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Loopback0 CAT3550

I am trying to set up a loopback0 port on my 3550-24. I want to use it as my management port. It lets me configure the loop back.

interface Loopback0

ip address 10.244.244.24 255.255.255.255

ip broadcast-address 10.244.244.255

But I can never ping it from my work station. I can't figure out what I am doing wrong. Can anyone help me please?

Thanks

Michael M. Williams

Network Systems Analyst

Information Technology Services

Tarleton State University

1 Accepted Solution

Accepted Solutions

Mike

There are at least 2 issues here. First and most important you need to enter the command ip routing to enable ip routing. Currently your switch is operating as a layer 2 only switch. You need to enable layer 3 processing to forward packets between VLANs and subnets. Without ip routing enabled it certainly will not do what you want it to do.

Second issue is the attempt to configure the static route. Here is what you entered:

ip route 0.0.0.0 10.244.244.24 255.255.255.255

it appears to contain the destination address, the next hop address, and the mask. But the mask needs to go immediately after the destination address. And the mask is inverted. so it should be:

ip route 0.0.0.0 0.0.0.0 10.244.244.24

Also as a layer 3 switch I am not convinced that the switch uses the loopback interface in the same way that IOS routers do. So even after you address these two problems there may still be some issues

HTH

Rick

HTH

Rick

View solution in original post

32 Replies 32

Wilson Samuel
Level 7
Level 7

Hi Michael,

Could you please let us see the config of the switch. Also, if I'm not wrong, you may try enabling Routing on the switch by "ip routing" and see if that helps.

HTH,

Kind Regards,

Wilson Samuel

Wilson,

here is my config.

version 12.2

no service pad

service timestamps debug uptime

service timestamps log datetime

service password-encryption

!

hostname network-office

!

enable secret xxxxx

!

no aaa new-model

clock timezone CST -6

clock summer-time CDT recurring

ip subnet-zero

!

!

!

!

!

!

spanning-tree mode pvst

spanning-tree extend system-id

!

vlan internal allocation policy ascending

!

no ip rcmd domain-lookup

ip rcmd rcp-enable

ip rcmd remote-host cwuser 165.95.23.140 cwuser

!

!

!

!

!

interface Loopback0

ip address 10.244.244.24 255.255.255.255

ip broadcast-address 10.244.244.255

!

interface FastEthernet0/1

switchport trunk encapsulation dot1q

switchport trunk native vlan 9

switchport mode trunk

duplex full

spanning-tree portfast

!

interface FastEthernet0/2

switchport access vlan 9

switchport mode dynamic desirable

spanning-tree portfast

!

interface FastEthernet0/3

switchport access vlan 9

switchport mode dynamic desirable

spanning-tree portfast

!

interface FastEthernet0/4

switchport access vlan 9

switchport mode dynamic desirable

spanning-tree portfast

!

interface FastEthernet0/5

switchport access vlan 9

switchport mode dynamic desirable

spanning-tree portfast

!

interface FastEthernet0/6

switchport access vlan 9

switchport mode dynamic desirable

spanning-tree portfast

!

interface FastEthernet0/7

switchport access vlan 104

switchport mode dynamic desirable

spanning-tree portfast

!

interface FastEthernet0/8

switchport access vlan 9

switchport mode dynamic desirable

spanning-tree portfast

!

interface FastEthernet0/9

switchport access vlan 3

switchport mode dynamic desirable

spanning-tree portfast

!

interface Vlan1

no ip address

!

interface Vlan9

ip address xxx.xx.21.113 255.255.255.128

!

ip default-gateway xxx.xx.21.125

ip classless

ip http server

ip http secure-server

!

!

logging trap critical

logging xxx.xx.23.140

snmp-server community TSUroCN RO

snmp-server community TSUrwCN RW

snmp-server contact

snmp-server system-shutdown

snmp-server enable traps snmp authentication lin

snmp-server enable traps cluster

snmp-server enable traps entity

snmp-server enable traps envmon fan shutdown sup

snmp-server enable traps vtp

snmp-server enable traps vlancreate

snmp-server enable traps vlandelete

snmp-server enable traps flash insertion removal

snmp-server enable traps port-security

snmp-server enable traps config-copy

snmp-server enable traps config

snmp-server enable traps hsrp

snmp-server enable traps bridge newroot topology

snmp-server enable traps stpx inconsistency root

y

snmp-server enable traps syslog

snmp-server enable traps rtr

snmp-server enable traps mac-notification

snmp-server enable traps vlan-membership

snmp-server host xxx.xx.23.140 TSUroCN

!

control-plane

!

!

line con 0

line vty 0 4

password xxxxxxxx

login

line vty 5 15

login

!

ntp clock-period 17180256

ntp server 10.1.1.1 key 0 prefer

end

network-office#

i get this error when i try to enter a route.

network-office#config t

Enter configuration commands, one per line. End with CNTL/Z.

network-office(config)#interface loopback0

network-office(config-if)#ip route 0.0.0.0 10.244.244.24 255.255.255.255

%Inconsistent address and mask

network-office(config)#

Thanks

mike

Hi

In which vlan is u r system connected.can u verify plz.

Thanks

Mahmood

Mahmood,

The switch IP that I have now and workstation are in the same VLAN. The IP I want to use for LooPback0 is not within any VLAN. I have a 6500 series that is using the same loopback0 IP range and I have no problem pining it. But when I try the 3550 I can't get it to work.

Thanks

Mike

HI

R u locally connected to this switch..?

If u then u need to use the default-gateway on ur system as the ip address of the SVI i.e vlan 9 as per u r config.

If u r not locally connected then u need either advertise u r loopback ip in any routing protocol or u need to have static routes for this network.

Thanks

Mahmood

Mahmood,

I am connected locally. How would I advertise my loopback. Where would I put the static route?

thanks

Mike

Hi Mike,

Please do "sh ip int brief" and "sh ip route" commands. To make sure that you add "ip routing" command in the switch. Because you are trying to let switch routes the networks!

let us know how things work out

Thot

Thot,

sh ip int brief

FastEthernet0/4 unassigned YES unset down down

FastEthernet0/5 unassigned YES unset down down

FastEthernet0/6 unassigned YES unset up up

FastEthernet0/7 unassigned YES unset down down

FastEthernet0/8 unassigned YES unset up up

FastEthernet0/9 unassigned YES unset up up

FastEthernet0/10 unassigned YES unset down down

FastEthernet0/11 unassigned YES unset down down

FastEthernet0/12 unassigned YES unset down down

FastEthernet0/13 unassigned YES unset down down

FastEthernet0/14 unassigned YES unset down down

FastEthernet0/15 unassigned YES unset down down

FastEthernet0/16 unassigned YES unset down down

FastEthernet0/17 unassigned YES unset down down

FastEthernet0/18 unassigned YES unset down down

FastEthernet0/19 unassigned YES unset down down

FastEthernet0/20 unassigned YES unset down down

FastEthernet0/21 unassigned YES unset down down

FastEthernet0/22 unassigned YES unset down down

FastEthernet0/23 unassigned YES unset up up

FastEthernet0/24 unassigned YES unset up up

GigabitEthernet0/1 unassigned YES unset down down

GigabitEthernet0/2 unassigned YES unset down down

Loopback0 10.244.244.24 YES manual up up

show ip route

network-office#show ip route

Default gateway is xxx.xx.21.125

Host Gateway Last Use Total Uses Interface

ICMP redirect cache is empty

network-office#

it only show the DF for VLAn 9, which is what the trunk port is config for.

thanks

mike

Hi

U need to enable ip routing

config t

ip routing

Thanks

Mahmood

Mahmood,

I enable ip routing.

Gateway of last resort is not set

10.0.0.0/32 is subnetted, 1 subnets

C 10.244.244.24 is directly connected, Loopback0

xxx.xx.0.0/25 is subnetted, 1 subnets

C xxx.xx.21.0 is directly connected, Vlan9

network-office#

Still can't ping it.

Thanks

mike

Hi

Whats the gateway on u r system,is it the ip address of svi ie. vlan9 of ur switch if so then u need to enable ip routing on u r switch n try.

Thanks

Mahmood

Mahmood,

network-office#show ip route

Default gateway is xxx.xx.21.125

Host Gateway Last Use Total Uses Interface

ICMP redirect cache is empty

network-office#

It is the gateway for VLAn 9.

What do I need to do to add gateway for Loopback0?

Thanks

mike

Hi

As informed earlier u need to enable ip routing.

u need not add gateway for loopback as it will be listed as directly connected on u r switch.

Just verify that u have the proper gateway config on u r system i.e PC.

Thanks

Mahmood

Mike

There are at least 2 issues here. First and most important you need to enter the command ip routing to enable ip routing. Currently your switch is operating as a layer 2 only switch. You need to enable layer 3 processing to forward packets between VLANs and subnets. Without ip routing enabled it certainly will not do what you want it to do.

Second issue is the attempt to configure the static route. Here is what you entered:

ip route 0.0.0.0 10.244.244.24 255.255.255.255

it appears to contain the destination address, the next hop address, and the mask. But the mask needs to go immediately after the destination address. And the mask is inverted. so it should be:

ip route 0.0.0.0 0.0.0.0 10.244.244.24

Also as a layer 3 switch I am not convinced that the switch uses the loopback interface in the same way that IOS routers do. So even after you address these two problems there may still be some issues

HTH

Rick

HTH

Rick
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