipv6 dhcpv6 (different subnets)

Indeed Kris after a hard time dealing with Packet Tracer discrepancies and instability, the router was only able to assign IPv6 addresses from a single pool independently of the presence of any other pools.

It was even using the same pool after completely erasing it from the configuration and rebooting the router. Obviously it doesn't support multiple instances tied to multiple pools.

In the same time we shouldn't expect Packet Tracer to behave 100% like IOS code because it's not an IOS, it emulates its behavior.

Packet Tracer is an excellent tool to get acquaintance with some technologies and features with just the software as an investment, further you will have to switch to tools like GNS3, and better to real equipments.

Having said that, it looks like the problem is completely out of the scope of Packet Tracer, because even IOS < 12.4(24)T do not support IA (Identity Association) used by DHCPv6 clients to query and manage a particular type of IPv6 addresses (Temporary or Non-Temporary) as shown below on IOS DHCPv6 server :


DHCPv6 server router, IOS 12.4(15)T8:

And on Linux dibbler-client:

The only way to overcome this is to use an IOS supporting IA_NA (>12.4(24) T) as I mentioned in a previous post with different implementation commands of DHCPv6 server using “address-prefix” under “ipv6 DHCP pool”

Here is the configuration I deployed using IOS 12.4(24)T as DHCPv6 server, and I mixed 3 different clients :

  • - IOS 12.4(24)T as DHCPv6 server – supporting interface command « ipv6 address dhcp »
  • -Linux Debian configured with Dibbler-Client
  • - Windows Vista configured with Dibbler-Client

DHCPv6#sh ver

Cisco IOS Software, 7200 Software (C7200-ADVENTERPRISEK9-M), Version   12.4(24)T2, RELEASE SOFTWARE (fc2)

Technical Support: http://www.cisco.com/techsupport

Copyright (c) 1986-2009 by Cisco Systems, Inc.

Compiled Mon 19-Oct-09 22:53 by prod_rel_team

ROM: ROMMON Emulation Microcode

BOOTLDR: 7200 Software (C7200-ADVENTERPRISEK9-M), Version 12.4(24)T2,   RELEASE SOFTWARE (fc2)

DHCPv6 uptime is 1 hour, 39 minutes

...

And with the following configuration:

!

ipv6   unicast-routing

ipv6   cef

ipv6   dhcp pool pool1

address prefix 2001:DB8:1111::/64 lifetime   infinite infinite

dns-server 2001:DB8:1201::1

domain-name domain1.com

!

ipv6   dhcp pool pool2

address prefix 2001:DB8:2222::/64 lifetime   infinite infinite

dns-server 2001:DB8:1202::1

domain-name domain2.com

!

ipv6   dhcp pool pool3

address prefix 2001:DB8:3333::/64 lifetime   infinite infinite

dns-server 2001:DB8:1203::1

domain-name domain3.com

!

!

interface   FastEthernet0/0

ipv6   address 2001:DB8:1111::1/64

ipv6 enable

ipv6 nd managed-config-flag

ipv6 dhcp server pool1

!

interface   FastEthernet0/1

ipv6   address 2001:DB8:2222::1/64

ipv6 enable

ipv6 nd managed-config-flag

ipv6 dhcp server pool2

!

interface   FastEthernet1/0

ipv6   address 2001:DB8:3333::1/64

ipv6 enable

ipv6 nd managed-config-flag

ipv6 dhcp server pool3

!

"ipv6 nd managed-config-flag" is used to instruct client to get IPv6 addresses through DHCPv6

IOS DHCP Server:

The server has assigned each client a different IPv6 address, DNS IPv6 address and a domain name from the corresponding pool configured o the interface:

DHCPv6#sh ipv6 dhcp pool

DHCPv6 pool: pool1

Address allocation prefix:   2001:DB8:1111::/64 valid 4294967295 preferred 4294967295 (1 in use, 0   conflicts)

DNS server: 2001:DB8:1201::1

Domain name: domain1.com

Active clients: 1

DHCPv6 pool: pool2

Address allocation prefix:   2001:DB8:2222::/64 valid 4294967295 preferred 4294967295 (1 in use, 0   conflicts)

DNS server: 2001:DB8:1202::1

Domain name: domain2.com

Active clients: 1

DHCPv6 pool: pool3

Address allocation prefix:   2001:DB8:3333::/64 valid 4294967295 preferred 4294967295 (1 in use, 0   conflicts)

DNS server: 2001:DB8:1203::1

Domain name: domain3.com

Active clients: 1

DHCPv6#

IOS DHCP Client:

FastEthernet0/0             [up/up]

   FE80::C803:90FF:FE38:0

    2001:DB8:1111:0:18D7:1F49:316D:335

DHCPv6Client#

DHCPv6Client#

DHCPv6Client#

DHCPv6Client#sh ipv6 dhcp interface

FastEthernet0/0 is in client mode

Prefix State is IDLE

Address State is OPEN

Renew for address will be sent   in 10:48:47

List of known servers:

   Reachable via address:   FE80::C804:90FF:FE38:8

  DUID: 00030001CA0490380008

   Preference: 0

   Configuration parameters:

     IA NA: IA ID 0x00040001, T1   43200, T2 69120

       Address:   2001:DB8:1111:0:18D7:1F49:316D:335/128

               preferred   lifetime INFINITY, valid lifetime INFINITY

     DNS server:   2001:DB8:1201::1

     Domain name: domain1.com

     Information refresh time: 0

Prefix Rapid-Commit: disabled

Address Rapid-Commit: disabled

DHCPv6Client#

Debian Client:

2011.12.23 17:08:48   Client Info     Creating SOLICIT   message with 1 IA(s), no TA and 0 PD(s) on eth1/3 interface.

2011.12.23 17:08:49   Client Info     Processing msg   (SOLICIT,transID=0xee14b2,opts: 1 3 8 6)

2011.12.23 17:08:49   Client Info     Received ADVERTISE on   eth1/3,TransID=0xee14b2, 5 opts: 2 1 3 23 24

2011.12.23 17:08:50   Client Info     Processing msg   (SOLICIT,transID=0xee14b2,opts: 1 3 8 6)

2011.12.23 17:08:50   Client Info     Creating REQUEST. Backup   server list contains 1 server(s).

2011.12.23 17:08:51   Client Info     Processing msg   (REQUEST,transID=0x201d85,opts: 1 3 8 6 2)

2011.12.23 17:08:51   Client Info     Received REPLY on   eth1/3,TransID=0x201d85, 5 opts: 2 1 3 23 24

2011.12.23 17:08:51   Client Notice   Address   2001:db8:2222:0:8d1b:4b3d:24e1:d21e/64 added to eth1/3 interface.

2011.12.23 17:08:51   Client Notice   Setting up DNS server   2001:db8:1202::1 on interface eth1/3.

2011.12.23 17:08:51   Client Notice   Setting up Domain   domain2.com on interface eth1/3.

user@debian:

user@debian:/etc/init.d$   ip a

1: eth1:   mtu 1500 qdisc pfifo_fast state UP   qlen 1000

   link/ether 08:00:27:83:6b:58 brd   ff:ff:ff:ff:ff:ff

   inet6 2001:db8:2222:0:a00:27ff:fe83:6b58/64   scope global dynamic

       valid_lft 2591973sec preferred_lft   604773sec

   inet6 fe80::a00:27ff:fe83:6b58/64 scope   link

       valid_lft forever preferred_lft   forever

user@debian:/etc/init.d$

Windows Client:

I hope this will be of help for you as it was for myself

AJN

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