A question to network experts

[Deepsmeg]

Does a subinterface on an 802.1Q VLAN trunk need an IP address within the scope of the management VLAN, or the VLAN to which it is connected?

If VLAN1 (the management VLAN) is using 192.168.0.0/29, so that you have these addresses:
Switch 1: 192.168.0.4
Switch 2: 192.168.0.5
Switch 3: 192.168.0.6

VLAN 2 is using 192.168.0.32/27
VLAN 3 is using 192.168.0.64/27
VLAN 4 is using 192.168.0.96/27

The ethernet link is connected to FastEthernet 0/0 on the router that the trunk is connected to.
Should the addresses on the interface be like this:
fa0/0.1 192.168.0.1
fa0/0.2 192.168.0.2
fa0/0.3 192.168.0.3

or

fa0/0.1 192.168.0.33
fa0/0.2 192.168.0.65
fa0/0.3 192.168.0.97

I've got the VLSM worked out, but I didn't read up on VTP enough.
In fact, during my skills test at college I messed up the VTP. This caused the sample network to not work. But I still passed because everything else I did was correct, so it would have worked if it were not for missing out a few commands.
No, I can't remember how I had addressed it.

Both ways make sense, in a way.
Host on VLAN2 has Switch2's IP as its default gateway. Switch2 kicks the packet out of fa0/1 to the router, which is its default gateway.

Or, the host on VLAN2 has the router's fa0/0.2 ip addess as its default gateway and the switch sends it up out of the relevant port.
This makes sense, since the switch couldn't care less what IP address it is being told to talk to, since it is at a lower level of the OSI model and only cares about the MAC address.


any help would be quite helpful.

[Stewsburntmonkey]

I believe it is the first way (ie fa0/0.1 192.168.0.1 ).

I know on a Cisco rounter you would do something like this to setup a subinterface:

Code: Select all

RP/0/RP0/CPU0:router# configure terminal
RP/0/RP0/CPU0:router(config)# interface TenGigE 0/2/0/4.1
RP/0/RP0/CPU0:router(config-subif)# dot1q vlan 10
RP/0/RP0/CPU0:router(config-subif)# ip addr 10.0.0.1/24
RP/0/RP0/CPU0:router(config-subif)# commit


Although I don't have much hands on experience with this sort of thing, so make of that what you will.

[Deepsmeg]

TenGigE?!
You've got some serious stuff there.
I'm worling on 26xx routers at college and a 2514 here.

That syntax looks a little different.
I'm more used to

Code: Select all

Router> en
Router# conf t
Router(config)# int fa0/0
Router(config-if)# int fa0/0.1
Router(config-subif)# encapsulation dot1q
Router(config-subif)# ip add 192.168.0.1 255.255.255.248
Router(config-subif)# exit
Router(config-if)# no shut
Router(config-if)# end
Router#


What version of IOS is your code for?

I suppose I ought to move on to the OSPF configuration and sort out the VTP later.

[Stewsburntmonkey]

I'm was using IOS 12.0 (I think).

But I think the address idea should be the same.

[Deepsmeg]

We use 12 at college, and my 2514 has 12 on it.
Odd.

[ph0rumsp@mmer]

i htink htat you should just forget about wireless networking @s itz jsut a cr@zy f@d htat will f@de whit time like the p2 processor was

[Flamekebab]

Wireless networking > *.
With a laptop it means I can go online all over the place, no need to cart around more cables.

[ph0rumsp@mmer]

wireless networking > *.
very unreliable in a crowded place where the signal can be bounced around also a lot better chance for virii to spread

[Deepsmeg]

Ok, this guy makes me laugh.
This isn't about wireless, 802.11
This is about VLAN Trunking using 802.1Q
If you're going to be a smartarse, at least do it properly.

[doormat]

Does a subinterface on an 802.1Q VLAN trunk need an IP address within the scope of the management VLAN, or the VLAN to which it is connected?

Oh, yeah! Everybody knows what that means! What kind of an idiot could fail to understand that?

[Deepsmeg]

802.1Q, 802.11g... so easy to get those mixed up, eh...
And I did say that the question was for network experts...

[doormat]

True, you did.

[Angry Armadillo]

i htink htat you should just forget about wireless networking @s itz jsut a cr@zy f@d htat will f@de whit time like the p2 processor was

My wireless network is perfect, I've never had any trouble with it.

[Deepsmeg]

I do find making wired networks a bit easier than wireless ones.
You don't have to worry about making WEP keys and SSID names that will be hard to guess and then ensuring the people that need to know the information do know it, etc.
machines. hub. cables. suitable addressing scheme. done.