为什么将端口MTU值回复缺省值，以及修改tcp mss 1400，仍有告警信息

%Sep 7 11:34:13:633 2022 ZJ-P-SR6608 BGP/5/BGP_STATE_CHANGED: BGP.: 11.48.126.95 state has changed from ESTABLISHED to IDLE for a notification received: Hold Timer Expired/ErrSubCode Unspecified.

%Sep 7 15:09:07:548 2022 ZJ-P-SR6608 ISIS/5/ISIS_NBR_CHG: IS-IS 1, Level-1 adjacency 0110.4989.0117 (GigabitEthernet3/1/7.255), state changed to UP. 

%Sep 7 15:09:07:549 2022 ZJ-P-SR6608 BFD/5/BFD_CHANGE_FSM: Sess[11.48.7.253/11.48.7.254, LD/RD:12406/33793, Interface:GE3/1/7.255, SessType:Ctrl, LinkType:INET], Ver:1, Sta: DOWN->INIT, Diag: 0

%Sep 7 15:09:28:388 2022 ZJ-P-SR6608 BFD/5/BFD_CHANGE_FSM: Sess[11.48.7.253/11.48.7.254, LD/RD:12406/33793, Interface:GE3/1/7.255, SessType:Ctrl, LinkType:INET], Ver:1, Sta: UP->DOWN, Diag: 1

interface GigabitEtherne某子接口

 mtu 1600

 ip address x.x.x.x 30

 pim sm

 isis enable 1

 isis circuit-level level-1

 isis circuit-type p2p isis cost 2000 

 isis authentication-mode md5 cipher $c$3$

 isis bfd enable 

 mpls enable

mpls ldp enable 

 vlan-type dot1q vid 260 

 bfd min-transmit-interval 100 

 bfd min-receive-interval 100

 bfd detect-multiplier 3

bgp 200

timer keepalive 10 hold 30

group VRR internal 

 peer VRR connect-interface LoopBack1 

 peer 11.49.126.95 group VRR

 peer 11.49.126.95 bfd