troubleshooting Question

layer 2 and 3 switches

Avatar of tolinrome
tolinromeFlag for United States of America asked on
RoutersNetworkingSwitches / Hubs
10 Comments2 Solutions504 ViewsLast Modified:
I would like to have a nice explanation on a couple of things regarding layer 2 & 3 switches. The last time I asked this question it kind of went in different directions, so to avoid that I'll try and be clearer. These things below are what I do not need explanations on (followed below that I will explain what I need to understand better). What I do not need explanations on:
- I understand what vlans are
- I understand the difference between layer 2 & 3 switches
- I know what vlan trunking\tagging is
- I know what a default gateway is
- I understand that Layer 3 switches does the IP routing and layer 2 doesn't (mac addresses).

What I need to understand clearly is:

When I look at a layer 2 switch (show run) I see that the default vlan1 has no ip address and is shut down, a new vlan was created vlan10 and this vlan was given an IP address and default gateway. But the switch its self was given an IP address as well.

For ex:
interface Vlan1
 no ip address
interface Vlan10
 ip address
 ip helper-address
 no ip route-cache
ip default-gateway

So I'm assuming the default gateway for the pc's that connect to this switch is which is also the IP of the inside interface of the firewall.

So if that is correct then this is what I don't understand:
Why is there an IP for interface and DG address for vlan10?
Why do I read that there can only be 1 management vlan per switch? What do they specifically mean by management vlan? There has to be obviously an IP address to telnet into ( But if its used for management only why then are almost all the interfaces associated with that vlan10?

Shouldn't there be a vlan interface to access the switch and another vlan for all the computers to associate with?

So basically I need to understand better the concept of interface vlan and management vlan and ip default gateway.

Don Johnston
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