manipulate ospf routing

[Shibu1978]

Hi all,

Basically we are having a Multicast setup.  both  A and B offices are being connected with STM-4 (622 Mbps) with IGP as OSPF. As of now everything is working well with this setup and no complaint .

Now since Primary link bandwidth is touching upto 622 Mbps  we are planning to send some traffic to backup STM-4 link

.

1) To send some vlan traffic always to backup STM-4 link here it is vlan 100 ( 10.20.6.0/24) what would be best way to do it.

Please find attached my network setup. 

Any suggestion would be highly appreciated. Pl reply

Thanks

[Reza Sharifi]

Hi,

Since the speed of both primary and backup links are the same , by default OSPF equity load balance the traffic for you.

HTH

[Shibu1978]

Hi Reza,

Thanks for the reply.

Since we have defined  difference" cost" on both links in our case there is no load balance happening between links. The traffic willl flow to backup link only when there is a failure in primary link.

Now primary link is almost utilized i am planning to send some vlan traffic to backup link. is theref any way i can send the specific traffic to backup link. can i use distribute-list to manipulate ospf routing?

Thanks

[Danilo Dy]

You can use OSPF load-balancing or CEF load-sharing.

http://www.cisco.com/en/US/tech/tk827/tk831/technologies_tech_note09186a0080094806.shtml

[Shibu1978]

Hi Dani,

I dont want to do loadbalancing between primary and backup links. I want the whole traffic except one vlan should be going always to Primary link. Since the primary link  is getting saturated i want to send some one vlan traffic always to backup link.  is there any way i can do it this with out disturbing the network.

Thanks... hope i made it clear now.

[Shibu1978]

Can anyone pl respond...thanks

[Bradford Chatterjee]

You could use a route-map to policy route some traffic to a specific next-hop IP address or interface.

[Shibu1978]

Hi Brad,

Thanks for your reply.

Since i am running multicast service(ssm) between locations does this route map support multicast traffic to be sent out ?

[RUSTOM BILLIMORIA · Accepted solution]

Hi Bradford,

Since you have multiple vlans, I assume that you either have sub-interfaces on the router or each vlan is connected to a seperate physical interface. We could increase the cost both ways for a particular vlan for ospf and have them use the backup link. If possible plz do post configs for the devices for me to understand them better.

Rustom Billimoria

[Shibu1978]

Hi Rustom,

By mistake i did click on the correct answer button next to u r comment. no how do i change it back ?

[RUSTOM BILLIMORIA]

oh man!!!!

My first rating (that too by mistake) :-(

Maybe i can help you out to the end for exchange for the correct answer :-)

By the way route-maps d not match multicast traffic.. unless and until you match the destination address.

I'd suggest we manipute a certain Subnet being sent across by ospf to manipulate the path.

for example you have 4 subnets

10.0.0.0/24

10.0.1.0/24

10.0.2.0/24

10.0.3.0/24

all routes are being prefered over the primary path. how about we set a route-map to manipulate one subnet and increase its cost before sending it over to the other neighbor. that way the other side prefers the backup link. Do manipulate traffic both ways or you will end up with asymetric routing.

If you need an sample config, just ask and i will provide it to you.

Cheers!!!

Rustom Billimoria.

[Shibu1978]

Hi Rustom,

Sorry for being late .

I hope you have understood my requirement correctly. if not please have a look at the diagram which i have attached along with the discussion.

I am going to add one more vlan 100 ( 10.20.6.0/24) to the existing setup and forward traffic( mainly Multicast-SSM traffic)  from this vlan exclusively to BACKUP STM 4 terminated in back up switch. at any point of time traffic from this vlan should be fall back to primary stm 4 link. when BACKUP STM 4 link gets down i may shut down this vlan interface manually.

As all routes are preffered over the primary STM 4 link whats the best way to achieve this requirement.  i dont have any control over B end devices. those devices are being managed by a( vendor )differnet team in other location .  So i have to do it requirement from A end which is my side.

Thanks for your time.

[RUSTOM BILLIMORIA]

Gotcha!!!. thanks for the info man.. just keep checking the post for furthre updates..

[Shibu1978]

Hi Rustom,

I have not done the configuration .  ....could you suggest me the best way to do it?  any sample configs?

Thanks

[RUSTOM BILLIMORIA]

Am already on it.. maybe a hour or so i'll be done.. just keep checking.