From: darbyweaver@yahoo.com
Date: Tue Apr 17 2007 - 23:01:59 ART
Suplepo,
Let me see if I can take a stab at this one, in fact I even labbed it up, just in case.
Please forgive my ignorance as it has been noted that my understanding of the technologies required are perhaps less than expected for a successful CCIE candidate, so I'll simply get to the point.
1. I interpret the question in somewhat the same the fashion as Todd has in that the router-id of 255.255.255.255 will win any given election and further the ip ospf priority of 255 will win in any given segment (forgive my order - the segment will win first and the router-id will provide the over-ride).
So the goal of being the DR is now accomplished. However, if no further actions are taken then the another router on the segment with a higher ip ospf priority or a higher router-id will become the DR and will simply rebooting a router that has a higher election value will not force a new election.
So the question remains: What can be done to stop this vicious circle?
Hmmm...
This is why we will need to perform the following task as my example I labbed for you will clearly illustrate.
2. Go to each OSPF router on the segment and issue the command ip ospf priority 0 on under the given interface.
This will forcce a router on the segment to NEVER EVER participate in ANY election whatsoever.
Therefore if this is done on each router in the given segment. One can safely reboot a DR or as I did in my example remove the routing process entirely (FASTER - A TIP/TRICK I PAID TO LEARN SOMEWHERE) and therefore ensure that the desired router is ALWAYS the DR per your task requirement.
Now in real life - someone could introduce a router and forget about the IP OSPF PRIORITY settings and give you a headache.
In the lab - I doubt the proctors will introduce more routers.
Therefore I think we have met the requirements of the task 100%.
But since my knowledge is feeble at best and my intellect perhaps less than others, I thought it best to show you what I mean so I labbed it up.
Does one good to reinforce these things from time to time, since I lack practice as well.
Here are my findings:
===========================================
Rack01R1(config)#do sh ip ospf int f0/0
FastEthernet0/0 is up, line protocol is up
Internet Address 10.10.10.1/24, Area 0
Process ID 1, Router ID 1.1.1.1, Network Type BROADCAST, Cost: 1
Transmit Delay is 1 sec, State DR, Priority 255
Designated Router (ID) 1.1.1.1, Interface address 10.10.10.1
No backup designated router on this network
Timer intervals configured, Hello 10, Dead 40, Wait 40, Retransmit 5
oob-resync timeout 40
Hello due in 00:00:02
Supports Link-local Signaling (LLS)
Index 1/1, flood queue length 0
Next 0x0(0)/0x0(0)
Last flood scan length is 1, maximum is 1
Last flood scan time is 0 msec, maximum is 0 msec
Neighbor Count is 2, Adjacent neighbor count is 2
Adjacent with neighbor 2.2.2.2
Adjacent with neighbor 3.3.3.3
Suppress hello for 0 neighbor(s)
interface FastEthernet0/0
ip address 10.10.10.1 255.255.255.0
ip ospf priority 255
duplex auto
speed auto
========================
Rack01R1(config)#no router ospf 1
Rack01R1(config)#
*Apr 18 01:40:52.666: %OSPF-5-ADJCHG: Process 1, Nbr 2.2.2.2 on FastEthernet0/0 from 2WAY to DOWN, Neighbor Down: Interface down or detached
*Apr 18 01:40:52.666: %OSPF-5-ADJCHG: Process 1, Nbr 3.3.3.3 on FastEthernet0/0 from 2WAY to DOWN, Neighbor Down: Interface down or detached
Rack01R2#sh ip ospf int f0/0
FastEthernet0/0 is up, line protocol is up
Internet Address 10.10.10.2/24, Area 0
Process ID 1, Router ID 2.2.2.2, Network Type BROADCAST, Cost: 1
Transmit Delay is 1 sec, State DROTHER, Priority 0
No designated router on this network
No backup designated router on this network
Timer intervals configured, Hello 10, Dead 40, Wait 40, Retransmit 5
oob-resync timeout 40
Hello due in 00:00:00
Supports Link-local Signaling (LLS)
Index 1/1, flood queue length 0
Next 0x0(0)/0x0(0)
Last flood scan length is 1, maximum is 1
Last flood scan time is 0 msec, maximum is 0 msec
Neighbor Count is 1, Adjacent neighbor count is 0
Suppress hello for 0 neighbor(s)
Rack01R2#sh run int f0/0
Building configuration...
Current configuration : 115 bytes
!
interface FastEthernet0/0
ip address 10.10.10.2 255.255.255.0
ip ospf priority 0
duplex auto
speed auto
end
Rack01R3#sh ip ospf int f0/0
FastEthernet0/0 is up, line protocol is up
Internet Address 10.10.10.3/24, Area 0
Process ID 1, Router ID 3.3.3.3, Network Type BROADCAST, Cost: 1
Transmit Delay is 1 sec, State DROTHER, Priority 0
No designated router on this network
No backup designated router on this network
Timer intervals configured, Hello 10, Dead 40, Wait 40, Retransmit 5
oob-resync timeout 40
Hello due in 00:00:07
Supports Link-local Signaling (LLS)
Index 1/1, flood queue length 0
Next 0x0(0)/0x0(0)
Last flood scan length is 1, maximum is 1
Last flood scan time is 0 msec, maximum is 0 msec
Neighbor Count is 1, Adjacent neighbor count is 0
Suppress hello for 0 neighbor(s)
Rack01R3#sh run int f0/0
Building configuration...
Current configuration : 115 bytes
!
interface FastEthernet0/0
ip address 10.10.10.3 255.255.255.0
ip ospf priority 0
duplex auto
speed auto
end
Rack01R1(config)#router ospf 1
Rack01R1(config-router)#router-id 255.255.255.255
Rack01R1(config-router)#network 10.10.10.1 0.0.0.0 area 0
Rack01R1(config-router)#do sh ip ospf int f0/0
FastEthernet0/0 is up, line protocol is up
Internet Address 10.10.10.1/24, Area 0
Process ID 1, Router ID 255.255.255.255, Network Type BROADCAST, Cost: 1
Transmit Delay is 1 sec, State WAITING, Priority 255
No designated router on this network
No backup designated router on this network
Timer intervals configured, Hello 10, Dead 40, Wait 40, Retransmit 5
oob-resync timeout 40
Hello due in 00:00:06
Wait time before Designated router selection 00:00:26
Supports Link-local Signaling (LLS)
Index 1/1, flood queue length 0
Next 0x0(0)/0x0(0)
Last flood scan length is 1, maximum is 1
Last flood scan time is 0 msec, maximum is 0 msec
Neighbor Count is 2, Adjacent neighbor count is 0
Suppress hello for 0 neighbor(s)
Rack01R1(config-router)#do sh ip ospf int f0/0
Rack01R1(config-router)#do sh ip ospf int f0/0
FastEthernet0/0 is up, line protocol is up
Internet Address 10.10.10.1/24, Area 0
Process ID 1, Router ID 255.255.255.255, Network Type BROADCAST, Cost: 1
Transmit Delay is 1 sec, State WAITING, Priority 255
No designated router on this network
No backup designated router on this network
Timer intervals configured, Hello 10, Dead 40, Wait 40, Retransmit 5
oob-resync timeout 40
Hello due in 00:00:02
Wait time before Designated router selection 00:00:02
Supports Link-local Signaling (LLS)
Index 1/1, flood queue length 0
Next 0x0(0)/0x0(0)
Last flood scan length is 1, maximum is 1
Last flood scan time is 0 msec, maximum is 0 msec
Neighbor Count is 2, Adjacent neighbor count is 0
Suppress hello for 0 neighbor(s)
Rack01R1(config-router)#
*Apr 18 01:44:49.838: %OSPF-5-ADJCHG: Process 1, Nbr 2.2.2.2 on FastEthernet0/0 from LOADING to FULL, Loading Done
Rack01R1(config-router)#do sh ip ospf int f0/0
FastEthernet0/0 is up, line protocol is up
Internet Address 10.10.10.1/24, Area 0
Process ID 1, Router ID 255.255.255.255, Network Type BROADCAST, Cost: 1
Transmit Delay is 1 sec, State DR, Priority 255
Designated Router (ID) 255.255.255.255, Interface address 10.10.10.1
No backup designated router on this network
Timer intervals configured, Hello 10, Dead 40, Wait 40, Retransmit 5
oob-resync timeout 40
Hello due in 00:00:04
Supports Link-local Signaling (LLS)
Index 1/1, flood queue length 0
Next 0x0(0)/0x0(0)
Last flood scan length is 1, maximum is 1
Last flood scan time is 0 msec, maximum is 0 msec
Neighbor Count is 2, Adjacent neighbor count is 2
Adjacent with neighbor 2.2.2.2
Adjacent with neighbor 3.3.3.3
Suppress hello for 0 neighbor(s)
Rack01R1(config-router)#
*Apr 18 01:44:54.830: %OSPF-5-ADJCHG: Process 1, Nbr 3.3.3.3 on FastEthernet0/0 from LOADING to FULL, Loading Done
=============================================
This is only one area of knowledge I know, so I guess I could be demonstratively weak in so many others...
However, I assure you my rather expensice education that I have received at the hands of the fine vendors on this list has not quite been as wasted as some might have others to believe...
But my own lab awaits soon, so I guess we shall see soon enough...
Even if it is the day the CCIE Lab Program has failed to meet its mission.
Ha! Ha!
Kills me...
From: "Todd, Douglas M." <DTODD@PARTNERS.ORG>
To: "Suplepo" <suplepo@yahoo.com>, <ccielab@groupstudy.com>
Subject: RE: OSPF Priority Question
Date: Tue, 17 Apr 2007 19:41:13 -0400
Reply-to: "Todd, Douglas M." <DTODD@PARTNERS.ORG>
Thread-index: AceBL6j6zxSVuKRgQ/i5w7PBbtCe0QAGP/mg
Thread-topic: OSPF Priority Question
The only solutions I can come up with are the following:
1) On the DR - give it the highest priority (255). Now, give this router the
RID
of 255.255.255.255 (I think that will still work).
2) IF the other router has the same priority as the "DR" the election process
will now go to the highest RID. The "DR" will win.
I believe then you have accomplished the task. The task does not say that the
router must remain the DR between reloads. It must remain the DR if the
priority
is challenged.
DMT
-----Original Message-----
From: nobody@groupstudy.com [mailto:nobody@groupstudy.com] On Behalf Of
Suplepo
Sent: Tuesday, April 17, 2007 4:18 PM
To: ccielab@groupstudy.com
Subject: OSPF Priority Question
If I see a question asking me to ensure a given router remains the DR for a
segment, even if a router with a higher priority is added to the network. Is
there some way to esnure this in the case of a reboot or process restart?
I know that simply adding a router with a higher priority will not "preempt"
the
existing DR, but is there anything that will over-ride a priority of 255 if
the
process restarts?
This archive was generated by hypermail 2.1.4 : Tue May 01 2007 - 08:28:36 ART