Mailing List Archive

Cisco LAC/LNS question
Why in the virtual-template section is there a
peer default ip address dhcp
but no
peer default ipv6 address dhcp

The only thing I can do is
peer default ipv6 pool <poolname>
which uses a local pool on the BRAS.

I would like to use an external DHCP server to hand out the PPP client
addresses. I believe "ipv6 dhcp relay destination <servername>" is only for
prefix delegation.

Any ideas?

Regards,

Frank Bulk
Re: Cisco LAC/LNS question [ In reply to ]
On Thu, Dec 30, 2010 at 05:25:54PM -0600, Frank Bulk - iName.com wrote:
> Why in the virtual-template section is there a
> peer default ip address dhcp
> but no
> peer default ipv6 address dhcp

Because IETF decided to not include global IP negotiation in IP6CP
in PPP. IP6CP only negotiates an interface identifiers which are then
used to create link-local addresses on both ends. Determination of
the global addresses is then supposed to happen with SLAAC or DHCPv6.

> The only thing I can do is
> peer default ipv6 pool <poolname>
> which uses a local pool on the BRAS.

That's for a local prefix delegation pool. See
http://www.ipv6-es.com/03/documents/cisco/index3.htm
4.1.2

> I would like to use an external DHCP server to hand out the PPP client
> addresses. I believe "ipv6 dhcp relay destination <servername>" is only for
> prefix delegation.

Not really, also for global IP.

If you need to assign "known" IPv6 global addresses to PPP clients,
you need to make them do DHCPv6 for it. One way is to send RAs on the
PPP session with managed config flag set.

Best regards,
Daniel

--
CLUE-RIPE -- Jabber: dr@cluenet.de -- dr@IRCnet -- PGP: 0xA85C8AA0
Re: Cisco LAC/LNS question [ In reply to ]
Hi,

seeing this thread, I was wondering ... we have our LAC/LNS working fine
so far, even with v6, but we have only tested with Cisco CPEs for now
... on the LNS side, I took this road:

interface Virtual-Template1
[..]
ipv6 unnumbered Loopback1
ipv6 enable
ipv6 mtu 1480
ipv6 nd reachable-time 30
no ipv6 nd ra suppress
peer default ip address pool dsl-pool
peer default ipv6 pool dslv6-pool

With a CPE that has ipv6 enabled on the dialer, an address is assigned
correctly, and the CPE is reachable via v6 just fine.

>From some comments or how-tos I saw at other places, I take it this way
will not necessarily work with any v6-capable CPE. E.g., Fredy K├╝nzler
held a nice presentation at DENOG#2, which showed the DHCPv6 usage (
http://www.denog.de/meetings/denog2/pdf/002-Kuenzler-Native_IPv6_via_xdsl.pdf
).

So what's the recommended way of handing out dynamic IPs to customers?
Can both the "Cisco way" I used and DHCPv6 be combined with the CPE just
using either which one suits them?

-garry
Re: Cisco LAC/LNS question [ In reply to ]
> So what's the recommended way of handing out dynamic IPs to customers?
> Can both the "Cisco way" I used and DHCPv6 be combined with the CPE just
> using either which one suits them?

If the CPE is not just a single host, there are two questions, possibly
with different answers.

1. How does the CPE get its own IPv6 interface address? The answer could be
SLAAC or DHCPv6. SLAAC is the lowest common denominator.

2. How does the CPE, acting as a router, get the subnet prefix that
it will announce to the customer network? DHCPv6-PD seems like the
obvious answer. See draft-ietf-v6ops-ipv6-cpe-router-08 for
the almost-agreed recommendations, and hold your breath for products.

Brian
RE: Cisco LAC/LNS question [ In reply to ]
Thanks, Daniel, this is now coalescing in my mind. I knew there was
something special about IPv6 and IPCP, but this example makes it concrete
for me.

Once I get this working with the Cisco 871W I'm testing with, then I'm off
to try with the D-Link 615 and 825, as well as a couple of DSL modems I have
on my counter.

Frank

-----Original Message-----
From: ipv6-ops-bounces+frnkblk=iname.com@lists.cluenet.de
[mailto:ipv6-ops-bounces+frnkblk=iname.com@lists.cluenet.de] On Behalf Of
Daniel Roesen
Sent: Friday, December 31, 2010 8:12 AM
To: ipv6-ops@lists.cluenet.de
Subject: Re: Cisco LAC/LNS question

On Thu, Dec 30, 2010 at 05:25:54PM -0600, Frank Bulk - iName.com wrote:
> Why in the virtual-template section is there a
> peer default ip address dhcp
> but no
> peer default ipv6 address dhcp

Because IETF decided to not include global IP negotiation in IP6CP
in PPP. IP6CP only negotiates an interface identifiers which are then
used to create link-local addresses on both ends. Determination of
the global addresses is then supposed to happen with SLAAC or DHCPv6.

> The only thing I can do is
> peer default ipv6 pool <poolname>
> which uses a local pool on the BRAS.

That's for a local prefix delegation pool. See
http://www.ipv6-es.com/03/documents/cisco/index3.htm
4.1.2

> I would like to use an external DHCP server to hand out the PPP client
> addresses. I believe "ipv6 dhcp relay destination <servername>" is only
for
> prefix delegation.

Not really, also for global IP.

If you need to assign "known" IPv6 global addresses to PPP clients,
you need to make them do DHCPv6 for it. One way is to send RAs on the
PPP session with managed config flag set.

Best regards,
Daniel

--
CLUE-RIPE -- Jabber: dr@cluenet.de -- dr@IRCnet -- PGP: 0xA85C8AA0
RE: Cisco LAC/LNS question [ In reply to ]
Hi,


On Fri, 31 Dec 2010, Frank Bulk - iName.com wrote:

> Thanks, Daniel, this is now coalescing in my mind. I knew there was
> something special about IPv6 and IPCP, but this example makes it concrete
> for me.
>
> Once I get this working with the Cisco 871W I'm testing with, then I'm off
> to try with the D-Link 615 and 825, as well as a couple of DSL modems I have
> on my counter.


It is worth looking at:
http://labs.ripe.net/Members/mirjam/ipv6-cpe-survey-updated-september-2010
http://labs.ripe.net/Members/marco/content-ipv6-cpe-survey

and the comments also.

Best Regards and hapy new year,
Janos Mohacsi



>
> Frank
>
> -----Original Message-----
> From: ipv6-ops-bounces+frnkblk=iname.com@lists.cluenet.de
> [mailto:ipv6-ops-bounces+frnkblk=iname.com@lists.cluenet.de] On Behalf Of
> Daniel Roesen
> Sent: Friday, December 31, 2010 8:12 AM
> To: ipv6-ops@lists.cluenet.de
> Subject: Re: Cisco LAC/LNS question
>
> On Thu, Dec 30, 2010 at 05:25:54PM -0600, Frank Bulk - iName.com wrote:
>> Why in the virtual-template section is there a
>> peer default ip address dhcp
>> but no
>> peer default ipv6 address dhcp
>
> Because IETF decided to not include global IP negotiation in IP6CP
> in PPP. IP6CP only negotiates an interface identifiers which are then
> used to create link-local addresses on both ends. Determination of
> the global addresses is then supposed to happen with SLAAC or DHCPv6.
>
>> The only thing I can do is
>> peer default ipv6 pool <poolname>
>> which uses a local pool on the BRAS.
>
> That's for a local prefix delegation pool. See
> http://www.ipv6-es.com/03/documents/cisco/index3.htm
> 4.1.2
>
>> I would like to use an external DHCP server to hand out the PPP client
>> addresses. I believe "ipv6 dhcp relay destination <servername>" is only
> for
>> prefix delegation.
>
> Not really, also for global IP.
>
> If you need to assign "known" IPv6 global addresses to PPP clients,
> you need to make them do DHCPv6 for it. One way is to send RAs on the
> PPP session with managed config flag set.
>
> Best regards,
> Daniel
>
> --
> CLUE-RIPE -- Jabber: dr@cluenet.de -- dr@IRCnet -- PGP: 0xA85C8AA0
>
>
>