Backbone 3750 + Edge 2960

Bonjour,
Je dois créer un backbone avec 4 3750 (2x stacks (IT et DR) reliés par 4 fibres) et un edge 2960, reliée en fibre redundant(une se le 1°stack et l'autre sur le 2°stack.
J'ai 2 vlans 170 et 190.
J'ai placé un pc sur le 2960 dans le vlan 170 et ma connectivité fonctionne.

Mon problème: Lorsque je débranche une fibre du 2960, je perd le réseau pendant 30 secondes (et c'est aussi 30 secondes lorsque je remets la fibre) C'est trop long.

Qui peut m'aider.

Voici mes configs:

IT#sh run
Building configuration...

Current configuration : 3835 bytes
!
version 12.2
no service pad
service timestamps debug uptime
service timestamps log uptime
no service password-encryption
!
hostname IT
!
enable secret 5 $1$P0KD$aY/LBfPYfVEf9gTYVozSB/
enable password test
!
no aaa new-model
switch 1 provision ws-c3750g-12s
switch 2 provision ws-c3750g-12s
system mtu routing 1500
ip subnet-zero
!
cluster enable Backbone 0
!
!
!
no file verify auto
!
spanning-tree mode rapid-pvst
spanning-tree extend system-id
spanning-tree backbonefast
spanning-tree vlan 170 priority 24576
spanning-tree vlan 190 priority 28672
!
vlan internal allocation policy ascending
!
interface Port-channel1
description Trunk_IT-DR
switchport trunk encapsulation dot1q
switchport trunk allowed vlan 170,190
switchport mode trunk
!
interface GigabitEthernet1/0/1
description Trunk to DR 1/4
switchport trunk encapsulation dot1q
switchport trunk allowed vlan 170,190
switchport mode trunk
channel-group 1 mode active
!
interface GigabitEthernet1/0/2
description Trunk to DR 2/4
switchport trunk encapsulation dot1q
switchport trunk allowed vlan 170,190
switchport mode trunk
channel-group 1 mode active
!
interface GigabitEthernet1/0/3
description Trunk to IT-Servers
switchport trunk encapsulation dot1q
switchport mode trunk
!
interface GigabitEthernet1/0/4
!
interface GigabitEthernet1/0/5
!
interface GigabitEthernet1/0/6
!
interface GigabitEthernet1/0/7
!
interface GigabitEthernet1/0/8
!
interface GigabitEthernet1/0/9
!
interface GigabitEthernet1/0/10
!
interface GigabitEthernet1/0/11
!
interface GigabitEthernet1/0/12
!
interface GigabitEthernet2/0/1
description Trunk to DR 3/4
switchport trunk encapsulation dot1q
switchport trunk allowed vlan 170,190
switchport mode trunk
channel-group 1 mode active
!
interface GigabitEthernet2/0/2
description Trunk to DR 4/4
switchport trunk encapsulation dot1q
switchport trunk allowed vlan 170,190
switchport mode trunk
channel-group 1 mode active
!
interface GigabitEthernet2/0/3
description Trunk to DR-Users
switchport trunk encapsulation dot1q
switchport mode trunk
!
interface GigabitEthernet2/0/4
!
interface GigabitEthernet2/0/5
!
interface GigabitEthernet2/0/6
!
interface GigabitEthernet2/0/7
!
interface GigabitEthernet2/0/8
!
interface GigabitEthernet2/0/9
!
interface GigabitEthernet2/0/10
!
interface GigabitEthernet2/0/11
!
interface GigabitEthernet2/0/12
!
interface Vlan2
ip address 144.93.177.2 255.255.255.0
standby ip 144.93.177.1
standby priority 200
standby preempt
!
interface Vlan170
ip address 144.93.170.2 255.255.254.0
standby ip 144.93.170.1
standby priority 200
!
interface Vlan190
ip address 144.93.190.2 255.255.254.0
standby preempt

DR#sh run
Building configuration...

Current configuration : 3943 bytes
!
version 12.2
no service pad
service timestamps debug uptime
service timestamps log uptime
no service password-encryption
!
hostname DR
!
!
no aaa new-model
switch 1 provision ws-c3750g-12s
switch 2 provision ws-c3750g-12s
switch 3 provision ws-c3750g-24ts-1u
system mtu routing 1500
udld aggressive

ip subnet-zero
!
!
mls qos map cos-dscp 0 8 16 26 32 46 46 56
!
!
macro global description cisco-global
errdisable recovery cause link-flap
errdisable recovery interval 60
no file verify auto
!
spanning-tree mode rapid-pvst
spanning-tree loopguard default
spanning-tree extend system-id
spanning-tree backbonefast
spanning-tree vlan 170 priority 28672
spanning-tree vlan 190 priority 24576
!
vlan internal allocation policy ascending
!
interface Port-channel1
description Trunk_IT-DR
switchport trunk encapsulation dot1q
switchport trunk allowed vlan 170,190
switchport mode trunk
!
interface GigabitEthernet1/0/1
description Trunk to IT 1/4
switchport trunk encapsulation dot1q
switchport trunk allowed vlan 170,190
switchport mode trunk
channel-group 1 mode active
!
interface GigabitEthernet1/0/2
description Trunk to IT 2/4
switchport trunk encapsulation dot1q
switchport trunk allowed vlan 170,190
switchport mode trunk
channel-group 1 mode active
!
interface GigabitEthernet1/0/3
description Trunk to IT-Users
switchport trunk encapsulation dot1q
switchport mode trunk
!
interface GigabitEthernet1/0/4
!
interface GigabitEthernet1/0/5
!
interface GigabitEthernet1/0/6
!
interface GigabitEthernet1/0/7
!
interface GigabitEthernet1/0/8
!
interface GigabitEthernet1/0/9
!
interface GigabitEthernet1/0/10
!
interface GigabitEthernet1/0/11
!
interface GigabitEthernet1/0/12
switchport trunk encapsulation dot1q
switchport mode trunk
!
interface GigabitEthernet2/0/1
description Trunk to IT 3/4
switchport trunk encapsulation dot1q
switchport trunk allowed vlan 170,190
switchport mode trunk
channel-group 1 mode active
!
interface GigabitEthernet2/0/2
description Trunk to IT 4/4
switchport trunk encapsulation dot1q
switchport trunk allowed vlan 170,190
switchport mode trunk
channel-group 1 mode active
!
interface GigabitEthernet2/0/3
description Trunk to DR-Users
switchport trunk encapsulation dot1q
switchport mode trunk
!
interface GigabitEthernet2/0/4
!
interface GigabitEthernet2/0/5
!
interface GigabitEthernet2/0/6
!
interface GigabitEthernet2/0/7
!
interface GigabitEthernet2/0/8
!
interface GigabitEthernet2/0/9
!
interface GigabitEthernet2/0/10
!
interface GigabitEthernet2/0/11
!
interface GigabitEthernet2/0/12
!
interface Vlan2
ip address 144.93.177.3 255.255.255.0
standby ip 144.93.177.1
standby preempt
!
interface Vlan170
ip address 144.93.170.3 255.255.254.0
standby ip 144.93.170.1
standby preempt
!
interface Vlan190
ip address 144.93.190.3 255.255.254.0
standby ip 144.93.190.1
standby priority 200
standby preempt

Edge#sh run
Building configuration...

Current configuration : 2534 bytes
!
version 12.2
no service pad
service timestamps debug uptime
service timestamps log uptime
no service password-encryption
!
hostname Edge
!
!
no aaa new-model
system mtu routing 1500
ip subnet-zero
!
!
!
!
no file verify auto
!
spanning-tree mode rapid-pvst
spanning-tree portfast bpduguard default
spanning-tree extend system-id
spanning-tree uplinkfast
spanning-tree backbonefast
no spanning-tree vlan 170,190
spanning-tree vlan 170 priority 40960
spanning-tree vlan 190 priority 20480
!
vlan internal allocation policy ascending
!
interface GigabitEthernet0/1
switchport access vlan 170
!
interface GigabitEthernet0/2
!
interface GigabitEthernet0/3
!
interface GigabitEthernet0/4
!
interface GigabitEthernet0/5
!
interface GigabitEthernet0/6
!
interface GigabitEthernet0/7
!
interface GigabitEthernet0/8
!
interface GigabitEthernet0/9
!
interface GigabitEthernet0/10
!
interface GigabitEthernet0/11
!
interface GigabitEthernet0/12
!
interface GigabitEthernet0/13
!
interface GigabitEthernet0/14
!
interface GigabitEthernet0/15
!
interface GigabitEthernet0/16
!
interface GigabitEthernet0/17
!
interface GigabitEthernet0/18
!
interface GigabitEthernet0/19
!
interface GigabitEthernet0/20
!
interface GigabitEthernet0/21
!
interface GigabitEthernet0/22
!
interface GigabitEthernet0/23
!
interface GigabitEthernet0/24
!
interface GigabitEthernet0/25
!
interface GigabitEthernet0/26
!
interface GigabitEthernet0/27
!
interface GigabitEthernet0/28
!
interface GigabitEthernet0/29
!
interface GigabitEthernet0/30
!
interface GigabitEthernet0/31
!
interface GigabitEthernet0/32
!
interface GigabitEthernet0/33
!
interface GigabitEthernet0/34
!
interface GigabitEthernet0/35
!
interface GigabitEthernet0/36
!
interface GigabitEthernet0/37
!
interface GigabitEthernet0/38
!
interface GigabitEthernet0/39
!
interface GigabitEthernet0/40
!
interface GigabitEthernet0/41
!
interface GigabitEthernet0/42
!
interface GigabitEthernet0/43
!
interface GigabitEthernet0/44
!
interface GigabitEthernet0/45
!
interface GigabitEthernet0/46
!
interface GigabitEthernet0/47
switchport mode trunk
spanning-tree vlan 170 cost 20
spanning-tree vlan 190 cost 18
!
interface GigabitEthernet0/48
switchport mode trunk
spanning-tree vlan 170 cost 18
spanning-tree vlan 190 cost 20
!
interface Vlan1
no ip address
no ip route-cache
shutdown
!
interface Vlan2
description Management
ip address 144.93.177.11 255.255.255.0
no ip route-cache
!
ip default-gateway 144.93.177.1
ip http server
!

Merci pour votre qide