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Description of problem:


Version-Release number of selected component (if applicable):
In a RHEL7 guest, the initial routing table is:

# ip r s
default via 192.168.122.1 dev eth0  proto static  metric 1024 
192.168.122.0/24 dev eth0  proto kernel  scope link  src 192.168.122.16

# ip route add default via 192.168.122.1 dev eth0  proto static

No error shown and check it again:

# ip r s
default via 192.168.122.1 dev eth0  proto static 
default via 192.168.122.1 dev eth0  proto static  metric 1024 
192.168.122.0/24 dev eth0  proto kernel  scope link  src 192.168.122.16 

There are two default routes. That's the problem.

How reproducible:
always

Expected results:
Ban adding the duplicate in routing table.

Additional info:

Forgot to say, I use following to reproduce:

iproute-3.10.0-6.el7.x86_64
kernel-3.10.0-48.el7.x86_64

This is not a bug, let alone a regression.  If anything, this is an RFE.  Adding identical routes with different metrics has always been possible.

Even though it doesn't make much sense at first, there may be some scenarios where users could want this.