Cisco RV180 problem with DHCP and Vlan

[Razvan Popescu]

Hi,

I have a RV180 router and I need it mainly for routing a /26 subnet over three vlans

VLAN ID	IP Address	Subnet Mask	DHCP Mode	DNS Proxy Status
1	82.xx.xx.xx	255.255.255.192	DHCP Server	Enabled
2	192.168.10.1	255.255.255.0	DHCP Server	Enabled
3	192.168.3.1	255.255.255.0	DHCP Server	Enabled

vlan 1 (default)

will be the default one and will have the ip 82.x.x.x, on this vlan I want to put two webservers with static/external ip

vlan2

will be for office use with the ip 192.168.10.1. I need for this DHCP enabled to give computers the correct ip in form 192.168.10.x. I will be configuring the static DHCP later on for those comps.

vlan3

will be for management with the ip 192.168.3.1. I don’t need DHCP will be using a static ip.

VLAN ID	Description	Inter VLAN Routing	Device Management	Port 1	Port 2	Port 3	Port 4
1	Default	Enabled	Enabled	Untagged	Untagged	Excluded	Excluded
2	Vlan2	Enabled	Enabled	Excluded	Excluded	Excluded	Untagged
3	Vlan3	Enabled	Enabled	Excluded	Excluded	Untagged	Excluded

Everything works, on port 1 the servers work with their static ip, on port 4 the office computers receive the correct ip from DHCP, 192.168.10.x and even on port 3 the dhcp works for my management ip. But randomly some computers start losing connectivity, some regain it but some won’t connect even if I use a static ip corresponding to their vlan. When I say they won’t connect I mean I can’t ping their gateway or the management ip of the router (all vlans have inter vlan routing enabled so no matter on what vlan I am, I can access the web interface for the router). It;s not from security settings on the computers or firewall.

I discovered they will connect if I use the static ip corresponding to vlan1 82.xx.xx.xx, but not the ip corresponding to their port number. DHCP stops working for a while, it will recover randomly.

What am I doing wrong? I don’t have other switches I could use for DHCP, I thought I could use some managed switches to solve the DHCP problem.

Thanks,

Razvan

[Razvan Popescu]

I tried with only two vlans and set the DHCP active only for the office "vlan2". Computers receive the correct ip but some of them won't register on the network, i tried to set the ip manualy on the computers but that computer will still be isolated.

Ex: computer A receives ip 192.168.10.25, Subnet 255.255.255.0, Gateway 192.168.10.1, for 2-3 minutes i can access the router on 192.168.10.1 and the internet, after a random time interval the gateway won't even respond to ping.It's not from firewall related issues as i set to accept all both incoming and outgoing. If i set a manual ip corresponding to vlan1 "default" everything works.It's like that computer is isolated so i believe it has to do with the asignment of Tagged, untagged and Excluded settings on the vlans.