From: Chris Larson (clarson52@xxxxxxxx)
Date: Thu Dec 06 2001 - 00:09:37 GMT-3
Ahhh. Thanx
----- Original Message -----
From: "W. Alan Robertson" <warobertson@earthlink.net>
To: <ccielab@groupstudy.com>
Sent: Monday, November 05, 2001 8:26 PM
Subject: Re: When to use "always"
> Close, but not quite.
>
> The "always" keyword has nothing to do with the routing table of the
> router upon which it is configured. It only affects the behaviour of
> what that router advertises to it's OSPF neighbors.
>
> When the "default-information originate always" is used, it does just
> that... That router advertises the 0.0.0.0/0 route to all of it's
> OSPF neighbors, and this route will be carried throughout the routing
> domain.
>
> The consequence of this is that if the advertising router doesn't
> actually have a default gateway, you have successfully blackholed the
> Internet (Or any route less specific than what you have in the routing
> tables throughout your routing domain).
>
> This may be ok, in certain circumstances... If the router which uses
> the "always" keyword is the only way out of the network, for example,
> but the circuit drops periodically, it's probably ok that you continue
> to advertise the route. It becomes a matter of personal preference;
> you are deciding where non-routable packets hit the bit-bucket. If
> your routing domain has a highly utilized serial connections of
> varying speeds (which is likely), you may find it bettter that
> non-routable traffic get dropped closer to the source, so as not to
> utilize precious bandwidth within your enterprise.
>
> Hope this helps...
>
> Alan
>
> ----- Original Message -----
> From: "Chris Larson" <clarson52@home.com>
> To: "Joe" <joe.morabito@home.com>; <ccielab@groupstudy.com>
> Sent: Wednesday, December 05, 2001 6:20 PM
> Subject: Re: When to use "always"
>
>
> > I do not understand what you are saying Cisco said, but my
> understanding of
> > this is that the default route will remain in the table regardless
> of
> > whether the next hop appear in the table or not.
> >
> > So if you had something like
> >
> > ip route 0.0.0.0 0.0.0.0 192.168.1.1
> >
> > and the 192.168.1.1 route was not in the table the default route
> would
> > disappear (ie. floating static ).
> >
> > by adding the keyword always the default route would remain in the
> table
> > whether a route to 192.168.1.1 was there or not. I would imagine if
> the
> > default info originate has the same keyword it works the same way.
> >
> >
> >
> >
> > ----- Original Message -----
> > From: "Joe" <joe.morabito@home.com>
> > To: <ccielab@groupstudy.com>
> > Sent: Wednesday, December 05, 2001 4:01 PM
> > Subject: When to use "always"
> >
> >
> > > Can someone please help me understand when exactly to use "always"
> when
> > > injecting a default route into ospf?
> > >
> > > CCO says that "always" disregards the requirement of already
> having a
> > default
> > > route for the router itself. If this is true, and you don't have
> "ip
> > route
> > > 0.0.0.0 0.0.0.0 x.x.x.x" and you are not using a route map, then
> will it
> > still
> > > work?
> > >
> > > Thanks.
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