From: Peter van Oene (pvo@usermail.com)
Date: Mon Dec 02 2002 - 06:11:34 GMT-3
Some modifications inline
On Mon, 2002-12-02 at 06:06, Adam Crisp wrote:
> Hi,
>
> This is probably some help to you!
>
> Type 1 = Router Link Advertisements , generated by every router.
> Type 2 = Multi-access segment Network Link Advertisements , generated by DR
> Type 3 = Summary Link Advertisements. Summary, generated by the ABR for
> EVERY type 1,2. Type 3 can be generated to describe a summary for a bigger
> lump of addresses. Works in both directions, so that a Type 3 from Area 1,
> can traveres the backbone and go into say Area 2. Depends upon your
> configuration.
Type 3 summaries are created from information in the ABRs routing
table. Hence, the ABR doesn't exactly summarized type 1/2's, but ospf
routes in its routing table that are defined as intra area. This is a
hair split I know ;-)
Another hair split point is that type 3's are not flooded inter area,
but generated anew for each area by relevant ABRs. In this case, a type
3 from area 1 never gets _flooded_ into area 2. The routing information
might be advertised in both areas, but it will be done so via a new LSA.
> Type 4 = Summary Link Advertisements. Generated by ASBR.
Type 4's are generated by ABRs when an ASBR exists in the area.
> Type 5 = Autonomous System (AS) External Link Advertisements. Generated by
> ASBR.
> Type 7 = Not-So-Stubby Areas (NSSA). Generated by external route sources
> within a NSSA, or by the ABR ro a NSSA area.
Generated by an NSSA ASBR
>
> A type 5 is what you'd see for you external routers as long as you weren't
> in a NSSA area, where you'd see a type 7 instead. the ABR for the NSSA area
> does a type 5 to type 7 conversion. This ABR might let in the type 3's from
> the other area. All depends upon the configuration of the router. >
> Good luck
>
> Adam
> -----Original Message-----
> From: nobody@groupstudy.com [mailto:nobody@groupstudy.com]On Behalf Of
> Pun, Alec CL
> Sent: 02 December 2002 10:37
> To: Surendran; 'Tom Young'; ccielab@groupstudy.com
> Subject: RE: OSPF lsa type
>
>
> how about LSA Type 4 ?
> I am not sure it will be solely originated by ABR or also from ASBR.
>
> alec
>
> -----Original Message-----
> From: Surendran [mailto:surenv@hpssk211.sgp.hp.com]
> Sent: Monday, December 02, 2002 2:28 PM
> To: 'Tom Young'; ccielab@groupstudy.com
> Subject: RE: OSPF lsa type
>
>
> It is more like this
>
> LSA Type 5 is external routers by ASBR
> LSA Type 7 is by NSSA
>
> Suren
>
> -----Original Message-----
> From: nobody@groupstudy.com [mailto:nobody@groupstudy.com] On Behalf Of
> Tom Young
> Sent: Sunday, December 01, 2002 8:39 PM
> To: ccielab@groupstudy.com
> Subject: OSPF lsa type
>
>
> Hi group
>
> Sorry for a very simple question, the ospf LSA type 3,4
> are all generated by ABR, and the type 7 is originated by
> ASBR, right ?
>
> thanks alot
>
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