[Xorp-users] questions about IPv6 get_link_local_address

[David Balnaves]

Hi,

Just a quick thanks as I found "default-system-config" addressed my issue
with setting the link-local address.

All the IPv6 implementations(linux, cisco, windows) I've seen sets a
link-local address automatically on the interface when the interface is
brought up.  I think considering this should always be available, having
XORP OSPFv3 probe for the link local address makes sense.  Its also the
behaviour of the "other" OSPFv3 implementation for linux.

I've also noticed that since setting "default-system-config", the IPv6
address assigned to the interface via RA has disappeared.  This may simply
be because linux IPv6 forwarding has been enabled with XORP OSPFv3 becoming
active.  I don't recall this happening when I manually set the link-local
address within XORP(and I dont know how it should deal with this).  From
what I remember, the RFC states that a "router"  (ie: host with ipv6
forwarding enabled) should not use addresses provided by RA.

David Balnaves

----- Original Message ----- 
From: "XORP at sipxx.com" <karl at sipxx.com>
To: <xorp-users at xorp.org>
Sent: Friday, October 09, 2009 10:00 AM
Subject: Re: [Xorp-users] questions about IPv6 get_link_local_address


> That's a reasonable scenario, I suppose. If users need to specify a
> parameter, they can, and if they use the default-system-config in
> addition, they get the rest from default.
>
> There were some other issues with this parameter from my experimentation.
> If I have an interface in the configuration file that uses
> 'default-system-config' and nothing else, it works as expected.
> But then, if I remove the directive from xorpsh->configure and replace
> it with an address specification and commit the change, the address does
> not get configured, I had to save the configuration in a file and
> restart rtrmgr in order for it to get configured accordingly. This was
> for an IPv4 address.
>
>
> Ben Greear wrote:
>> XORP at sipxx.com wrote:
>>> I am not so sure it really should do this totally automatically just
>>> because OSPFv3 requires a particular kind of address. So may other
>>> modules and this can become very non-transparent if each module just
>>> goes about acquiring its own parameters.
>>> This what the 'default-system-config' parameter really seems to be
>>> good for.
>>> What I would like to suggest however, is to provide additional
>>> qualifiers to this parameter so one can differentiate what kind of
>>> system configuration gets imported.
>>> so for example:
>>> ....
>>>     default-system-config {
>>>        address-link-local-ipv6: true
>>>        address-link-local-ipv4: false
>>>        address-ipv4: false
>>>        address-ipv6: true
>>>     }
>>>
>> How about we just probe for anything not specified by the user?  We
>> can do the probe
>> in fea so all of the modules can get the same information.
>>
>> Thanks,
>> Ben
>>
>
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