Howard, Thanks for the explanation too. However, I still have 2 questions regarding default-information originate command.
> If there's more than one default router, you definitely don't want the always keyword. Why? Wouldn't the ASBR still be able to advertise it's default route to other routers? > AFAIK, if the router was default-free, you couldn't use > default-information originate without always, because the router > would never have a local default to meet the ALWAYS condition. In > that case, you'd have to have BGP or a static route specify it, and > redistribute that route into OSPF. If the ASBR was default-free (who hasn't got a default route), wouldn't it be true if you can ONLY use the default-information originate (without the "Always" keyword")? Thanks in advance. Best Regards, Hunt Lee ""Howard C. Berkowitz"" wrote in message [EMAIL PROTECTED]">news:[EMAIL PROTECTED]... > >Regarding this command... > >"Default-information originate [always]" > >this is documented as saying... > >this generates the default route into OSPF even if the path to the default > >route goes down... > >and... > >even when the router has no default route, with the magic keyword "always" > it > >will create a "default route"...pointing to where?? > >Q: What's the point of advertising a route if it is indeed DOWN? Isn't this > >like saying i know that Exit5 is closed but I'm gona keep directing all > >motorists to go to Exit 5 anyway? > > > >Please clarify this for me. > > > >Elmer > > Imagine you have a fairly large OSPF area. If the default route goes > down, all the topological databases have to be updated and > propagated. While if JUST the default route were involved, the > Dijkstra computation will not have to be run, there still will be > bandwidth and processor utilization. > > If there is only one router generating default, and it goes down, the > traffic is going to fail anyway. To take your traffic analogy, > default-information always is indeed like directing the traffic > LEAVING THE AREA to Exit 5, but not otherwise disturbing those cars > that don't care about Exit 5. > > If there's more than one default router, you definitely don't want > the always keyword. > > Now--as far as where it points: "it depends". All it points to is > the router generating default. That router may or may not have a > default route of its own -- it might be a default-free BGP router as > well as an ASBR. It could have a default route of its own that points > somewhere outside the AS or area. > > AFAIK, if the router was default-free, you couldn't use > default-information originate without always, because the router > would never have a local default to meet the ALWAYS condition. In > that case, you'd have to have BGP or a static route specify it, and > redistribute that route into OSPF. Message Posted at: http://www.groupstudy.com/form/read.php?f=7&i=38627&t=33729 -------------------------------------------------- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
