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E5400 / 5300 OSPF link cost calculation

 
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Aarón
Frequent Advisor

E5400 / 5300 OSPF link cost calculation

Hello,

 

I was just wondering if there is a way to change the reference bandwitdth in the OSPF cost calculation. Right now we have 10G links and 1G links and we noticed both have the same default cost (1). We would like to change it so the 10G link have a cost of 1 and the 1G links have a cost of 10.

 

I know that in cisco this can be done with the command "ospf auto-cost reference-bandwidth" but I have not found anything in the documentaion.

 

 

We can do it manually but we have loads of 1G OSPF links and it can lead to misconfigurations.

 

 

Thanks!

 

Aarón

6 REPLIES
LorenzoCastro
Frequent Advisor

Re: E5400 / 5300 OSPF link cost calculation

Yes you can change the reference bw within the OSPF context configuration mode with the bandwidth-reference command.

Aarón
Frequent Advisor

Re: E5400 / 5300 OSPF link cost calculation

Hello Lorenzo,

 

I could not find that command within the OSPF context. I have not the latest firmware installed, the latest firmware we have deployed is K.15.07.0008.

 

All I got from the configuration options in the 5400zl is this:

 

TEST(config)# router ospf 
 area                  Define/remove an OSPF area, area range or virtual link.
 default-metric        The default metric used for advertising external routes
                       imported into OSPF by this router.
 disable               Disable OSPF.
 distance              Set administrative distance to associate with 
                       intra-area, inter-area and AS-external routes learned by
                       OSPF.
 enable                Enable OSPF.
 logging               Enables or Disables OSPFv2 Logging.
 metric-type           The default metric type used for advertising external 
                       routes imported into OSPF by this router.
 redistribute          Specify source protocols which will be redistributed 
                       into OSPF.
 restart               configure OSPFv2 graceful restart -'no restart ..' sets
                       restart parameters to the default value.
 restrict              Prevent redistribution of routes via OSPF.
 rfc1583-compatibility Enable/disable RFC-1583 compatibility.
 spf-throttle          Enable and configure SPF throttling.
 trap                  Enable/disable OSPF traps.
 <cr>

 

I couldn't find it either in the documentation and release notes I got, am I missing something?

 

Thank you for your help,

 

Aarón

LorenzoCastro
Frequent Advisor

Re: E5400 / 5300 OSPF link cost calculation

Hello Aaron,

 

My apologies, it looks like the bandwidth-reference command is only an A series and not an E series command.  From what I can see it will have to be adjusted on each link using the ip ospf link cost command.  Please see the multicast and routing configuration guide here

 

http://bizsupport2.austin.hp.com/bc/docs/support/SupportManual/c03114779/c03114779.pdf

 

HP Stack E3800(vlan-1)# ip ospf cost
 <1-65535>             Enter an integer number for the 'cost'
                       command/parameter.
HP Stack E3800(vlan-1)# ip ospf cost 1
HP Stack E3800(vlan-1)# vlan 999

HP Stack E3800(vlan-999)# ip ospf cost
 <1-65535>             Enter an integer number for the 'cost'
                       command/parameter.
HP Stack E3800(vlan-999)# ip ospf cost 10

Aarón
Frequent Advisor

Re: E5400 / 5300 OSPF link cost calculation

Hello Lorenzo,

 

that's a shame for a moment I thought I could it with only one command... Let's hope HP can add this feature in future releases as it doesn't seem to be really hard to implement.

 

Thank you very much for your help!

 

Kind regards,

 

Aarón

Peter_Debruyne
Honored Contributor
Solution

Re: E5400 / 5300 OSPF link cost calculation

Well, this is not implemented for a reason. The problem with a routed vlan interface is that the underlying vlan could have 10Mbit AND 100Mbit/Gigabit ports. So it would be very difficult to know for the device to know the REAL bandwidth to the next hop. (it is easy for us when we know there is only 1 port to 1 next hop, but a vlan can allow x ports, and intermediate devices could exist between this router and the next hop).

 

They could have opted for some default, but it seems they just wanted the admin to decide/configure on the actual link speed to the next hop.

 

Same would apply partially to comware. There is a "reference bandwidth" which can be set under ospf, but this is only really valid for the routed ports (int x - port link-mode route), the routed vlan interfaces will just be set to a default cost, not the actual vlan link speed ( altough I have seen various results for this on MSR router vs switch platforms).

 

Best regards,Peter

 

Aarón
Frequent Advisor

Re: E5400 / 5300 OSPF link cost calculation

Hello Peter,

thank you for your help, we did notice later that not having a specific interface for OSPF the "reference bandwitdth" is not even logical. We already started configuring all our switches with the cost we needed to ;)

Kind regards,

Aarón