Router to Cisco SG350-28 Managed switch?

[lolcocks]

Hello,

I have internet coming in from my ISP directly into a router.

I was wondering if I can route a cable from one of the ports on the router into the switch so that all the clients on my switch would be able to get internet access?

What settings should I be looking at? I am unable to find the exact terminology of what it's called.

Thank you.

[Seb Rupik · Accepted solution]

Hi there,

The simplest solution would be to ensure all of the SG350 ports are in mode access. Essentially this would result in all switchports belonging to the same VLAN (ID1). Performing a factory reset of the SG350 may be the quickest way to achieve this depending on your level of switch administration skills. 

If you fancy using the CLI let us know and we can provide the required commands.

cheers,

Seb.

[lolcocks]

Thank you for your quick response.

I do agree, I am quite the newbie, this is my first time handling a switch.

But I did update the firmware to 2.5.0.79 (which is the latest one currently available) and after that did a reset by holding the reset button for a few seconds.

After that I plugged in all the cables, everything seems to be working fine for the default settings.

I plugged in the cable from the router into port 15 on the switch but I don't think it got automatically configured.

I did enable the DHCP server, it wouldn't be interfering with the port on which the router is plugged in right?

[Mark Malone]

it shouldnt no , after defaulting the switch everything will be on vlan 1 , so if you have multiple vlans you should make the port 15 a trunk and allow all , if only using vlan 1 it should be good

[Seb Rupik]

If you are able to connect to the management webGUI on the SG350 check that spanning-tree portfast is enabled on every port. This will speed up the time it takes for a swithport to begin forwarding traffic.

cheers,

Seb.

[lolcocks]

Thank you good sir! Everything is working now.

And what is even better is that now the router is acting as the DHCP server and all traffic is being routed through it. I don't know what the terminology is called, I would like to know but it's working great for me now.

This help me with both wired and wireless clients being on the same LAN.

Also, can I ask one more question?

I have two internet connections.

One I plugged into is now working fine.

I have a backup connection which I would also like to plug into the switch but is there a way I can make it active only if the first one goes down?

Thank you for all your help @Seb Rupik  and @Mark Malone 

[Seb Rupik]

Happy to have helped. Please can you mark this post as solved ;)

Regarding the second ISP router, this is normally achvied through IP SLAs but since the SG350 is not doing any routing, you need to rely on the primary router to provide the intelligence.

If it allowed it you might be able to use DHCP Option 33 to install two static routes in client routing tables.

Or perhaps simpler, if you are not planning on changing the network topology too much, would be to manually configure persistent static routes on the clients themselves. Giving the static route to the primary router a lower metric value.

....but I am not sure if the OS would remove a route when the next-hop becomes unreachable.

cheers,

Seb.

[Seb Rupik]

Actually there is another option, but we will need to do some additional config to your switch.

To keep things simple, configure both ISP routers so they are on the same subnet, but have a different IP address, say:

ISP_1 : 192.168.0.1 /24

ISP_2 : 192.168.0.2 /24

Connect ISP_1 router to Gi15 and ISP_2 to Gi16 . Now we need to create a new user VLAN on the SG350. When the packets are received destined to the internet the static routes are consulted. If the switch can no longer reach 192.168.0.1 then it will route all traffic to 192.168.0.2 :

!
vlan 20
!
int vlan 1
  ip address 192.168.0.254 255.255.255.0
!
int vlan 20
  ip address 10.10.20.254 255.255.255.0
!
ip dhcp server
!
ip dhcp pool network VLAN-20
  address low 10.10.20.1 high 10.10.20.63 255.255.255.0
  default-router 10.10.20.254
  domain-name mydomain
  dns-server 8.8.8.8
!
int range gi0-14
  switchport mode access
  switchport access vlan 20
  spanning-tree portfast
!
int range Gi15-16
  switchport mode access
  switchport access vlan 1
  spanning-tree portfast
!
ip route 0.0.0.0 192.168.0.1 5
ip route 0.0.0.0 192.168.0.2 10
!

This will not work if the the internet connection on the router goes down but the router still stays up, ie 192.168.0.1 is still reachable.

Also you need to configure both routers to route traffic destined for 10.10.20.0/24 to the SG350:

!
ip route 10.10.20.0 255.255.255.0 192.168.0.254
!

Also NAT on the ISP routers will need to be adjusted to translate traffic with a source address of 10.10.20.0/24 in addition to 192.168.0.0/24

cheers,

Seb.

[lolcocks]

Thank you so much @Seb Rupik and yes, I will mark this thread as solved now.

Thank you so much for helping a newbie out.

I will certainly try out your solution tonight once everyone has left the office.

Thank you! :)