Configure SG500-P28 as default route of 2 network with same subnet ID

[saravanan.manthaiyan]

Hi,

I have 2 networks with same subnet ID. I would like to how to configure the SG 500-P28 for make communication between these two network. I don't have background of Networking so i am using the GUI for configuring the router.

Host IP 192.168.21.2 till 30

Subnet 255.255.255.128

Gateway 192.168.21.1

Host IP 192.168.21.130

Subnet 255.255.255.128

Gateway 192.168.21.128

I think, i am using the right gateway. Please advice. Thanks in advance!

[Mark Malone]

Hi

you cant have 2 subnets exact same with 2 different gateways its going to confuse the device and the hosts , that wont work and will cause you problems

[saravanan.manthaiyan]

Hi,

So, we need to have a different subnet. 

[Mark Malone]

Hi

Yes you should have 2 different subnets with separate gateways  , the sg500 is a layer 3 device so it can route between the 2 subnets no problem doing intervlan routing , use a 192.168.22.x/24 or something similar to what you have already , when you have 2 different gateway's set for same subnet the packets may end up getting dropped half the time losing large amount of traffic for you

[saravanan.manthaiyan]

Thanks for your prompt response and suggestion. I have seen the below subset table. is it right? if it right, what is the gateway i suppose to use for both network. 

Subnets

Netmask:   255.255.255.128 = 25  11111111.11111111.11111111.1 0000000
Wildcard:  0.0.0.127             00000000.00000000.00000000.0 1111111

Network:   192.168.21.0/25       11000000.10101000.00010101.0 0000000 (Class C)
Broadcast: 192.168.21.127        11000000.10101000.00010101.0 1111111
HostMin:   192.168.21.1          11000000.10101000.00010101.0 0000001
HostMax:   192.168.21.126        11000000.10101000.00010101.0 1111110
Hosts/Net: 126                   (Private Internet)


Network:   192.168.21.128/25     11000000.10101000.00010101.1 0000000 (Class C)
Broadcast: 192.168.21.255        11000000.10101000.00010101.1 1111111
HostMin:   192.168.21.129        11000000.10101000.00010101.1 0000001
HostMax:   192.168.21.254        11000000.10101000.00010101.1 1111110
Hosts/Net: 126                   (Private Internet)

[Mark Malone]

Yes that's correct , 2 gateways , that's a class C subnet split down the middle , 126 hosts each subnet

Gateway 192.168.21.127

Gateway 192.168.21.254

[saravanan.manthaiyan]

Ok, thanks. If i want to go with the above setup, could you guide me on how to configure at SG 500-P28. 

I was trying to add the Ipv4 interface, but could not add both and it says illegal Ip.

VLAN 1 192.168.21.127 255.255.255.128

VLAN 2 192.168.21.254 255.255.255.128

[Mark Malone]

I don't actually use SMB switches but I do see some basic guides online how to set them up which may help you

you could just try full subnets too as a test  incase it has an issue with vlsm subnets like /25s  

192.168.21.0/24  192.168.21.254

192.168.22.0/24 192.168.22.254

Creating VLANs, Assigning IP Addresses, Default Gateway, DNS Name-Server & Enabling IP Routing

http://www.firewall.cx/cisco-technical-knowledgebase/cisco-switches/885-cisco-switches-sg500-52p.html

[saravanan.manthaiyan]

Thanks. I will check