Enquiry about OSPF Cost

[tcanthonypoon]

Hi there,

I would like ask for your expertise how to get riding of non-voice traffic passing through the10M MetroEthernet voice link in the following WAN overview:

Host End 1
Data VLAN: 173.105.0.0/16
Voice VLAN: 10.105.0.0/16
Voice & Data VLAN > SW1 (173.105.80.1) connect to R1-R3

Host End 2
Data VLAN: 173.106.0.0/16
Voice VLAN: 10.106.0.0/16
Voice & Data VLAN > SW2 (173.106.80.1) connect to R4-R6

Host End 1--------------------------------------------MetroEthernet---------------------------------Host End 2 
R1(173.105.0.4) 10M link for voice -------------------------------------------------------------- R4(173.106.0.4) 10M  link for voice
R2(173.105.0.5) 30M link for data --------------------------------------------------------------- R5(173.106.0.5)  20M link for data
R3(173.105.0.6) 30M link for data --------------------------------------------------------------- R6(173.106.0.6) 20M link for data

SW1, SW2, R1-R6 are OSPF enabled (domain 0).

R1, R2, R3 form HRSP Group 1 with virtual IP (173.105.0.2) . R1 has highest priority.
R4, R5, R6 form HRSP Group 2 with virtual IP (173.106.0.2) . R4 has highest priority.

R1 and R2 with ip ospf cost 2 specified
R2, R3, R5, R6 with no ip ospf cost specified.

SW1 connect R1, R2, R3 and OSPF enabled (domain 0). Voice traffic is directed by static route on SW1 "ip route 10.106.0.0 255.255.0.0 173.105.0.2. Other is traffic controlled by OSPF routes.
SW2 connect R4, R5, R6 and OSPF enabled (domain 0). Voice traffic is directed by static route on SW2 "ip route 10.105.0.0 255.255.0.0 173.106.0.2. Other is traffic controlled by OSPF routes.

We found non-voice traffic is passing through the 10M link for voice and saturate it. This cause our Cisco IP phone quality and Cisco UCCX IVR cluster heartbeat problem. We traced the OSPF routes for this traffic and found that the route listing three links are on list with equal metric 7 and traffic share count 1.

Can I make the non-voice traffic taking the path of 20M/30M data links over 10M voice links by adjusting ospf cost below?
-change R1 and R2 ip ospf cost 2 to 100
-add R2, R3, R5, R6 ip ospf cost 1

Many thanks for your sharing and comment in advance.

Anthony

[Reza Sharifi]

Hi,

Can you provide a diagram of your topology?

The problem is when you change the OSPF metric, it will effect all your traffic including voice and data.

It seems to me that you need to deploy some sort of PBR (see link), but if you provide a diagram, we can probably understand your topology better.

http://www.cisco.com/c/en/us/td/docs/ios/12_2/qos/configuration/guide/fqos_c/qcfpbr.html

HTH

[tcanthonypoon]

Dear Reza,

Thanks for your reply.Attached please find the topology diagram for your reference.

BR,

Anthony

[Reza Sharifi]

Hi,

Thanks for the diagram.  So you have multiple circuits with different speeds connecting to a metro Ethernet cloud. You would need to set up PBR on each switch in each location (sw1 and sw2) to send for example a voice vlan via a 30Mb link and data vlan via a 20Mb link. For PBR to work, you also need to have IP services license installed on your 3750 switches.

HTH

[Richard Burts]

I agree with my colleague Reza that if you change the OSPF cost that it will affect all traffic in the same way and your problem will continue as it has been. He is correct that if you want to send a certain type of traffic on a particular link that PBR is the most often used solution for this.

HTH

Rick

[tcanthonypoon]

Hi Richard,

Thanks for your comment.

Our situation is not so simple. We have many VLANs in each of our two main datacenters with dedicated voice VLANs. Cisco IPT servers are installed at these two locations. All of our offices are interconnected by MetroEthernet. The MetroEthernet links and routers are all subscribed by carrier.

For controlling voice traffic, we have static route to direct voice VLAN through the 10M voice link via the HSRP group VIP on the carrier WAN routers (1 voice and 2 data links routers)

For replication traffic, PBR are implanted in the carrier WAN router to direct this traffic through the 20M replication link.

For all other traffics, OSPF will route through the multiple links(1 voice link & 2 equal-speed data links each side) . Since 10M voice & two 20M/30M data links are within the OSPF domain 0, it is possible the non-voice traffic passing through the voice link.

We believe that the existing carrier WAN design has the following handicap:

Voice traffic correctly passes through the 10M voice link in normal situation (If the voice link down, the voice traffic will pass through other 2 data links ) but the non-traffic possibly pass through any of the 3 links. We think there was no such high burst non-voice traffic in the past . By data volume increased, the intermittent high burst of non-voice traffic can saturate the voice link in recent months.

We want to found any workaround to get rid of non-voice traffic passing through the voice link.

BR,
Anthony