[Xorp-hackers] Re: [Xorp-cvs] XORP cvs commit: xorp/etc/templates xorp/ospf xorp/xrl/interfaces xorp/xrl/targets

[Hasso Tepper]

Atanu Ghosh wrote:
>     Hasso> And this allows to configure to originate default into
>     Hasso> backbone area as well? And disable summary origination into
>     Hasso> backbone area? Junos have these options available only in
>     Hasso> case of nssa and stub areas - ie. nssa and stub are nodes in
>     Hasso> area:
>
> The "default-lsa" configuration only applies if the area is stub or
> nssa. I tried to make this clear in the help text.
>
> XORP# create ?
> Possible completions:
>   default-lsa     Originate default route in stub or not-so-stubby
> areas summaries       Generate summaries into stub or not-so-stubby
> areas
>
>     Hasso> hasso@lab-junos1# show nssa { default-lsa { default-metric
>     Hasso> 10; type-7; } no-summaries; }
>
>     Hasso> [edit protocols ospf area 10.10.10.10] hasso@lab-junos1#
>
> I looked at the Juniper stub and nssa configuration and it is difficult
> for us to emulate. I haven't actually tried it but I assume that the
> stub and nssa configuration blocks are mutually exclusive on a Juniper,

Yes, they are.

> I don't think its possible for us to enforce that requirement in a
> template file. I stayed with a single variable to select the area type
> and a "default-lsa" configuration block from which values could be used
> if appropriate.

Maybe we need something like "conflicts" keyword to define nodes which 
conflicts with each other?

>     Hasso> Note, that it allows to configure type-7 default only in
>     Hasso> case of nssa area as well (bugzilla #555).
>
> Looking at RFC 3101 again it seems that the type of the default LSA is
> based on the summary state. If summaries are enabled then the default
> LSA is a Type-7 LSA, if summaries are disabled then the default LSA is
> a Type-3 LSA. The Juniper type-7 is a backward compatibility switch to
> allow a Type-3 default LSA if summaries are disabled.
>
> The options are:
> 1) To use the summary state to determine that type of the LSA as
> specified in RFC 3101. Thus requiring no further switches.
>
> 2) Add a type-7 variable so the type of the default LSA is user
> selectable.

Yes, Juniper developers implemented Type-3 default only at first (note, 
that there is "should be" in sentence about Type-7 default in RFC3101, so 
Type-7 default isn't really must be) and implemented Type-7 later with 
switch for backward compatibility. I'd say that option 1 should be way to 
go for Xorp.


regards,

-- 
Hasso Tepper