From: John Underhill (stepnwlf@magma.ca)
Date: Sat Jun 12 2004 - 15:33:58 GMT-3
I don't even want to think about re-addressing the network, (I don't
particularly enjoy long talks with my manager..), with NAT operations,
routing, VPNs, and all the static addressing, it would be a lot of work, and
down time..
I think I will mock this up with a couple hosts and put a sniffer on the
wire to see how it works..
I'm sure I am not the only person who would like to see redundancy in a
design of this kind, and with wireless gaining ground on the LAN, secure
address assignments are becoming a real issue.. I'll let you know if it
works.
----- Original Message -----
From: "Kenneth Wygand" <KWygand@customonline.com>
To: <stepnwlf@magma.ca>; <ccielab@groupstudy.com>
Sent: Saturday, June 12, 2004 2:15 PM
Subject: Re: DHCP Failover
> John,
>
> Not sure about the solution you are recommending, but does your current IP
addressing scheme lends itself nicely to a /23 conversion?
>
> Ken
> --------------------------
> Sent from my BlackBerry Wireless Handheld
>
>
> -----Original Message-----
> From: John Underhill <stepnwlf@magma.ca>
> To: Kenneth Wygand <KWygand@customonline.com>; ccielab@groupstudy.com
<ccielab@groupstudy.com>
> Sent: Sat Jun 12 14:10:55 2004
> Subject: Re: DHCP Failover
>
> Unfortunately this doesn't scale very will on a /24 subnet.. What I mean
to
> do, is move away from centralized address management, and have access
> routers handle dhcp for the local fabric. Right now I am using an active
> cluster dhcp/dns solution, but for security reasons, (lease spoofing,
> particularly for wireless, and more restrictive traffic policies at access
> points..), I would like to go with a distributed solution. The only
problem
> is redundancy.. I was thinking of using HSRP to load share on redundant
> gateways, and splitting the scope between the two dhcp servers, each
> assigning different gateways.. the only problem is, there are 200+ nodes
on
> this segment, so if one of the DHCP servers goes down, a divided scope
will
> not have enough address space to service the network. So what I was
thinking
> was: could I log both dhcp servers to a central database on a server, let
> them both use the same scope, and maintain redundancy and the full address
> space, while avoiding address assignment conflicts. So the question
becomes,
> what does the 'ip dhcp database tftp://x.x.x.x/filename' do exactly? I am
> under the impression, that it stores mappings for recovery purposes, but
how
> dynamic is it? Do the servers simply write to the file, or do they do a
> lookup in the database before assigning an address? If it was the latter,
I
> could have both servers connected to the same database to avoid address
> conflicts, and load share the gateways.
>
>
> ----- Original Message -----
> From: "Kenneth Wygand" <KWygand@customonline.com>
> To: <stepnwlf@magma.ca>; <ccielab@groupstudy.com>
> Sent: Saturday, June 12, 2004 1:38 PM
> Subject: Re: DHCP Failover
>
>
> > John,
> >
> > Just set up two DHCP servers on the same segment but have each one lease
> out a non-overlapping subset of the dynamic IP addresses in that range.
This
> works perfectly. If you'd like, I can explain how this actually works
behind
> the scenes once I get to a real computer (on a blackberry right now). Let
me
> know and hope this helps.
> >
> > Ken
> > --------------------------
> > Sent from my BlackBerry Wireless Handheld
> >
> >
> > -----Original Message-----
> > From: nobody@groupstudy.com <nobody@groupstudy.com>
> > To: ccielab@groupstudy.com <ccielab@groupstudy.com>
> > Sent: Sat Jun 12 12:52:42 2004
> > Subject: DHCP Failover
> >
> > I was wondering if by using the (ip dhcp database
tftp://x.x.x.x/filename,
> > maybe in conjunction with the update arp - secure dhcp..), could I
create
> > overlapping scopes, and use this for redundancy? This file will store
the
> > binding information, but I'm wondering if the dhcp servers consult this
> file
> > before leasing an address, or is it simply warehousing the binding
> > information.. Can someone think of some other way to create a
> > redundant/failover dhcp solution using ios dhcp?
> >
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