+ Post New Thread
Results 1 to 2 of 2
Wired Networks Thread, DHCP Servers, Double routers etc in Technical; Probably over-complicating this massively but I'll try and explain why the headache Two physical sites. New network infrastructure built on ...
  1. #1

    synaesthesia's Avatar
    Join Date
    Jan 2009
    Location
    Northamptonshire
    Posts
    5,489
    Thank Post
    527
    Thanked 876 Times in 683 Posts
    Blog Entries
    15
    Rep Power
    438

    DHCP Servers, Double routers etc

    Probably over-complicating this massively but I'll try and explain why the headache

    Two physical sites. New network infrastructure built on SCCM going in August. Each site has 2 servers each, a DC and the SCCM/other bits server.
    DC will do DHCP and DNS.
    So we can manage collections and boundaries properly in SCCM (2012) we need to separate the two sites via IP.
    Subnets created in AD to do this

    (rough outline : if we have 192.168.48.0/22 allocated, 192.168.48.0/24 and 49.0/24 are bound to site A, 50.0/24 and 51.0/24 to site B)
    That makes the SCCM side of things a piece of cake to manage. AD is simple enough.

    However, I'd like to make sure the right machines get the right address from DHCP - from the right DHCP server, mostly!
    So Site A PC's pick up IP addresses in the scope from the Site A DC, and Site B from Site B DC etc. A client will usually pick up its DHCP stuff from the nearest server which *should* in practice work OK, especially if we lengthen lease time a little. But that won't always be the case, and I'd prefer to keep stuff that deploys from boundaries rather than collections to each site rather than traversing the link.

    There's a decent core switch at each site - a HP5406ZL. Currently it's set up entirely flat, and we'd rather not go into too much bother with vlans etc.
    I'm vaguely estimating that involves:

    Giving each switch a reasonable IP within the two subnets (i.e. site A router would be 192.168.48.2 and site B would be 192.168.50.2)
    Enable routing on each switch with default route being the router supplied by ISP for internet access
    Set dhcp-helper on each switch to the relevant site DHCP server

    That seems reasonable simple to me - however a few concerns.
    The routers would be on separate subnets but being within within the /22 would still be able to communicate - do I need to therefore split into 4 x /24s and have a superscope on each DHCP server to cope with the 2 x /24s?
    Failover - this, I believe means we'd lose failover (i.e. if site A DHCP server keeled over, B wouldn't be contactable for the clients)

    Would anyone have any suggestions on keeping failover/resiliency whilst still being able to differentiate between the two sites in SCCM/AD?

  2. #2

    Join Date
    Jun 2012
    Location
    Manchester
    Posts
    12
    Thank Post
    0
    Thanked 1 Time in 1 Post
    Rep Power
    0
    I think I understand what you're asking...

    You should create a routed link between the sites. This would mean creating a new subnet purely between the switches/routers which link the sites, or use routed ports on your HP switch (whichever is most suitable) with a small /30 subnet.

    If you configure IP helpers on each site, they won't really be a problem as the local DHCP server should respond first and offer an IP address. The client should only accept an offer from the remote DHCP server if it doesn't receive one from the local subnet.

    You won't need to create Superscopes either, as the DHCP server will know the netmask based on its own NIC.

    Also, you'll need to configure some kind of routing between the two site routers, or configure static routes so each LAN knows the way to the other one (vital for DHCP to be able to service hosts on the remote sites).

    Hope that makes sense

SHARE:
+ Post New Thread

Similar Threads

  1. Replies: 0
    Last Post: 27th February 2008, 06:42 PM
  2. Changing DHCP server IP label
    By NetworkGeezer in forum Wireless Networks
    Replies: 0
    Last Post: 23rd March 2007, 01:44 PM
  3. Add additional dhcp server
    By Uraken in forum Wireless Networks
    Replies: 2
    Last Post: 20th February 2007, 11:25 PM
  4. Downsides to passing tftp server via 2003 DHCP server?
    By pete in forum Wireless Networks
    Replies: 7
    Last Post: 11th July 2006, 10:07 PM
  5. DHCP Server
    By SimpleSi in forum *nix
    Replies: 8
    Last Post: 17th May 2006, 11:09 AM

Thread Information

Users Browsing this Thread

There are currently 1 users browsing this thread. (0 members and 1 guests)

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •