2

PC 1 is on VLAN 10

PC 2 is on VLAN 20

Router 1 is on VLAN 30

Between SW and Router2 is trunk which allow vlans 10-30

I can ping between PC1 and PC2, but I can't ping from Router 1 any PC. Should I add additional routing ?

UPDATE:

Simpler version ( still not work )

I have a topology like this :

enter image description here

Here is my configuration :

Switch

int fa0/1
sw mode access 
sw access vlan 10

int fa0/2
sw mode access
sw access vlan 20

int fa0/3
sw mode trunk
sw trunk allowed vlan 10-20

Router R_1 configuration

int fa0/0.10
encapsulation dot1q
ip address 10.0.10.1 255.255.255.0

int fa0/0.20
encapsulation dot1q
ip address 10.0.20.1 255.255.255.0

Configuration on PC

ip : 10.0.10.100/24  default gateway : 10.0.10.1

Configuration on Router R_2

int fa0/0
ip address 10.0.20.100 255.255.255.0

Route configurations of R_2

Gateway of last resort is not set

     10.0.0.0/24 is subnetted, 2 subnets
C       10.0.10.0 is directly connected, FastEthernet0/0.10
C       10.0.20.0 is directly connected, FastEthernet0/0.20

After show run:

Router#show run
Building configuration...

Current configuration : 719 bytes
!
version 12.4
no service timestamps log datetime msec
no service timestamps debug datetime msec
no service password-encryption
!
hostname Router
!
!
!
!
!
!
ip cef
no ipv6 cef
!
!
!
!
!
!
!
!
!
!
!
!
spanning-tree mode pvst
!
!
!
!
!
!
interface FastEthernet0/0
 no ip address
 duplex auto
 speed auto
!
interface FastEthernet0/0.10
 encapsulation dot1Q 10
 ip address 10.0.10.1 255.255.255.0
!
interface FastEthernet0/0.20
 encapsulation dot1Q 20
 ip address 10.0.20.1 255.255.255.0
!
interface FastEthernet0/1
 no ip address
 duplex auto
 speed auto
 shutdown
!
interface Vlan1
 no ip address
 shutdown
!
ip classless
!
ip flow-export version 9
!
!
!
!
!
!
!
line con 0
!
line aux 0
!
line vty 0 4
 login
!
!
!
end

Route configuration of R_2

Gateway of last resort is 10.0.20.1 to network 0.0.0.0

     10.0.0.0/24 is subnetted, 1 subnets
C       10.0.20.0 is directly connected, FastEthernet0/0
S*   0.0.0.0/0 [1/0] via 10.0.20.1

after show run:

Router#show run
Building configuration...

Current configuration : 596 bytes
!
version 12.4
no service timestamps log datetime msec
no service timestamps debug datetime msec
no service password-encryption
!
hostname Router
!
!
!
!
!
!
ip cef
no ipv6 cef
!
!
!
!
!
!
!
!
!
!
!
!
spanning-tree mode pvst
!
!
!
!
!
!
interface FastEthernet0/0
 ip address 10.0.20.100 255.255.255.0
 duplex auto
 speed auto
!
interface FastEthernet0/1
 no ip address
 duplex auto
 speed auto
 shutdown
!
interface Vlan1
 no ip address
 shutdown
!
ip classless
ip route 0.0.0.0 0.0.0.0 10.0.20.1 
!
ip flow-export version 9
!
!
!
!
!
!
!
line con 0
!
line aux 0
!
line vty 0 4
 login
!
!
!
end
14
  • You need to provide configurations so that we can see where you may have gone wrong.
    – Ron Maupin
    Dec 1, 2015 at 21:45
  • It's just a standard configuration of vlans. If I add new PC to the same VLAN as Router 1 I can ping from this new PC computers PC1 and PC2. All computers have default gateway to Router 2.
    – Amon
    Dec 1, 2015 at 21:48
  • 1
    If you want help, we need to see your work. Apparently something is wrong, and we can't guess what it is.
    – Ron Maupin
    Dec 1, 2015 at 21:49
  • 1
    That's not a topology, that's a tag cloud. As @RonMaupin said, please provide details.
    – Teun Vink
    Dec 1, 2015 at 21:52
  • 1
    OK. What doesn't seem to be working now? This configuration is different than your initial description. What pings, and what doesn't?
    – Ron Maupin
    Dec 1, 2015 at 23:47

1 Answer 1

1

I think the part you are missing is that one VLAN cannot talk to another VLAN without having a router between the two VLANs; it's like they are separate cables on separate interfaces.

The switch is a layer-2 device which knows nothing about layer-3 addresses. It can't bridge traffic between VLANs, which is the point of VLANs. The switch will only send traffic from a port on one VLAN to ports or trunks with the same VLAN. It simply cannot take traffic from R_2 on VLAN 20 and send it to the PC on VLAN 10.

Logically, R_2 connects to R_1 on one interface, and the PC connects to R_1 on a different interface. The PC has an implicit default route to its gateway (R_1). R_2 doesn't have an implicit default route so it only knows about the directly connected routes (VLAN 20) and any static routes or routes learned via a routing protocol, but you aren't running a routing protocol. That's why you had to configure a static route.

Static routes, like what you configured on R_2 simply do not scale and are not flexible or dynamic. The real way to do this is to run a common routing protocol on both routers so that R_2 automatically receives a route to VLAN 10 from R_1.

0

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