SG500x Layer 3 routing?

[CaseyJ374]

Hi, so I apologize at first that I'm new to this type of networking that I'm having to setup and could use some help:

I have 2 Cisco SG500X-24 switches that have 3 vlans (1, 5, 10) and connected via fiber (on different floors) on fiber port 2.  I have an IP address setup for the 5 vlan for management, and is untagged to access port 24, but tagged on fiber port 2 (trunk port).  The 10 vlan does not have an IP addresses, and it's untagged for ports 1-23, and fiber port 1 and tagged on fiber port 2 (trunk port).  The 1 vlan is not on any port.

From my ISP, (which is connected to fiber port 1),  I received a "Layer 3 IP" which consists of 50.0.0.40/30 (not real subnet) and has layer 3 ip of 50.0.0.42 with a default gateway of 50.0.0.41. This is the ISP's gateway.  Also, I was given a /25 subnet, of 50.0.0.128/25 but no gateway.  Just a block of IP's. 

Each 1-23 port on each switch (in the 10 vlan) needs to be able to use one of the /25's, however, I'm not sure what to add where to get this routing to work.

I know that if I assign my laptop the IP from the /30, I can surf while plugged into any of the 1-23 ports, so I know the connection to the ISP is valid.  Finally, each port in the 1-23 is checked with "protected mode" so users can't go sniffing around.

Any help would be greatly appreciated!

[Deepak Kumar]

Hi,

As I a getting your point that you are connecting your ISP connection direct to switch. But it is not possible becuase your ISP has supplied /30 subnet (Public IP). Now you need a router to perform NATing for your internal subnet. Your connection must be like:

ISP Connection-------->Router--------------->SG300

Public Network             NAT+routing                   Switching.

NATing is not possible on the SG300 Switch.

Regards,

Deepak Kumar

[CaseyJ374]

I’m not worried about the internal subnet, that will have a nat router connected later.. that is just a management ip (which is why its only on port 24 and tagged on the trunk to the other switch). It’s more about how to get the 50.0.0.128/25 to route.

[Georg Pauwen]

Hello,

50.0.0.40/30 and 50.0.0.128/25 are not overlapping, so why don't you just assign an IP address such as 50.0.0.129/25 to the VLAN 10 interface and then the remaining IP addresses from the 50.0.0.128/25 range to your clients in VLAN 10, with the VLAN 10 interface being the default gateway ?

Sorry if this sounds too simple, I might have missed your point...

[CaseyJ374]

I tried that, and couldn’t get any traffic to route. Do I need a separate vlan for the /30 directly connected to the isp’s fiber port, then the vlan 10 have the /25’s? If so, what would I add as my route to get the /25’s to route through the /30?

[Georg Pauwen]

Hello,

I assume you have IPv4 routing enabled (page 274 of the attached admin guide) ? Do you have the next hop router IP address defined as well (page 276) ? With IPv4 routing enabled, routing between your VLAN 10 interface and the WAN interface should be automatic...

https://www.cisco.com/c/dam/en/us/td/docs/switches/lan/csbms/Sx500/administration_guide/500_Series_Admin_Guide.pdf

[CaseyJ374]

This worked, and all is good. Thank you for your help!