On 18 Feb 2011, at 14:26, Phil Mayers wrote: > On 18/02/11 14:16, Dean, Barry wrote: >> I have been asked to do just this and I am working on the solution >> now. >> >> We wanted to use multiple pools of VLANs/Subnets and assign "Staff" >> to one pool and "Students"# to the other. Then to select a VLAN >> within the pool, use a hashing function and select a VLAN. >> >> One concern I have is when is post-auth called? Would it get called >> for interim authentication requests? Because I don't want to be >> changing the VLAN mid sessions, which could potentially happen with a >> non-deterministic hash! > > There is no such thing as an "interim" authentication request. > > Post-auth is called after every auth. > > I suspect you are referring to feature(s) on the switch(es) you use > where it will "re-auth" the client after X minutes. That's just another, > separate authentication as far as FreeRadius is concerned
Yep, I was referring to the entries I see in my logs for
"Interim-Update", which is of course an Accounting record, and I had always
assumed this went with an Auth as well, but have never looked in detail to see!
So I am most likely talking rubbish!
>>
>> In my tests I have been creating a hash from the 'State' attribute
>
> That's a very bad idea. It will change mid-session and cause you huge
> problems.
>
I will not be using this then :-)
> We do pervasive VLAN assignment on a large scale here, and my advice is
> the same as others in the thread - don't use a hash value. Just map a
> user or group to a vlan.
>
> If you need to "balance the numbers of users on a vlan" (why?) then you
> should log the vlan assignments to SQL and run a post-processing script
> that changes the assignment to keep the "load balanced".
>
> Personally we just run big subnets to reduce the waste of IP space and
> configuration overhead.
>
I don't design the wireless network here, I just make the RADIUS work as best I
can. It has been decided to have smaller private IP ranges each associated with
a VLAN and balance the routing of these across two routers. Then I was asked if
I can distribute the users across these VLANS evenly.
I am beginning to think a round robin allocation might just do!
However, the goal posts could move again yet! Latest news is that we will have
1 pool of VLANs, so time to tear up the existing code and take a fresh look! I
currently have no idea how big these subnets will be either.
----------------------
Barry Dean
Principal Programmer/Analyst
Networks Group
Computing Services Department
Tel: 0151 795 9540
Skype: barryvdean
<<attachment: h1_a.png>>
---
Nice boy, but about as sharp as a sack of wet mice.
-- Foghorn Leghorn
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