Re: DHCP Server - Default-router List

Everyone,
Thank you very much for all of your response. I really appreciate it. Now
this is making a lot more sense. Basically in the RFC it doesn't say what
clients should do but only that servers could present clients with multiple
addresses. Each client's implementation might do something differently.

I just found that windows uses the Dead Gateway detection feature of TCP/IP
to failover between gateways, here is the reg key:

EnableDeadGWDetect
Key: Tcpip\Parameters
Value Type: REG_DWORD - Boolean
Valid Range: 0,1 (False, True)
Default: 1 (True)
*Description*: If you set this parameter to 1, TCP uses the Dead Gateway
Detection feature. *With this feature, TCP requests IP to change to a backup
gateway if it retransmits a segment several times without receiving a
response. Backup gateways may be defined in the AdvancedTCP/IP
configurationdialog box in the Network Control Panel.
* section of the

Thanks so much GroupStudy!!!! Now i can move on without leaving an unturned
stone :)

Tom

On Fri, Nov 19, 2010 at 3:29 PM, Tyson Scott <tscott_at_ipexpert.com> wrote:

> By default clients will select the first address as their default gateway.
> You can also selectively assign metrics to default routers on clients to
> have some choose one and others choose the other. Not a real scalable
> design.
>
> Regards,
>
> Tyson Scott - CCIE #13513 R&S, Security, and SP
> Managing Partner / Sr. Instructor - IPexpert, Inc.
> Mailto: tscott_at_ipexpert.com
>
>
> -----Original Message-----
> From: nobody_at_groupstudy.com [mailto:nobody_at_groupstudy.com] On Behalf Of
> Tom
> Kacprzynski
> Sent: Friday, November 19, 2010 4:16 PM
> To: Mahaffey, Brian
> Cc: Cisco certification
> Subject: Re: DHCP Server - Default-router List
>
> Brain,
> Thank you for your response. I'm trying to figure out what is the feature
> for in the DHCP server. How could a DHCP server give out up to 8 IP
> addresses that can be used as a default route. Yes HSRP would work great to
> provide first hop redundancy, but why would cisco provide the option of
> giving out 8 IP addresses if the client will take the first address. As far
> as i could see, yes it does take the first one, even if that first one is
> not reachable, so no arp or icmp ping for it from the client.
>
>
> Regards,
>
> Tom
>
>
>
>
> On Fri, Nov 19, 2010 at 3:09 PM, Mahaffey, Brian <bmahaffey_at_pelco.com
> >wrote:
>
> > Have you looked into HSRP and just giving the clients one default
> > router? I would assume the client would accept the first one it
> > receives, but I am just guessing.
> >
> > -----Original Message-----
> > From: nobody_at_groupstudy.com [mailto:nobody_at_groupstudy.com] On Behalf Of
> > Tom Kacprzynski
> > Sent: Friday, November 19, 2010 12:50 PM
> > To: Cisco certification
> > Subject: Re: DHCP Server - Default-router List
> >
> > Anyone, please? I'm stuck.
> >
> > thanks
> >
> >
> > On Thu, Nov 18, 2010 at 7:21 PM, Tom Kacprzynski <tom.kac_at_gmail.com>
> > wrote:
> >
> > > Hello,
> > > Just a quick question regarding IOS DHCP server and the default-router
> > > list.
> > >
> > > If I have a pool that specifies multiple default routers, but what I
> > don't
> > > understand is how does the client pick one of the other?
> > >
> > > Sample config below.
> > >
> > > Rack1R1#sh run | s pool
> > > ip dhcp pool TEST
> > > network 155.1.146.0 255.255.255.0
> > > default-router 155.1.146.10 155.1.146.1
> > > dns-server 155.1.146.1
> > >
> > > Based on this the client takes the first IP address for default
> > router,
> > > even if that router is not reachable it does not failover.
> > >
> > > Does anyone know how you could use the two IP addresses and how does
> > the
> > > client switch between them?
> > >
> > > Thank you,
> > >
> > > Tom Kacprzynski
> >
> >
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Received on Fri Nov 19 2010 - 15:49:43 ART