OSPF Cost Metric

[johnlloyd_13]

all,

please advise which is more practical and the proper design to use OSPF cost for route metric. is it the bandwidth or ip ospf cost interface command?.

R1(config)#int s0/0/0

R1(config-if)#bandwidth ?

  <1-10000000>  Bandwidth in kilobits

R1(config)#int s0/0/0
R1(config-if)#ip ospf cost ?
  <1-65535>  Cost

[cadet alain]

Hi,

As bandwidth command is also used in QoS and as reference  bandwidth is 100000 Mbps then I would suggest using  the ip ospf cost method

if you are using QoS or if you have Gig or TenGig ports because otherwise cost = 1 like Fastethernet.

Regards.

Alain

[johnlloyd_13]

hi alain,

thanks for your feedback! i guess i should go with the ip ospf cost command since majority of our links are at gig and 10 gig e ports. one last thing, could i set up both coz we have QoS in place for our WAN links?

[cadet alain · Accepted solution]

Hi,

could i set up both coz we have QoS in place for our WAN links?

of course the ip ospf cost command overrides the cost calculated with the reference-bandwidth

But it all depends of your topology and what you want to achieve with it.if you find the ospf cost of your wan links is ok with the

default algorithm don't change anything for these links.

Concerning your Gig and Te links with the default they'll all have same cost but then the routing decision will  also be linked to the ospf design you have.

Regards.

Alain.