IOS DHCPv6 deployment schemes


The following four posts are dedicated to DHCPv6 deployment. For the reasons I mentioned in the previous post, I used IOS version 12.4(24)T for all routers.

(XXXX:YYYY pattern in certain IPv6 addresses is used to hide a part of prefixes for privacy purpose)

Stateful DHCPv6 [1/4]

Rapid-commit

For this classic client-server DHCPv6 model, I deployed both modes rapid and normal commit.

Picture1: Stateful DHCPv6 rapid-commit topology

Server configuration [> 12.4(24) T]:

ipv6 unicast-routing

ipv6 dhcp pool pool23

address prefix 2001:DB8:23::/64 lifetime infinite infinite

dns-server XXXX:YYYY:8B6B:90E0::57

dns-server 2001:DB8::57

domain-name nouri.com

 

interface FastEthernet0/1

ipv6 address 2001:DB8:23::2/64

ipv6 dhcp server pool23 rapid-commit

 

R2(config-if)#do #do sh ipv6 int brief

FastEthernet0/0 [administratively down/down]

unassigned

FastEthernet0/1 [up/up]

FE80::C803:37FF:FEAC:62001:DB8:23::2

FastEthernet1/0 [administratively down/down]

unassigned

FastEthernet1/1 [administratively down/down]

unassigned

R2(config-if)#

Client configuration [> 12.4(24) T]:

ipv6 unicast-routing

!interface FastEthernet0/0

ipv6 address dhcp
rapid-commit

ipv6 enable

Make sure to explicitly enable IPv6 on the interface otherwise the interface will not send the SOLLICIT message as shown below:

R3(config-if)#

*Oct 23 00:41:58.363: IPv6 DHCP: IPv6 not ready on FastEthernet0/0, message not sent

With Rapid-Commit only 2 messages exchanged between the client and the server:

The Client asks for an address by sending SOLLICIT message and the Server responds with the address in REPLY message.

The other messages used in Normal-commit, the default mode, are used in an environment with redundant DHCPv6 servers so they are informed of the allocated addresses to avoid duplicate address assignment.

R3(config-if)#*Oct 23 00:43:13.179: IPv6 DHCP: Sending SOLICIT to FF02::1:2 on FastEthernet0/0
*Oct 23 00:43:13.287: IPv6 DHCP: Received REPLY from FE80::C803:37FF:FEAC:6 on FastEthernet0/0
*Oct 23 00:43:13.287: IPv6 DHCP: Adding server FE80::C803:37FF:FEAC:6*Oct 23 00:43:13.291: IPv6 DHCP: Processing options*Oct 23 00:43:13.291: IPv6 DHCP: Adding address 2001:DB8:23:0:70F8:B144:49B6:1FC8/128 to FastEthernet0/0*Oct 23 00:43:13.299: IPv6 DHCP: T1 set to expire in 43200 seconds*Oct 23 00:43:13.303: IPv6 DHCP: T2 set to expire in 69120 seconds

*Oct 23 00:43:13.303: IPv6 DHCP: Configuring DNS server XXXX:YYYY:8B6B:90E0::57

*Oct 23 00:43:13.303: IPv6 DHCP: Configuring DNS server 2001:DB8::57

*Oct 23 00:43:13.303: IPv6 DHCP: Configuring domain name nouri.com

*Oct 23 00:43:13.303: IPv6 DHCP: DHCPv6 address changes state from SOLICIT to OPEN (ADDR_REPLY_RECEIVED) on FastEthernet0/0

R3(config-if)#

Picture2: Rapid-Commit packet exchange

R3(config-if)#do show ipv6 int brief

FastEthernet0/0 [up/up]

FE80::C806:CFF:FE88:82001:DB8:23:0:70F8:B144:49B6:1FC8

FastEthernet0/1 [administratively down/down]

unassigned

R3(config-if)#

Verification:

DHCPv6 Server R2:

R2#sh ipv6 dhcp binding

Client: FE80::C806:CFF:FE88:8DUID: 00030001CA060C880008

Username : unassigned

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

Address: 2001:DB8:23:0:8A1:BD85:5F98:2321

preferred lifetime INFINITY, , valid lifetime INFINITY,

R2#

DHCP roles are configured per-interface

R2#sh ipv6 dhcp interface

FastEthernet0/1 is in server mode

Using pool: pool23

Preference value: 0

Hint from client: ignored

Rapid-Commit: enabled

R2#

After the assignment, the server is aware of the client.

R2#sh ipv6 dhcp pool

DHCPv6 pool: pool23

Address allocation prefix: 2001:DB8:23::/64 valid 4294967295 preferred 4294967295 (1 in use, 0 conflicts)

DNS server: XXXX:YYYY:8B6B:90E0::57

DNS server: 2001:DB8::57

Domain name: nouri.com

Active clients: 1

R2#

DHCPv6 Client R3:

 

R3#sh ipv6 dhcpThis device’s DHCPv6 unique identifier(DUID): 00030001CA060C880008R3#

 

R3#sh ipv6 dhcp interface

FastEthernet0/0 is in client modePrefix State is IDLEAddress State is OPEN

Renew for address will be sent in 10:18:52List of known servers:

Reachable via address: FE80::C803:37FF:FEAC:6

DUID: 00030001CA0337AC0008

Preference: 0

Configuration parameters:

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

Address: 2001:DB8:23:0:8A1:BD85:5F98:2321/128

preferred lifetime INFINITY, valid lifetime INFINITY

DNS server: XXXX:YYYY:8B6B:90E0::57

DNS server: 2001:DB8::57

Domain name: nouri.com

Information refresh time: 0

Prefix Rapid-Commit: disabled

Address Rapid-Commit: enabled

R3#

The client is pointing a static route to the DHCP client interface, because it is a point-to-point segment, no next-hop is needed.

R3#ping ipv6 2001:DB8:23::2

Type escape sequence to abort.

Sending 5, 100-byte ICMP Echos to 2001:DB8:23::2, timeout is 2 seconds:

!!!!!

Success rate is 100 percent (5/5), round-trip min/avg/max = 8/22/44 msR3#

Normal-commit (default)

Picture3: Stateful DHCPv6 normal-commit topology

 

 

 

 

 

 

 

 

 

 

 

 

 

R2 (server):

interface FastEthernet0/1ipv6 address 2001:DB8:23::2/64

ipv6 dhcp server pool23

R3 (Client):

interface FastEthernet0/0ipv6 address dhcp

ipv6 enable

To enable Normal-commit, enough to omit the keyword “rapid-commit”

The ADVERTISE message proposes a prefix to the client and waits for a REQUEST message from this last (destined to all DHCP agents FF02::1:2).

This way, all DHCP servers will be informed of the new IPv6 address assignment.

R3 (client) debug ipv6 dhcp:

R3(config-if)#

*Oct 23 17:41:57.463: IPv6 DHCP: Sending SOLICIT to FF02::1:2on FastEthernet0/0*Oct 23 17:41:57.511: IPv6 DHCP: Received ADVERTISE from FE80::C803:37FF:FEAC:6on FastEthernet0/0*Oct 23 17:41:57.511: IPv6 DHCP: Adding server FE80::C803:37FF:FEAC:6*Oct 23

17:41:58.611: IPv6 DHCP: Sending REQUEST to FF02::1:2on FastEthernet0/0

*Oct 23 17:41:58.611: IPv6 DHCP: DHCPv6 address changes state from SOLICIT to REQUEST (ADDR_ADVERTISE_RECEIVED) on FastEthernet0/0

*Oct 23 17:41:58.655: IPv6 DHCP: Received REPLY from FE80::C803:37FF:FEAC:6on FastEthernet0/0

*Oct 23 17:41:58.655: IPv6 DHCP: Processing options

*Oct 23 17:41:58.655: IPv6 DHCP: Adding address 2001:DB8:23:0:9D54:7AB6:AC57:8230/128 to FastEthernet0/0

*Oct 23 17:41:58.663: IPv6 DHCP: T1 set to expire in 43200 seconds

*Oct 23 17:41:58.663: IPv6 DHCP: T2 set to expire in 69120 seconds

*Oct 23 17:41:58.663: IPv6 DHCP: Configuring DNS server XXXX:YYYY:8B6B:90E0::57

*Oct 23 17:41:58.667: IPv6 DHCP: Configuring DNS server 2001:DB8::57

*Oct 23 17:41:58.667: IPv6 DHCP: Configuring domain name nouri.com

*Oct 23 17:41:58.667: IPv6 DHCP: DHCPv6 address changes state from REQUEST to OPEN (ADDR_REPLY_RECEIVED) on FastEthernet0/0

R3(config-if)#

Picture4: Stateful DHCPv6 normal-commit message exchange

Advertisements

About ajnouri
Se vi deziras sekure komuniki eksterbloge, jen mia publika (GPG) ŝlosilo: My public key for secure communication: http://pgp.mit.edu:11371/pks/lookup?op=get&search=0x41CCDE1511DF0EB8

2 Responses to IOS DHCPv6 deployment schemes

  1. Pingback: IPv4 and IPv6 dual-stack PPPoE | CCIE, the beginning!

  2. Pingback: IPv4 and IPv6 dual-stack PPPoE | ytd2525

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out / Change )

Twitter picture

You are commenting using your Twitter account. Log Out / Change )

Facebook photo

You are commenting using your Facebook account. Log Out / Change )

Google+ photo

You are commenting using your Google+ account. Log Out / Change )

Connecting to %s

%d bloggers like this: