VLAN internal IP address

Cisco Lan switches catalyst family of la...
March 27, 2010 at 03:12:59
Specs: cisco IOS
hey experts,

I have a Q.
can the int. ip of a vlan differ from one switch to another in the same network or domain??(meaning if i have 2 cisco switches sw1 and sw2 can vlan 10 int on sw1 have the ip 192.168.1.1/24 while on sw2 the same vlan 10 has 192.168.2.1/24???

and does VTP advertise the vlan subnets???


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#1
March 28, 2010 at 08:14:50
interface ip address not internal ip address

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#2
March 28, 2010 at 11:30:39
There's plenty of information on VTP on the internet....remember, google is your friend.

When you say "interface" do you mean the uplink ports?

Normally, one uses the default management VLAN - VLAN 1 to address network appliances like routers and switches. These of course have to all use the same subnet in order to communicate with each other. You use "trunk" ports to interconnect network appliances which use VLAN 1 as their base VLAN and that VLAN "carries" all other VLAN's.

Example:

VLAN 1 (management VLAN) = 192.168.1.0/24
VLAN 2 (Subnet 2 - Client) = 192.168.2.0/24
VLAN 3 (Subnet 3 - Servers) = 192.168.3.0/24
VLAN 4 (Subnet 4 - Printers) = 192.168.4.0/24

Let's say you have a Core Switch and 4 wiring closets each with one 48 port switch. Assuming your 'data center' contains the core switch and servers and each wiring closet connects to the core switch vai a fibre optic backbone.

Core Switch:
IP = 192.168.1.250 (VLAN 1 = management VLAN)

Closet 1
Switch IP: 192.168.1.1

Closet 2
Switch IP: 192.168.1.2

Closet 3
Switch IP: 192.168.1.3

Closet 4
Switch IP: 192.168.1.4

In this example, each switch has all other VLAN's configured on the switch with ports assigned to each.

Uplink ports on all switches would be configured as trunk with
Base VLAN = 1
Allowed VLAN's = 1, 2, 3, 4


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#3
March 28, 2010 at 13:34:16
long reply thank u and i hope that ur finger tips are fine :D

anyway that's not what i meant... i didn't mean the uplink ports i meant the vlan interface itself like when u go to the vlan 1 int. and assign an ip address for switch management

but let's assume that i have vlan 100 that's gonna participate in HSRP on 2 switchs
now u must give these vlans IPs one for each switch so on sw1 vlan 100 might have the ip of 192.168.1.1/24 and on sw2 the same vlan 100 will have another ip add. let's say 192.168.1.2/24

my Q. is If VTP is advertising the vlan 100 IP won't that cause a problem ????

I know that VTP runs on layer 2 but I've read some were that VTP advertisements contains the vlan int. add.

that's it and thanks for ur effort


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#4
March 29, 2010 at 06:24:16
long reply thank u and i hope that ur finger tips are fine :D

No worries, I've been working in IT for 15+ years and my typing skills are excellent. I can type 80+ wpm for quite long periods of time without tiring my poor old hands. My first response took about 2 1/2 minutes of my time to type out.

my Q. is If VTP is advertising the vlan 100 IP won't that cause a problem ????

I'm not sure I follow you. What is it you wish to advertise? As I understand VTP, all it does is advertise VLAN's across linked switches.

but let's assume that i have vlan 100 that's gonna participate in HSRP on 2 switchs
now u must give these vlans IPs one for each switch so on sw1 vlan 100 might have the ip of 192.168.1.1/24 and on sw2 the same vlan 100 will have another ip add. let's say 192.168.1.2/24

Why would you assign IP's? To what are you assigning the IP's?

As I stated in my first reply, you assign IP's to switches on the management VLAN, VLAN 1. All other VLAN's (ie: data VLAN's) get assigned to ports.

As I stated previously, we use VRRP with dual redundant core switches and their IP's are VLAN 1 (management VLAN).
Core 1:
192.168.1.249
Core 2:
192.168.1.251
Advertised default gateway = 192.168.1.250
(we use .250 as the DG in all our subnets).

The core switches are joined with an IST (inter switch trunk) which makes them redundant. The point of HSRP, as I understand it, we don't use it right, is the same thing, to provide redundancy. In our case, if Core 1 is running as the "DG" and it fails, the DG role moves automatically over to Core 2. The actual VRRP advertised DG address never changes from the client point of view.

Now if you're using cisco core switches I would presume they configure similarly using their proprietary cisco HSRP. However, I'm not sure you could do this on just any two switches and it seems to me, in order to work, your two switches would have to be joined by an IST and be advertising a 3'd IP like we do.

Just an FYI from me to you for future reference. You may want to try typing using proper capitalization, punctuation and grammar. Not doing so looks VERY unprofessional and makes it a lot harder to read. If you want to be seen as a professional, and be taken serious by professionals, you'll want to type like a mature, literate adult and not like a child.

If you look and compare, you'll see all my responses are a lot easier to read than yours are. That's because our brains are trained to see the capitalization and punctuation. Take it away and we have to slow down and start reading one word at a time.


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