Ospf between mellanox and Cisco 10gig

[master118]

Hi,

I have two mellanox switches connected to Cisco L3 switch stack using two 10gig interfaces. On cisco two ten gig links are configured as port-channel trunk at L2 and on Mellanox  10gig interface from each switch is connected to Cisco is set on MLAG port channel at L2. OSPF configured on top at l3 on VLAN SVIs.

The ospf routing table on Cisco showing two paths to reach 192.168.2.0 network that is behind mellanox. The ospf reference bandwidth on Cisco L3 switch showing 100Mbps and the reference bandwidth on Mellanox showing 100Gbps.

How to adjust ospf to 10-gig port-channel interface on both cisco and mellanox?

Is there any chance of sub optimal routing because of two paths to the same route?

please see the following picture

[Georg Pauwen]

Hello,

100MB is the default reference bandwdith for OSPF on Cisco. In order to change that, use the 'auto-cost reference-bandwidth 10000' command under the OSPF process:

R1(config)#router ospf 1

R1(config-router)#auto-cost reference-bandwidth 10000

10000 equals 10000Mbit equals 10Gigabit...

Is that what you are after ?

[master118]

Hi Georg,

Thank you for you reply. As auto-cost reference-bandwidth command needs setting on all routers, this would mean I need to set this on routers connected, but I have other routers connected to Cisco L3 switch that are out of my administrative jurisdiction and cannot be applied. I would prefer an interface command or something that applies on a link between l3 cisco switch and mellanox. Because the OSPF is not applied on physical interfaces and enabled on VLAN SVI's, is there any option? Also, the link between the cisco and mellanox is a Port-channel with a total bandwidth of 20Gbps, what is the correct option? 

Having multiple paths between cisco and mellanox to reach network 192.168.2.0/24, would this cause sub-optimal route? Instead of having one ospf multi access network between Cisco and Mellanox, is it better to have a two point to point networks between these two?