Pourquoi mon interface vlan ne veut pas devenir up ?

An article by Olivier Legras    1 Commentaire

Lorsque l’on veut accéder à un switch à distance, on active une interface d’administration à laquelle on attribue une adresse ip.

Pour cela, on crée une interface vlan spécialement pour cette fonction :

int vlan 1

no switchport

ip address 192.168.0.1 255.255.255.0

exit

Une interface vlan ne monte pas tant qu’il n’y a pas d’interface up appartenant à ce vlan.

Pour vérifier qu’une interface appartient bien au vlan 1 :

SWITCH# show vlan

VLAN Name                             Status    Ports
—- ——————————– ——— ——————————
1    default                          active    Gi0/1, Gi0/2, Gi0/3, Gi0/4
                                                Gi0/5, Gi0/6, Gi0/7, Gi0/8
                                                Gi0/9, Gi0/10, Gi0/11, Gi0/12
                                                Gi0/13, Gi0/14, Gi0/15, Gi0/16
                                                Gi0/17, Gi0/18, Gi0/19, Gi0/20
                                                Gi0/25, Gi0/26, Gi0/27, Gi0/28
1002 fddi-default                     act/unsup
1003 token-ring-default               act/unsup
1004 fddinet-default                  act/unsup
1005 trnet-default                    act/unsup

VLAN Type  SAID       MTU   Parent RingNo BridgeNo Stp  BrdgMode Trans1 Trans2
—- —– ———- —– —— —— ——– —- ——– —— ——
1    enet  100001     1500  -      -      -        -    -        0      0

VLAN Type  SAID       MTU   Parent RingNo BridgeNo Stp  BrdgMode Trans1 Trans2
—- —– ———- —– —— —— ——– —- ——– —— ——
1002 fddi  101002     1500  -      -      -        -    -        0      0
1003 tr    101003     1500  -      -      -        -    -        0      0
1004 fdnet 101004     1500  -      -      -        ieee -        0      0
1005 trnet 101005     1500  -      -      -        ibm  -        0      0

Remote SPAN VLANs
——————————————————————————

Primary Secondary Type              Ports
——- ——— —————– ——————————————

Vérifier qu’au moins une interface est connecté de la liste des interfaces appartenant au vlan 1 :

SWITCH#sh ip int brief
Interface              IP-Address      OK? Method Status                Protocol
Vlan1                  192.168.0.1 YES manual up                    up
GigabitEthernet0/1     unassigned      YES unset  down                  down
GigabitEthernet0/2     unassigned      YES unset  down                  down
GigabitEthernet0/3     unassigned      YES unset  down                  down
GigabitEthernet0/4     unassigned      YES unset  down                  down
GigabitEthernet0/5     unassigned      YES unset  down                  down
GigabitEthernet0/6     unassigned      YES unset  down                  down
GigabitEthernet0/7     unassigned      YES unset  down                  down
GigabitEthernet0/8     unassigned      YES unset  down                  down
GigabitEthernet0/9     unassigned      YES unset  down&#1
60;                 down
GigabitEthernet0/10    unassigned      YES unset  down                  down
GigabitEthernet0/11    unassigned      YES unset  down                  down
GigabitEthernet0/12    unassigned      YES unset  down                  down
GigabitEthernet0/13    unassigned      YES unset  down                  down
GigabitEthernet0/14    unassigned      YES unset  down                  down
GigabitEthernet0/15    unassigned      YES unset  down                  down
GigabitEthernet0/16    unassigned      YES unset  down                  down
GigabitEthernet0/17    unassigned      YES unset  down                  down
GigabitEthernet0/18    unassigned      YES unset  down                  down
GigabitEthernet0/19    unassigned      YES unset  up                    up
GigabitEthernet0/20    unassigned      YES unset  up                    up
GigabitEthernet0/21    unassigned      YES unset  down                  down
GigabitEthernet0/22    unassigned      YES unset  down                  down
GigabitEthernet0/23    unassigned      YES unset  down                  down
GigabitEthernet0/24   unassigned      YES unset  down                  down
GigabitEthernet0/25    unassigned      YES unset  down                  down
GigabitEthernet0/26    unassigned      YES unset  down                  down
GigabitEthernet0/27    unassigned      YES unset  down                  down
GigabitEthernet0/28    unassigned      YES unset  down                  down

Ici les interfaces Gi0/19 et Gi0/20 appartiennent au vlan 1. Donc l’interface Vlan1 monte.

Si  l’interface n’est pas up/up et que vous avez des ports actifs dans le vlan1, vérifié que l’interface est bien active :

SWITCH#sh int vlan1
Vlan1 is administratively down, line protocol is down
  Hardware is EtherSVI, address is 001c.0e10.8f40 (bia 001c.0e10.8f40)
  Description: Vlan Administration
  Internet address is 192.168.0.1/24
  MTU 1500 bytes, BW 1000000 Kbit, DLY 10 usec,
     reliability 255/255, txload 1/255, rxload 1/255
  Encapsulation ARPA, loopback not set
  ARP type: ARPA, ARP Timeout 04:00:00
  Last input 00:00:00, output 00:00:02, output hang never
  Last clearing of "show interface" counters never
  Input queue: 1/75/0/0 (size/max/drops/flushes); Total output drops: 0
  Queueing strategy: fifo
  Output queue: 0/40 (size/max)
  5 minute input rate 6000 bits/sec, 3 packets/sec
  5 minute output rate 0 bits/sec, 0 packets/sec
     293737 packets input, 54600214 bytes, 0 no buffer
     Received 0 broadcasts (26495 IP multicast)
     0 runts, 0 giants, 0 throttles
     0 input errors, 0 CRC, 0 frame, 0 overrun, 0 ignored
     13933 packets output, 1076363 bytes, 0 underruns
     0 output errors, 2 interface resets
     0 output buffer failures, 0 output buffers swapped out

Si vous êtes dans ce cas, vous n’avez pas activé l’interface vlan :

SWITCH#sh run int vlan1
Building configuration…

Current configuration : 160 bytes
!
interface Vlan1
description Vlan Administration
ip address 192.168.0.1 255.255.255.0
no ip route-cache
 shutdown
end

 

Pour remédier à ce probleme, aller dans la configuration de l’interface :

SWITCH#conf t
Enter configuration commands, one per line.  End with CNTL/Z.
SWITCH(config)#int vlan1
SWITCH(config-if)#no shut

SWITCH(config-if)#exit

Vérifiez que l’interface vlan 1 n’est plus en administratively down (sh int vlan1)