Cisco SG-300 Layer 3 and RV042 - Internet

[Jay Dd]

Hi everyone,

We have Cisco SG-300 switch(Layer 3 mode) which is connected to a RV042 router to provide internet on VLANs.

We have Static Routing Table - Destination IP "0.0.0.0" and Next Hop Router IP Address "192.168.1.254" which is the RV042 router.

We have Multiple Subnet enabled on the RV042 router.

Our problem is on the RV042 router, it only allow max of 5 multiple subnet entry. we have around 20 VLANs on Cisco SG-300 switch.

Any way to bypass that 5 limit multiple subnet entry?

Or any other way to configure the Cisco SG-300 Layer 3 and RV042 for the VLANs to have internet connection?

Thanks in advance!

[cchamorr]

Hello,

On general terms, you don't need the RV042 to know about all the VLANS it only needs to know about one.

The requirements are these:

1- Make sure the Rv042 and the SG300 are on the same subnet for the management VLAN for example.

2- Setup the SG300 on layer 3 and assign IP addresses to all the VLANS on it.

3- Configure all the ports on the SG300 with the desired VLANS.

4- Make sure the PC's are using the IP address assign to every VLAN on the switch as the default gateway.

5- Create a default route for all traffic on the switch pointing to the IP address of the router on the subnet shared with the router.

6- On the router create static routes for all the subnets on the switch pointing back to the IP address of the switch on the management VLAN (On the same subnet as the router) 

This is it, with this configuration you are allowing the switch to do all the routing among VLANS, when they try to go to the internet, that traffic will be forwarded to the RV042 (no need for multiple subnets to be enabled on this router), the traffic will go out and on the way back it will use the static routes to get back onto the main IP address of the switch which will in turn route it to the appropriate VLAN.

I hope this helps.

[Jay Dd]

Thanks cchamorr for the reply.

1 to 4 - Done

5 - is this what you meant? configured it on the switch.

IPv4 Static Routing Table

Destination IP Prefix          Next Hop Router IP Address

     0.0.0.0                         192.168.1.254

6 - is this what you meant? configured it on the router.

Static Routing

Destination IP : 192.168.10.0   <----------one of the VLAN's subnet for example

Subnet Mask : 255.255.255.0

Default Gateway : 192.168.1.1 <----------- subnet in which the switch and router belongs

Hop Count (Metric, max. is 15) :15

Interface :  LAN

Thanks in advance!

J

[cchamorr]

Hello, 

I'm sorry I couldn't reply earlier but I was a little busy.

I thought the best idea was to give you screenshots of a very similar configuration to make everything clear.

Here is my scenario:

1 - Switch on layer 3 with IP address of 192.168.1.254 on VLAN 1

2- 3 more VLANS configured on the switch, all with IP addresses, the switch is doing the routing.

VLAN 1 - 192.168.1.254

VLAN 6 - 192.168.6.1

VLAN 10 - 192.168.10.1

VLAN 100 - 192.168.100.1

3- Router has an IP address of 192.168.1.1 (Same subnet as switch).

4- Switch has a default route pointing back to the IP address of the router

5- The router has static routes for VLANS 6, 10 and 100 (no need to include VLAN 1 as it is shared with the switch)

I was going to set this up myself but I discussed the case with mdobiac and he already had the same setup configured and working on his lab so he was kind enough to provide the screenshots.

Please let me know if this is clear enough.

I hope this was helpful

[Jay Dd]

Thanks cchamorr for a quick response.

I have the same exact configuration you posted above. Unfortunately, by disabling the multiple subnet option, it took away the internet from the VLANs.

If I disable the multiple subnet option, PC(192.168.10.100 for example) CANNOT ping the router(192.168.1.254) at all, but the switch vlan gateway(192.168.10.1) CAN.

If I enable the multiple subnet option, PC(192.168.10.100) CAN ping the router(192.168.1.254), but the switch vlan gateway(192.168.10.1) CANNOT.

Am I missing something here, or I really need the multiple subnet option enabled?

Thanks in advance.

J

[cchamorr]

You shouldn't need the multiple subnet option, there must be something we are missing. Can you please tell me what is the IP address of the router and switch on the default or management VLAN?

[Jay Dd]

Im using VLAN 3 with IP address 192.168.1.1

Router IP address is 192.168.1.254

Hmmm. Im not using the default VLAN 1. Do you think it has something to do with this?

Upon checking,

Current Default VLAN ID:	1

Thanks!

J

[cchamorr]

Everything looks right. 

I will use a RV042 tomorrow and will test this on the lab. By the way, what firmware version on router and switch? What boot code on switch?

I don't think Vlan 1 has anything to do with it.

Going to bed now, its 2:35 am in my location. Good night

[cchamorr]

Just thought about something else. 

From a PC connected to the switch on a different VLAN run a trace route to 8.8.8.8 and let's see where it stops. 

Also make sure the PCs are using the IP address of it's VLAN on the switch as the default gateway   

Thank you

[Jay Dd]

Here.

PC1

IP:192.168.15.99

Subnet:255.255.255.0

GW:192.168.15.1

DNS:192.168.1.254

tracert 8.8.8.8

Tracing route to google-public-dns-a.google.com [8.8.8.8]
over a maximum of 30 hops:

  1     1 ms     6 ms     6 ms  192.168.15.1
  2     *        *        *     Request timed out.
  3     *        *        *     Request timed out.
  4     *        *        *     Request timed out.
  5     *        *        *     Request timed out.
  6     *        *        *     Request timed out.
  7     *        *        *     Request timed out.
  8     *        *        *     Request timed out.
  9     *        *        *     Request timed out.
 10     *        *        *     Request timed out.

[cchamorr]

Hello, 

I'm very sorry for the delay, it has been one of those days.

It took me forever but I was able to lab this configuration up. This is what I have:

1- RV042 with ip address of 192.168.1.254 (DHCP server disabled)

2- SG300-10 on layer 3 with VLANS 1, 6, 10 and 100

3- The switch is the DHCP server for all the VLANS

VLAN 1 = 192.168.1.1

VLAN 6 = 192.168.6.1

VLAN 10 = 192.168.10.1

VLAN 100 = 192.168.100.1

I then tried to set this up exactly as I explained to you on the previous post and, much to my surprise it didn't work.

I cannot get online, even though I can trace route to from any VLAN to the IP address of the router (192.1681.254)

This is what I discovered:

On this router, for you to be able to get it to work as intended you need to create the static routes on the router pointing back to the IP address of the switch (192.168.1.1) for all VLANS.

The part we are missing is that you also have to have the multiple subnet enabled and have the wanted subnets added to it, which I understand is your limitation, but I found a workaround that works just fine on my lab.

The work around is this:

Just Super net the subnets that you are trying to allow so, for instance, if you have a configuration like mine where all your subnets start with 192.168.x.x just enable the multiple subnets option and add a super net for all of them so 192.168.1.1 255.255.0.0. This setup will include all your current subnets and will allow the router to get them to the internet.

Also, if you have a miz of 192.x.x.x and 172.x.x.x and 10.x.x.x you can use the same system and add all the rules so the router knows about them. 

I did test this leaving just the multiple subnets and removing the static routes but it failed.

Make sure that when you are testing you do have live users on the VLANS.

Please let me know if you need screenshots, I'm a little busy at the moment and I haven't been able to get them yet but if you need them I will be happy to get them later

I hope this is helpful, please let us know.

[leecoxhouse1]

I am doing this with a SG300-28 switch and a RV180 router.  The key things are to define an access port untagged on your default VLAN, I use VLAN1 to connect your router.  The other key points are to use the router as the default gateway for the L3 switch.  Then use the L3 switch as the default gateway per VLAN for all the other devices.  You then need to create a static route back from the router for all VLANs except the default VLAN.  The switch will handle all the VLAN traffic and the router will handle all the internet traffic.

[cchamorr]

Thank you for your post.

Unfortunately the Rv042 is a little different as you will definitely have to use the multiple VLAN subnets option and add them to the device, otherwise, no matter if you have the static routes created or not, it won't work.

But on mostly any other device it will work without an issue.

[cchamorr]

Hello,.

I just wanted to touch base with you and find out if you were able to get it to work using the workaround.

If it worked for you please make sure to mark the answer as correct so that other users can benefit from it.

Thank you

[Jay Dd]

Thanks cchamorr! Let me know the result of your test.

Switch:
SG300-28 28-Port Gigabit Managed Switch
Version 1.3.7.18

Boot Version: 1.3.5.06

Router: 

RV042 10/100 4-Port VPN Router  

Firmware Version: v4.2.2.08

Thanks!

J