it is happening bcos link between RA and RB is 2mbps higher than link between Ra and Rc but your second sentence about taking down the link between RB and RC is quit amazing as it should take RA to RC direct link of 512 kbps well for troubleshooting further we need to look at routing table and metrics why it is misbehaving like this.
you need to specify which interfaces are in area 0 and area 10 from these three router's well above what you are publishing and routing table and ospf configuration will gives us the braoder view of the topology.
Are you using any bandwidth command in interface mode like bandwidth 512.
make sure everywhere you are using bandwidth command and one more thing to add with devang which ip address or network you are trying to ping and if you can put routing table as well to clearly find out the problem as in my opinion everything should work fine and if it is loopback address from RC and published in area 0 or 10 it will be reachable directly ro RC not from RB.
well if there any other link between RB to RC other than this 128 k link than we need to look at it.
We are pleased to announce availability of Beta software for 16.6.3. 16.6.3 will be the second rebuild on the 16.6 release train targeted towards Catalyst 9500/9400/9300/3850/3650 switching platforms. We are looking for early feedback from custome...