From: Huizinga, Rene (rhuizinga@upcbroadband.com)
Date: Tue May 22 2007 - 12:18:55 ART
I believe this comes down to the intra-area over inter-area rule in OSPF.
If I understand the description correctly from this email, the remote
router-id may play a role in here. Since that's in Area0, it may be the
tie-breaker in this. If this is this tie-breaker, then intra- over
inter-area, regardless of cost et all !
Cya
-----Original Message-----
From: nobody@groupstudy.com [mailto:nobody@groupstudy.com] On Behalf Of Eric
Poulin
Sent: Tuesday, May 22, 2007 4:42 PM
To: M S; ccielab@groupstudy.com
Subject: RE: Question about OSPF preferring higher cost route from area0
over lower cost from another area?
Here's the output:
Rack1R5#sh run | beg router ospf
router ospf 1
router-id 150.1.5.5
log-adjacency-changes
network 150.1.5.5 0.0.0.0 area 0
network 183.1.0.5 0.0.0.0 area 0
network 183.1.45.5 0.0.0.0 area 45
--- M S <michaelgstout@hotmail.com> wrote:
---------------------------------
I would like to see the "show run | b router ospf" output.
Thank you.
---------------------------------
From: Eric Poulin <epoulins@yahoo.com>
Reply-To: Eric Poulin <epoulins@yahoo.com>
To: ccielab@groupstudy.com
Subject: Question about OSPF preferring higher cost route from area0 over
lower cost from another area?
Date: Mon, 21 May 2007 21:04:27 -0700 (PDT) Hi GS,
I have two routers, R4 and R5, running OSPF between each other over Frame
Relay (Area0) and also Ethernet (Area45). R5 is learning an inter-area route
150.1.6.6/32 from R4 over both links. The OSPF cost to reach R4 over the FR
is 64 and Ethernet is 1. Please can someone explain me why R5 prefers the
route over the frame Relay as opposed to the Ethernet? I was expecting R5 to
chose its Ethernet link with a cumulative cost of 3 instead of the FR
interface with a cumulative cost of 66? Are routes for the same prefix
preferred within Area0?
Thanks for your help,
Eric
----------------------------
Rack1R5#sh ip ospf neighbor
Neighbor ID Pri State Dead Time Address Interface
150.1.4.4 0 FULL/DROTHER 868 msec 183.1.0.4 Serial0/0
150.1.4.4 1 FULL/DR 00:01:46 183.1.45.4
FastEthernet0/1
----------------------------
Rack1R5#sh ip route ospf
150.1.0.0/16 is variably subnetted, 9 subnets, 2 masks
O IA 150.1.6.6/32 [110/66] via 183.1.0.4, 00:05:09, Serial0/0
----------------------------
Rack1R5#sh ip ospf database summ 150.1.6.6
OSPF Router with ID (150.1.5.5) (Process ID 1)
Summary Net Link States (Area 0)
Routing Bit Set on this LSA
LS age: 1865
Options: (No TOS-capability, DC, Upward)
LS Type: Summary Links(Network)
Link State ID: 150.1.6.6 (summary Network Number)
Advertising Router: 150.1.4.4
LS Seq Number: 80000012
Checksum: 0xC323
Length: 28
Network Mask: /32
TOS: 0 Metric: 2
Summary Net Link States (Area 45)
LS age: 1865
Options: (No TOS-capability, DC, Upward)
LS Type: Summary Links(Network)
Link State ID: 150.1.6.6 (summary Network Number)
Advertising Router: 150.1.4.4
LS Seq Number: 80000012
Checksum: 0xC323
Length: 28
Network Mask: /32
TOS: 0 Metric: 2
----------------------------
Rack1R5#sh ip ospf database router 150.1.4.4
OSPF Router with ID (150.1.5.5) (Process ID 1)
Router Link States (Area 0)
Routing Bit Set on this LSA
LS age: 186
Options: (No TOS-capability, DC)
LS Type: Router Links
Link State ID: 150.1.4.4
Advertising Router: 150.1.4.4
LS Seq Number: 80000018
Checksum: 0x8AE6
Length: 48
Area Border Router
Number of Links: 2
Link connected to: a Transit Network
(Link ID) Designated Router address: 183.1.0.5
(Link Data) Router Interface address: 183.1.0.4
Number of TOS metrics: 0
TOS 0 Metrics: 64
Link connected to: a Stub Network
(Link ID) Network/subnet number: 150.1.4.4
(Link Data) Network Mask: 255.255.255.255
Number of TOS metrics: 0
TOS 0 Metrics: 1
Router Link States (Area 45)
Routing Bit Set on this LSA
LS age: 576
Options: (No TOS-capability, DC)
LS Type: Router Links
Link State ID: 150.1.4.4
Advertising Router: 150.1.4.4
LS Seq Number: 8000001C
Checksum: 0x6C97
Length: 36
Area Border Router
Number of Links: 1
Link connected to: a Transit Network
(Link ID) Designated Router address: 183.1.45.4
(Link Data) Router Interface address: 183.1.45.4
Number of TOS metrics: 0
TOS 0 Metrics: 1
----------------------------
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