From: Adam Crisp (adam.crisp@totalise.co.uk)
Date: Mon Dec 02 2002 - 09:02:37 GMT-3
Hi,
A few people have pointed out to me that I typo'd the type 4 LSA
description. This was especially embarassing because the initial thread was
about type 4 LSA's. Appologies.
indeed type 4 LSA's are generated by an ABR.
A type 4 LSA is a host route to a ASBR.
An example:
Router 5 redistributes a static route to 100.0.0.0/24. (tag 5555)
This router is therefore an ASBR.
In my topology:
Router5 - solely in Area 33. ID 135.1.5.5,
Router3 - ABR for Area 33, ID 135.1.3.3
Router4 = Area0 router.
thus issuing a show ip ospf database on Router4 gives:
Summary ASB Link States (Area 0) !type 4
Link ID ADV Router Age Seq# Checksum
135.1.5.5 135.1.3.3 1 0x80000001 0x9F70
Type-5 AS External Link States
Link ID ADV Router Age Seq# Checksum Tag
100.0.0.0 135.1.5.5 661 0x80000001 0x6684 5555
sorry for any confusion.
Adam
-----Original Message-----
From: nobody@groupstudy.com [mailto:nobody@groupstudy.com]On Behalf Of
Jaroslaw Zak
Sent: 02 December 2002 11:40
To: adam.crisp@totalise.co.uk; Alec.CL.Pun@pccw.com;
surenv@hpssk211.sgp.hp.com; gitsyoung@yahoo.co.jp;
ccielab@groupstudy.com
Subject: RE: OSPF lsa type
Adam,
I dont agree with your statement about Type 4. To the best of my knowledge
summary advert (if) generated by ASBR is LSA-5 (external route) and thats
how its presented in routing table (E1/E2).
Type 4 is host route to ASBR and is generated by ABR, so all routers within
areas know how to get to ASBR advertising Type 5.
Please correct me if i'm wrong
Jarek
>From: "Adam Crisp" <adam.crisp@totalise.co.uk>
>Reply-To: "Adam Crisp" <adam.crisp@totalise.co.uk>
>To: "Pun, Alec CL" <Alec.CL.Pun@pccw.com>, "Surendran"
><surenv@hpssk211.sgp.hp.com>, "'Tom Young'" <gitsyoung@yahoo.co.jp>,
><ccielab@groupstudy.com>
>Subject: RE: OSPF lsa type
>Date: Mon, 2 Dec 2002 11:06:10 -0000
>
>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 4 = Summary Link Advertisements. Generated by ASBR.
>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.
>
>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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