[c-nsp] Cisco 4506 dhcpv6 interface-id, remote-id

[Christian Kratzer]

Hi,

On Wed, 31 May 2017, Pshem Kowalczyk wrote:

> I haven't worked with this particular switch, but does it act as a
> relay-agent? I.e is the message you get a RELAY-FWD one (type 12) with the
> actual message inside? If so you could unpack the switch IP address from
> the outer message and use option 18 to id the port.

it is a plain layer2 config with the ipv6 lightweight dhcp relay agent (ldra)
that transparently inserts the dhcp options into the packets

   http://www.cisco.com/c/en/us/td/docs/switches/lan/catalyst4500/XE3-9-0E/15-25E/configuration/guide/xe-390-configuration/dhcpv6_options_18_37_lrda.html

The ldra feature seems to be implemented quite similarly over all switches running IOS XE.

So there is no switch ip to extract.  Also both isc dhcp and the new kea would
not be able to match the requests with more than one criteria

With other dslam/switches we can configure specific strings as interface-id or
remote-id and match them as follows

     host foo {
         host-identifier v6relopt 1 dhcp6.interface-id "customer-lineid-12345";
         fixed-prefix6 2001:db8:cafe:1200::/56;
     }

We need to identfiy lines in the dhcp for two use cases:

1. assignment of static prefixes
2. logging of assignments to customers

Apprently there are some new commands in IOS 3.9 that I will need to test tomorrow.

Still hoping per interface user configurable interface-id or remote-id will be available on the platform soon.

Greetings
Christian



>
> kind regards
> Pshem
>
> On Wed, 31 May 2017 at 23:43 Christian Kratzer <ck-lists at cksoft.de> wrote:
>
>> Hi,
>>
>> I have multiple c4506 with 80 port linecards in a dhcp based point to
>> point ftth deployment.
>>
>> We already use dhcp option82 circuit-id for identifying customer ipv4
>> assignments in the dhcp server.
>>
>>   ip dhcp snooping vlan 10 information option format-type circuit-id
>> override string <ourlineid>
>>
>> This is good as it allows us to provision our lineid to be used for the
>> circuit-id value.
>>
>> For ipv6 I was intending to use dhcpv6 options 18 or 37 for interface-id
>> or remote-id.
>>
>> Sadly both seem to provide non user configurable values that are only
>> unique in context of the router in question.
>>
>> Option18 provides us with: Gi2/3
>>
>> Option37 provides binary data that does also not inlucude a hostname.
>>
>> Gi2/3 is of course not unique in a network of more than one switch.
>>
>> It seems to be the whole feature is utterly useless.  I have also not
>> found a single cisco platform that would provide user configurable ipv6
>> opt18 or 37.
>>
>> Is a feature like this somewhere on the roadmaps  for the c4506 platform ?
>>
>> Greetings
>> Christian
>>
>> --
>> Christian Kratzer                   CK Software GmbH
>> Email:   ck at cksoft.de               Wildberger Weg 24/2
>> Phone:   +49 7032 893 997 <+49%207032%20893997> - 0       D-71126
>> Gaeufelden
>> Fax:     +49 7032 893 997 <+49%207032%20893997> - 9       HRB 245288,
>> Amtsgericht Stuttgart
>> Mobile:  +49 171 1947 843 <+49%20171%201947843>
>>  Geschaeftsfuehrer: Christian Kratzer
>> Web:     http://www.cksoft.de/
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>

-- 
Christian Kratzer                   CK Software GmbH
Email:   ck at cksoft.de               Wildberger Weg 24/2
Phone:   +49 7032 893 997 - 0       D-71126 Gaeufelden
Fax:     +49 7032 893 997 - 9       HRB 245288, Amtsgericht Stuttgart
Mobile:  +49 171 1947 843           Geschaeftsfuehrer: Christian Kratzer
Web:     http://www.cksoft.de/