Single network multiple areas

[bobbie0001]

A major network is advertised as summary in one area and few of the routes from that network is configured in another area. What will happen in that case?

[Muhammad Thanveer · Accepted solution]

What I understand is LSA 1 and LSA 2 of any area will be summary LSAs for other Areas.

If you can elaborate a bit more might be I can help you 

BR

Thanveer

"Please Rate All Helpful Posts"

[bobbie0001]

Lets say 2 routers

The summarization of 1st router 84.84.x.0(84.84.1.0 to 84.84.5.0)

The summarization of 2nd router 84.84.x.0(84.84.6.0 to 84.84.9.0)

How can you configure this summarization. both routers in different areas

Please post the commands.

Thanks in advance

[Muhammad Thanveer · Accepted solution]

Hello bobbie,

Please find the commands as follows,

But the problem is with subnetting if you want to summarize with mask 255.255.248.0 it yields to 84.84.0.0 to 84.84.7.0

and mask 255.255.254.0 yeilds to 84.84.8.0 to 84.84.9.0

area # range network netmask	This command is executed in OSPF router configuration mode on an Area Boarder Router (ABR) to configure Inter-Area route summarization. These summary routes will be advertised into the OSPF backbone area (Area 0).
summary-address network netmask	This command is executed in OSPF router configuration mode on an Autonomous System Boundary Router (ASBR) to configure External route summarization.

[Muhammad Thanveer]

Point to be noted ABR is the Router which has at least one interface in Area 0 and it is not in down state

BR

Thanveer

"Please Rate All Helpful Posts"

[bobbie0001]

Thank you for reply and great info.

May i ask you what is BR you always typing?

Please don't mind if personnel?

[Muhammad Thanveer]

It Meant Best Regards, my dear friend

and Some times i type IMO, In My Opinion.

Bobbie a small suggestion for you,

if you find the answer from the forums, who ever may help you, please mark it as answered. It will give satisfaction for us and encourages us to answer more and it can be easy for others to review the answered discussions for their issues.

BR

Thanveer

"Please Rate All Helpful Posts"

[bobbie0001]

k sure

[Muhammad Thanveer]

Thanks Friend

[bobbie0001]

Hello Thanveer

Just for confirmation that i understood from this command area#range network netmask 

if you apply this command, will this summarization works?

router1#84.84.1.0 to 84.84.5.0

router2#84.84.6.0 to 84.84.9.0

Thanks in advance

[Muhammad Thanveer]

Hello bobbie,

Network and network mask is important to consider here, we cannot summarize 84.84.1.0 to 84.84.5.0 but we can summarize 84.84.0.0 to 84.84.7.0 with a mask 255.255.255.248

and for 84.84.8.0 to 84.84.9.0 mask will be 255.255.254.0

BR

Thanveer

"Please Rate All Helpful Posts"

[Muhammad Thanveer]

The above statement said by me is not correct, 

Please find the best one as blandekic said in the duplicate thread of the same as HERE 

LSA1 and LSA2 will not become summary LSA ever, LSA3. 

LSA type 1 identifies a router, while LSA2 identifies a network with a DR, and will never be advertised outside of that area.

LSA3 is a summary from another area but with details removed.

You can learn more here: https://en.wikipedia.org/wiki/Link-state_advertisement

My understanding was wrong. Actually question was what happens when we summarise a major network into one area while part of it there in another area?