bgp抖动
现象：active-est状态正常，est后无法学到路由，到holdtime时间后返回到active状态。
报错日志：
BGP RECV 10.0.129.173+65498 -> 10.0.129.174+179
May 20 18:09:23.166414 BGP RECV message type 4 (KeepAlive) length 19
May 20 18:09:23.166454 bgp_read_v4_message: done with 10.0.129.173 (External AS 65145) received 19 octets 0 updates 0 routes
May 20 18:09:28.575260 bgp_hold_timeout: peer 10.0.129.173 (External AS 65145) read-subjob 0x0 last checked 90 last recv'd 6 last sent 7 last keepalive 7
May 20 18:09:28.596425 bgp_read_v4_message: receiving packet(s) from 10.0.129.173 (External AS 65145)
May 20 18:09:28.596507
May 20 18:09:28.596507 BGP RECV 10.0.129.173+65498 -> 10.0.129.174+179
May 20 18:09:28.596553 BGP RECV message type 3 (Notification) length 21
May 20 18:09:28.596699 bgp_read_v4_message:11447: NOTIFICATION received from 10.0.129.173 (External AS 65145): code 4 (Hold Timer Expired Error), socket buffer sndcc: 1574 rcvcc: 0 TCP state: 4, snd_una: 353734002 snd_nxt: 353735576 snd_wnd: 16384 rcv_nxt: 2616674094 rcv_adv: 2616690457, hold timer out 90s, hold timer remain 1:23.978734s
May 20 18:10:00.607559 BGP_RESET_PENDING_CONNECTION: 10.0.129.173 (External AS 65145): reseting pending active connection
May 20 18:10:00.608637 advertising graceful restart receiving-speaker-only capability to neighbor 10.0.129.173 (External AS 65145)
May 20 18:10:00.608684 advertising LLGR receiving-speaker-only capability to neighbor 10.0.129.173 (External AS 65145)
May 20 18:10:00.608794 bgp_send: sending 19 bytes to 10.0.129.173 (External AS 65145)
May 20 18:10:00.608843
May 20 18:10:00.608843 BGP SEND 10.0.129.174+179 -> 10.0.129.173+56431
May 20 18:10:00.610192 BGP SEND message type 4 (KeepAlive) length 19
May 20 18:10:00.627108
May 20 18:10:00.627108 BGP RECV 10.0.129.173+56431 -> 10.0.129.174+179
May 20 18:10:00.627162 BGP RECV message type 4 (KeepAlive) length 19
May 20 18:10:00.627873 advertising graceful restart receiving-speaker-only capability to neighbor 10.0.129.173 (External AS 65145)
May 20 18:10:00.627919 advertising LLGR receiving-speaker-only capability to neighbor 10.0.129.173 (External AS 65145)
May 20 18:10:00.657193 bgp_read_v4_message: receiving packet(s) from 10.0.129.173 (External AS 65145)
May 20 18:10:00.657277 bgp_read_v4_message: done with 10.0.129.173 (External AS 65145) received 23 octets 1 update 0 routes
May 20 18:10:26.333625 bgp_read_v4_message: receiving packet(s) from 10.0.129.173 (External AS 65145)
May 20 18:10:26.333746
May 20 18:10:26.333746 BGP RECV 10.0.129.173+56431 -> 10.0.129.174+179
May 20 18:10:26.333794 BGP RECV message type 4 (KeepAlive) length 19
May 20 18:10:26.333836 bgp_read_v4_message: done with 10.0.129.173 (External AS 65145) received 19 octets 0 updates 0 routes
May 20 18:10:29.758890 bgp_keepalive_timeout: peer 10.0.129.173 (External AS 65145) last checked 29 last recv'd 3 last sent 29 last keepalive 68
May 20 18:10:29.758966 bgp_send: sending 19 bytes to 10.0.129.173 (External AS 65145)
May 20 18:10:29.759018
May 20 18:10:29.759018 BGP SEND 10.0.129.174+179 -> 10.0.129.173+56431
May 20 18:10:29.759062 BGP SEND message type 4 (KeepAlive) length 19
May 20 18:10:55.060380 bgp_read_v4_message: receiving packet(s) from 10.0.129.173 (External AS 65145)
May 20 18:10:55.060583
May 20 18:10:55.060583 BGP RECV 10.0.129.173+56431 -> 10.0.129.174+179
May 20 18:10:55.060629 BGP RECV message type 4 (KeepAlive) length 19
May 20 18:10:55.060665 bgp_read_v4_message: done with 10.0.129.173 (External AS 65145) received 19 octets 0 updates 0 routes
May 20 18:10:56.583850 bgp_keepalive_timeout: peer 10.0.129.173 (External AS 65145) last checked 56 last recv'd 2 last sent 27 last keepalive 27
May 20 18:10:56.583932 bgp_send: sending 19 bytes to 10.0.129.173 (External AS 65145)
May 20 18:10:56.583981
May 20 18:10:56.583981 BGP SEND 10.0.129.174+179 -> 10.0.129.173+56431
May 20 18:10:56.584025 BGP SEND message type 4 (KeepAlive) length 19
May 20 18:11:24.796215 bgp_read_v4_message: receiving packet(s) from 10.0.129.173 (External AS 65145)
May 20 18:11:24.796340
May 20 18:11:24.796340 BGP RECV 10.0.129.173+56431 -> 10.0.129.174+179
May 20 18:11:24.796384 BGP RECV message type 4 (KeepAlive) length 19
May 20 18:11:24.796421 bgp_read_v4_message: done with 10.0.129.173 (External AS 65145) received 19 octets 0 updates 0 routes
May 20 18:11:25.896821 bgp_keepalive_timeout: peer 10.0.129.173 (External AS 65145) last checked 85 last recv'd 1 last sent 29 last keepalive 29
May 20 18:11:25.896897 bgp_send: sending 19 bytes to 10.0.129.173 (External AS 65145)
May 20 18:11:25.896947
May 20 18:11:25.896947 BGP SEND 10.0.129.174+179 -> 10.0.129.173+56431
May 20 18:11:25.896990 BGP SEND message type 4 (KeepAlive) length 19
May 20 18:11:30.628457 bgp_hold_timeout: peer 10.0.129.173 (External AS 65145) read-subjob 0x0 last checked 90 last recv'd 6 last sent 5 last keepalive 5
May 20 18:11:30.655635 bgp_read_v4_message: receiving packet(s) from 10.0.129.173 (External AS 65145)
May 20 18:11:30.655709
May 20 18:11:30.655709 BGP RECV 10.0.129.173+56431 -> 10.0.129.174+179
May 20 18:11:30.655753 BGP RECV message type 3 (Notification) length 21
May 20 18:11:30.655888 bgp_read_v4_message:11447: NOTIFICATION received from 10.0.129.173 (External AS 65145): code 4 (Hold Timer Expired Error), socket buffer sndcc: 1574 rcvcc: 0 TCP state: 4, snd_una: 2507764170 snd_nxt: 2507765725 snd_wnd: 16384 rcv_nxt: 1435059388 rcv_adv: 1435075751, hold timer out 90s, hold timer remain 1:23.972738s
May 20 18:12:02.685292 advertising graceful restart receiving-speaker-only capability to neighbor 10.0.129.173 (External AS 65145)
May 20 18:12:02.685379 advertising LLGR receiving-speaker-only capability to neighbor 10.0.129.173 (External AS 65145)
May 20 18:12:02.686391 bgp_pp_recv:4270: NOTIFICATION sent to 10.0.129.173 (External AS 65145): code 6 (Cease) subcode 7 (Connection Collision Resolution), Reason: dropping 10.0.129.173 (External AS 65145), connection collision prefers 10.0.129.173+64697 (proto)
May 20 18:12:02.686430 bgp_send: sending 21 bytes to 10.0.129.173 (External AS 65145)
May 20 18:12:02.686472
May 20 18:12:02.686472 BGP SEND 10.0.129.174+51143 -> 10.0.129.173+179
May 20 18:12:02.686514 BGP SEND message type 3 (Notification) length 21
May 20 18:12:02.688413 advertising graceful restart receiving-speaker-only capability to neighbor 10.0.129.173 (External AS 65145)
May 20 18:12:02.688457 advertising LLGR receiving-speaker-only capability to neighbor 10.0.129.173 (External AS 65145)
May 20 18:12:02.688556 bgp_send: sending 19 bytes to 10.0.129.173 (External AS 65145)
May 20 18:12:02.688605
May 20 18:12:02.688605 BGP SEND 10.0.129.174+179 -> 10.0.129.173+64697
May 20 18:12:02.688648 BGP SEND message type 4 (KeepAlive) length 19
May 20 18:12:02.715123
May 20 18:12:02.715123 BGP RECV 10.0.129.173+64697 -> 10.0.129.174+179
May 20 18:12:02.715174 BGP RECV message type 4 (KeepAlive) length 19
May 20 18:12:02.715856 advertising graceful restart receiving-speaker-only capability to neighbor 10.0.129.173 (External AS 65145)
May 20 18:12:02.716970 advertising LLGR receiving-speaker-only capability to neighbor 10.0.129.173 (External AS 65145)
May 20 18:12:02.735204 bgp_read_v4_message: receiving packet(s) from 10.0.129.173 (External AS 65145)
May 20 18:12:02.735285 bgp_read_v4_message: done with 10.0.129.173 (External AS 65145) received 23 octets 1 update 0 routes
May 20 18:12:27.785583 bgp_read_v4_message: receiving packet(s) from 10.0.129.173 (External AS 65145)
May 20 18:12:27.785705
May 20 18:12:27.785705 BGP RECV 10.0.129.173+64697 -> 10.0.129.174+179
May 20 18:12:27.785752 BGP RECV message type 4 (KeepAlive) length 19
May 20 18:12:27.785791 bgp_read_v4_message: done with 10.0.129.173 (External AS 65145) received 19 octets 0 updates 0 routes
May 20 18:12:30.175101 bgp_keepalive_timeout: peer 10.0.129.173 (External AS 65145) last checked 27 last recv'd 2 last sent 27 last keepalive 64
May 20 18:12:30.175182 bgp_send: sending 19 bytes to 10.0.129.173 (External AS 65145)
May 20 18:12:30.175232
May 20 18:12:30.175232 BGP SEND 10.0.129.174+179 -> 10.0.129.173+64697
May 20 18:12:30.175277 BGP SEND message type 4 (KeepAlive) length 19
May 20 18:12:55.635525 bgp_read_v4_message: receiving packet(s) from 10.0.129.173 (External AS 65145)
May 20 18:12:55.635652
May 20 18:12:55.635652 BGP RECV 10.0.129.173+64697 -> 10.0.129.174+179
May 20 18:12:55.635702 BGP RECV message type 4 (KeepAlive) length 19
更改接口tcp-mss后正常