Inter vlan routing

shaunebop

Hi guys,have currently been struggling a bit with inter vlan routing and wondered weather you could clear one thing up for me?

I Have set my pc's with the correct ip addresses and default gateways,set trunking on my switch using dot1 q encappsulation and createated the right sub interfaces on my router for the 2 vlans i have created on my switch.

My question is the only way i can get to ping from one pc to the other is if i use a routing protocol on the router like rip and advertise the networks,have i set everything up right because i was led to believe that you did not need to advertise the networks as they are directly connected?

Thanks for any help,Shaun

phantasm

Which router and switch are you using?

shaunebop

Sorry,im using a 2650 router and a 2924 switch

Thanks

bighornsheep

good luck:

http://www.cisco.com/warp/public/473/50.shtml

cisco_trooper

shaunebop wrote:

Hi guys,have currently been struggling a bit with inter vlan routing and wondered weather you could clear one thing up for me?

I Have set my pc's with the correct ip addresses and default gateways,set trunking on my switch using dot1 q encappsulation and createated the right sub interfaces on my router for the 2 vlans i have created on my switch.

My question is the only way i can get to ping from one pc to the other is if i use a routing protocol on the router like rip and advertise the networks,have i set everything up right because i was led to believe that you did not need to advertise the networks as they are directly connected?

Thanks for any help,Shaun

Did you create vlan interfaces on your router? It is not enough to have the VLANs defined. You must also define the layer 3 interface and give it an IP address within the subnet you have defined for those VLANs.

shaunebop

Yes i created the subinterfaces on the router and used dot1q encapsulation and assigned them to the correct vlan.
It all works as it should if i advertise the networks using rip but if i dont it just wont seem to work?

bighornsheep

shaunebop wrote:

Yes i created the subinterfaces on the router and used dot1q encapsulation and assigned them to the correct vlan.
It all works as it should if i advertise the networks using rip but if i dont it just wont seem to work?

Please read the cisco document, you don't need to implement a routing protocol.
Make sure the switchport is configured as a trunk.
If your native vlan isn't vlan 1, you will need to specify that with your subinterface configuration as well.

shaunebop

Cheer's for the document,i tried configuring everythink exactly to that document at the weekend,but no joy.

My native vlan is 1 and i have the switchport configured as a trunk?

This one's really doing my head in

shaunebop

Here is the router config if this helps?
Cheer's

version 12.3
service timestamps debug uptime
service timestamps log uptime
no service password-encryption
!
hostname Router
!
boot-start-marker
boot-end-marker
!
!
no network-clock-participate slot 1
no network-clock-participate wic 0
no aaa new-model
ip subnet-zero
!
!
!
ip cef
!
!
!
!
!
!
!
!
!
!
!
!
!
!
!
interface FastEthernet0/0
no ip address
duplex auto
speed auto
!
interface FastEthernet0/0.1
encapsulation dot1Q 1 native
ip address 192.168.100.49 255.255.255.240
!
interface FastEthernet0/0.2
encapsulation dot1Q 2
ip address 192.168.100.17 255.255.255.240
!
interface FastEthernet0/0.3
encapsulation dot1Q 3
ip address 192.168.100.33 255.255.255.240
!
ip http server
ip classless
!
!
!
!
!
!
!
!
line con 0
line aux 0
line vty 0 4
login
!
!
!
end

bighornsheep

interface FastEthernet0/0.1
encapsulation dot1Q 1 native
ip address 192.168.100.49 255.255.255.240
!
interface FastEthernet0/0.2
encapsulation dot1Q 2
ip address 192.168.100.17 255.255.255.240
!
interface FastEthernet0/0.3
encapsulation dot1Q 3
ip address 192.168.100.33 255.255.255.240 

Code looks good, just remember that PCs in VLAN 1 needs to have 192.168.100.49 /28 as the DG, and make sure you set a mask of /28
PCs in VLAN 2 needs 192.168.100.17 /28 as DG
PCs in VLAN 3 needs 192.168.100.33 /28 as DG

It's a 2924 switch right? on the port that is trunking, do a show int <int #> switchport, make sure that it's actually trunking VLANs 1, 2, 3 to the router.

on that switchport, check to make sure you have:

switchport mode trunk
switchport trunk allow vlan 1,2,3
switchport trunk encap dot1q

shaunebop

Here is the switch config guys.

Im not sure what you mean by setting the mask/28 ?
Maybe this is where im going wrong?
Anyway,thanks for all your help so far
version 12.0
no service pad
service timestamps debug uptime
service timestamps log uptime
no service password-encryption
!
hostname Switch
!
!
!
!
!
!
!
ip subnet-zero
!
!
controller LongReachEthernet 0
!
controller LongReachEthernet 1
!
controller LongReachEthernet 2
!
controller LongReachEthernet 3
!
controller LongReachEthernet 4
!
controller LongReachEthernet 5
!
controller LongReachEthernet 6
!
controller LongReachEthernet 7
!
controller LongReachEthernet 8
!
controller LongReachEthernet 9
!
controller LongReachEthernet 10
!
controller LongReachEthernet 11
!
controller LongReachEthernet 12
!
controller LongReachEthernet 13
!
controller LongReachEthernet 14
!
controller LongReachEthernet 15
!
controller LongReachEthernet 16
!
controller LongReachEthernet 17
!
controller LongReachEthernet 18
!
controller LongReachEthernet 19
!
controller LongReachEthernet 20
!
controller LongReachEthernet 21
!
controller LongReachEthernet 22
!
controller LongReachEthernet 23
!
!
interface FastEthernet0/1
switchport trunk encapsulation dot1q
switchport mode trunk
!
interface FastEthernet0/2
switchport access vlan 2
!
interface FastEthernet0/3
!
interface FastEthernet0/4
!
interface FastEthernet0/5
!
interface FastEthernet0/6
!
interface FastEthernet0/7
!
interface FastEthernet0/8
switchport access vlan 3
!
interface FastEthernet0/9
!
interface FastEthernet0/10
!
interface FastEthernet0/11
!
interface FastEthernet0/12
!
interface FastEthernet0/13
!
interface FastEthernet0/14
!
interface FastEthernet0/15
!
interface FastEthernet0/16
!
interface FastEthernet0/17
!
interface FastEthernet0/18
!
interface FastEthernet0/19
!
interface FastEthernet0/20
!
interface FastEthernet0/21
!
interface FastEthernet0/22
!
interface FastEthernet0/23
!
interface FastEthernet0/24
!
interface VLAN1
ip address 192.168.100.50 255.255.255.240
no ip directed-broadcast
no ip route-cache
!
ip default-gateway 192.168.100.49
!
line con 0
transport input none
stopbits 1
line vty 5 15
!
end

shaunebop

Forgot to mention the default-gateways are set correctly on the pc's
I know you mean a 28 bit subnetmask but i dont know where or what i need to set it on?

bighornsheep

This thread is turning into a hand holding exercise. How are you assigning IP addresses to your PCs? are you running DHCP? or simply configuring static addresses?

An ip address contains the address portion AND a subnet mask portion, when you assign a PC in vlan 2 the address 192.168.100.18 for example, you have to put the proper subnet mask to match the addressing scheme for that vlan, since you are using 255.255.255.240, that's a /28 in CIDR notation, in other words, for a PC in vlan 2 this is a sample configuration:
IP address: 192.168.100.18
subnet mask: 255.255.255.240
default gateway: 192.168.100.17

I'm going to let someone else do the kindness if you are still having problems, not sure what else I can clarify for you.

good luck.

shaunebop

Cheer's ,The pc's are set correctly,just misinterprited what you ment.

Thanks for your help guys and if anyone else has any ideas why i have to advertise these networks to get inter vlan routing to work i would much appreciated it.

dtlokee

A routing protocol will have no effect on a network with only one router. The only thing I can imagine would be the hosts are configured to run rip also and are getting routing information from the router in that configuration which would mean the default gateways, ip addresses, or subnet masks are incorrectly set on the hosts. Do the hosts have more than one adapter or more than one default gateway specified? Did you put in the correct mask (255.255.255.240) on the hosts? Can you ping the hosts default gateway? Can you ping the default gateway on the remote subnets?

shaunebop

Thanks dtlokee,I am running a wireless nic on one of the pc's as well and as soon as i switched it off wwwwwwwhhhhhhhhhheeeeeeeeyyyyy it all works perfect.

Thanks so much everyone