10-29-2013 07:28 PM - edited 03-04-2019 09:27 PM
Hi all,
I would like to know if it is possible to influence the traffic for a network to take one next hop if I have 2 routes with the same cost in OSPF? in a BMA environment.
R10#sh ip route 1.1.1.1
Routing entry for 1.1.1.1/32
Known via "ospf 1", distance 110, metric 21, type intra area
Last update from 10.10.10.2 on FastEthernet0/0, 00:40:09 ago
Routing Descriptor Blocks:
* 10.10.10.3, from 1.1.1.1, 00:40:09 ago, via FastEthernet0/0
Route metric is 21, traffic share count is 1
10.10.10.2, from 1.1.1.1, 00:40:09 ago, via FastEthernet0/0
Route metric is 21, traffic share count is 1
I want to send the traffic to 1.1.1.1 through 10.10.10.2 and keep 10.10.10.3 as a backup.
They are Intra Area routes and both neighbors are learned by the same interface BMA.
R10#sh ip ospf neighbor
Neighbor ID Pri State Dead Time Address Interface
20.20.20.2 1 FULL/BDR 00:00:32 10.10.10.2 FastEthernet0/0
30.30.30.2 1 FULL/DR 00:00:38 10.10.10.3 FastEthernet0/0
I tried to change the metric with distrubute and a route map but no luck
any ideas?
Please let me know if you need more details.
Solved! Go to Solution.
10-29-2013 11:55 PM
Hi Omar,
you could change the network type to "point-to-multipoint non-broadcast".
A very interesting option especially for this type is that you can assign cost on a per-neighbor basis on a multiaccess interface:
(config-rtr)# neighbor
Optionally, you may want to change the timers (default: 30/120s).
Compared to Broadcast network type, Point-to-Multipoint Non-Broadcast
However, if you have only 3-4 routers in the subnet, the advantages of Broadcast over Point-to-Multipoint shouldn't keep you from using that network type if you want to be able to influence the forwarding paths in a multiaccess network. I've already done this in production networks to overcome undesired adjacencies in a VPLS and implement backup-paths as well.
HTH
Rolf
10-29-2013 10:32 PM
Hi,
increase the cost of the connected neighbour router interface, at which IP 10.10.10.3 is configured using (ip ospf cost "value") at interface configuration mode.
Thanks
Shashi
10-29-2013 11:55 PM
Hi Omar,
you could change the network type to "point-to-multipoint non-broadcast".
A very interesting option especially for this type is that you can assign cost on a per-neighbor basis on a multiaccess interface:
(config-rtr)# neighbor
Optionally, you may want to change the timers (default: 30/120s).
Compared to Broadcast network type, Point-to-Multipoint Non-Broadcast
However, if you have only 3-4 routers in the subnet, the advantages of Broadcast over Point-to-Multipoint shouldn't keep you from using that network type if you want to be able to influence the forwarding paths in a multiaccess network. I've already done this in production networks to overcome undesired adjacencies in a VPLS and implement backup-paths as well.
HTH
Rolf
10-30-2013 05:34 PM
Thank you Rolf your solution worked for me to influce a path for an especific neighbor as next hop.
Thank you ALL I appreciate your comments
10-30-2013 12:18 AM
Change the cost. Draw a topology and provide more information if you want a more detailed answer. Remember that cost is calculated inbound.
Daniel Dib
CCIE #37149
10-30-2013 07:57 AM
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Besides Rolf's solution, another option might be to adjust interface cost, or interface costs, on one of either of the two adjacent (common network) routers. As OSPF intra-area costs are cumulative, this make the two paths costs unequal.
10-30-2013 03:33 PM
just change the cost and you are done one path will be backup and one active
if you want exact point where to give cost share your diagram
Sent from Cisco Technical Support iPhone App
10-31-2013 12:00 PM
Thank you Rolf your solution worked for me to influce a path for an especific neighbor as next hop.
Thank you ALL I appreciate your comments
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