newbie question, lost connection when ip routing enabled?

[sc.bill.lee]

hi there,

i am configuring a 3560, everthing is fine until i enable the "ip routing"

i lost connection to all vlan, any idea?

thanks in advance.

[cadet alain]

Hi,

try changing this command: ip default-gateway x.x.x.x into ip route 0.0.0.0 0.0.0.0 x.x.x.x

Regards.

Alain

[Richard Burts]

Bill

If the suggestion from Alain does not solve your issue then I suggest that you post the configuration of the switch. This might help us to identify the issue.

HTH

Rick

[sc.bill.lee]

Sorry bros, let me make my question more clear

actually, my situation is..

the core switch 3750 serves voice/servers/etc..all the vlans, routings (e.g. routing all traffic excluding 10.x.x.x to ISP_A)

a newly added Room B, got an old 3560, made truncking to 3750

Need to achieve:

users in room B use ISP_B for internet, all other traffic goes back to 3750

Question:

is that i need to do routes in 3560? is that i need to enable ip routing in 3560?

[cadet alain]

Hi,

post the config from 3750 and 3560.

Regards.

Alain

[Richard Burts]

Bill

Given what is in the drawing I would think that you would need to enable routing on the 3560. You would want to configure a default route that would send traffic from the local VLANs out to ISP B. And you would want routes on the 3560 that would send traffic for the VLANs/subnets in room A to the 3750.

HTH

Rick

[sc.bill.lee]

3750 and 3560 have common vlan now, they can talk to each other,

but when I tried to enable "ip routing" in 3560, I lost connection to the 3560, any idea?

[Kishore Chennupati]

You probably still have  "ip default-gateway" . This works only for a layer2 siwtch only. So, once you enable ip routing this functionality is no more valid and you loose connection as the switch doesnt have a default gateway.

but you should still be able to log into it from 3750 and check "sh ip route" and it will show you nothing.

Hope this give you some idea.

[Kishore Chennupati]

hi,

to add to what rick mentioned make sure you have common vlans between the switches that need to talk and configure a trunk and enable ip routing on the 3560. This will enable the vlans to talk to each other.

For the internet traffic configure a default route on the 3560 and that will allow traffic destined for internet to go out via ISP B.

HTH

Kishore

[sc.bill.lee]

C3560-GZH-01#sh run

Building configuration...

Current configuration : 4399 bytes

!

version 12.2

no service pad

service timestamps debug uptime

service timestamps log uptime

no service password-encryption

!

hostname C3560-GZH-01

!

enable secret

!

no aaa new-model

system mtu routing 1500

vtp domain SCGZHnetwork

vtp mode transparent

ip subnet-zero

!

!

!

!

no file verify auto

!

spanning-tree mode pvst

spanning-tree extend system-id

spanning-tree vlan 1 priority 36864

!

vlan internal allocation policy ascending

!

vlan 8

name PBX

!

vlan 9

name servers

!

vlan 19

name Network-devices

!

vlan 160

name Workstations

!

interface GigabitEthernet0/1

switchport access vlan 160

switchport mode access

!

interface GigabitEthernet0/2

switchport access vlan 160

switchport mode access

!

interface GigabitEthernet0/3

switchport access vlan 160

switchport mode access

!

interface GigabitEthernet0/4

switchport access vlan 160

switchport mode access

!

interface GigabitEthernet0/5

switchport access vlan 160

switchport mode access

!

interface GigabitEthernet0/6

switchport access vlan 160

switchport mode access

!

interface GigabitEthernet0/7

switchport access vlan 160

switchport mode access

!

interface GigabitEthernet0/8

switchport access vlan 160

switchport mode access

!

interface GigabitEthernet0/9

switchport access vlan 160

switchport mode access

!

interface GigabitEthernet0/10

switchport access vlan 160

switchport mode access

!

interface GigabitEthernet0/11

switchport access vlan 160

switchport mode access

!

interface GigabitEthernet0/12

switchport access vlan 160

switchport mode access

!

interface GigabitEthernet0/13

switchport access vlan 160

switchport mode access

!

interface GigabitEthernet0/14

switchport access vlan 160

switchport mode access

!

interface GigabitEthernet0/15

switchport access vlan 160

switchport mode access

!

interface GigabitEthernet0/16

switchport access vlan 160

switchport mode access

!

interface GigabitEthernet0/17

switchport access vlan 160

switchport mode access

!

interface GigabitEthernet0/18

switchport access vlan 160

switchport mode access

!

interface GigabitEthernet0/19

switchport access vlan 160

switchport mode access

!

interface GigabitEthernet0/20

switchport access vlan 160

switchport mode access

!

interface GigabitEthernet0/21

switchport access vlan 160

switchport mode access

!

interface GigabitEthernet0/22

switchport access vlan 160

switchport mode access

!

interface GigabitEthernet0/23

description ***ASA 5510***

switchport access vlan 9

switchport mode access

!

interface GigabitEthernet0/24

description ***PABX***

switchport access vlan 8

switchport mode access

!

interface GigabitEthernet0/25

description 3560_3750_Fibre

switchport trunk encapsulation dot1q

switchport mode trunk

!

interface GigabitEthernet0/26

!

interface GigabitEthernet0/27

!

interface GigabitEthernet0/28

!

interface Vlan1

no ip address

no ip route-cache

!

interface Vlan8

ip address 10.161.8.2 255.255.255.0

no ip redirects

no ip unreachables

ip accounting output-packets

!

interface Vlan9

description ***----Server VLAN----***

ip address 10.161.9.2 255.255.255.0

no ip redirects

no ip unreachables

!

interface Vlan19

ip address 10.161.19.2 255.255.255.0

no ip route-cache

!

ip classless

ip http server

!

!

control-plane

!

line con 0

login local

line vty 0 4

login local

line vty 5 15

login

!

end

C3560-GZH-01#

[Kishore Chennupati]

Hi,

Currently the switch is acting like a Layer2 switch. Also, I cant see any default GW? Where is the switch going to send the traffic to?

[sc.bill.lee]

yes, it's still acting as layer 2, all the traffic is now going through another 3750 connected to g0/25

what I need to achieve is making all the clients connected to 3560 going internet by the firewall connected to 3560 g0/23

but when I enable ip routing in 3560, i lost connection to it....

[JohnTylerPearce]

From looking at your configuration, it appears that all your ports on the 3560 are on VLAN160. I don't see a vlan interface for VLAN160 on the 3560? Where is the default gateway for VLAN160 located? If you want the 3560 in Room B to use the ISP from B you will need a vlan interface on 3560 and point a default route to the ASA, and then the ASA should hae a default route going towards the ISP next hop.

[sc.bill.lee]

actually all vlan is in room A 3750, i would like to make 3560 all traffic goes ISP_B except traffic for 10.x.x.x

[Kishore Chennupati]

No Connectivity After IP Routing is Enabled

One of the most common issue people face is the loss of connectivity  once IP routing is enabled on the switch. A common cause for this issue  is the command used to specify the default gateway for the device.

If IP routing is not enabled on the device, the command is ip default-gateway.

3750-1#ip default-gateway A.B.C.D
!--- where A.B.C.D is the IP address of the default router

If IP routing is enabled, use the ip route command in order to specify the default router for that device.

3750-1#ip route 0.0.0.0 0.0.0.0 A.B.C.D

Taken from the link

http://www.cisco.com/en/US/products/hw/switches/ps5023/products_tech_note09186a00807ccc79.shtml

Hope this helps