Layer3 3750

[alanrstat]

I am running a stack of two 3750 with Version 12.2(25r)SEE4. I am trying to do some layer three but it doesn't seem to be working correctly. I looked it up and it says that my version does limited layer 3. Anyone have an idea what that means?

I have vlan interfaces configured. I have IP routing on. I have a default route set. I didn't do the no switchport because that my default gateway is on one of the vlans I have configured. Is that a problem?

[Alexander Maroukian]

Hi,

What are you trying to do with layer 3? What is the name of your IOS image?

Best regards,

Alex

[Jon Marshall]

I'm assuming your are running IP Base, hence the limited routing ie. no support for EIGRP/OSPF/BGP.

Even with IP Base you can still do routing with static routes. Any L3 vlan interfaces on the switch will automatically route netween themselves without any static routes.

Have you enabled "ip routing" on the switch ?

If so can you post config together with a full description of what isn't working.

Jon

[Joseph W. Doherty]

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Posting

If the IOS is IP Base, RIP should be supported for dynamic routing.

[alanrstat]

Yes I am running IP Base. I have enabled IP routing. I do an IP route and it shows me all my vlans. and list my gateway of last resort.

My gateway is a PIX with only 10/100 ports. I am trying to run backups from one vlan to the other without having to traverse the PIX.

[Jon Marshall]

So what exactly are the symptoms you are seeing ?

If you see the routes are directly connected then the backups between vlans should not be going to the pix. How do you know it is not working ?

Jon

[alanrstat]

At the time of backups my PIX is showing piles of traffice in the one interface and out the other. When I do a traceroute from one vlan interface to the other it comes back right away. If I do a traceroute to the vlan I'm trying to backup from the cource of vlanint of the backup server vlan its hops are shown just like any other going through the PIX

[Jon Marshall]

Have you set the default-gateways on the devices to be the IP addresses on the L3 vlan interfaces ? eg.

a device in vlan 10 would need the default-gateway set to the IP address used on the L3 vlan interface for vlan 10 on the 3750.

Jon

[alanrstat]

No I do not have it configured this way. I have my devices gateways configured to the PIX.

int vlan201 192.168.200.60/27

server to back up IP address 192.168.200.58/27 GW PIX address 192.168.200.33/27

So the gatew way on the server to back up should be 192.168.200.60/27 instead of 192.168.200.33/27? That makes sense.

[Jon Marshall · Accepted solution]

Yes, basically you need all devices pointing to their L3 vlan interface IP on the 3750 so the 3750 can route between the vlans.

Also, as Alexander mentioned make sure you have on the 3750

ip route 0.0.0.0 0.0.0.0

However before you do this you need to make sure the pix knows about the internal vlans otherwise you may lose internet connectivity. So on the pix you would need -

route inside <3750 IP address>

for each subnet on the 3750 except the subnet the pix is connected into. The 3750 IP address from the above example is the IP address of the L3 vlan interface that the pix is also connected into.

Alternatively as Joseph mentioned your 3750 will support RIP so you could use RIP between the pix and 3750 but it depends on how many subnets you have really. If you only have a few subnets/vlans on the 3750 it is just as easy to add statics to the pix.

Edit - from your last post is looks like the <3750 IP address> should be 192.168.200.60

Jon

[alanrstat]

This looks exactly like my problem. Thank you very much for your help. If I had the enhanced version on the 3750 I would be set since thats what I'm running ont the PIX. Looks like I'm going to be adding some static.

[Alexander Maroukian]

Hi,

Have you setup ip addresses on your svi?

Best regards,

Alex

EDIT: when you use "ip routing" to set the default gateway use "ip route 0.0.0.0 0.0.0.0 ", not "ip default-gateway" command.