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Cisco VLAN routing

Last Modified: 2014-08-09
Attached is a quick diagram of the network. Currently everything works fine, except the connection from the HP Switch in the 192.168.43.xx network to the 192.168.41.xx network. It doesn't work because the Cisco 3750 did not have the correct license to configure routing across vlans. We have installed the correct license now, but as soon as we enable IP routing on the 3750, the existing route (to the 192.168.1.xx) breaks.

the 3750 switch's gateway is the firewall. workstations plugged into the switch can still access 192.168.1.x resources. however the switch itself cannot ping or be access from the 192.168.1.x network.

I can't see the problem enabling IP Routing would cause, but it's immediate. Remove IP Routing, and everything goes back to normal. I'm pretty sure enabling IP routing is the first step to configure a second vlan and  routing to the HP (192.168.43.x) network.
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tankergoblinIT Executive

may i ask is your 41.6 can ping to what firewall are you using?
Most Valuable Expert 2015

What is the configuration of the cisco switch?
tankergoblinIT Executive

also why you need so many L3 switch since you already use vlan.. why dont put everything in one switch.


The 3com L3 switch was are only one. The addition of the .43 network came with it's own HP L3 switch from the vendor. A whole rack of servers, preconfigured and ready to run, but required a 10GB connection from .43 to .41
Couldn't get a suitable module for the 3com, had to make the existing cisco (was layer 2) a layer3 switch to route vlan over 10GB module.


to tanker... It's a Fortigate 200b.
certain traffic we permit from .41 to .1
ICMP is allowed.
tankergoblinIT Executive

so can you ping from .41 to .1? since you already have hp l3 switch why not retire your 3 com and connect .1 to your hp?

let me get it clear now your problem is your .43 cannot access to your .1?


Attached is the config.
Most Valuable Expert 2015
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The HP switch is new, and came in a rack of servers from a vendor. They have a maintenance agreement that includes that switch. Also, it is not located near the 3COM, would require mass cabling. Regardless...neither the 3com or the HP switch is a current problem.

We added Layer 3 to the cisco so we could vlan it to the HP.
The new license installed normally... says IPBase.

But when I enable IP routing on the cisco, (so I can configure the new vlan interface connecting to the HP)... the cisco switch immediately becomes disconnected from the 1.1 network.

I can't see why.
Most Valuable Expert 2015

did you add a default route and terminate the gateway for the HP on a vlan?


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