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I am attempting to configure routing on a Catalyst 3650 running LAN Base to meet a particular set of criteria. For context: the switch is being configured as part of a lab environment that will allow for pre-configuration of equipment that will ultimately reside in another facility.

The switch has been configured with 4 VLAN's, each with an IP address and corresponding DHCP pool (DHCP running on switch). ip routing has been enabled and inter-VLAN routing is working as expected.

The final requirement is that the internet be reachable from within each VLAN. I expected that by having a hosts default-gateway set to the VLAN interface IP and a default route in the routing table to the upstream router that this would be achievable, assuming there was at least one interface on the same network as the upstream router. I have attempted the following to no avail:

  • Configured a VLAN with an IP address on the same network as the upstream router.
  • Configured a physical interface Gi1/0/1 with no switchport and assigned it an IP address on the same network was the upstream router.

In both cases I can ping the IP address of the VLAN interface (first case) or the physical interface (second case), but cannot ping the upstream router.

How might I achieve my objective?

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You need IP Base or better to use it as a full layer-3 switch/router. With LAN Base, it is a layer-2 switch, and you only have limited static routing.

With IP Base or better, you use the ip routing command to enable routing, and you need routing (either on the switch, or on an external router) to allow traffic between networks, then you can use full routing features without setting static routes.

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  • I suspected that was a possibility. Just one additional question: with ip routing enabled I am presently able to reach hosts within other directly connected networks without static routes. When I run show ip route I see local and connected routes for networks and hosts directly connected. Does that make sense that these networks and hosts would be routed but not the traffic to the upstream router and thereby internet?
    – sardean
    May 12, 2018 at 2:38
  • Of course you can reach directly connected networks because the router in your switch inherently knows about those networks. The other two ways it can learn about networks is with static configuration (which your switch can do), or through a routing protocol (which your switch cannot do). To use the public Internet, you will need at least a statically configured default route (0.0.0.0/0) pointing to your WAN router. You need static routes to any networks not directly connected to the switch.
    – Ron Maupin ♦
    May 12, 2018 at 2:43
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    @dean, another thing you are going to need is for the router to have statically configured routes to all the networks behind the switch because you cannot use a routing protocol to tell the router about those networks.
    – Ron Maupin ♦
    May 12, 2018 at 3:16

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