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Does route in OSPF have to be "adjacent"?
johnifanx98
Member Posts: 329
in CCNA & CCENT
For example, router A and B are neighbor but not adjacent. Then is it a possible a route going through from A to B?
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networker050184
Mod Posts: 11,962 Mod
What do you mean are neighbor but not adjacent?An expert is a man who has made all the mistakes which can be made. -
Optionsjohnifanx98
Member Posts: 329
networker050184 wrote: »What do you mean are neighbor but not adjacent?
This is OSPF. In a broadcast network, not every pair of routers are "adjacent". -
Optionsaltdrugz
Member Posts: 69 ■■□□□□□□□□
Maybe you are confused with the status and specially with the Two-way status. In a multiaccess broadcast network such as Ethernet, routers others than DRs and BDRs may stay in Two-way state and still be able to send adjacencies. As far as 2 routers are able to become neighbors they are able to exchange LSAs. So what is needed is the requirements of their handshake (Values in the Hello's packets that must be identical to both ends)
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Optionsnetworker050184
Mod Posts: 11,962 Mod
The DR serves the function of distributing LSAs. Once that is done the routers run SPF and forward traffic as seen fit whether that be through the DR or other routers on the segment.An expert is a man who has made all the mistakes which can be made.
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Optionsaltdrugz
Member Posts: 69 ■■□□□□□□□□
Well I didnt state it correctly. From CCNA Guide of Aaron Balchunas "On a multi access network, OSPF routers will only form Full adjacencies with DRs and BDRs. Non-DRs and non BDRs will still form adjacencies but will reamain in a 2-way state. This is normal OSPF behavior"
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OptionsxXErebuS
Member Posts: 230
Well I didnt state it correctly. From CCNA Guide of Aaron Balchunas "On a multi access network, OSPF routers will only form Full adjacencies with DRs and BDRs. Non-DRs and non BDRs will still form adjacencies but will reamain in a 2-way state. This is normal OSPF behavior"
Still on par with what networker050184 said; the DR / BDR has "adjacencies" with every OSPF router even if they are not directly connected neighbors; the others have no reason to know about every OSPF router since they can get their LSA information about them from the DR / BDR so they form two way adjacencies with directly connected neighbors.
