Solved: Routing over a trunk

Patrick Evans · ‎05-07-2014

I have a packet tracer lab that i am using to learn my CCNA on.

I have 2 sites connected together by layer 3 switches and i cannot ping between the sites.

The trunk is vlan10 with addresses on each side of 1.1.1.1/30 and 1.1.1.2/30

From each switch i can ping the other side.

I have some machines on 192.168.100.0/24 in Vlan 20

and machines on the other switch on 10.0.10.0/25 Vlan 30

From Vlan20 i can ping the local side of Vlan 10 and the same from Vlan 30 but i cant ping over the trunk.

Can anyone give me a hint as to why not?

SWITCH 1

version 12.2

no service timestamps log datetime msec
no service timestamps debug datetime msec
no service password-encryption
!
hostname ScunthorpeSwitch
!
!
!
enable secret 5 *****
!
!
!
ip routing
!

!
interface FastEthernet0/1
!
interface FastEthernet0/2
switchport access vlan 20
switchport mode access
!
interface FastEthernet0/3
switchport access vlan 30
switchport mode access
!
interface FastEthernet0/24
switchport access vlan 10
switchport trunk encapsulation dot1q
switchport mode trunk
!

interface Vlan1
no ip address
!
interface Vlan10
ip address 1.1.1.2 255.255.255.252
!
interface Vlan30
ip address 10.0.10.253 255.255.255.0
!
ip classless
ip route 0.0.0.0 0.0.0.0 FastEthernet0/24
!

VLAN Name Status Ports

---- -------------------------------- --------- -------------------------------
1 default active Fa0/1, Fa0/4, Fa0/5, Fa0/6
Fa0/7, Fa0/8, Fa0/9, Fa0/10
Fa0/11, Fa0/12, Fa0/13, Fa0/14
Fa0/15, Fa0/16, Fa0/17, Fa0/18
Fa0/19, Fa0/20, Fa0/21, Fa0/22
Fa0/23, Gig0/1, Gig0/2
10 FIRBELINK active
20 SHEFFIELD active Fa0/2
30 SCUNTHORPE active Fa0/3
40 SERVERS active
1002 fddi-default act/unsup

ScunthorpeSwitch#sho interfaces trunk
Port Mode Encapsulation Status Native vlan
Fa0/24 on 802.1q trunking 1

Port Vlans allowed on trunk
Fa0/24 1-1005

Port Vlans allowed and active in management domain
Fa0/24 1,10,20,30,40

Port Vlans in spanning tree forwarding state and not pruned
Fa0/24 1,10,20,30,40

SWITCH 2

version 12.2

no service timestamps log datetime msec
no service timestamps debug datetime msec
no service password-encryption
!
hostname "Sheffield Switch"
!
!
!
enable secret 5 **************
!
!
!
ip routing
!

username ***** password 0 ********
!

!
no ip domain-lookup

!
interface FastEthernet0/1
switchport access vlan 20
switchport mode access
!
interface FastEthernet0/2
switchport access vlan 20
switchport mode access
!
interface FastEthernet0/3
switchport mode access
shutdown

!
interface FastEthernet0/24
description FIBER BETWEEN SITES
no switchport
no ip address
duplex auto
speed auto
!
!
interface Vlan1
no ip address
!
interface Vlan10
ip address 1.1.1.1 255.255.255.252
!
interface Vlan20
ip address 192.168.100.250 255.255.255.0
!
ip classless
ip route 0.0.0.0 0.0.0.0 FastEthernet0/24
!
!
!
banner motd ^C
******* , Do Not Enter ****** ^C

VLAN Name Status Ports
---- -------------------------------- --------- -------------------------------
1 default active Fa0/3, Fa0/4, Fa0/5, Fa0/6
Fa0/7, Fa0/8, Fa0/9, Fa0/10
Fa0/11, Fa0/12, Fa0/13, Fa0/14
Fa0/15, Fa0/16, Fa0/17, Fa0/18
Fa0/19, Fa0/20, Fa0/21, Fa0/22
Fa0/23, Gig0/1, Gig0/2
10 FIRBELINK active
20 SHEFFIELD active Fa0/1, Fa0/2
30 SCUNTHORPE active
40 SERVERS active

Sheffield Switch#sho interfaces trunk
Port Mode Encapsulation Status Native vlan
Fa0/24 on 802.1q trunking 1

Port Vlans allowed on trunk
Fa0/24 1-1005

Port Vlans allowed and active in management domain
Fa0/24 1,10,20,30,40

Port Vlans in spanning tree forwarding state and not pruned
Fa0/24 1

Marvin Rhoads · ‎05-07-2014

You have no routing protocol running so the L3 switches only know about connected and static routes. The only static route you have is the default:

ip route 0.0.0.0 0.0.0.0 FastEthernet0/24

The interface you tell it to use is a L2 interface, so you're effectively not routing with that default. If you create an SVI (Layer 3 switched virtual interface) for each VLAN on all the switches (i.e. add interfaces for VLAN 20 on switch 1 and VLAN 30 on switch 2), it will work. also if you made the default route on each switch be the other switch's VLAN 10 L3 interface, that would also work.

You could also setup actual routing like OSPF or EIGRP but that's outside the scope for CCNA practice.

View solution in original post

Marvin Rhoads · ‎05-07-2014

You have no routing protocol running so the L3 switches only know about connected and static routes. The only static route you have is the default:

ip route 0.0.0.0 0.0.0.0 FastEthernet0/24

The interface you tell it to use is a L2 interface, so you're effectively not routing with that default. If you create an SVI (Layer 3 switched virtual interface) for each VLAN on all the switches (i.e. add interfaces for VLAN 20 on switch 1 and VLAN 30 on switch 2), it will work. also if you made the default route on each switch be the other switch's VLAN 10 L3 interface, that would also work.

You could also setup actual routing like OSPF or EIGRP but that's outside the scope for CCNA practice.

Patrick Evans · ‎05-08-2014

HI Marvin, I tried both methods out and they both work. I may have made my switches VTP transparent earlier on. I guess if I didnt then this problem wouldn't have occurred as all the Vlans would be in place?

Actually I believe that EIGRP and OSPF are both on the new CCNA, but I wont come through to that module for another couple of weeks.

Thanks for your help.

Patrick