Basic Qn regarding VLANs

Hi, i have some queries about VLANs which i hope someone could help clarify for me.

1) I understand that VLAN 1 is the defaut or adminstrative VLAN but why is it that an IP address is allocated to this? Is it for browser connections(GUI) to the switch ?

2) If i am using a console connection to the switch, then i dont need to allocate an IP address to VLAN 1 right?

Thanks for your time.

mrpringles,

VLAN1 as you correctly noted is the administrative, or management VLAN. All switches use this VLAN to communicate with each other, exchange messages and traffic depending on the configuration.

By assigning and IP address to the management VLAN, you are able to telnet to the switch and performance administrative actions, or use neat programs such as CNA (Cisco Network Assistant) to connect and configure the switch.

In layer 3 switches, such as the 3550, 3560, 3750, 4500 series, each VLAN is assigned an IP Address which is then used as a default gateway for each host belonging to that VLAN. Layer 3 switches can perform advanced functions such as interVLAN routing (please check our VLAN articles), where as you can understand, IP addresses on the VLAN interfaces is mandatory.

Closing, you are not required to assign an IP address to VLAN 1 in order to configure your switch. It is however a good idea to provide an IP address to VLAN1 in order to make use of your switch's features.

Hope that helps.

Cheers,

Hi Chris, thanks alot for your input. It was clear and precise but i do have another question now.

If i am using a normal Cisco switch say the 2900series one, would that mean i would require a router to provide inter vlan routing by defining the gateway on the router's logical sub-interfaces? I would only be required to configure the VLAN's respective subnets on the switch right?


Thanks again for your time.

hi mrpringles, i did see your Ques concerning InterVlan routing.

InterVlan routing is the process of routing trafic between diffrent VLANs.There are tow types pf switches:

1- Layer 2 switches.
2- Layer 3 switches.

the diffrence between the tow types is that layer 2 switches does not have the capability to perform InterVlan Routing, insted there should be a router connected to that switche via TRUNK to perform that function; then you would be required to assigne an ip address to each subinterface connected to each VLAN.
NOTE: using more than one router to each VLAN solves the problem that the router physical interface will be the single point of faluire and the overloading phinomina.
the Layer 3 switch as mintioned thankfully by chris is capable of InterVlan Routing bec in the same time they are called MLS(MULTI LAYER SWITCHES) they operate at both Layer 2 and 3.

NOTE: it is recommende to use a router with MLS's in order to load balance the trafic and to provide Redundancy to increase falt tollerance.

hope my information is rghit .. plz reply to me in case i am wrong.