We are noticing a very strange behaviour on Cisco 7606 Router.
Cisco 7606 is running with RSP720-3C-GE as a processing engine and we have a line card 76-ES+XC-20G3C connected on the chassis on slot 4.
When we connect a SFP(GLC-LH-SM=) and fiber link on port gig 4/9 or gig 4/10 we notice that the CPU utilization goes beyond 70% and the port adjusts itself to 100 Mbps. Strange!!
If I manually set the port speed to 1 Gbps on 4/9 CPU still goes high. When CPU shoots high we notice interuppts to be 33-35% while the maximum CPU consuming process is "Online Diag EEM" which consumes 12-15 % of CPU.
While the same SFP and the same fiber link if connected on port gig 4/6 the CPU utilization is normal and the port adjusts to 1 Gbps automatically. The CPU stays stable at 25-30 % total utilization with hardly 8-9% of interrupts.
The configuration of port gig 4/6, 4/9 and 4/10 is exactly same.
There is no traffic on the the link yet but just mere connection on 4/9 or 4/10 causes CPU hike. We have changed the SFPs too and checked but no change in behaviour.
But if I connect a GLC-T and terminate a CAT-5 on 4/9 or 4/10 the CPU remains normal but adjusts to 100 Mbps. The image running on the 7600 is 122-33.SRE5. Is there any restriction related to this card or 7600 series?