Chapitre 6 Flashcards
C’est quoi le but du VLAN
Organisation et flexibilité
Le VLAN est considéré comme étant un réseau logiquement…
Séparé
Quelles sont les seules requêtes qui sont quand même envoyées sur les VLANs?
Les diffusions et les requêtes ARP.
Quels sont les bénéfices des VLANS?
- Sécurité
- réduction des cout
- Meilleur performance
- petits domaine de diffusion
- maintenance plus facile
Ou est-ce-que l’on peut utiliser le mode trunking?
entre 2 switchs
entre une switch et un serveur 802.1qNIC*
pour déplacer un pont d’un VLAN à un autre il faut utiliser :
switch port access VLAN #
Qu’est ce qui arrive lorsqu’on utilise no switch port access vlan #?
retourne le VLAN au VLAN 1
lorsqu’on utilise no vlan vlan-id?
efface un vlan spécifique et si un port spécifique est associé à ce vlan celui-ci devient inactif.
Avec quoi est-ce-qu’un VLAN native est-t’il associé?
un port trunk 802.1q
Qu’est-ce-qu’un port trunk?
C’est un port faisant le lien entre deux commutateurs ayant plus de 1 VLAN.
Traffic coming from many diffrent VLANs have to be what?
Tagged.
Quelle est la taille d’une étiquette VLAN
4 octets
Les trames n’ayant pas d’étiquette sont envoyé à quel VLAN ?
Au VLAN par défaut, 1.
Les VLAN native sont défini avec quel spécification?
IEEE 802.1Q
Qu’est-ce-qu’un VLAN voice, VoIP a besoin pour bien fonctionner?
- une bandepassante qui assure une QoS
- Transmission priority
- Rerouting capabilities
- Latency of maximum 150ms
C’est quoi un trunk?
C’est un lien point à point entre deux commutateurs qui detiennent chacun au moins deux vlans.
what does the vlan tag field consist of?
- Type field
- user priority
- Canonical format identifier
- VLAN ID
What happens when a Cisco switch receives an untagged frame?
It sends it to the native VLAN.
What happens when a cisco switch receives an untagged frame and there is no native VLAN as well as no trunk port?
The frame is dropped.
What does CoS stand for?
Class of service.
What does the command do : show interfaces fa0/18 switchport?
displays the configuration of the interface switch port
Where are the Vlan database configuration stored?
In a data file called vlan.dat
What does the switchport mode access command do?
It configures a PORT assigned to a VLAN as a Permanently access mode port.
What does the command switchport access vlan vlan-id do?
it assigns the chosen port to a chosen vlan.
What command should one use to configure many ports to a specific vlan?
interface range f0/X - Y
What is a special property of the switchport access vlan command?
it forces the creation of a VLAN if it wasn’t create prior to it’s usage.
What command should you use to display a list of vlans on screen
show vlan brief
What command do you use to put a port back into the default vlan 1?
no switchport access vlan
How do you delete a vlan?
conf t -> no vlan vlan-id -> end
Before deleting a Vlan what is preferable to do?
reassign all the ports associated to that vlan to another vlan or to the default vlan otherwise those ports will not be able to communicate.
To allow a vlans on a specific trunk link what command should you use?
swichport trunk allowed vlan X, Y, Z, …
What does the command “no switchport trunk allowed vlan” do?
It reset the trunk port configuration to allow all vlans to pass through it.
What happens if you use the command “no switchport trunk native vlan”
it reset the native vlan to its default value which is vlan 1.
To reset a port to access mode what command should one use on that port?
switchport mode access
To see the switchport configurations on a specific port what command should one use?
show interfaces f0/1 switchport
What is inter-vlan routing?
The process which is used to forward network traffic from one vlan to another using routing.
Quels sont les trois types d’inter-vlan routing?
- Legacy inter-vlan routing
- Router-on-a-stick
- Layers 3 switching using SVI’s
What is legacy inter-vlan routing?
There is an interface for each vlan on the router.
What is Router-on-a-stick routing?
The router transmits and differentiates between two vlans thanks to subinterfaces that are matched to their vlan counterparts.
- One port, many vlans communicating through it.
What is the encapsulation dot1q used for?
It is used to encapsulate a frame with the right vlan tag when in the router. In example:
interface g0/0.10
