Subnet -Vlan Communication

Unanswered Question
Feb 5th, 2008
User Badges:

Hi all,


is it possible for the Networks 1& 2 commute.


network1: 81.0.0.0,hosts 81.0.0.1 to 6

broadcast 81.0.0.7 subnet mask 255.255.255.248 and

network2: 81.0.0.8,hosts 81.0.0.9 to 14

broadcast 81.0.0.15 subnet mask 255.255.255.248


will they come under different Vlans

  • 1
  • 2
  • 3
  • 4
  • 5
Overall Rating: 0 (0 ratings)
Loading.
Jon Marshall Tue, 02/05/2008 - 03:54
User Badges:
  • Super Blue, 32500 points or more
  • Hall of Fame,

    Founding Member

  • Cisco Designated VIP,

    2017 LAN, WAN

Hi


yes they are separate subnets and if you have them in separate vlans you will need a router or L3 switch to for the hosts to communciate with each other.


HTH


Jon

Hi Anand


You do not give very much information to work with, however if you have created 2 VLAN's on a switch and assigned 6 ports to each VLAN.


Then you have connected all the hosts with IP addresses in the range 81.0.0.1 to 81.0.0.6 to the ports assigned to one VLAN and all the hosts with IP addresses in the range 81.0.0.9 to 81.0.0.14 to the ports assigned to the second VLAN, then NO, these networks could not communicate without using a layer 3 device (either a router or if your switch has layer 3 functionality) as they are two totally different subnets (as defined by their respective subnet masks), even though the subnets are contiguous.


However if your switch has all the ports assigned to a single VLAN and you configure the hosts to use a /28 mask (255.255.255.240) instead of the /29 mask (255.255.255.248) then they would communicate, as all the hosts would think that they are members of the same /28 subnet.


The host will work out from the network/subnet mask assigned to it whether the host it is trying to communicate with is part of the same network/subnet or not. If it is, the packet will be sent towards that host. If it is not, then the packet will be sent towards the default router. If no default router is configured, the packets will be dropped and a "host not available" type message displayed to the user.


Please note that this second option is NOT a recommendation on how to get these two subnets to communicate. It's simply to illustrate that it could be possible. In a live environment the recommended method to get inter VLAN/Subnet communication is by the use of a layer 3 device.



Best Regards,


Michael

networking11 Thu, 02/07/2008 - 04:17
User Badges:

In the attached diagram,the Routers in Daisy chain are to be connected to Aggregation Router and within the Daisy chain , the router have to be redundant .


Can u suggest me how to



Attachment: 

Actions

This Discussion