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New Member

ospf and qos problem ??

Hi guys.

i have a senario where router A (RTR A) connected to router b through 4 serial links and ospf is enabled and cost is manually assigned 50.similarly RTR C and RTR D.

RTR A and RTRC are connected through fast ethernet cost 50.

in normal case RTRA traffic poiting to RTR B.

Now i want if suppose utilisation of links of RTR A and RTR B pair reaches above 80% the traffic get shifted to RTR c ,RTR D pair.

How is it possible ,what qos commands we would have to use.

RTR A --------4x50---------RTRB




RTRC--------4x50------- RTR D

Hope i m clear.




Re: ospf and qos problem ??

If you are refering to the TOS capabilities of OSPF, Cisco never implemented these options and they have since been depreciated in RFC 2178:

G.10 Deleting the TOS routing option

The TOS routing option has been deleted from OSPF. This action was

required by the Internet standards process ([Ref24]), due to lack of

implementation experience with OSPF's TOS routing. However, for

backward compatibility the formats of OSPF's various LSAs remain

unchanged, maintaining the ability to specify TOS metrics in router-

LSAs, summary-LSAs, ASBR-summary-LSAs, and AS-external-LSAs (see

Sections 12.3, A.4.2, A.4.4, and A.4.5).

You could look at MPLS Traffic Engineering, this would provide you with a solution to your query. The following URL's cover MPLS TE functionality.

New Member

Re: ospf and qos problem ??


No i was not refering to TOS capability of OSPF.I think we will have to use some QOS for it.but not getting it.

I simply wants a mechanism that as soon as my trffic on link reaches say 80% traffic utilisation ,my traffic get shifted to the other RTR C RTR D pair