The BGP routes advertised very slowly when there are many routes in route table (200,000 routes). The advertise process takes hours and still not able to finish.

Problem:

• 200,000 routes in total.
• 4 routers are synced with controller.
• After all the routes are synced with the controller, restart one of the 4 routers. The rebooted router receives route very slowly.

There is no ERROR or WARN in the karaf log.
The wireshark capture shows a lot of retransmission for the UPDATE message.

I am suspecting the HIGH WATERMARK or LOW WATERMARK is too high caused the netty channel sent out too much data at a time. With some congestion on the network, netty fails to transmit all the UPDATE message efficiently.