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Network Design - Need to subnet/VLAN existing network. Does this make sense? RRS feed

  • Question

  • I currently have four offices located in two cities.  The offices in each city are linked with a wireless bridge and between the two cities I have a point-to-point T1 line.  Each city has it's own subnet and for the most part the setup in one city is identical to the other city except for the different subnet.

    Unfortunately I have run out of IP addresses and need to expand so instead of opening up my subnet I'd like to create some VLans for different equipment placing the phone system and IP phones on one VLan, the infrastructure (switches, routers, etc) on another, then the servers and users on the last one.  Currently I do not have any layer three switches but I'm also quickly running out of ports so I figure I will be buying one. 


    I would like the offices in City A to look like this:

    VLAN 10 - 10.0.10.x - Infrastructure (switches/routers/bridges)

    VLAN 20 - 10.0.20.x - Servers, Printers, Users, etc

    VLAN 30 - 10.0.30.x - Phone System / IP Phones


    I would like the offices in City B to look like this:

    VLAN 10 - 10.1.10.x - Infrastructure (switches/routers/bridges)

    VLAN 20 - 10.1.20.x - Servers, Printers, Users, etc

    VLAN 30 - 10.1.30.x - Phone System / IP Phones

    The Point-to-Point routers are capable of multiple IP addresses so I could forward all VLan traffic back and forth and just put a single Layer 3 switch doing routing in a single office since I could push all tagged traffic over the point to point.  The issue is when something on 10.1.20.x wants to talk to 10.1.30.x....it would have to travel across the P2P to be routed back down to technically the same switch the traffic came from.  So I'm guessing that two layer 3 swtiches will be used, one at each location.

    Can anyone confirm this design is ok or suggest a better design.  Each city has it's own internet and proxy server.  City A houses the accounting system, City B has almost nothing stored.  Both citys have their own AD, DHCP, and DNS.

    -Allan

    Thursday, February 9, 2012 5:41 PM

Answers

  • Ok then

    let get back to your design

    I think actual design is ok,separate vlans on each site,you can build diferent subnets for voice,to be separated from data,(and use QOS if avaible)

    we need also nr of users

    ip phone users and AD users on each site to build a good configuration,and you have also to calculate futured growth.

    there are 2 points,

    1) if you get a biger subnet you should consider broadcast trafick on switch

    2) if you get small subnets you should consider throughput on the routers.

      Maybe if u separete vioce from data,you will have the required ip address avaible for users.


    Renato Kurti CCNA,MCP,MCTS,MCITP:EA

    • Marked as answer by Kevin Remde Sunday, February 12, 2012 3:21 PM
    Friday, February 10, 2012 2:31 PM
  • As there are not many users

    you can choose a /23 subnet with 510 hosts ,

    ex

    10.0.0.1 255.255.254.0 (510 total ip)

    City A -DHCP pool 10.0.0.50-10.0.1.126 (total 320+ ip ) (50 reserver for menagment,servers,printers ect)

    City B -DHCP pool 10.0.1.126-10.0.1.254 (120+ ip )

    i dont know your switch type,but if they are Cisco i will definetly go for this

    Renato


    Renato Kurti CCNA,MCP,MCTS,MCITP:EA

    • Marked as answer by Kevin Remde Sunday, February 12, 2012 3:21 PM
    Friday, February 10, 2012 4:57 PM

All replies

  • Hi Allan

    I think aditional info is needed,

    can you provide?

    1) if you have dhcp in each site ,do they have diferent address pool (ex dhcp in city A address 1-125,dhcp in city B 126-254)

    2) what point to point routers are you using?(they can do the route between vlans?) maybe you dont need L3 switch,that are expensive

    3) what kind of trafic goes through point to point line?(useres access only servers ? there is any file server? application server? ip phone trafic?ect)

    4) what are you useing as ip phone system and when is installed?


    Renato Kurti CCNA,MCP,MCTS,MCITP:EA

    Friday, February 10, 2012 10:23 AM
  • Right now DHCP is providing the same addresses on diffferent subnets, 10.0.0.65 - 229 for City A and 10.0.1.65 - 229 for City B.

    The routers I'm using are AdTrane NetVanta 3505's.  They do have routing abilities I believe. 

    The traffic through the P2P is about 1/3 VoIP (between phone systems in each office) , 1/3 data transfers for applications (files & accounting software), and 1/3 misc (DFS syncs, AD syncs, etc).  The majority of services are in City A.

    I didn't even think about using the P2P routers.  They need to be replaced soon...they are 6+ years old but if replacing them with a newer modem (with warenty) would save me from having to get two Layer 3 switches then that would be the easiest solution and cost wise might work out to be about the same.

    -Allan

    Friday, February 10, 2012 12:18 PM
  • Ok then

    let get back to your design

    I think actual design is ok,separate vlans on each site,you can build diferent subnets for voice,to be separated from data,(and use QOS if avaible)

    we need also nr of users

    ip phone users and AD users on each site to build a good configuration,and you have also to calculate futured growth.

    there are 2 points,

    1) if you get a biger subnet you should consider broadcast trafick on switch

    2) if you get small subnets you should consider throughput on the routers.

      Maybe if u separete vioce from data,you will have the required ip address avaible for users.


    Renato Kurti CCNA,MCP,MCTS,MCITP:EA

    • Marked as answer by Kevin Remde Sunday, February 12, 2012 3:21 PM
    Friday, February 10, 2012 2:31 PM
  • Our DHCP scope is 164 addresses with about 10 left open in City A and if our growth is sustained, which every indicator points to, I will run out of those in the next couple months.  The phones right now are a small portion of the network, 15 IP addresses total, so moving those off would help but only for about a year.  So with that said I will need to move more then just the phones off but I want those off just so I can prioritize the VLAN for voice (right now I'm using DSCP tagging rules and I rather get rid of all that).

    I understand the throughput issue...and it's a big one if I use the routers to route the info instead of using a Layer 3 switch.  I may have to go the layer 3 switch route just becuse of that.   I need another 48 port switch so the difference between aL2 and a L3 is around $1k.  Although I can then do just one Layer 3 in City A since I'd say 95% of the routing would be in that office.  Then I could use the other P2P router for routing on the other end but that add's some extra complexity. 

    Friday, February 10, 2012 4:04 PM
  • As there are not many users

    you can choose a /23 subnet with 510 hosts ,

    ex

    10.0.0.1 255.255.254.0 (510 total ip)

    City A -DHCP pool 10.0.0.50-10.0.1.126 (total 320+ ip ) (50 reserver for menagment,servers,printers ect)

    City B -DHCP pool 10.0.1.126-10.0.1.254 (120+ ip )

    i dont know your switch type,but if they are Cisco i will definetly go for this

    Renato


    Renato Kurti CCNA,MCP,MCTS,MCITP:EA

    • Marked as answer by Kevin Remde Sunday, February 12, 2012 3:21 PM
    Friday, February 10, 2012 4:57 PM
  • They are Dell switches.  I think I rather have a VLAN just for users and quickly route on a L3 switch just to keep my users seperate.  Plus that gives me a extra 90 IP addresses for the user group...by the time I run out of those I'll have to redo everything anyway.

    Thanks for your help.

    Friday, February 10, 2012 5:36 PM
  • :)

    Ok good luck

    Regards


    Renato Kurti CCNA,MCP,MCTS,MCITP:EA

    Friday, February 10, 2012 5:38 PM