>причина в конфигурации, которую вы не показали...
Конфигурации следующие:
К 4 порту Cat2950№3 подключен 1 порт Cat2950№4 через бриджи
Cat2950№3
version 12.1
no service single-slot-reload-enable
no service pad
service timestamps debug datetime localtime show-timezone
service timestamps log datetime localtime show-timezone
service password-encryption
!
hostname Ermolaevskaya
!
logging buffered 40000 debugging
enable password 7 XXX
!
clock timezone MSK 3
clock summer-time MSD recurring last Sun Mar 3:00 last Sun Oct 2:00
!
vlan 60
!
vlan 61
!
vlan 214
!
vlan 215
!
vlan 272
!
vlan 273
!
vlan 274
!
vlan 275
!
vlan 276
!
vlan 277
!
vlan 278
!
vlan 279
!
vlan 280
!
vlan 281
!
vlan 282
!
vlan 283
!
vlan 284
!
vlan 285
!
vlan 286
!
vlan 287
!
vlan 288
!
vlan 289
!
vlan 290
!
vlan 291
!
vlan 292
!
vlan 376
!
vlan 377
!
vlan 378
!
vlan 379
!
vlan 380
!
vlan 381
!
vlan 382
!
vlan 383
!
vlan 384
!
vlan 385
!
vlan 386
!
vlan 387
!
vlan 388
!
vlan 432
!
vlan 433
!
vlan 434
!
vlan 435
!
vlan 436
!
vlan 901
ip subnet-zero
vtp domain XXX
vtp mode transparent
!
no spanning-tree optimize bpdu transmission
spanning-tree extend system-id
!
!
interface FastEthernet0/1
description Main Link
switchport mode trunk
no ip address
duplex full
speed 10
!
!
interface FastEthernet0/4
description Pokrovka
switchport trunk allowed vlan 1,375-403,900-999
switchport mode trunk
no ip address
duplex full
speed 10
!
...
interface Vlan1
ip address x.x.x.x
no ip route-cache
!
ip default-gateway x.x.x.x
no ip http server
!
!
line con 0
line vty 0 4
login local
line vty 5 15
login
!
end
Cat2950№4
version 12.1
no service pad
service timestamps debug datetime localtime show-timezone
service timestamps log datetime localtime show-timezone
service password-encryption
!
hostname Pokrovka_Switch
!
logging buffered 40000 debugging
!
clock timezone MSK 3
clock summer-time MSD recurring last Sun Mar 3:00 last Sun Oct 2:00
ip subnet-zero
!
vtp domain XXX
vtp mode transparent
!
!
spanning-tree mode pvst
no spanning-tree optimize bpdu transmission
spanning-tree extend system-id
!
!
vlan 5,376-388
!
interface FastEthernet0/1
description In
switchport mode trunk
bandwidth 2048
no ip address
duplex full
speed 10
!
interface FastEthernet0/2
description Turavia
switchport access vlan 376
switchport mode access
no ip address
!
interface FastEthernet0/3
description Sibico
switchport access vlan 377
no ip address
shutdown
!
interface FastEthernet0/4
description Dom nedvizhimosti
switchport access vlan 378
no ip address
!
interface FastEthernet0/5
description Pansionat Solnechnii
switchport access vlan 379
no ip address
!
interface FastEthernet0/6
description Aptrend
switchport access vlan 380
no ip address
!
...
interface Vlan1
ip address x.x.x.x
no ip route-cache
!
ip default-gateway x.x.x.x
no ip http server
!
!
line con 0
line vty 0 4
login local
line vty 5 15
login
!