From: cciein2006@yahoo.com
Date: Wed Sep 21 2005 - 13:17:20 GMT-3
Hello group,
I am seeing some interesting behaviour on my ospf network with virtual links.
Here is a diagram:
Area 1
_________________
| |
| |
(RTR1) (RTR2)
| Area2 |
| | 141.108.10.0/30
| |
(RTR3)-_-_-(RTR4)
Area 0
Router ID's
RTR1 131.108.5.1
RTR2 131.108.6.2
RTR3 141.108.10.10
RTR4 141.108.10.6
Area 1 contains the ethernet segment between RTR1 and RTR2
Area 2 contains the Serial Links between RTR1 and RTR3 and between RTR2 and RTR4
Area 0 contains the Serial Link between RTR3 and RTR4.
Virtual links are configured between RTR1 and RTR3 and between RTR2 and RTR4.
My problem is that RTR1 prefers the path to 141.108.10.0 network via two serial links (R1 to R3 and R3 to R4)
rather than the ethernet segment to R2.
RTR1#show ip route 141.108.10.0
Routing entry for 141.108.10.0/30
Known via "ospf 1", distance 110, metric 192, type inter area
Last update from 141.108.10.10 on Serial3/0, 19:25:21 ago
Routing Descriptor Blocks:
* 141.108.10.10, from 141.108.10.6, 19:25:21 ago, via Serial3/0
Route metric is 192, traffic share count is 1
RTR1#
RTR1#show ip ospf database summary 141.108.10.0
OSPF Router with ID (131.108.5.1) (Process ID 1)
Summary Net Link States (Area 0)
LS age: 83 (DoNotAge)
Options: (No TOS-capability, DC, Upward)
LS Type: Summary Links(Network)
Link State ID: 141.108.10.0 (summary Network Number)
Advertising Router: 131.108.6.2
LS Seq Number: 80000001
Checksum: 0xDF6
Length: 28
Network Mask: /30
TOS: 0 Metric: 64
Routing Bit Set on this LSA
LS age: 1577 (DoNotAge)
Options: (No TOS-capability, DC, Upward)
LS Type: Summary Links(Network)
Link State ID: 141.108.10.0 (summary Network Number)
Advertising Router: 141.108.10.6
LS Seq Number: 80000005
Checksum: 0x7677
Length: 28
Network Mask: /30
TOS: 0 Metric: 64
Summary Net Link States (Area 1)
LS age: 1747
Options: (No TOS-capability, DC, Upward)
LS Type: Summary Links(Network)
Link State ID: 141.108.10.0 (summary Network Number)
Advertising Router: 131.108.5.1
LS Seq Number: 80000023
Checksum: 0xDA88
Length: 28
Network Mask: /30
TOS: 0 Metric: 192
LS age: 1447
Options: (No TOS-capability, DC, Upward)
LS Type: Summary Links(Network)
Link State ID: 141.108.10.0 (summary Network Number)
Advertising Router: 131.108.6.2
LS Seq Number: 80000025
Checksum: 0xC41B
Length: 28
Network Mask: /30
TOS: 0 Metric: 64
Summary Net Link States (Area 2)
LS age: 1749
Options: (No TOS-capability, DC, Upward)
LS Type: Summary Links(Network)
Link State ID: 141.108.10.0 (summary Network Number)
Advertising Router: 131.108.5.1
LS Seq Number: 80000023
Checksum: 0xDA88
Length: 28
Network Mask: /30
TOS: 0 Metric: 192
LS age: 1749
Options: (No TOS-capability, DC, Upward)
LS Type: Summary Links(Network)
Link State ID: 141.108.10.0 (summary Network Number)
Advertising Router: 141.108.10.10
LS Seq Number: 80000025
Checksum: 0xA0E8
Length: 28
Network Mask: /30
TOS: 0 Metric: 128
RTR1#
Why would OSPF choose a path with metric 192 over 64?
This archive was generated by hypermail 2.1.4 : Sun Oct 02 2005 - 14:40:16 GMT-3