linux-cp: handle ipv4 routes when interface is disabled
linux-cp: handle ipv4 routes when interface is disabled

Type: improvement

Currently, when an interface is brought down administratively, IPv4
routes that resolve through that interface remain in the FIB. However,
the kernel removes those routes but doesn't send any notifications about
that. Desynchronization between the kernel and VPP happens.

With this change, when a notification received from the kernel
indicating that an interface was brought down, in addition to bringing
the VPP interface down, walk the IPv4 FIB bound to that interface and
remove any entries that resolve through that interface and were added
with one of the linux-cp FIB sources.

Signed-off-by: Alexander Chernavin <005bca4307cd9b117df45182181fee477edfa768@netgate.com>
Change-Id: I0cd14bb63c9e6616ae1c5739b17c3bf33b186bc2

chrisy/vpp,chrisy/vpp,FDio/vpp,FDio/vpp,FDio/vpp,chrisy/vpp,chrisy/vpp,FDio/vpp,FDio/vpp,FDio/vpp,FDio/vpp,chrisy/vpp,chrisy/vpp,FDio/vpp,chrisy/vpp,chrisy/vpp