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IP Routing on 3550

ddaugherty1264
Level 1
Level 1

‎03-30-2007 06:03 AM - edited ‎03-05-2019 03:12 PM

Starting point: 8-3550 Switches, 1-2811 router (10.2.232.250), all on one subnet 10.2.232.0:255.255.252.0, one VLAN=1. ALL WORKS FINE.

I'm adding VLANs and I need to enable routing on the switches for Inter-VLAN routing. However, when I enable ip routing on the frist switch, the 'network' still works (stations work fine) however, in about 3 minutes, I can no longer HTTP nor ping the VLAN 1 interface. I'm guessing the 3 min delay is routing info updating. I can't even reach it on the switch itself. So, I can't manage it in Network Assistant, nor the web interface. I can still get to any other switch VLAN interface.

Here is before conf info:

no ip subnet-zero

no file verify auto

spanning-tree mode pvst

spanning-tree portfast default

spanning-tree extend system-id

vlan internal allocation policy ascending

interface Vlan1

ip address 10.2.232.203 255.255.252.0

ip default-gateway 10.2.232.250

ip classless

ip http server

Here is after:

no ip subnet-zero

ip routing

no file verify auto

spanning-tree mode pvst

spanning-tree portfast default

spanning-tree extend system-id

vlan internal allocation policy ascending

interface Vlan1

ip address 10.2.232.203 255.255.252.0

ip default-gateway 10.2.232.250

ip classless

ip route 0.0.0.0 0.0.0.0 10.2.232.250

ip http server

This driving me crazy and not a good experience with ip routing on the 3550. It probably comes down to me misconfiguring something, but I don't know what.

Please assist and I will be singing praises about you!

Thanks.

Labels:
0 Helpful
29 Replies 29

jasonrandolph
Level 1
Level 1
In response to svanhandel

‎04-06-2007 02:02 PM

Correct. Once the routing process is enabled IP default gateway no longer functions.

I'm wondering why "no IP subnet-zero" is enabled and why all the switch ports are set to dynamic desirable, but that is really neither here nor there.

What does the output of "show ip route" provide?

What is the default gateway of your client machines?

0 Helpful

Richard Bradfield
Level 6
Level 6

‎04-03-2007 08:45 PM

Have you fixed this problem? looking at the posts on this it does not address the problem

has your 3550 have EMI or SMI IOS loaded that determines whether you could do L3 switching otherwise

You do your L3 routing on the 2811

create subinterfaces on the etherner ports

trunk to the switches, then on the switch ports use the "Switchport access vlan" command to select the required vlan

0 Helpful

ecornwell
Level 2
Level 2

‎04-25-2007 11:35 AM

Hello,

I was wondering if anyone has made any headway on this. We just put a 3550 in service and ran into the same problem.

I've got a very similar setup. I was working in the switch earlier today when this problem happened. I turned off ip routing and reloaded. Everything worked fine. I was able to pass a little data with the switch configured without routing but DHCP wouldn't work. I turned on ip routing and DHCP started working. A little while later my telnet session was closed and when I tried to reconntect the switch wouldn't respond.

I've got the latest code as of today loaded on the switch and still no luck.

0 Helpful

vettiyattil.parameswaran
Level 1
Level 1
In response to ecornwell

‎04-25-2007 08:01 PM

Hi,

can you pl. post the config

regards

param

0 Helpful

ecornwell
Level 2
Level 2
In response to vettiyattil.parameswaran

‎04-26-2007 04:32 AM

version 12.2

no service pad

service timestamps debug datetime localtime show-timezone

service timestamps log datetime localtime show-timezone

service password-encryption

!

hostname SWITCH

!

enable secret ********************

no aaa new-model

clock timezone EST -5

clock summer-time EST recurring

ip subnet-zero

ip routing

!

no file verify auto

spanning-tree mode pvst

spanning-tree extend system-id

!

vlan internal allocation policy ascending

!

interface FastEthernet0/1

descr Currenlty used Port

switchport trunk encapsulation dot1q

switchport mode trunk

!

interface FastEthernet0/2

switchport mode dynamic desirable

!

interface FastEthernet0/3

switchport mode dynamic desirable

!

interface FastEthernet0/4

switchport mode dynamic desirable

!

interface FastEthernet0/5

switchport mode dynamic desirable

!

interface FastEthernet0/6

switchport mode dynamic desirable

!

interface FastEthernet0/7

switchport mode dynamic desirable

!

interface FastEthernet0/8

switchport mode dynamic desirable

!

interface FastEthernet0/9

switchport mode dynamic desirable

!

interface FastEthernet0/10

switchport mode dynamic desirable

!

interface FastEthernet0/11

switchport mode dynamic desirable

!

interface FastEthernet0/12

switchport mode dynamic desirable

!

interface FastEthernet0/13

switchport mode dynamic desirable

!

interface FastEthernet0/14

switchport mode dynamic desirable

!

interface FastEthernet0/15

switchport mode dynamic desirable

!

interface FastEthernet0/16

switchport mode dynamic desirable

!

interface FastEthernet0/17

switchport mode dynamic desirable

!

interface FastEthernet0/18

switchport mode dynamic desirable

!

interface FastEthernet0/19

switchport mode dynamic desirable

!

interface FastEthernet0/20

switchport mode dynamic desirable

!

interface FastEthernet0/21

switchport mode dynamic desirable

!

interface FastEthernet0/22

switchport mode dynamic desirable

!

interface FastEthernet0/23

switchport mode dynamic desirable

!

interface FastEthernet0/24

switchport mode dynamic desirable

!

interface GigabitEthernet0/1

switchport mode dynamic desirable

!

interface GigabitEthernet0/2

descr PORT NO LONGER USED

switchport trunk encapsulation dot1q

switchport mode trunk

!

interface Vlan1

ip address 1.1.0.10 225.255.252.0

!

interface Vlan60

ip address 1.2.0.1 255.255.252.0

ip helper-address 1.1.0.2

!

interface Vlan61

ip address 1.3.0.1 255.255.252.0

ip helper-address 1.1.0.2

!

interface Vlan62

ip address 1.4.0.1 255.255.252.0

ip helper-address 1.1.0.2

!

ip default-gateway 1.1.0.1

ip classless

ip route 0.0.0.0 0.0.0.0 1.1.0.1 permanent

ip http server

ip http secure-server

!

control-plane

!

ntp server 1.1.0.1

end

I changed a few things to hide addresses and stuff.

0 Helpful

ddaugherty1264
Level 1
Level 1
In response to ecornwell

‎04-26-2007 07:36 AM

All - I got tired of messing with this. My guess is there is a bug in the IOS version. I configured a 'router on a stick', and all works as expected.

0 Helpful

ecornwell
Level 2
Level 2
In response to ddaugherty1264

‎04-26-2007 07:50 AM

That's too bad... I was afriad that would happen.

What exactly is a 'router on a stick?'

0 Helpful

cprice2k7
Level 1
Level 1
In response to ddaugherty1264

‎04-27-2007 08:12 AM

I had a similar issue with a 3550 switch. I opened a TAC case and was told to remove the MLS entries. Unfortunately I changed jobs before this could get implemented.

0 Helpful

rseiler
Level 3
Level 3

‎04-27-2007 09:03 AM

You were only doing this on *ONE* 3550 switch, right? Not all 8? You would only need to do the ip routing on *ONE* (core?) 3550 switch and cannot have *ANY* other switches configured for routing without a much more complicated config.

Just checking. You sent one config but I would be interested in the config of the other 7 switches.

I have had *ZERO* issues with the Cisco 3550 switch for IP routing over the last 5 years...

Let me know if you would like to troubleshoot this further...

0 Helpful

ecornwell
Level 2
Level 2
In response to rseiler

‎04-27-2007 09:17 AM

I would love to get this working. We only have one layer 3 switch in this network and it was purchased to do vlan routing. Do you see anything wrong with the config I posted? I've followed the documents I found and the switch is setup almost the exact same way.

0 Helpful

rseiler
Level 3
Level 3
In response to ecornwell

‎04-27-2007 10:53 AM

I'm more interested in the config of the other 7 switches. How are they connected and configured?

0 Helpful

ecornwell
Level 2
Level 2
In response to rseiler

‎04-28-2007 09:44 AM

That wasn't me that posted that, I'm just having the exact same problem. The 3550 is the only layer 3 switch we have in that network. All other switches are connected through 802.1q trunks.

0 Helpful

rll3
Level 1
Level 1
In response to ecornwell

‎04-30-2007 12:11 PM

Hi,

Have you tried using vlan 1 as the native vlan for all trunks on connected switches?

vlan 1 or your management vlan should be used.

This should solve your issue. Each switch should have an dot1q trunk w/VLAN1 configured as the native vlan. This way your trunks will always pass traffic and you should be able to communicate with your switches (vty) on the configured vlan1 address.

0 Helpful

ecornwell
Level 2
Level 2
In response to rll3

‎04-30-2007 12:23 PM

I'm not really sure what you're asking. Typically we don't change the native vlan on the switch.

We configure all switches for 802.1q trunks and we haven't had any problems at our main facility. We have used a very similar config on a 3750 and it works without and problems at another facility.

The really strange thing is that it works for a little while then just stops responding.

0 Helpful

rll3
Level 1
Level 1

‎04-30-2007 12:13 PM

just for kicks... how was the router configured that connected to this switch?

did it have subinterfaces?

0 Helpful
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