Traffic divert to backup link

[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 unimportant (Traffic) Source IPs ( say 10.20.1.1 to 25 ) to backup link what would be best way to achieve it.  Is it possible policy based routing ? does multicast support pbr?

2) When primary STM gets down and entire traffic shift to backup STM   these IPs ( 10.20.1.1 to 25) should be given low priority on the backup link or traffic from these ips can be terminated.

Please find attached my network setup. 

Any suggestion would be highly appreciated. Pl reply

Thanks

Shibu

[Richard Burts · Accepted solution]

Shibu

To divert some traffic to a backup link as you describe the solution of Policy Based Routing generally works well.

As far as I know PBR works on unicast traffic but not on multicast.

You can configure the routers to do failover in combination with PBR. And I would think that you could configure some QOS on the backup line to make the unimportant traffic less priority. In normal operation where there is light traffic  on the backup line there is not congestion and even with QOS the traffic should flow ok. And in a failover where all traffic is on the backup then the QOS would slow down the unimportant traffic.

HTH

Rick

[Shibu1978]

Hi Rick,

Thanks for the reply.

"You can configure the routers to do failover in combination with PBR. And I would think that you could configure some QOS on the backup line to make the unimportant traffic less priority".

1) Since PBR does not work on multicast to send some unimportant (Traffic) Source IPs ( say 10.20.1.1 to 25 ) to backup STM link which way should i use for...any configuration help would be much appreciated. 

In normal operation where there is light traffic  on the backup line there is not congestion and even with QOS the traffic should flow ok. And in a failover where all traffic is on the backup then the QOS would slow down the unimportant traffic".

2) Can i have some configuration samples on cisco 4506-E SUP7-E platform to achive this QOS part.

[Shibu1978]

Hello Rick,

Please find below the QOS i have planned for the above discussed setup.  Could you check and tell me whether this configs will achieve my goal.

"

class-map match-all test
  match access-group name test

policy-map test
class test
   set dscp af41
    bandwidth 32

IP access-lst extended  test
    10 permit ip host 10.20.1.60 any
    20 permit ip host 10.20.1.61 any
    30 permit ip host 10.20.1.62 any
    40 permit ip host 10.20.1.62 any
    50 permit ip host 10.20.1.63 any
    60 permit ip host 10.20.1.64 any
    70 permit ip host 10.20.1.65 any
    80 permit ip host 10.20.1.66 any
    90 permit ip host 10.20.1.67 any
    100 permit ip host 10.20.1.68 any
    110 permit ip host 10.20.1.69 any
    120 permit ip host 10.20.1.70 any
    130 permit ip host 10.20.1.71 any
    140 permit ip host 10.20.1.72 any

"

Backup Stm-4 connected interface ( Should it give required output if we apply its on the individual device connected interfaces)

Service policy output test

===============================

If above QOQ works i might plan to add static routes from Site B ( backup router) to  Site A ( backup router) ..i think that way i can avoid in configuring PBR between routers to do failover

Please put your suggestions pl

Thanks

[Shibu1978]

Hi Rick

Any suggestions on this ? thanks

[Richard Burts]

Shibu

I think that it looks reasonable.

HTH

Rick

[Shibu1978]

Hello Riachards,

Thanks for the reply

Meanwhile  if i plan with a different method with distribute-list on the ospf in A end devices will the below can be achived

1) The traffic from A-end selected ips from vlan 100 will always be push through backup Stm-4 link  means at B-End they will should only get those ips through OSPF via backup stm-4  at any point of time. during this stm link failure they should not be getting this traffic via primary link. 

Is there anyway with distribute-list or with route-map can be achive this. any working configuration sample would be a grreat help

Thanks in advance for your suggestions

[Shibu1978]

Hi Richards,

Pl give your suggestions pl

[Richard Burts · Accepted solution]

Shibu

With OSPF a distribute list does not work in the way that it does with other routing protocols. With protocols such as EIGRP an outbound distribute list can suppress advertisement of some prefixes to other neighbors. But it does not do this with OSPF. In OSPF any prefix that is in the OSPF data base (technically it is any LSA that is in the OSPF data base) will be advertised to neighbors no matter what you attempt to do in an outbound distribute list.

An inbound distribute list in OSPF can prevent a prefix from appearing in the local routing table. But it can not prevent the LSA from being stored in the data base and can not prevent advertisement of that LSA to other neighbors.

So I am not sure that you can achieve your requirements with distribute list in OSPF.

HTH

Rick

[Shibu1978]

Dear Richards,

Thanks for your reply. I have read your previous posts in this forum regarding the distribute -list in ospf protocol.

thanks again for the clarity on this