Different VLAN with the same IP address segment communicate through the layer three switches

1. Case background

A customer LAN network, the using address is 10.10.X.X and subnet mask is, and each point equipment did not set up a unified gateway address.

When a customer’s new equinoctial is overmuch, local area network (LAN) to reach a certain size, the network equipment of the carrier learned MAC address will reach the limit, and can’t add any equinox. Customers put forward under the condition of without changing network structure, to increasing the dozens of points.

After trying and adopted several ways, the customer demands never be completed, at last, Huawei puts forward a solution: adopt Super vlan. Every new point adopt different vlan, keep the original IP address and subnet mask, Finally, all the VLAN converge to the headquarters of the three layer 3 switch equipment.

2. The Experimental topology and address planning

3. process of establishing

3.1 Established network, configure the IP address, when all IP address in the VLAN 1, Verify network connectivity.

3.2. According to VLAN plan, adjust each port of VLAN

[SW_core]vlan batch 10 20 30 [SW_core-GigabitEthernet0/0/1]port link-type access  [SW_core-GigabitEthernet0/0/1]port default vlan 10  # interface GigabitEthernet0/0/1 port link-type access port default vlan 10 # [SW_core-GigabitEthernet0/0/2]port link-type access  [SW_core-GigabitEthernet0/0/2]port default vlan 20 # interface GigabitEthernet0/0/2 port link-type access port default vlan 20 # [SW_core-GigabitEthernet0/0/3]port link-type access  [SW_core-GigabitEthernet0/0/3]port default vlan 30 # interface GigabitEthernet0/0/3 port link-type access port default vlan 30 #

At this time, do connectivity test

From this figure we can see that ping test is illogical, because all destination host are unreachable and there is no forwarding packet gateway address.

3.3. Create super vlan and configure it

[SW_core]vlan batch 1000 [SW_core]vlan 1000 [SW_core-vlan1000]aggregate-vlan [SW_core-vlan1000]access-vlan 10 20 30 [SW_core]interface Vlanif 1000 [SW_core-Vlanif1000]ip address 16 [SW_core-Vlanif1000]arp-proxy inter-sub-vlan-proxy enable

The test results?

3.4. The core switches on check the attribute configuration of vlan

[SW_core]display vlan  The total number of vlans is : 5 -------------------------------------------------------------------------------- U: Up;         D: Down;         TG: Tagged;         UT: Untagged; MP: Vlan-mapping;               ST: Vlan-stacking; #: ProtocolTransparent-vlan;    *: Management-vlan; -------------------------------------------------------------------------------- VID  Type   
 Ports  ------------------------------------------------------------------------------- 1    common  UT:GE0/0/4(D)      GE0/0/5(D)      GE0/0/6(D)      GE0/0/7(D)                              GE0/0/8(D)      GE0/0/9(D)      GE0/0/10(D)     GE0/0/11(D)                              GE0/0/12(D)     GE0/0/13(D)     GE0/0/14(D)     GE0/0/15(D)                              GE0/0/16(D)     GE0/0/17(D)     GE0/0/18(D)     GE0/0/19(D)                              GE0/0/20(D)     GE0/0/21(D)     GE0/0/22(D)     GE0/0/23(D)                              GE0/0/24(D)         10   sub     UT:GE0/0/1(U)         20   sub     UT:GE0/0/2(U)         30   sub     UT:GE0/0/3(U)         1000 super VID  Status  Property      MAC-LRN Statistics Description   --------------------------------------------------------------------------------   1    enable  default       enable  disable    VLAN 0001    10   enable  default       enable  disable    VLAN 0010    20   enable  default       enable  disable    VLAN 0020    30   enable  default       enable  disable    VLAN 0030    1000 enable  default       enable  disable    VLAN 1000    [SW_core]

4. Summary

Communicate between different vlan, the ordinary method is using sub-interface or configure each segment of the gateway address to interface Vlanif, multiple vlan to set up themselves IP address. This article is mainly on the propose not changing the same IP address of the network settings, remains the original network structure, to complete the new added NE.

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