Is it possible to play multiplayer games across different Vlans?

[Abdullah Net]

Hello there,

Before i got into cisco world, i used to play a game called "Zero hour" with my brother using normal linksys router while we are in different rooms and it worked fine for a couple of years.

Now everything in my house runs with cisco equipments. I have 3560G as my main switch and i put my brother into VLAN 20 and myself into VLAN 40. I applied some ACLs to separate traffic from VLAN 20 and 40 as a security measure. We both can access the internet just fine.

According to some researches i did, "Zero hour" uses udp broadcast on port 8086 for detecting other LAN multiplayers and i know that the idea of vlans is to separate and kill boardcasts. So, is is possible to play the game with my brother without having to remove the ACLs and without enabling "ip routing" between vlans?

Simplified Configuration Sample

-----------------------------------------------

!

hostname SW-3560G-POE

!

interface FastEthernet0/5

description Jason (my brother)

power inline never

switchport access vlan 20

switchport mode access

spanning-tree portfast

!

interface FastEthernet0/12

description ME

power inline never

switchport access vlan 40

switchport mode access

spanning-tree portfast

!

interface Vlan20

ip address 192.168.20.1 255.255.255.0

ip access-group 120 in

!

interface Vlan40

ip address 192.168.40.1 255.255.255.0

ip access-group 140 in

!

access-list 120 permit ip 192.168.20.0 0.0.0.255 192.168.20.0 0.0.0.255

access-list 120 deny ip 192.168.20.0 0.0.0.255 192.168.0.0 0.0.255.255

access-list 120 permit ip any any

!

access-list 140 permit ip 192.168.40.0 0.0.0.255 192.168.40.0 0.0.0.255

access-list 140 deny ip 192.168.40.0 0.0.0.255 192.168.0.0 0.0.255.255

access-list 140 permit ip any any

!

Your help is appreciated

Thanks in advance

Abdul,

[cadet alain · Accepted solution]

Hi,

you could try using ip helper-address:

on your vlan interfaces: ip helper-address x.x.x.x  where x.x.x.x is the other  IP address in the other VLAN.

in global config:

ip forward-protocol udp 8086

You'll have to modify the ACLs accordingly to  permit this unicast traffic between the VLANs

Regards

Alain

Don't forget to rate helpful posts.

[Abdullah Net]

Alain,

"You'll have to modify the ACLs accordingly to  permit this unicast traffic between the VLANs"

Care to mention an example of such modification?

Abdul,

[cadet alain]

Hi Abdul,

of course:

ip access-list extended 120

10 permit udp 192.168.20.0 0.0.0.255 192.168.40.0 0.0.0.255 eq 8086

ip access-list extended 140

10 permit udp 192.168.40.0 0.0.0.255 192.168.20.0 0.0.0.255 eq 8086

Regards

Alain

Don't forget to rate helpful posts.

[Abdullah Net]

Alain,

It worked

Thanks,

[Abdullah Net]

Alain,

Do i also need to add "ip directed-broadcast" to my vlan interfaces?

I don't really understand what does this command actually do.

Abdul,

[devils_advocate]

The command allows directed broadcasts, i.e broadcasts directed at the Subnet Broadcast address of that SVI.

If its working fine  then I would not add the command above.

As its your home network there is little risk but in a production network you would not enable directed broadcast without careful planning and safeguards such as ACL's.

Cheers

[cadet alain]

Hi,

You would need this command if you were specifying the broadcast address in your ip helper-address command but I rather suggested using the unicast address of the other player on the other VLANso you don't need this.

Regards

Alain

Don't forget to rate helpful posts.

[Abdullah Net]

Alain,

This is exactly what i am going to try out.

Thanks for confirming my point.

Abdul,