In the OSPF routing, Why can't use the command "no auto-summary"?

[ckfurtn01]

Hello
I will post the article here because this question.
The question for OSPF.

Am I more than trying a variety of routing's a wonder suddenly become, OSPF is why there is no "no auto-summary" of commands like protocols such as RIP and EIGRP?

It's strange grammar?
Yes, using the Google Translator.
Please consider it.

[Mike P]

ckfurtn01,

By default, RIP and EIGRP summarize networks to their classful boundaries.  No auto-summary disables that feature.  

In OSPF, we need to configure wildcard masks to identify our networks.  For example, in EIGRP network 10.1.1.0/24, with auto-summary enabled, will advertise a 10.0.0.0/8 network.  In OSPF, to identify the same 10.1.1.0/24 network we would advertise 10.1.1.0 0.0.0.255 area X.  If we wanted to do the classful boundary then it would be 10.0.0.0 0.255.255.255 area X.

OSPF, in short, does not perform auto-summarization so it is not a needed command.  Hope this helps.

v/r

Mike

[Charles Hill]

Route summarization is only used in two places within OSPF and this is due to the nature of the protocol. 

The link state database has to be identical everywhere. 

Route summarization is only allowed on ABRs and ASBRs, which is used for external summarization.

Hope this helps. 

[Maksim K]

OSPF as a link state routing protocol (deals with LSAs rather than routes) does not auto summarize (doesn't support "auto-summary").