OSPF elections

sir subaru · 07-20-2006, 11:38 PM

Hi, i'm studying up on OSPF elections and would like something clarified

I'm aware that any loopback address would take priority over a set IP address but have managed to confuse myself when it comes to elections taking place

eg.
Router 1
Loopback: 192.168.0.1
FastEthernet 0/0: 10.10.10.1
Serial 0/0: 172.16.0.1
Priority: 1

Router 2
No loopback
FastEthernet 0/0: 10.10.10.2
Serial 0/0: 172.15.0.1
Priority: 1

It would be Router 1's loopback address (192.168.0.1) vs Router 2's Serial (172.15.0.1) and Router 1 becomming the DR because it's IP/RouterID is higher

But what if this situation occured
Router 1
Loopback: 10.1.1.1
FastEthernet 0/0: 10.10.10.1
Serial 0/0: 172.16.0.1
Priority: 1

Router 2
No loopback
FastEthernet 0/0: 10.10.10.2
Serial 0/0: 172.20.0.1
Priority: 1

Where Router 2s serial address is higher than Router 1s loopback. Would Router 2 still become the DR in this case or would Router 1 still win because it's got a loopback?
If someone could clarify this it would be appreciated

viswnaga · 09-20-2009, 10:21 PM

Yes, Loopback always win the physical interface, no matter whether the IP is lower or higher, even through the loopback IP is very least one 1.0.0.1, it win the race.

TechnoBro · 11-08-2009, 10:17 AM

Router 2 would win the election and become DR. The election process doesnt care how the router acquired its ID, it just cares which router has the higher ID.(lol just noticed the post date)

**johnwill** · 11-08-2009, 04:19 PM

Yep, this thread is past it's prime.

07-20-2006, 11:38 PM	#1 (permalink)
sir subaru Registered User Join Date: Jul 2003 Location: New Zealand Posts: 99 OS: Windows XP	OSPF elections Hi, i'm studying up on OSPF elections and would like something clarified I'm aware that any loopback address would take priority over a set IP address but have managed to confuse myself when it comes to elections taking place eg. Router 1 Loopback: 192.168.0.1 FastEthernet 0/0: 10.10.10.1 Serial 0/0: 172.16.0.1 Priority: 1 Router 2 No loopback FastEthernet 0/0: 10.10.10.2 Serial 0/0: 172.15.0.1 Priority: 1 It would be Router 1's loopback address (192.168.0.1) vs Router 2's Serial (172.15.0.1) and Router 1 becomming the DR because it's IP/RouterID is higher But what if this situation occured Router 1 Loopback: 10.1.1.1 FastEthernet 0/0: 10.10.10.1 Serial 0/0: 172.16.0.1 Priority: 1 Router 2 No loopback FastEthernet 0/0: 10.10.10.2 Serial 0/0: 172.20.0.1 Priority: 1 Where Router 2s serial address is higher than Router 1s loopback. Would Router 2 still become the DR in this case or would Router 1 still win because it's got a loopback? If someone could clarify this it would be appreciated

09-20-2009, 10:21 PM	#2 (permalink)
viswnaga Registered User Join Date: Sep 2009 Posts: 2 OS: xp	Re: OSPF elections Yes, Loopback always win the physical interface, no matter whether the IP is lower or higher, even through the loopback IP is very least one 1.0.0.1, it win the race.

11-08-2009, 10:17 AM	#3 (permalink)
TechnoBro Registered User Join Date: Nov 2009 Posts: 2 OS: windows xp, vista, 7; unix: ubuntu, backtrack	Re: OSPF elections Router 2 would win the election and become DR. The election process doesnt care how the router acquired its ID, it just cares which router has the higher ID.(lol just noticed the post date) Last edited by TechnoBro; 11-08-2009 at 10:18 AM.

11-08-2009, 04:19 PM	#4 (permalink)
johnwill Manager, Networking Forums Join Date: Sep 2002 Location: S.E. Pennsylvania, US Posts: 41,623 OS: Windows 7, XP-Pro, Vista, Linux Blog Entries: 1	Re: OSPF elections Yep, this thread is past it's prime. __________________ If TSF has helped you, Tell us about it! or Donate to help keep the site up! Microsoft MVP - Windows Desktop Experience