How to enable layer 3 routing on switch

Unanswered Question
Jun 7th, 2006


I have a 371098-001 switch with IOS 12.2(25)SED. I've been told its a layer 3 switch, however I don't know how to enable it to do routing, could someone please help me with this?



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devang_etcom Wed, 06/07/2006 - 02:51

hi dan,

yes you can have routing on can convert the perticular port in to the layer 3 using command no switchport under the perticular interface. and you can also configure the routing protocol and to eable routing i think you have to go for ip routing command



ankurbhasin Wed, 06/07/2006 - 03:00

Hi Dan,

As it is a layer 3 switch you will be able to configure routing and routing between the vlans which is intervlan routing.

To configure intervlan routing you have to configure logical interface for vlans after creating the vlans in vlan database and then assign them an ip address.

To configure layer 2 ports as layer 3 you have to give a command "no switchport" at interface config mode and assign an ip address and no shut.

To configure routing protocol you have to configure it the way you do on normal routers.

BUT very imp is that by default "ip routing" is disable you have to enable it first for any routing to work.

Make sure you enable "ip routing" command on global config mode.

Have a look at this link which will guide you how you can do normal routing and also to configure routing protocols on 3750 switch on the IOS code you are having on your switch

HTH, if yes please rate the post.


dan_track Wed, 06/07/2006 - 03:06

Hi Ankur,

Thanks for the reply. The problem is that I don't have teh command "ip routing" on the switch, so I can't enable or disable it?

Any ideas what impact this has on enabling layer 3 functionality?



dan_track Wed, 06/07/2006 - 03:07


Just to add I do have the comand "ip host-routing", does this help in any way?



ankurbhasin Wed, 06/07/2006 - 03:12

Hi Dan,

If it is 3750 switch it will 100% be having "ip routing" command and without enabling this command routing functionality will not work.

try this

switch(config)#ip routing

ip host-routing is to configure your communication server to act as a terminal server and this will not enable layer 3 functionality on your switch.

Can you past the "sh version", "sh run" and output of ip ? from global config mode from your switch?



dan_track Wed, 06/07/2006 - 03:28


Firstly thanks everyone for your replies.

switch(config)#ip routing


bl-sw-38(config)#ip routing


% Invalid input detected at '^' marker.

I've attached teh outputs of "sh version" and "sh run"

ip ? :

bl-sw-38(config)#ip ?

Global IP configuration subcommands:

access-list Named access-list

accounting-list Select hosts for which IP accounting information is


accounting-threshold Sets the maximum number of accounting entries

accounting-transits Sets the maximum number of transit entries

address-pool Specify default IP address pooling mechanism

alias Alias an IP address to a TCP port

default-gateway Specify default gateway (if not routing IP)

dhcp Configure DHCP server and relay parameters

dhcp-client Configure parameters for DHCP client operation

dhcp-server Specify address of DHCP server to use

domain IP DNS Resolver

domain-list Domain name to complete unqualified host names.

domain-lookup Enable IP Domain Name System hostname translation

domain-name Define the default domain name

finger finger server

ftp FTP configuration commands

gdp Router discovery mechanism

gratuitous-arps Generate gratuitous ARPs for PPP/SLIP peer addresses

host Add an entry to the ip hostname table

host-routing Enable host-based routing (proxy ARP and redirect)

hp-host Enable the HP proxy probe service

http HTTP server configuration

icmp ICMP options

igmp IGMP global configuration

local Specify local options

name-server Specify address of name server to use

radius RADIUS configuration commands

rcmd Rcmd commands

reflexive-list Reflexive access list

security Specify system wide security information

source IP source

source-route Process packets with source routing header options

sticky-arp Allow the creation of sticky ARP entries

subnet-zero Allow 'subnet zero' subnets

tacacs TACACS configuration commands

tcp Global TCP parameters

telnet Specify telnet options

tftp tftp configuration commands

Hope this helps



devang_etcom Wed, 06/07/2006 - 03:39

Dan this will help you

Configuring routing consists of several main procedures:

To support VLAN interfaces, create and configure VLANs on the switch stack, and assign VLAN membership to Layer 2 interfaces.

Configure Layer 3 interfaces.

Enable IP routing on the switch.

Assign IP addresses to the Layer 3 interfaces.

Enable selected routing protocols on the switch.

Configure routing protocol parameters

rate this post if it helps



dan_track Wed, 06/07/2006 - 04:31


If it's not a 3750, and it can't do routing, then why what would be the benefit of asking to set ip addressess for each interface?



devang_etcom Wed, 06/07/2006 - 03:15

dan do one thing

type just ip ?

what option is there i think you will find routing in it...



devang_etcom Wed, 06/07/2006 - 09:57

so as per his post it is asking for the ip is it for the management or what...



dan_track Thu, 06/08/2006 - 01:13

Hi All,

Thanks for the input. I guess this one reamins a mistery, unless someone can come up with a solution.

Just for information sake, how would having an IP on each interface help with management?




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