From: Joseph Brunner (joe@affirmedsystems.com)
Date: Tue Aug 05 2008 - 03:31:00 ART
Isn't this a variant of the same question you asked Saturday night Brian and
Scott solved for you?
The intra-area router is preferred off R3 regardless of cost. cost cant be
used to beat intra-area...
-Joe
_____
From: dave dave [mailto:funccie@gmail.com]
Sent: Tuesday, August 05, 2008 1:33 AM
To: Cisco certification; bdennis@internetworkexpert.com;
blog@internetworkexpert.com; Joseph Brunner
Subject: OSPF: Please help to understand behaviour
Hi Expert,
I really eed your help to understand this scnario, behaviour but dont
know why?????????
r1--------------------- r2 <--R1 & R2 all links in area 1
| area 1 |
| |
| area 1 area 1 |
| |
area 0
r3--|-|-----------|-|---- r4 <--vlan 100 create on both R3 & R4 on L2
port channel for ospf neighborship. Vlan 100 on R3 & R4 is in OSPF area 0.
---|-|-----------|-|---
| area 0 |
| |
|area 2 area 2 |
| |
r5------------------- r6 <-- (on R4 RIP route 192.168.1.1 redistribute
in ospf) <--R3 & R4 all links in area 2
When i am advertising the RIP route 192.168.1.1 into ospf via redistrubution
as type e1, my trace is follow the path of r1 ->r3->r5 ->r6. I am expecting
the path as r1-->r3-->r4-->r6.
note:1. auto-cost refrance-band is configure as 10000 (10gb on all router)
2. All links are configure as 100MBPS except vlan 100 & links between
r3 to r4.
3. vlan 100 & 2 links (L2 port cahnnel no 1) between r3 to r4
configure as 1gb
PLEASE HELP TO UNDERSTAND THE BEHAVIOUR>
r1#traceroute 192.168.1.1 pr 1
Type escape sequence to abort.
Tracing the route to 192.168.1.1
1 10.66.1.6 56 msec
2 10.66.1.10 60 msec
3 10.66.2.2 76 msec
r1# sh ip ospf database external
OSPF Router with ID (200.1.1.1) (Process ID 1)
Type-5 AS External Link States
Routing Bit Set on this LSA
LS age: 64
Options: (No TOS-capability, DC)
LS Type: AS External Link
Link State ID: 100.100.100.0 (External Network Number )
Advertising Router: 100.2.2.2
LS Seq Number: 80000008
Checksum: 0x86FB
Length: 36
Network Mask: /24
Metric Type: 1 (Comparable directly to link state metric)
TOS: 0
Metric: 20
Forward Address: 0.0.0.0
External Route Tag: 0
Routing Bit Set on this LSA
LS age: 64
Options: (No TOS-capability, DC)
LS Type: AS External Link
Link State ID: 192.168.1.0 (External Network Number )
Advertising Router: 100.2.2.2
LS Seq Number: 80000002
Checksum: 0xF357
Length: 36
Network Mask: /24
Metric Type: 1 (Comparable directly to link state metric)
TOS: 0
Metric: 20
Forward Address: 0.0.0.0
External Route Tag: 0
Type-5 AS External Link States
Link ID ADV Router Age Seq# Checksum Tag
100.100.100.0 100.2.2.2 30 0x80000008 0x0086FB 0
192.168.1.0 100.2.2.2 30 0x80000002 0x00F357 0
r1#
r1#sh ip route 192.168.1.1
Routing entry for 192.168.1.0/24
Known via "ospf 1", distance 110, metric 320, type extern 1
Last update from 10.66.1.2 on FastEthernet1/10, 00:01:36 ago
Routing Descriptor Blocks:
* 10.66.1.6, from 100.2.2.2, 00:01:36 ago, via FastEthernet1/11 TO R3
Route metric is 320, traffic share count is 1
10.66.1.2, from 100.2.2.2, 00:01:36 ago, via FastEthernet1/10 TO R2
Route metric is 320, traffic share count is 1
r1#
r2#sh ip ro 192.168.1.1
Routing entry for 192.168.1.0/24
Known via "ospf 1", distance 110, metric 220, type extern 1
Last update from 10.66.1.10 on FastEthernet1/11, 00:02:56 ago
Routing Descriptor Blocks:
* 10.66.1.10, from 100.2.2.2, 00:02:56 ago, via FastEthernet1/11 TO R4
Route metric is 220, traffic share count is 1
r2#
r3#sh ip ro 192.168.1.1
Routing entry for 192.168.1.0/24
Known via "ospf 1", distance 110, metric 220, type extern 1
Last update from 10.66.2.5 on FastEthernet1/10, 00:03:13 ago
Routing Descriptor Blocks:
* 10.66.2.5, from 100.2.2.2, 00:03:13 ago, via FastEthernet1/10 TO R5
Route metric is 220, traffic share count is 1
r3#
r4#sh ip ro 192.168.1.1
Routing entry for 192.168.1.0/24
Known via "ospf 1", distance 110, metric 120, type extern 1
Last update from 10.66.2.9 on FastEthernet1/10, 00:23:03 ago
Routing Descriptor Blocks:
* 10.66.2.9, from 100.2.2.2, 00:23:03 ago, via FastEthernet1/10 TO R6
Route metric is 120, traffic share count is 1
r5#sh ip ro 192.168.1.1
Routing entry for 192.168.1.0/24
Known via "ospf 1", distance 110, metric 120, type extern 1
Last update from 10.66.2.2 on FastEthernet1/11, 00:23:13 ago
Routing Descriptor Blocks:
* 10.66.2.2, from 100.2.2.2, 00:23:13 ago, via FastEthernet1/11 TO R6
Route metric is 120, traffic share count is 1
r6#sh ip ro 192.168.1.1
Routing entry for 192.168.1.0/24
Known via "connected", distance 0, metric 0 (connected, via interface)
Redistributing via ospf 1, rip
Advertised by ospf 1
rip
Routing Descriptor Blocks:
* directly connected, via Loopback192
Route metric is 0, traffic share count is 1
Regards
Dave
Blogs and organic groups at http://www.ccie.net
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