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Home > Archive > CCNP > April 2001 > switching ?????????
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switching ?????????
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| Hey all i setup a lab at home and ran into some interesting stuff with 2 switches.
I read in the book just a second age that you can have 2 different subnets in the same VLAN. How can you pass a packet from pcA in subnet A to pcB in subnet B (in vlan1).
Now i thought you have to route between different subnets, different vlans.
I have a situation where host A 10.1.1.1 /16 plugged into vlan2 on switch A 10.1.1.4 /16 can ping
host b 10.1.2.1 /16 on switch b 10.1.2.3 /16
with or without trunking doesnt make a difference as long as there is a crossover connecting both switches.
Then I take host A move to switch B plug into vlan 2 and still i can ping. So if i have the pc plugged into 2 seperate switches all in vlan 1 i can ping. If i have one in vlan 1 and 1 in vlan 2 I can ping. Im confused,,, am i missing something??????? | |
| firechicken 2001-04-13, 8:50 am |
| Could you post a show vlan? I'm suspecting something, but I don't want to open my big mouth again and be wrong  Oh, the shame of it all... | |
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| quote:
Originally posted by 007
I read in the book just a second age that you can have 2 different subnets in the same VLAN. How can you pass a packet from pcA in subnet A to pcB in subnet B (in vlan1).
Now i thought you have to route between different subnets, different vlans.
A router can route between logical as well as physical subnets. That's the same for VLAN as for ordinary LAN. To do it, configure the router with secondary IP address on the interface connected to the (V)LAN with multiple subnets.
I am looking forward to firechickens explanation for your second problem.
Terje | |
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| hey guys i dont have the boxes in front of me,, its in my home lab,,, ill try and get the configs over the weekend and post them....
thanks | |
| Detour 2001-04-20, 12:38 pm |
| first off, 10.1.1.1/16 and 10.1.2.1/16 are both in the same ip subnet, so that's why by default they can ping each other. As for vlans, if you aren't using trunking each switches' vlan configuration can be different. For instance, if switch A is crossovered to switch B w/o trunking, switch B will default all traffic from switch A as being in the vlan configured on the port of the crossover. ie, Switch A plugs into switch B on port 0/33 w/o trunking. Port 33 is set for vlan 5 on switch B. All traffic from switch a, regardless of their vlan config on A, will default to vlan 5 while on switch B. | |
| Stickman 2001-04-20, 1:03 pm |
| interesting...I believe 007 has the crossover plug in Fa0/1 on switch as...which was configured on VLAN1 on Switch B Fa0/1 in vlan2 w/o trunking...
If this is still the case | |
| wildtxn 2001-04-21, 6:58 pm |
| what the book is talking about is
say you have two or more switches.
to go across vlans, you need a router
or route switch module.
you can have multiple subnets in one vlan by adding secondary addresses in
the rsm or router vlan interface.
no different than adding a secondary address to a serial interface.
also, I'm not saying you are doing this,
but I wouldn't make it practice using vlan 1 for anything other than management. |
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