[c-nsp] OSPF Reference bandwidth auto-cost and LAG

[Oliver Boehmer (oboehmer)]

Alastair Johnson <> wrote on Monday, August 11, 2008 12:56 PM:

> Hi,
> 
> I am trying to understand how IOS implements the OSPF reference
> bandwidth related to LAG interfaces.
> 
> The only background material I can find on this is along the lines of:
>
http://www.cisco.com/en/US/tech/tk365/technologies_q_and_a_item09186a008
0094704.shtml#q3
> 
> Can anyone confirm whether LAG/Port-Channel interfaces have the
> reference BW recalculated based on the active member links?
> 
> e.g. if I have ref BW = 100G, and a P-C with 2 10GE links, it should
> be metric = 5.
> 
> If one 10GE link disappears from the bundle, do I have metric = 10?

yes, the bandwidth on the port-channel interface is based on the number
of active links, and OSPF's cost will adjust automatically. 

	oli