From: John Hooper (john.hooper@homith.com)
Date: Thu Sep 13 2007 - 06:57:12 ART
G'Day Again,
Ahh !!!!! Now I can see it. It was looking at me in the
face all the time. Thanks so much Shiran I was looking at the headings but not
'Reading' them :)
Router# show ip ospf database
OSPF Router with ID(192.168.1.11) (Process ID 1)
Router Link States(Area 0)
Link ID ADV Router Age Seq# Checksum Link
count
192.168.1.8 192.168.1.8 1381 0x8000010D 0xEF60 2
192.168.1.11 192.168.1.11 1460 0x800002FE 0xEB3D 4
192.168.1.12 192.168.1.12 2027 0x80000090 0x875D 3
192.168.1.27 192.168.1.27 1323 0x800001D6 0x12CC 3
Net Link States(Area 0)
<---------------------------------------------------------------------------T
hese are the headings I was looking at but not READING them :)
Link ID ADV Router Age Seq# Checksum
172.16.1.27 192.168.1.27 1323 0x8000005B 0xA8EE
172.17.1.11 192.168.1.11 1461 0x8000005B 0x7AC
Type-10 Opaque Link Area Link States (Area 0)
<------------------------------------------These are the headings I was
looking at but not READING them :)
Link ID ADV Router Age Seq# Checksum Opaque ID
10.0.0.0 192.168.1.11 1461 0x800002C8 0x8483 0
10.0.0.0 192.168.1.12 2027 0x80000080 0xF858 0
10.0.0.0 192.168.1.27 1323 0x800001BC 0x919B 0
10.0.0.1 192.168.1.11 1461 0x8000005E 0x5B43 1
Gee I need to learn to open my eyes up more. Thanks again for your valuable
input.
Cheers
John
----- Original Message -----
From: shiran guez
To: John Hooper
Cc: ccielab@groupstudy.com
Sent: Thursday, September 13, 2007 7:42 PM
Subject: Re: Understanding the command 'show ip ospf database' better
well it is actually very simple,
the database is divide in such a way that you can see the the LSA that where
received in a real structured manner
mean you will see the LSA type and area it is related to in the title and
bellow the title what are the received updates for that LSA.
and how do you know the type of the area you are in well to know that you
need to understand the OSPF concept and know that for example if you see LSA
type 7 then you are in NSSA area and if you see an area that have only LSA
type 1 ( and you have a neighbor relationship) it mean that you are in a No
DR/BDR ospf mode and you probably in a stub or even totally stuby area.
LSA 1 is router advertisement - each router in OSPF generate it
LSA 2 is network advertisement - only DR generate it for example in point to
point envio there is not DR/BDR relation so there is no LSA 2
LSA 3 is a summary advertisement - only ABR generate it because the OSPF is
a link state protocol each member of the OSPF are must have the same OSPF DB,
the multi area concept solve the need to have a very large and unnecessary
update in the DB
LSA 4 is little confusing it is specific advertisement generated by the ABR
to specify the location of the ASBR
LSA 5 is generated by the ASBR
LSA 6 is related to OSPF ver 3 as i recall
LSA 7 is the same as 5 but in a NSSA area
the rest I do not remember and I think the rest are not actually relevant
that much.
there is a lot more to it then what I have specified but I think it is a
start.
as a general note you must know OSPF end to end to pass the CCIE and I think
all will agree with me on that.
I hope this was a little helpful
On 9/13/07, John Hooper <homith@homith.com> wrote:
G'Day Group,
Just a question regarding the command "show ip ospf
database". If I was given an output from "show ip ospf database" and asked
to
explain what area the router is in and what type of area is, I can work
out
what ospf area the router is in but I am confused on how to work out the
area
type it is (eg is it a standard OSPF area, or stub or totally stubby, etc
..)
If anyone can point me in the right direction I know I am just missing
something here in my head :)
Cheers
John
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Shiran Guez
MCSE CCNP NCE1
http://cciep3.blogspot.com
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