Addition on hidden command "bfd multihop/singlehop" and "ptm-enable" per interface...

Addition on hidden command "bfd multihop/singlehop" and "ptm-enable" per interface command

CM-10435
Issue: IBGP BFD sessions are created as multi-hop even though peer is single-hop away. This is causing an interop issue with ICOS.
Root Cause: By design all IBGP peers are registered with BFD as multi-hop.
Fix:
• Changed the default behavior of always treating IBGP BFD sessions as mult-hop. shared_network variable is used to determine whether the IBGP peer is single hop or multi-hop away. The logic for determining whether EBGP peer is single hop or multi-hop has not been changed.
• Since the default behavior has been changed, it will cause interop issues between 2.5 and 3.0 IBGP BFD sessions. A new hidden command “bfd multihop/singlehop” has been introduced to overcome the interop issues.

dell-s6000-10(config-router)# neighbor 30.0.2.6 bfd
<2-255> Detect Multiplier
<cr>
dell-s6000-10(config-router)# neighbor 30.0.2.6 bfd multihop
dell-s6000-10(config-router)# no neighbor 30.0.2.6 bfd multihop
dell-s6000-10(config-router)#
dell-s6000-10(config-router)# neighbor 30.0.2.6 bfd multihop
dell-s6000-10(config-router)# do show running-config
!
router bgp 100
neighbor igroup peer-group
neighbor igroup bfd 5 500 500
neighbor igroup bfd multihop
neighbor 30.0.2.2 remote-as 100
neighbor 30.0.2.2 peer-group igroup
neighbor 3101:abc:bcad::2 remote-as 100
neighbor 3101:abc:bcad::2 peer-group igroup
neighbor 30.0.2.6 remote-as 200
neighbor 30.0.2.6 bfd multihop
neighbor 3102:abc:bcad::6 remote-as 200
neighbor 3102:abc:bcad::6 bfd
neighbor 3102:abc:bcad::6 ebgp-multihop 255
!

CM-10260
Issue: “Unable to connect to socket” message keeps getting logged when ptmd process doesn’t exist.
Root Cause: BFD clients (bgpd, ospfd and ospf6d) during initialization try to register with BFD/PTM by default. This results in continuous logging If PTM does not exist since there is no max on number of retries.
Fix:
• Stop the retries to connect to PTM after max reconnect timer of 5 mins is reached.
• Added zebra debug event wrapper to message logging to prevent it from showing by default.

CM-4541
Issue: Addition of a new command "ptm-enable" or "no ptm-enable" per interface to enable/disable PTM link status checks for an interface.
Fix: Currently there is only one ptm-enable global command that enables/disables PTM status updates for all interfaces. This new command will give the handle to individually stop interface from reacting on the PTM status updates.
• by default interface uses the ptm-enable global configuration
• "no ptm-enable" on an interface will disable PTM status updates from taking affect for that interface. This can bring the interface up if it was brought down due to PTM status update.
• "ptm-enable" on an interface will cause the interface to fallback to the global ptm-enable configuration value and will bring the interface up or down based on the last stored PTM status update if global ptm is enabled.

Ticket: CM-10435, CM-10260 and CM-4541
Signed-off-by: Radhika Mahankali
Reviewed-by: Donald Sharp, Kanna Rajagopal