InterVlan Routing

Unanswered Question
Aug 1st, 2007

On a 3750 switch do you need a routing protocol like rip, rip2 or ospf running in order for InterVlan routing to work?

I have this problem too.
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sundar.palaniappan Wed, 08/01/2007 - 05:38

Not necessary. If the 3750 switch does not need to exchange routing updates with other devices in the network then simply enable 'ip routing' in the switch and create vlan interfaces to route inter-vlan traffic.

HTH

Sundar

albolabris Wed, 08/01/2007 - 05:47

My servers are in one vlan my workstation is in another vlan

I cannot reach the servers unless I turn on rip.

I have "ip routing" enabled on the switch

Does this sound correct?

Vlan 1 10.4.0.0 = Servers

Vlan 2 10.10.0.0 = Workstation

ankbhasi Wed, 08/01/2007 - 05:51

Hi Friend,

No you do not need RIP to make communication between 2 vlans. Can you paste your complete "sh run" and "sh ip route" after disabling rip and also update on which ports you have connected you servers and clients.

Regards,

Ankur

sundar.palaniappan Wed, 08/01/2007 - 05:52

Did you configure the server and workstation to use the switch's respective vlan interface IP address as their default gateway?

Jon Marshall Wed, 08/01/2007 - 05:52

Hi

No this doesn't sound correct.

Hav you set the default gateway of your client to the vlan 2 interface address and the default gateway fo your servers to the vlan 1 interface address ?.

Can you ping the client default gateway from a client and the same from a server.

If possible could you post the config.

Jon

albolabris Wed, 08/01/2007 - 06:52

Ok I setup 2 Workstations in each vlan set the gateways as the Vlan address, removed all routing protocol and I can ping each Workstation...So InterVlan routing is working...Thank you!!!

Now a little more complicated problem, I cannot change the Gateway on the servers they're in Vlan1 right now and there gateway is the juniper box which is 10.4.9.1 out to the internet.

This is not a problem if I load rip I can reach them.

Now the more complicated problem if I use rip ver2 or ospf it does not work, but if I use just rip it works.

Any Ideas?

ougryphon Wed, 08/01/2007 - 08:26

I'm not an expert, but here it goes. You can route between vlans because they are directly connected. However, you cannot route to the internet gateway because without a routing protocol running, your switch can't discover the route to the internet. My guess is that your gateway is running RIP to advertise its route to the internet. Therefore, your switch needs to run RIP in order to receive route updates from the internet gateway.

Does this explaination make sense to the experts?

-Patrick

albolabris Wed, 08/01/2007 - 08:55

Yes when I run rip I can get to the servers as well as the internet. The issue I'm having is it only works running Rip if I use Rip Version 2, OSPF or EIGRP routing does not work...

This works

!

router rip

network 10.0.0.0

!

ip classless

ip route 0.0.0.0 0.0.0.0 10.4.9.1

ip http server

ip http secure-server

!

This does not

!

router rip

version 2

network 10.0.0.0

no auto-summary

!

ip classless

ip route 0.0.0.0 0.0.0.0 10.4.9.1

ip http server

ip http secure-server

!

ougryphon Wed, 08/01/2007 - 09:07

Right, so if the internet gateway is advertising routes using RIP version 1 (which it sounds like it is doing, you can check it with a sniffer) and your switch is listening for OSPF, RIP2, or EIGRP then the switch will not discover the route to the gateway. Besides using RIPv1, I think you can also set the default static route to be the address of your internet gateway box.

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