EBGP路由运行半个月以上后会报hold timer错误，求助求助！！！

与华为路由器直连的一台交换机，配置EBGP路由，运行半年后，目前经常报错hold timer，信息如下：
show ip bgp neighbors
BGP neighbor is 10.21.19.185, remote AS 200, local AS 100, external link
BGP version 4, remote router ID 11.11.11.11
BGP state = Established, up for 00:02:01
Last read 00:00:17, hold time is 180, keepalive interval is 60 seconds
Neighbor capabilities:
Route refresh: advertised and received (old and new)
Address family IPv4 Unicast: advertised and received
Received 27 messages, 0 notifications, 0 in queue
Sent 331 messages, 20 notifications, 0 in queue
Route refresh request: received 0, sent 0
Minimum time between advertisement runs is 30 seconds
For address family: IPv4 Unicast
BGP table version 21, neighbor version 21

last reset： 01w1d23h ，due to BGP notification sent
notification error massage：（Hold timer Expired/Unspecified Error Subcode）