Assigning Vlan IPs ranges

[MrMaxwell]

Hello All,

To make a long story short networking isn't my main job and I'm trying to add a new Vlan to our network, but I don't understand how the Vlans know their IP range on the switch.

I've done some reading and watched a few YouTube videos on the Alcatel switches, but when looking at our existing switch configuration I don't get how our Vlans know their IP ranges.

I thought the "IP interface" command assigned the IP and mask of a Vlan's range, but when I look at one of my switches, below is what I get.

And please correct me if I'm wrong, IP interface just assigns an address on a Vlan to the switch, correct?


NETSW-CAC -> show vlan
Vlan type: std => Standard Vlan
Vlan type: rtr => Router Vlan, reserved for rtr-port IP Interface
stree mble src
vlan type admin oper 1x1 flat auth ip ipx tag lrn name
-----+------+------+------+------+------+----+-----+-----+-----+-----+---------------------
1 std on on on on off on NA off on NetSvrPrnt
2 std on on on on off off NA off on Trusted
4 std on on on on off off NA off on Devices
10 std on on on on off off NA off on Guest
36 std on on on on off off NA off on Site_A
40 std on on on on off off NA off on Employees
42 std on on on on off off NA off on Labs
200 std on on on on off off NA off on Fiber
201 std on on on on off off NA off on IT
254 std on on on on off off NA off on APs

NETSW-CAC -> show ip interface
Total 3 interfaces
Name IP Address Subnet Mask Status Forward Device
--------------------+---------------+---------------+------+-------+----------------------------------------------------
Loopback 127.0.0.1 255.0.0.0 UP NO Loopback
dhcp-client 0.0.0.0 0.0.0.0 DOWN NO vlan 1
vlan_1 192.248.144.219 255.255.255.0 UP YES vlan 1


I appreciate any help on this issue.

Thank you.
Z. Maxwell

[Gleylancer]

A VLAN does not need to know its IP Range for it to work.

Think of it as a VLAN being the street, and an IP Address being the car. The street doesn't care what cars are driving on it, but the car cares that the street actually exists.

In this case, the street is OSI Layer 2, and the car is OSI layer 3. Layer 3 does not work without Layer 2, and Layer 2 does not work without Layer 1 (which is physics, like a cable, or in my example it would be planet earth

In theory, you could put multiple IP networks into one VLAN without the switch ever knowing, but it is not recommended to do this.

Your thought that the ip interface command just assigns an ip address in that one Vlan is correct.

ip interface "assign-a-vlan-name" address 1.2.3.4 mask 255.255.255.0 vlan 10 - puts ip address 1.2.3.4 into vlan 10