Re: Routing between two subnet

Yangjp715 · ‎07-15-2018

Hi all,

I need to build an isolated network for a CUCM migration. The CUCM ip address and gateway is in 192.168.0.0/24, but the IP of the NTP server is 10.0.0.5/24. the following is my lab connection:

ESXi host (VMs in 192.168.0.0/24)-->SW2950(all interfaces are in VLAN1, default-gateway is 10.0.0.5)-->Cisco 2821 G0/0(Primary ip 192.168.0.1/24, the secondary IP 10.0.0.5/24). Is there any way that the NTP server 10.0.0.5 can be reached from VMs in 192.168.0.0/24?

Thanks in advance,

Eric

Thanks,

Eric

chrihussey · ‎07-16-2018

As long as the proper default gateways are defined for each subnet there should be connectivity. Is this not the case?

Yangjp715 · ‎07-16-2018

I connected my laptop to the 2950 in VLAN 1 and using IP 102.168.0.x to ping 10.0.0.5. It was not reachable, but 192.168.0.1 was pingable since they are in the same VLAN.

chrihussey · ‎07-16-2018

Can you post the config of the router, or at the very least the interface that connects to the switch?

Thanks

Yangjp715 · ‎07-16-2018

Current configuration : 1307 bytes
!
! Last configuration change at 22:51:56 UTC Sun Jul 15 2018
! NVRAM config last updated at 22:51:58 UTC Sun Jul 15 2018
! NVRAM config last updated at 22:51:58 UTC Sun Jul 15 2018
version 15.1
service timestamps debug datetime msec
service timestamps log datetime msec
no service password-encryption
!
hostname R1
!
boot-start-marker
boot-end-marker
!
!
!
no aaa new-model
!
!
dot11 syslog
ip source-route
!
!
ip cef
!
!
!
no ipv6 cef
!
multilink bundle-name authenticated
!
!
!
!
!
!
!
!
!
!
!
voice-card 0
!
crypto pki token default removal timeout 0
!
!
!
!
license udi pid CISCO2821 sn FHK1306F3D9
!
redundancy
!
!
!
!
!
!
!
!
!
!
interface GigabitEthernet0/0
ip address 10.192.1.5 255.255.255.0 secondary
ip address 10.192.143.1 255.255.255.0
duplex auto
speed auto
!
interface GigabitEthernet0/1
no ip address
shutdown
duplex auto
speed auto
!
ip forward-protocol nd
no ip http server
no ip http secure-server
!
!
ip route 10.192.1.0 255.255.255.0 GigabitEthernet0/0
ip route 10.192.143.0 255.255.255.0 GigabitEthernet0/0
!
nls resp-timeout 1
cpd cr-id 1
!
!
!
!
!
!
control-plane
!
!
!
!
mgcp profile default
!
!
!
!
!
gatekeeper
shutdown
!
!
!
line con 0
line aux 0
line vty 0 4
login
transport input all
!
scheduler allocate 20000 1000
ntp source GigabitEthernet0/0
ntp master 4
end

Switch:

Current configuration : 1467 bytes
!
version 12.1
no service pad
service timestamps debug uptime
service timestamps log uptime
no service password-encryption
!
hostname Switch
!
!
ip subnet-zero
!
spanning-tree mode pvst
no spanning-tree optimize bpdu transmission
spanning-tree extend system-id
!
!
interface FastEthernet0/1
no ip address
!
interface FastEthernet0/2
no ip address
!
interface FastEthernet0/3
no ip address
!
interface FastEthernet0/4
no ip address
!
interface FastEthernet0/5
no ip address
!
interface FastEthernet0/6
no ip address
!
interface FastEthernet0/7
no ip address
!
interface FastEthernet0/8
no ip address
!
interface FastEthernet0/9
no ip address
!
interface FastEthernet0/10
no ip address
!
interface FastEthernet0/11
no ip address
!
interface FastEthernet0/12
no ip address
!
interface FastEthernet0/13
no ip address
!
interface FastEthernet0/14
no ip address
!
interface FastEthernet0/15
no ip address
!
interface FastEthernet0/16
no ip address
!
interface FastEthernet0/17
no ip address
!
interface FastEthernet0/18
no ip address
!
interface FastEthernet0/19
no ip address
!
interface FastEthernet0/20
no ip address
!
interface FastEthernet0/21
no ip address
!
interface FastEthernet0/22
no ip address
!
interface FastEthernet0/23
no ip address
!
interface FastEthernet0/24
no ip address
!
interface Vlan1
ip address 10.192.1.4 255.255.255.0
no ip route-cache
!
ip default-gateway 10.192.1.5
ip http server
!
!
line con 0
line vty 5 15
!
end

chrihussey · ‎07-16-2018

Hello,

Am I missing something? I don't see an interface with 192.168.0.x as primary IP and 10.0.0.x as secondary IP?

Please clarify.

Yangjp715 · ‎07-16-2018

Sorry for misunderstanding. Actually all VMs are in the subnet 10.192.143.0/24, and the NTP server is 10.192.1.5 in production. I just used 192.168.0.0/24 and 10.0.0.0/24 for example.

chrihussey · ‎07-17-2018

OK....so these static routes are not necessary so remove them:

!

ip route 10.192.1.0 255.255.255.0 GigabitEthernet0/0
ip route 10.192.143.0 255.255.255.0 GigabitEthernet0/0

!

Then, you could try adding "no ip redirects" to the G0/0 interface on the router.

Finally, just verifying that the default gateways for the devices are the respective IPs of the two subnets on the G0/0 interface. So if you are on the 10.192.1.x network the gateway is 10.192.1.5 and if you are on the 10.192.143.x, it's 10.192.143.1 Correct?

Yangjp715 · ‎07-17-2018

Yes, it is correct.

Yangjp715 · ‎07-17-2018

Do i need to replace the 2950 by using a layer 3 switch and configure a default route on it, such as "ip route 0.0.0.0 0.0.0.0 10.192.1.5".

Yangjp715 · ‎07-17-2018

Is there anybody who have ideas for building an isolated network environment in Lab environment? Thanks.