DHCPv6 Option 18 (interface-id) relay problem

Thu Nov 8 12:37:13 UTC 2012

Hello Christian,

thanks a lot for the reply.

Do you know how I have to change my configuration?
I couldn't find andy documentation for that...

Thanks in advance...

Andreas Hanke

Hi,

On Wed, 7 Nov 2012, Andreas Hanke wrote:

> Hello together,
>
> I am working on a problem with my ISC DCHP Version 4.2.4-P2 server for IPv6 since a lot of days.
> But I could not found a solution. So I hope someone could help me.
>
> - Situation:
> I have to discover the Host by an interface id to give him a fixed IP address.
> This interface id will inserted by an DSLAM which is connected to a lot of DSL Modems.
> The interface id is the identifier, on which physical port the DSL Modem is connected.
> I like to use the host definition into my dhcp.conf:
> example:
>
> host ws {
>        host-identifier option dhcp6.interface-id "Interface-ID: DSLAM01 eth 2/1/01/21"
>        fixed-address6 2001:db8:1:1::701;
> }

have you tried it out ? I would be interested in hearing the results.

A quick look at the dhcp6 code shows it does call find_host_by_option() to find a host.
This possible might do what you want but I am not 100% sure.

Greetings
Christian

Am 08.11.2012 13:07, schrieb Andreas Hanke:

Hello Frank,

I don't like to use RADIUS with PPoE because the overhead of the DHCP
traffic is slimmer and so have more performance.

Other ideas in the DHCP word?

thanks a lot

Andreas Hanke

Am 08.11.2012 13:00, schrieb dhcp-users-request at lists.isc.org<mailto:dhcp-users-request at lists.isc.org>:

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Today's Topics:

   1. RE: DHCPv6 Option 18 (interface-id) relay problem (Frank Bulk)
   2. Re: DHCPv6 Option 18 (interface-id) relay problem
      (Christian Kratzer)

----------------------------------------------------------------------

Message: 1
Date: Wed, 7 Nov 2012 19:41:01 -0600
From: "Frank Bulk" <frnkblk at iname.com><mailto:frnkblk at iname.com>
To: <dhcp-users at lists.isc.org><mailto:dhcp-users at lists.isc.org>
Subject: RE: DHCPv6 Option 18 (interface-id) relay problem
Message-ID: <000801cdbd52$1c2e80b0$548b8210$@iname.com><mailto:000801cdbd52$1c2e80b0$548b8210$@iname.com>
Content-Type: text/plain; charset="iso-8859-1"

Can you use RADIUS instead?

Frank

From: dhcp-users-bounces+frnkblk=iname.com at lists.isc.org<mailto:dhcp-users-bounces+frnkblk=iname.com at lists.isc.org>
[mailto:dhcp-users-bounces+frnkblk=iname.com at lists.isc.org] On Behalf Of
Andreas Hanke
Sent: Wednesday, November 07, 2012 1:52 AM
To: dhcp-users at lists.isc.org<mailto:dhcp-users at lists.isc.org>
Subject: DHCPv6 Option 18 (interface-id) relay problem

Hello together,

I am working on a problem with my ISC DCHP Version 4.2.4-P2 server for IPv6
since a lot of days.
But I could not found a solution. So I hope someone could help me.

- Situation:
I have to discover the Host by an interface id to give him a fixed IP
address.
This interface id will inserted by an DSLAM which is connected to a lot of
DSL Modems.
The interface id is the identifier, on which physical port the DSL Modem is
connected.
I like to use the host definition into my dhcp.conf:
example:

host ws {
        host-identifier option dhcp6.interface-id "Interface-ID: DSLAM01 eth
2/1/01/21"
        fixed-address6 2001:db8:1:1::701;
}

- My setup:
Client PC with DSL Modem <-------------> DSLAM which is inserting a option
18 with the interface id <-----------> CISCO 7606-S Router which have a
helper at the interface which is connected to the DHCP server. This helper
forward the DCHP Message to the DHCP server and works as a relay
<-----------> ISC DCHP server for IPv6

- Parts of my server configuration:
----------------------------------------------------------------------------
-------------------------------------------------------
# Please see:
http://www.ipamworldwide.com/dhcp-options/isc-dhcpv6-options.html
#This function logs the DHCPv6 client id, which means the Link Local Address
(Option 1)
log(info,concat("Client-ID: " , binary-to-ascii(16,8,"-",option
dhcp6.client-id)));
#This function logs the DHCPv6 interface id, which means the port of the
DSLAM (Option 18)
log(info,concat("Interface-ID: " , option dhcp6.interface-id));
----------------------------------------------------------------------------
-------------------------------------------------------

- My problem:
The ISC DHCP server could not discover the interface-id (Option 18), which
is inserted by the DSLAM -> get no log message (see configuration).
The client-id (Option 1), which is inserted by the Client PC with DSL Modem
works fine -> get log message (see configuration).

I tested it without CISCO and without DSLAM/DSL Modem direct connect over an
Networkswitch and inserting the interface-id (Option 18) by the Client PC,
that works -> get log message (see configuration).

After that I analysed the TCP packets. What I found out is, that the
difference is that:
- Message type "RELAY-FORW (12)" with CISCO and DSLAM/DSL Modem:
<field name="dhcpv6.msgtype" showname="Message type: Relay-forw (12)"
size="1" pos="62" show="12" value="0c"/>
- Message type "SOLICIT (1)" without CISCO and DSLAM/DSL Modem:
<field name="dhcpv6.msgtype" showname="Message type: Solicit (1)" size="1"
pos="62" show="1" value="01"/>

Side information:
If I configured an ipv6 range without host definitions into my dhcp.conf the
Client PC get in both situations an ip6 address.

Could you tell me if the message type is the problem and if yes what I have
to change?
If no, what went wrong?

I have attached the both network packets with situation 1 "with CISCO and
DSLAM" and situation 2 "without CISCO and DSLAM".

Thanks a lot for your help!

________________________________
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