Unsolved Network+ Switches and L3 routing

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Hey guys,

I've been working my way through the Net+ shows and enjoying them, but when I went through the Switches episode I came away a bit confused. Maybe it's just me, or maybe it can be clarified in a future episode.

VLANs

When the guys were talking about VLANs, they talked a lot about trunking and VTP and setting up trunk ports for inter VLAN communication. Great, that all sounded good. In this section the IP Routing command was not talked.

Then they talked about setting up an IP address and default gateways, and how this was required for remote administration and routing VLAN traffic. Ronnie activated ip routing and added int fa0/13 for this.

I can see needing IP routing enabled to route between VLANs, but I'm confused about what to do with the switchport he configured (13). Is this really only required if the switch is routing to a VLAN that it is not connected via a trunk port? For remote administration couldn't you just add the IP to vty rather than a physical port? Would I hook fa0/13 to my router?

I just generally came away confused about inter VLAN routing and the connection to the IP address.

Brett

@Brett-Ferrell said in Network+ Switches and L3 routing:

Hey guys,

I've been working my way through the Net+ shows and enjoying them, but when I went through the Switches episode I came away a bit confused. Maybe it's just me, or maybe it can be clarified in a future episode.

VLANs

When the guys were talking about VLANs, they talked a lot about trunking and VTP and setting up trunk ports for inter VLAN communication. Great, that all sounded good.
In this section the IP Routing command was not talked.

Ok. When talking about managing switches (Layer 2), VTP and trunking are not going to need IP routing turned on.

Then they talked about setting up an IP address and default gateways, and how this was required for remote administration and routing VLAN traffic. Ronnie activated ip routing and added int fa0/13 for this.

I can see needing IP routing enabled to route between VLANs, but I'm confused about what to do with the switchport he configured (13).

I believe I did explain that you can take a switchport and turn it into a routed port if you need to. This needed at times when you want to configure a layer 3 switchport as a routed port instead. Remember that Layer 3 switches can do routing so if you want to use it as a router you can do so. This particular configuration of the port has nothing to do with the inter-vlan routing.

Is this really only required if the switch is routing to a VLAN that it is not connected via a trunk port?

No, The configuration on fa0/13 is when you need for your Layer 3 switch to have IP address on a port. It has nothing to do with inter-vlan routing.

For remote administration couldn't you just add the IP to vty rather than a physical port?

I'm not sure how to add an IP address to vty lines. So this is something i don't know how to do.

Would I hook fa0/13 to my router?

You would connect to as you would connect to any router. If you wanted that port fa0/13 to become your default gateway. You could make it so. It just make that particular port into a router port.

I just generally came away confused about inter VLAN routing and the connection to the IP address.

I can only try to clarify here. I do not believe we talked about inter vlan routing in the episode:
We discussed switch management using VTP, turning a switchport into a routed port, and creating vlans, POE, trunking and trunk ports but no where did we cover or mention inter-vlan routing or inter vlan routing...nor it's configuration. So if you do have questions on inter-vlan routing please feel free to ask here.
I'm not the brightest guy here and there are plenty of our members that are networking geniuses beyond my skills that are willing to help.

Also, if you do want to learn more about inter vlan routing please check out the CCENT or CCNA shows. In those shows we go into inter vlan routing and demonstrate the configuration there.

Brett

Brett ,

You can't set an IP to a VTY line. At least to the best of my knowledge. What you could do is set an IP on the VLAN interface. This will give you remote access to a switch without having to set up routing.

here is a simple example

Now here are the configurations

There are no other settings configured on this switch or router besides the default ones. I can now Telnet into the switch which now has the address 192.168.128.2.

However, there is a big security problem with having Management traffic run over the same VLAN as normal traffic. To remedy this you would have a dedicated VLAN for management traffic. This is where you would need to set up routing to get to this dedicated VLAN.

So If we set up VLAN99 as a dedicated VLAN for management of the Switch, administrators would have to set up paths to get to VLAN99 when they are not on VLAN99.

Or if you are a real security nut you could make it so the only way to access VLAN99 is to be plugged into a port that is on VLAN99. As long as you statically assign yourself (or if you want to get fancy set up DHCP on VLAN99) an IP on the same subnet as the management IP you can access it without setting up routing.

Edit: so i goofed. You should set up VTY login on the switch instead of the router, hopefully this didn't add to the confusion.