From: Sila Moni (silamoni@yahoo.com)
Date: Tue Jul 05 2005 - 16:40:26 GMT-3
Hi Rajib,
Sorry about the acronym. VL stands for virtual-link. Here's what I think.
Putting the detail of your configure aside, I think that you are correct by setting the cost of both ethernet and serial links the same because OSPF only loadbalance using equal cost (by default OSPF supports 4 equal paths). http://www.cisco.com/warp/public/105/loadbal_cef.html
By creating a VL (virtual-link) to resolve your discontiguous OSPF network, you are making your next hop from R4 area 5 to R2 area 0 via the VL interface. By doing so, I believe you only see one path in your routing table. However, in actuality, you do loadbalancing when you sent packet from R4 to R2/R1. By the way, why do you set your maximum-paths to 6?
There is no way that I can confirm w/o labbing this. If my statements are faults, please correct me.
Regards,
Sila
Rajib Khan <rajib56666@yahoo.com> wrote:
Hi Sila
Thanks for your reply. I am not sure what VL means. Follwoing route from R4 to R1's loopback address which was know via R3 ethernet interface 1.1.40.3 next hope. Any idea
R4#sh ip route 1.1.1.1
Routing entry for 1.1.1.1/32
Known via "ospf 5", distance 110, metric 31, type
Last update from 1.1.40.3 on Ethernet0, 08:33:17 a
Routing Descriptor Blocks:
* 1.1.40.3, from 1.1.3.3, 08:33:17 ago, via Ethern
Route metric is 31, traffic share count is 1
Thanks
Raj
Sila Moni <silamoni@yahoo.com> wrote:
Does your routing table show that R4 prefers the VL as its next hope? That's the problem.
Rajib Khan <rajib56666@yahoo.com> wrote: Hello group,
I am trying to understand ospf load balancing following is my diagram
Area 0 --------- area 5
R1 -------- R2 area 6 R3 ------ R4
---------
Please note there are 2 links between R2 and R3
What I have noticed in the routing table that traffic from R1 and R4 are not load balancing IA route between R2 and R3 even though I have configured ip ospf costs same.
Any idea what needs to be done? Following is my config
R2
router ospf 5
router-id 1.1.2.2
log-adjacency-changes
area 6 virtual-link 1.1.3.3
network 1.1.2.0 0.0.0.255 area 0
network 1.1.20.0 0.0.0.255 area 6
network 1.1.6.0 0.0.0.255 area 6
network 1.1.4.0 0.0.0.255 area 0
maximum-paths 6
int e0
ip add 1.1.20.2 255.255.255.0
ip ospf network point-to-point
ip ospf cost 10
interface Serial1.5 oint-to-point
ip address 1.1.6.2 255.255.255.0
no ip route-cache
ip ospf network point-to-point
ip ospf cost 10
no ip mroute-cache
frame-relay interface-dlci 302
R3
interface Ethernet4
ip address 1.1.20.4 255.255.255.0
no ip route-cache
ip ospf cost 10
no ip mroute-cache
media-type 10BaseT
end
interface Serial1
ip address 1.1.6.3 255.255.255.0
encapsulation frame-relay
no ip route-cache
ip ospf network point-to-point
ip ospf cost 10
no ip mroute-cache
frame-relay map ip 1.1.6.2 202 broadcast
frame-relay interface-dlci 202
!
router ospf 5
router-id 1.1.3.3
log-adjacency-changes
area 6 virtual-link 1.1.2.2
network 1.1.3.0 0.0.0.255 area 6
network 1.1.20.0 0.0.0.255 area 6
network 1.1.6.0 0.0.0.255 area 6
network 1.1.40.0 0.0.0.255 area 5
maximum-paths 6
!
Thanks in advance
Raj
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