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June 24th, 2025 12:33
Dell MX9116N Inter-VLAN routing
Hi! I have a Dell MX9116N switch operating in full switch mode with two SVIs in L3 mode:
interface vlan10
mode L3
no shutdown
ip address 192.168.245.1/24
!
interface vlan20
mode L3
no shutdown
ip address 192.168.4.2/29
!
I have routes set-up to forward traffic from 0.0.0.0/0 to 192.168.4.1:
*S 0.0.0.0/0 via 192.168.4.1 vlan20 1/0 00:06:10
However I can't get inter-vlan routing to work (i.e. routing from vlan10 to vlan 20)
switch-1(config)# ping -Ivlan10 192.168.4.1
PING 192.168.4.1 (192.168.4.1) from 192.168.245.1 br10: 56(84) bytes of data.
--- 192.168.4.1 ping statistics ---
2 packets transmitted, 0 received, 100% packet loss, time 5ms
Is there anything specific that one needs to run to set this up?
mattb13
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June 26th, 2025 11:28
Hi Chris,
Thank you so much for your help here.
I ran through your diagnostics and just for my own sanity tried using a non-default VRF. That seems to have fixed things (though I'm not sure why!)
Matt
DELL-Chris H
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June 24th, 2025 16:57
Mattb13,
Since you're already have the MX9116n in Full Switch Mode, with SVIs configured for Layer 3, and experiencing issues, here are some things I would consider looking at.
1. Confirm VLAN Interface Status
Ensure both VLAN interfaces are up and have active ports assigned:
show ip interface brief
You should see both vlan10 and vlan20 in an up/up state. If either is down, inter-VLAN routing will not work.
2. Verify Host Connectivity
Ensure that:
Devices in VLAN 10 have a default gateway of 192.168.245.1
Devices in VLAN 20 have a default gateway of 192.168.4.2
Also, test pinging between hosts in each VLAN (not just the SVI IPs).
3. Check VLAN Membership on Interfaces
Make sure the physical interfaces are correctly assigned to VLANs:
show vlan
You should see ports assigned to VLAN 10 and VLAN 20. If no ports are members of VLAN 20, the SVI will not come up.
4. Confirm Routing Table
Run:
show ip route
You should see both directly connected networks:
192.168.245.0/24 via vlan10
192.168.4.0/29 via vlan20
If either is missing, the SVI may not be active.
5. Disable Proxy ARP (if enabled)
Sometimes proxy ARP can interfere with inter-VLAN routing. You can disable it globally or per interface:
interface vlan10
no ip proxy-arp
exit
interface vlan20
no ip proxy-arp
exit
6. Check for ACLs or VRF Isolation
Since you're using the default VRF, ensure there are no ACLs or policies blocking traffic between VLANs:
show access-lists
Also confirm both SVIs are in the same VRF:
show vrf
7. Test from the Switch Itself
Try pinging from the switch using the source interface:
ping 192.168.4.2 source 192.168.245.1
Let me know what you find.
mattb13
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June 24th, 2025 12:50
Some more details:
1) I can't ping the router on its address (192.168.4.2) from vlan10 either
2) I'm using the default vrf as BGP doesn't work in non-default vrfs
3) BGP does work within 192.168.245.0/24 so intra-vlan routing does work