[hcip] OSPF special area, summary, certification

Catalog

One 、 Special area

        Stub

         Completely Stub

        Nass

         Completely Nass

Two 、 Summary

3、 ... and 、 authentication

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One 、 Special area

Special areas for optimization OSPF  Of LSDB  Space , Only non backbone areas can be configured as special areas

Special area classification ：

（1）Stub

（2） Completely Stub

（3）Nssa

（4） Completely Nssa

        Stub

（1） Sent by all interfaces in this area Hello  In the message E  Not set

（2）OSPF  The router will not 4、5  class LSA  Pass it to OSPF  neighbor

（3）ABR  A default 3  class LSA, help  stub  Devices in the area access the external network

（4） Because of a lack of 4、5  class LSA, Therefore, sub optimal paths may be generated

（5） It is not allowed to introduce external routes

         Completely Stub

（1） stay Stub  On the basis of general 3  class LSA  Also filter

（2） Due to the absence of 3、4、5  class LSA, Suboptimal paths may occur

        Nass

（1） Configure to Nass  After area ,Option  Inside N  Position position , Indicates that the device can handle 7  class LSA「NSSA LSA」

（2） External routes can be introduced

（3） When 5  class LSA  Get into Nssa  Area will be converted to 7  class LSA

（4）Nssa  In the area ABR  Will 7  class LSA  Convert to 5  class LSA, Then pass it to other areas

（5）Nssa  In the area ABR  Will automatically generate a 7  Class default LSA, help Nssa  Devices in the area access external routing information introduced by other areas

（6） When ABR  Generate a line in an area 7  class LSA  after , It will not calculate the 7  class LSA

（7）Nssa  Due to the lack of 5  class LSA, When there are multiple ABR  when , Suboptimal paths may occur

（8） from RID  Big ABR  To execute 7  turn 5

（9）7  turn 5  when , Inherit Cost、FA  Address 、 External route type inheritance

7  class LSA  Of FA How to produce

And 5  class LSA  Of FA When the production conditions are the same ：FA  The address is the next hop to the external route

And 5  class LSA  Of FA When the production conditions are different ： Select first UP  Of Loopback  Interface ; If there is no Loopback  Interface , Choose the first one UP  The physical interface of

         Completely Nass

（1） stay Nssa  On a regional basis , take 3  class LSA  Also filter

（2） Completely Nssa  Due to the lack of equipment in the area 3、5  class LSA, It may lead to sub optimal paths when accessing inter regional or extraterritorial routes

（3）ABR  Will produce 3  Class default , There will be 7  Class default

Two 、 Summary

（1） The default summary route Cost  Inherit the largest in the detailed route Cost

（2） The detailed route vibrates , It does not affect the summary route

（3）ABR  Generate a line in an area LSA  after , If you also receive others in this area ABR  Produced the same 3  class LSA, Then the 3  class LSA

stay ASBR  Summarize the external routes generated by itself on

（1） in the light of  type-1  External routing for , Summary routing Cost  Value is the largest in all detailed routes Cost  value

（2） in the light of  type-2 External routing for , Summary routing Cost  Value is the largest in all detailed routes Cost  value + 1

（3） stay Nssa  Regional ABR  It can also be aimed at 7  turn 5  To summarize , Need to be in 7  turn 5  On the router of

3、 ... and 、 authentication

OSPF  Certification is divided into 「 Plaintext Authentication 」 and 「MD5  authentication 」

Interface authentication and area authentication can be used at the same time ; For the region 0  Certification of , At the same time, it will also take effect on the virtual link

stub： Configure this area as stub Area 
stub no-summary： Configure this area as complete stub Area 
nssa： Configure this area as nssa Area 
nssa no-summary： Configure this area as complete nssa Area 
abr-summary「 Network segment 」「 Mask 」cost「 expenses 」： Aggregate routing 
asbr-summary「 Network segment 」「 Mask 」
ospf authentication-mode simple plain「 password 」： Interface plaintext authentication 
ospf authentication-mode md5「KID」plain「 password 」： Interface md5 authentication 
ospf authentication-mode null： Deny Authentication