From: Colin Barber (Colin.Barber@telewest.co.uk)
Date: Sat Jun 14 2003 - 15:23:40 GMT-3
The DHCP request packet contains a field for the relay agent address. If the
router is configured with a helper-address command it adds its interface
address into that field. Once the DHCP server receives the packet it looks
at this relay field and from that issues an address for that subnet.
The only problem you run into with this is if you are using secondary
addresses on the interface. The router uses its primary address for the
relay ip and therefore you cannot get an address from the secondary ranges.
-----Original Message-----
From: Castelino, Flavian [mailto:Flavian.Castelino@nexinnovations.com]
Sent: 12 June 2003 17:35
To: Emad; CCIE LAB (E-mail)
Subject: RE: switching::DHCP pool choice
I meant 'default router' option on DHCP scope for the VLAN...not default
router for the DHCP server.
For example - scope for VLAN 77 has IP range 10.77.1.1 to 10.77.1.253;
default router option as 10.77.1.254..then your interface VLAN 77 on the
backbone router should have IP address 10.77.1.254 and a helper-address
command pointing to IP address of DHCP server. The DHCP server can be on
any VLAN...
C'mon, I am sure you can do this...
Flavian
-----Original Message-----
From: Emad [mailto:emad@zakq8.com]
Sent: Thursday, June 12, 2003 1:56 AM
To: Castelino, Flavian; CCIE LAB (E-mail)
Subject: RE: switching::DHCP pool choice
No , the DHCP server does have another gateway which is the gateway for
the whole network but it exists of course on the same backbone L3 Plz
advise
-----Original Message-----
From: Castelino, Flavian [mailto:Flavian.Castelino@nexinnovations.com]
Sent: Wednesday, June 11, 2003 5:36 PM
To: Emad; CCIE LAB (E-mail)
Subject: RE: switching::DHCP pool choice
The helper-address command on the VLAN 77 interface on backbone
switch/router will direct requests from PCs on VLAN 77 to the DHCP
server. Ensure that default router for the subnet on the DHCP scope is
the VLAN 77 IP address
Flavian
-----Original Message-----
From: Emad [mailto:emad@zakq8.com]
Sent: Wednesday, June 11, 2003 1:04 AM
To: Castelino, Flavian; CCIE LAB (E-mail)
Subject: RE: switching::DHCP pool choice
Importance: High
I mean how can I force the PCs that will be connected to certain VLAN ,
say VLAN 77 , to take their Ips from subnet 77 range on the DHCP , does
your solution fit with that or we have to work around that again
Waiting
-----Original Message-----
From: Castelino, Flavian [mailto:Flavian.Castelino@nexinnovations.com]
Sent: Tuesday, June 10, 2003 4:37 PM
To: Emad; CCIE LAB (E-mail)
Subject: RE: switching::DHCP pool choice
Emad,
U will need layer 3 vlan interfaces on ur backbone switch corresponding
to the vlans on your edge switches, a ip helper-address command on each
layer 3 interface pointing to your DHCP server.
Flavian
-----Original Message-----
From: Emad [mailto:emad@zakq8.com]
Sent: Monday, June 09, 2003 2:27 PM
To: CCIE LAB (E-mail)
Subject: switching::DHCP pool choice
Folks,
I have a question here about certain case:
I have backbone switch connected to multiple edge switches , and I need
to have different VLANs , each connected to one edge switch , I
configured DHCP server with multiple subnets range , each switch has one
vlan with only one subnet , the question is, considering the backbone is
their gateway , how can I force each edge switch to have certain subnet
from the DHCP range , if it is possible , from backbone or from the edge
switches themselves!! Thanx in advance
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