Reduce broadcast traffic between 2 locations

[qus83]

Hi all

we have problem regarding to traffic via mpls between 2 locations

in main office we have

 core c3850 stack 192.168.1.1

access c3650 stack connected to servers, printers 

vlan 120 for servers , vlan 130 voice

and the branch location

cisco c3650 switch

they asked me to replace the switch and add new vlan to reduce the broadcast traffic but the vlan is in the same range as  core (192.168.1.90)

the problem is as long as the vlan in same range we can not reduce the  broadcast traffic and it should be in this range because all the servers are located in main office 

we can not use the same subnet cuz we will face the same problem 

we should  create new subnet to reduce the traffic but the problem we should connect to the servers vlan 102 in main office so it will pass through the vlan102

so how we can solve this problem ?????

[andresfr]

Hi Qus83,

So, is the connection between the two sites a Layer 2 MPLS?

If so, you could have a trunk between the two sites so you can pass traffic for multiple VLANs:

Site_A_SW-------Trunk-------L2 MPLS-------Trunk-------Site_B_SW

Then, if you want devices in VLAN 120 to communicate with devices in a different/new VLAN (let's say VLAN 102) you could configure VLAN SVIs on those switches so you can have inter-VLAN routing:

Site_A_SW# configure terminal

Site_A_SW(config)# interface vlan 120

Site_A_SW(config-if)# ip add <ip_address> <network_mask>

Site_A_SW(config-if)# no ip redirects

Site_A_SW(config-if)# no ip directed-broadcast

Site_A_SW(config-if)# exit

Site_A_SW(config)# interface vlan 102

Site_A_SW(config-if)# ip add <ip_address> <network_mask>

Site_A_SW(config-if)# no ip redirects

Site_A_SW(config-if)# no ip directed-broadcast

Can do the same on Site_B_SW. In that way you'll have the new VLAN to reduce the broadcst domain and devices in each VLAN should be able to communicate using inter-VLAN routing if their default-gateway is set to the IP address configured for the VLAN they belong to.

I hope this helps.

Regards,

[qus83]

Hi Andresfr

Thanks for your reply

in main office the vlan server (120), voice vlan (130) and all vlans are already configured so the problem the high traffic between main office and branch (trunk already configured between them) 

Site_A_SW# configure terminal

Site_A_SW(config)# interface vlan 120

Site_A_SW(config-if)# ip add 192.168.20.1

Site_A_SW(config-if)# no ip redirects

Site_A_SW(config-if)# no ip directed-broadcast

Site_A_SW(config-if)# exit

Site_A_SW(config)# interface vlan 130

Site_A_SW(config-if)# ip add  192.168.30.1

in Branch office they want connected to servers in main vlan 120 and voice 

so should I configure new vlan with new range like below

Site_B_SW(config)# interface vlan 102

Site_B_SW(config-if)# ip add  192.168.2.1

and beside that configure vlan server and voice again here in the branch

Site_B_SW# configure terminal

Site_B_SW(config)# interface vlan 120

Site_B_SW(config-if)# ip add 192.168.20.1

Site_B_SW(config-if)# no ip redirects

Site_B_SW(config-if)# no ip directed-broadcast

Site_B_SW(config-if)# exit

Site_B_SW(config)# interface vlan 130

Site_B_SW(config-if)# ip add  192.168.30.1

Site_B_SW(config-if)# no ip redirects

Site_B_SW(config-if)# no ip directed-broadcast

AND gateway will be to mgm ip 192.168.1.1 for core in main 

Please correct me if i'm wrong ??

[Georg Pauwen]

Hello,

depending on the number of clients, a way to reduce broadcast traffic would be to add static ARP entries for all your clients and servers, on all participating switches. 

[qus83]

Hi Georg

Thanks for your reply

so you mean it doesn't need to create new vlan only add static arp in global configuration mode ???