Re: ISA array at HO and cache server at remote sites
- From: puja gugnani <puja_gugnani@xxxxxxxxx>
- To: "\[ISAserver.org Discussion List\]" <isalist@xxxxxxxxxxxxx>
- Date: Sun, 4 Aug 2002 13:30:13 -0700 (PDT)
Thanks again Jim,
From your inline message i understand that we need to
configure the downstream server as a web proxy with a
routing script setting (in the IE LAN setting). This
will help the dowstream proxy identify which one of
the two ISA servers in the array it should sent the
request to.
Some additional questions are:
1) Would i be correct to believe that this setup will
create a hirerachial chain with the upstream servers.
2) We are planning to setup the downstream ISA server
on a domain controller which is also and AD
intergrated DNS. Have there been any reported problems
of setting up ISA server on a DC?
3) The client machines on the head office, will point
to the Array name which will have a DNS entry with 2
servers for the same name. Will all requests be
directed to the 1st ISA server in the DNS list and
then that ISA server will identify which of the 2 ISA
servers is best suited to respond based on the CARP
cashing algorithm?
Thanks for your assistance.
--- Jim Harrison <jim@xxxxxxxxxxxx> wrote:
> http://www.ISAserver.org
>
>
> More inline... ;-)
>
> Jim Harrison
> MCP(NT4, W2K), A+, Network+, PCG
> http://isaserver.org/authors/harrison
> http://jalojash.org/isatools
> Read the books!
>
> ----- Original Message -----
> From: "puja gugnani" <puja_gugnani@xxxxxxxxx>
> To: "[ISAserver.org Discussion List]"
> <isalist@xxxxxxxxxxxxx>
> Sent: Sunday, August 04, 2002 9:40 AM
> Subject: [isalist] Re: ISA array at HO and cache
> server at remote sites
>
>
> http://www.ISAserver.org
>
>
> Thanks Jim,
>
> Would it be correct to say that:
>
> 1) The clients at the remote site would point to the
> local proxy/cache server (downstream ISA server)
>
> ** yes, exactly so
>
> 2) The down stream server will periodically poll the
> array at the head office to get the array member
> list
> and will compute the hashing algorithm (URL+server).
> It will then send the request to specific ISA server
> in the array which has the highest hash value. What
> i
> like to confirm is that does this hashing function
> at
> the downstream compute the exact upstream server to
> which the request is to be sent or do we need DNS
> round robin to send the request to the alternate
> servers in the array and then the array decides
> which
> server will respond to the request based on the
> hashing function. Is that what you meant by the
> routing scrip at the downstream server.
>
> ** Yes, the configuration script (you can observe it
> by going to http://<yourISA>/wpad.dat) tells
> the downstream ISA how to route traffic, though it
> has nothing to do with CARP. The actual
> mechanism is a little more complicated than that.
>
> 3) As for the clients at the head office, i agree we
> will configure them to use the array name and define
> the name in the DNS, would it be required that the
> DNS
> use round robin for assigning the requests to the
> specific server in the array
>
> ** DNS Round Robin is cheap, easy to implement and
> not very useful for a load-balancing or failover
> tool.
> It forces the client to make routing decisions based
> on data it may or may not have available.
> All the clients will :
> 1. use the first entry in the list unless it fails
> to respond
> 2. make exactly the same decision for any given
> failure scenario
>
> Thanks again
>
> --- Jim Harrison <jim@xxxxxxxxxxxx> wrote:
> > http://www.ISAserver.org
> >
> >
> > Inline...
> >
> > Jim Harrison
> > MCP(NT4, W2K), A+, Network+, PCG
> > http://isaserver.org/authors/harrison/
> > Read the books!
> >
> > ----- Original Message -----
> > From: "puja gugnani" <puja_gugnani@xxxxxxxxx>
> > To: "[ISAserver.org Discussion List]"
> > <isalist@xxxxxxxxxxxxx>
> > Sent: Sunday, August 04, 2002 4:51 AM
> > Subject: [isalist] ISA array at HO and cache
> server
> > at remote sites
> >
> >
> > http://www.ISAserver.org
> >
> >
> > We have an internet leaded line at the head
> office.
> > All the remote offices connect to the head office
> to
> > access the internet. I have an ISA Server Array
> > containing 2 ISA Servers (integrated mode) at the
> > head
> > office. I'm placing 1 ISA Server (downstream
> server)
> > at the remote offices for proxy/caching purpose
> thus
> > forming a hirerchial chain.
> >
> > 1) Can the downstream ISA Server compute the hash
> > and
> > send the request to the appropriate server at the
> > hea
> > office? If so what will be needed at the
> downstream
> > server to do so?
> >
> > ** downstream ISA servers can be told to use the
> > routing script and will behave as any other web
> > proxy cleint in that case
> >
> > 2) If not will I need to implement DNS round robin
> > at
> > the remote sites to send the request to the
> > alternate
> > servers in the Array at the Head Office, which
> will
> > then use CARP hashing algorithm to compute the
> > server
> > which should respond to the request.
> >
> > ** bear in mind that CARP is array-limited and
> > arrays are site-limited. Since the downstream ISA
> > is
> > unlikely to be a member of an upstream array, it
> > won't play in the CARP sandbox
> >
> > 3) How will the client computers in the head
> office
> > be
> > configured to access the array?
> >
> > ** Ideally, you would configure the ISA array to
> use
> > the array name and create a DNS entry for that
> > name.
> >
> > Thanks in advance
> >
> > __________________________________________________
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> >
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