07-24-2013 07:55 AM - edited 03-07-2019 02:33 PM
I have a router 1841 and a swith Catalyst 3560, to set a router on a stick
I set up the vlans, 3 loopback interface with 3 networks, and truck ports in the swith, set up subinterface with fa 0/0 port in the router. It seems the router will not route between vlans. I can not ping the loopback addresss in the switch from the router, and I can not ping from the swith to the default gateway in the router.
PDid anybody encounter this kind of problems with router 1841
Thanks!
Solved! Go to Solution.
07-24-2013 08:05 AM
Hello Grace,
Remove the Loopback1, Loopback2 and Loopback3 from your 3560. You have configured them with IP addresses that overlap the addressing on your router's subinterfaces. Because of this, you have tricked your 3560 into believing that the entire networks 172.16.10.0/24, 172.16.20.0/24, 172.16.30.0/24 are connected to the Loopback intefaces while in fact, they are not. Your 3560 must not believe these networks are located on Loopback interfaces because it will never send the packets to the router.
Also, the configuration of the DHCP server should be done only on those devices that actually have direct IP connectivity with the networks they serve. Currently, because your 3560 switch behaves as a Layer2 switch with a direct IP connectivity only to Vlan100, the configuration of the DHCP server is misplaced. Correctly, it should be configured on the router because it is connected to all VLANs in question. Later, as you proceed, you will learn about DHCP Relay Agent service that allows you to put a DHCP server into a different network than the clients are, but let's not complicate things right now.
Best regards,
Peter
07-24-2013 07:59 AM
Here is my config on Router 1841:
Current configuration : 1357 bytes
!
! Last configuration change at 14:22:11 UTC Wed Jul 24 2013
!
version 15.0
service timestamps debug datetime msec
service timestamps log datetime msec
no service password-encryption
!
hostname RT-test2
!
boot-start-marker
boot-end-marker
!
!
no aaa new-model
!
!
!
dot11 syslog
ip source-route
!
!
!
!
ip cef
!
multilink bundle-name authenticated
!
!
!
!
!
license udi pid CISCO1841 sn FTX1246Z0W4
!
redundancy
!
!
!
!
!
!
!
!
!
interface FastEthernet0/0
no ip address
duplex auto
speed auto
!
!
interface FastEthernet0/0.10
encapsulation dot1Q 10
ip address 172.16.10.1 255.255.255.0
!
interface FastEthernet0/0.20
encapsulation dot1Q 20
ip address 172.16.20.1 255.255.255.0
!
interface FastEthernet0/0.30
encapsulation dot1Q 30
ip address 172.16.30.1 255.255.255.0
!
interface FastEthernet0/0.100
encapsulation dot1Q 100
ip address 172.16.100.1 255.255.255.0
!
interface FastEthernet0/1
no ip address
shutdown
duplex auto
speed auto
!
!
interface Serial0/0/0
no ip address
shutdown
!
!
!
router eigrp 1
network 172.16.0.0
network 172.16.10.0 0.0.0.255
network 172.16.20.0 0.0.0.255
network 172.16.30.0 0.0.0.255
network 172.16.100.0 0.0.0.255
!
ip forward-protocol nd
no ip http server
no ip http secure-server
!
!
!
!
!
!
!
!
control-plane
!
!
!
line con 0
line aux 0
line vty 0 4
login
!
scheduler allocate 20000 1000
end
Here is the config on the swith:
Current configuration : 5163 bytes
!
version 12.2
no service pad
service timestamps debug uptime
service timestamps log uptime
no service password-encryption
!
hostname SW-Server
!
!
no aaa new-model
ip subnet-zero
ip routing
no ip domain-lookup
ip dhcp excluded-address 172.16.10.1
ip dhcp excluded-address 172.16.10.200 172.16.10.254
ip dhcp excluded-address 172.16.20.1
ip dhcp excluded-address 172.16.20.200 172.16.20.254
ip dhcp excluded-address 172.16.30.1
ip dhcp excluded-address 172.16.30.200 172.16.30.254
!
ip dhcp pool Dhcp-Vlan10
network 172.16.10.0 255.255.255.0
default-router 172.16.10.1
!
ip dhcp pool Dhcp-Vlan20
network 172.16.20.0 255.255.255.0
default-router 172.16.20.1
!
ip dhcp pool Dhcp-Vlan30
network 172.16.30.0 255.255.255.0
default-router 172.16.30.1
!
ip dhcp-server 172.16.10.200
!
!
!
no file verify auto
spanning-tree mode pvst
spanning-tree extend system-id
!
vlan internal allocation policy ascending
!
interface Loopback1
ip address 172.16.10.201 255.255.255.0
!
interface Loopback2
ip address 172.16.20.201 255.255.255.0
!
interface Loopback3
ip address 172.16.30.201 255.255.255.0
!
interface FastEthernet0/1
switchport mode access
!
interface FastEthernet0/2
switchport mode access
!
interface FastEthernet0/3
switchport mode access
!
interface FastEthernet0/4
switchport mode access
!
interface FastEthernet0/5
switchport mode access
!
interface FastEthernet0/6
switchport mode access
!
interface FastEthernet0/7
switchport mode access
!
interface FastEthernet0/8
switchport mode access
!
interface FastEthernet0/9
switchport mode access
!
interface FastEthernet0/10
switchport access vlan 10
switchport mode access
!
interface FastEthernet0/11
switchport access vlan 10
switchport mode access
!
interface FastEthernet0/12
switchport access vlan 10
switchport mode access
!
interface FastEthernet0/13
switchport access vlan 10
switchport mode access
!
interface FastEthernet0/14
switchport access vlan 10
switchport mode access
!
interface FastEthernet0/15
switchport access vlan 10
switchport mode access
!
interface FastEthernet0/16
switchport access vlan 10
switchport mode access
!
interface FastEthernet0/17
switchport access vlan 10
switchport mode access
!
interface FastEthernet0/18
switchport access vlan 10
switchport mode access
!
interface FastEthernet0/19
switchport access vlan 10
switchport mode access
!
interface FastEthernet0/20
switchport access vlan 20
switchport mode access
!
interface FastEthernet0/21
switchport access vlan 20
switchport mode access
!
interface FastEthernet0/22
switchport access vlan 20
switchport mode access
!
interface FastEthernet0/23
switchport access vlan 20
switchport mode access
!
interface FastEthernet0/24
switchport access vlan 20
switchport mode access
!
interface FastEthernet0/25
switchport access vlan 20
switchport mode access
!
interface FastEthernet0/26
switchport access vlan 20
switchport mode access
!
interface FastEthernet0/27
switchport access vlan 20
switchport mode access
!
interface FastEthernet0/28
switchport access vlan 20
switchport mode access
!
interface FastEthernet0/29
switchport access vlan 20
switchport mode access
!
interface FastEthernet0/30
switchport access vlan 30
switchport mode access
!
interface FastEthernet0/31
switchport access vlan 30
switchport mode access
!
interface FastEthernet0/32
switchport access vlan 30
switchport mode access
!
interface FastEthernet0/33
switchport access vlan 30
switchport mode access
!
interface FastEthernet0/34
switchport access vlan 30
switchport mode access
!
interface FastEthernet0/35
switchport access vlan 30
switchport mode access
!
interface FastEthernet0/36
switchport access vlan 30
switchport mode access
!
interface FastEthernet0/37
switchport access vlan 30
switchport mode access
!
interface FastEthernet0/38
switchport access vlan 30
switchport mode access
!
interface FastEthernet0/39
switchport access vlan 30
switchport mode access
!
interface FastEthernet0/40
switchport mode access
!
interface FastEthernet0/41
switchport mode access
!
interface FastEthernet0/42
switchport mode access
!
interface FastEthernet0/43
switchport mode access
!
interface FastEthernet0/44
switchport mode access
!
interface FastEthernet0/45
switchport mode access
!
interface FastEthernet0/46
switchport mode access
!
interface FastEthernet0/47
description trunk to router
switchport trunk encapsulation dot1q
switchport mode trunk
!
interface FastEthernet0/48
description trunk to SW-Client
switchport trunk encapsulation dot1q
switchport mode trunk
!
interface GigabitEthernet0/1
switchport mode access
!
interface GigabitEthernet0/2
switchport mode access
!
interface GigabitEthernet0/3
switchport mode access
!
interface GigabitEthernet0/4
switchport mode access
!
interface Vlan1
no ip address
shutdown
!
interface Vlan10
no ip address
!
interface Vlan20
no ip address
!
interface Vlan30
no ip address
!
interface Vlan100
ip address 172.16.100.2 255.255.255.0
!
ip default-gateway 172.16.100.1
ip classless
ip http server
!
!
control-plane
!
!
line con 0
line vty 0 4
no login
line vty 5 15
no login
!
!
end
Thanks in advanced!
07-24-2013 08:05 AM
Hello Grace,
Remove the Loopback1, Loopback2 and Loopback3 from your 3560. You have configured them with IP addresses that overlap the addressing on your router's subinterfaces. Because of this, you have tricked your 3560 into believing that the entire networks 172.16.10.0/24, 172.16.20.0/24, 172.16.30.0/24 are connected to the Loopback intefaces while in fact, they are not. Your 3560 must not believe these networks are located on Loopback interfaces because it will never send the packets to the router.
Also, the configuration of the DHCP server should be done only on those devices that actually have direct IP connectivity with the networks they serve. Currently, because your 3560 switch behaves as a Layer2 switch with a direct IP connectivity only to Vlan100, the configuration of the DHCP server is misplaced. Correctly, it should be configured on the router because it is connected to all VLANs in question. Later, as you proceed, you will learn about DHCP Relay Agent service that allows you to put a DHCP server into a different network than the clients are, but let's not complicate things right now.
Best regards,
Peter
07-25-2013 07:01 AM
Hi! Peter:
Thank you for all the help. I removed all the loopbacks, and add ip helper-address to each subinterface in the router. Now I can ping and get IP for my hosts now.
Thanks again!
Grace
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