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chethan
Contributor

Inter-VLAN routing issues - FortiGate

Hello everyone,

 

Before implementing the following configuration in production I'm testing it out in GNS3 and I'm facing issues with Inter-VLAN routing. I have configured FortiGate to act as router-on-a-stick.

 

  1. I have created VLAN 100 and VLAN 200 on the switch and allowed it over the trunk interface that is connected to the FortiGate. Configured the ports connecting the end devices as access ports.
  2. Created same VLANs on the FortiGate and attached it to the interfaces that is connected to the switch.
  3. Created the required Firewall polices, VLAN 100 -> VLAN 200 and VLAN 200 -> VLAN 100.
  4. From device in VLAN 100, I'm able to ping the VLAN 100 SVI IP address and the SVI IP address on VLAN 200. But unable to reach the other device in VLAN 200 and vice-versa.
  5. Packet sniffer on FortiGate shows that It is receiving the packet on VLAN 100 interface but it is not sending it out of VLAN 200 interface. 

Please, find the attached images for the reference. I believe I'm not missing anything here. Any suggestions would be helpful.

 

 

Network Diagram:

 

chethan_1-1652270777734.png

 

Firewall Polices:

 

chethan_2-1652270777739.png

 

VLAN Interface details:

 

chethan_3-1652270777742.png

 

Sniffer Output:

 

chethan_4-1652270777744.png

 

Thank you

 

 

 

IMPORTANT UPDATE: 

 

Hey everyone,

 

This is important I guess,

 

I just replaced the new FortiGate running FortiOS 7.2 with ForiOS 6.4.9. And, Inter-VLAN routing is happening now without any problem.

 

I have same configuration in place like the one that I had earlier.

 

Is this a bug or anything in 7.2 release? Can the Fortinet staff confirm this please?

 

Please find my updated screenshots:

 

chethan_0-1652357915030.png

 

PC1 to PC2:

chethan_1-1652357937273.png

 

PC2 to PC1:

chethan_2-1652357956362.png

 

Thank you

 

 

 

 

Chethan
NSE 4
ChethanNSE 4
1 Solution
jintrah_FTNT

Hi Chethan,

 

I tested this on a 7.2 device and it is found to work, so issue should be local to your environment only.

 

jintrah_FTNT_0-1652428999364.pngjintrah_FTNT_1-1652429192067.png

 

jintrah_FTNT_2-1652429279470.png

 

best regards,

Jin

 

View solution in original post

40 REPLIES 40
chethan

Hi, I have mentioned you in another similar reply. 

 

Thank you

Chethan
NSE 4
ChethanNSE 4
SveN2
New Contributor

Hi,

looking at the sniffer echo request reaches the firewall but did not leave it.
Form my experience, 99% I had a similar issue it was either routing or firewall policy.
I understand no routing is required as both vlans are directly connected.
And from the other screenshot firewall policy looks good, too.
But have you checked the logs on the Fortigate, anyway? Does the log is showing any denies?
Are you sure the objects used in the policy have the correct IP configured?
Because that has happened to me multiple time. Object name looks good but the IP configured in that object had an error like two digits in the wrong order or something.

 

chethan

Hello, 

 

I have enabled all logs, but I do not see any violation logs there. 

Yes, The objects are configured correctly. Those are subnet address type. I have attached the screenshot in my previous replies.

 

 

Chethan
NSE 4
ChethanNSE 4
chethan

Hi SveN2,

 

I have updated my original post. Kindly, check!

 

Thank you

Chethan
NSE 4
ChethanNSE 4
jintrah_FTNT
Staff
Staff

Hi Chethan,

 

It appears like FortiGate itself not able to reach 10.0.200.10 in first place, did you check?  Is it possible to gather the below debug flows while pinging 10.0.200.10,

 

#diag deb reset

#diag deb flow filter trace start 5

#diag deb flow filter proto 1

#diag deb flow filter add 10.0.100.10

#diag deb flow show con en

#diag deb flow show fun en

#diag deb con time en

#diag deb en

 

Best regards,

Jin

 

sw2090
Honored Contributor

but 10.0.200.254 is a vlan interface on the FortiGate - how can the FGT not reach its own interfaces?

-- 

"It is a mistake to think you can solve any major problems just with potatoes." - Douglas Adams

-- "It is a mistake to think you can solve any major problems just with potatoes." - Douglas Adams
jintrah_FTNT

edited the original post, it was meant to be 10.0.200.10 instead.

 

Best regards,

Jin

chethan

Hi,

 

I have updated my original post. Kindly, check!

 

Thank you

Chethan
NSE 4
ChethanNSE 4
chethan

FortiGate is able to reach both the end devices in both VLANs.

I have replaced FortiGate 7.2 with FortiGate 6.4.9 and it is working.

I have updated my original post. please check.

 

Thank you

Chethan
NSE 4
ChethanNSE 4
jintrah_FTNT
Staff
Staff

Hi Chethan,

 

If you upgrade the new FortiGate 6.4.9 to 7.2 following upgrade paths, are you hitting the same issue?

 

Best regards,

Jin

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