zebra: uplink tracking and startup delay for EVPN-MH

zebra: uplink tracking and startup delay for EVPN-MH

Local ethernet segments are held in a protodown or error-disabled state
if access to the VxLAN overlay is not ready -
1. When FRR comes up the local-ESs/access-port are kept protodown
for the startup-delay duration. During this time the underlay and
EVPN routes via it are expected to converge.
2. When all the uplinks/core-links attached to the underlay go down
the access-ports are similarly protodowned.

The ES-bond protodown state is propagated to each ES-bond member
and programmed in the dataplane/kernel (per-bond-member).

Configuring uplinks -
vtysh -c "conf t" vtysh -c "interface swp4" vtysh -c "evpn mh uplink"

Configuring startup delay -
vtysh -c "conf t" vtysh -c "evpn mh startup-delay 100"

>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
EVPN protodown display -
========================
root@torm-11:mgmt:~# vtysh -c "show evpn"
L2 VNIs: 10
L3 VNIs: 3
Advertise gateway mac-ip: No
Advertise svi mac-ip: No
Duplicate address detection: Disable
  Detection max-moves 5, time 180
EVPN MH:
  mac-holdtime: 60s, neigh-holdtime: 60s
  startup-delay: 180s, start-delay-timer: 00:01:14 <<<<<<<<<<<<
  uplink-cfg-cnt: 4, uplink-active-cnt: 4
  protodown: startup-delay <<<<<<<<<<<<<<<<<<<<<<<
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>

>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
ES-bond protodown display -
===========================
root@torm-11:mgmt:~# vtysh -c "show interface hostbond1"
Interface hostbond1 is up, line protocol is down
  Link ups:       0    last: (never)
  Link downs:     1    last: 2020/04/26 20:38:03.53
  PTM status: disabled
  vrf: default
  OS Description: Local Node/s torm-11 and Ports swp5 <==> Remote  Node/s hostd-11 and Ports swp1
  index 58 metric 0 mtu 9152 speed 4294967295
  flags: <UP,BROADCAST,MULTICAST>
  Type: Ethernet
  HWaddr: 00:02:00:00:00:35
  Interface Type bond
  Master interface: bridge
  EVPN-MH: ES id 1 ES sysmac 00:00:00:00:01:11
  protodown: off rc: startup-delay  <<<<<<<<<<<<<<<<<
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>

>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
ES-bond member protodown display -
==================================
root@torm-11:mgmt:~# vtysh -c "show interface swp5"
Interface swp5 is up, line protocol is down
  Link ups:       0    last: (never)
  Link downs:     3    last: 2020/04/26 20:38:03.52
  PTM status: disabled
  vrf: default
  index 7 metric 0 mtu 9152 speed 10000
  flags: <UP,BROADCAST,MULTICAST>
  Type: Ethernet
  HWaddr: 00:02:00:00:00:35
  Interface Type Other
  Master interface: hostbond1
  protodown: on rc: startup-delay <<<<<<<<<<<<<<<<
root@torm-11:mgmt:~#
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>

Signed-off-by: Anuradha Karuppiah <anuradhak@cumulusnetworks.com>