Циска 3750 (версия IOS C3750-ADVIPSERVICESK9-M 12.2(25)SEE), в основном с подключенными к ней рабочими станциями. В сислог сыпятся сообщения типа
12-05-2007    14:31:35    Local7.Notice    Dec  5 11:28:33: %LINEPROTO-5-UPDOWN: Line protocol on Interface FastEthernet3/0/15, changed state to up
12-05-2007    14:31:33    Local7.Notice    Dec  5 11:28:31: %LINEPROTO-5-UPDOWN: Line protocol on Interface FastEthernet3/0/15, changed state to down
12-05-2007    14:30:50    Local7.Notice    Dec  5 11:27:49: %LINEPROTO-5-UPDOWN: Line protocol on Interface FastEthernet3/0/15, changed state to up

sh int показыват следующее:

FastEthernet3/0/15 is up, line protocol is up (connected)
  Hardware is Fast Ethernet, address is 001a.a299.5c11 (bia 001a.a299.5c11)
  MTU 1500 bytes, BW 100000 Kbit, DLY 100 usec,
     reliability 255/255, txload 1/255, rxload 1/255
  Encapsulation ARPA, loopback not set
  Keepalive set (10 sec)
  Full-duplex, 100Mb/s, media type is 10/100BaseTX
  input flow-control is off, output flow-control is unsupported
  ARP type: ARPA, ARP Timeout 04:00:00
  Last input never, output 00:00:58, output hang never
  Last clearing of "show interface" counters never
  Input queue: 0/75/0/0 (size/max/drops/flushes); Total output drops: 0
  Queueing strategy: fifo
  Output queue: 0/40 (size/max)
  5 minute input rate 0 bits/sec, 0 packets/sec
  5 minute output rate 0 bits/sec, 0 packets/sec
     1498133 packets input, 285223525 bytes, 0 no buffer
     Received 15373 broadcasts (0 multicast)
     0 runts, 0 giants, 0 throttles
     11 input errors, 0 CRC, 0 frame, 0 overrun, 0 ignored
     0 watchdog, 366 multicast, 0 pause input
     0 input packets with dribble condition detected
     86561342 packets output, 882099028 bytes, 0 underruns
     0 output errors, 0 collisions, 1 interface resets
     0 babbles, 0 late collision, 0 deferred
     0 lost carrier, 0 no carrier, 0 PAUSE output
     0 output buffer failures, 0 output buffers swapped out

И так практически по всем интерфейсам. В err-disable не уходят.  

Конфиг такой (вкратце):
version 12.2
no service pad
service timestamps debug uptime
service timestamps log datetime
service password-encryption
service sequence-numbers
!
hostname Cat_3750
!
logging buffered 262144 debugging
enable secret 5 $1$af.7$oM8OfWOn7gwAvKwMvo.gL1
!
switch 1 provision ws-c3750-48ts
switch 2 provision ws-c3750g-24t
switch 3 provision ws-c3750-48ts
switch 4 provision ws-c3750-48ts
ip subnet-zero
!        
ip ssh time-out 60
ip ssh authentication-retries 2
!        
!        
!        
!        
!        
no file verify auto
spanning-tree mode pvst
spanning-tree portfast default
spanning-tree extend system-id
!        
vlan internal allocation policy ascending
!        
!        
interface FastEthernet1/0/1
!        
interface FastEthernet1/0/2

****
interface GigabitEthernet4/0/1
spanning-tree portfast disable
!        
interface GigabitEthernet4/0/2
!        
interface GigabitEthernet4/0/3
!        
interface GigabitEthernet4/0/4
!        
interface Vlan1
ip address dhcp
!        
ip classless
no ip http server
no ip http secure-server
!        
ip access-list standard ro
!        
logging trap notifications
logging 192.168.1.27

access-list 50 deny   any log
snmp-server community public RO ro
radius-server source-ports 1645-1646
!        
control-plane
!        

end      

!

На портах с отключенным STP висят коммутаторы.

Вопрос в следующем: такое положение дел в пределах нормы или что-то глючит/не правильно настроено? В принципе, на коннект пользователи не жалуются, но как-то неспокойно на душе.