From: Church, Chuck (cchurch@xxxxxxxx)
Date: Thu May 23 2002 - 08:51:24 GMT-3
I'm not sure about that command, but you can use the ping parameter:
itest01(config)#ip dhcp ?
conflict DHCP address conflict parameters
database Configure DHCP database agents
excluded-address Prevent DHCP from assigning certain addresses
limited-broadcast-address Use all 1's broadcast address
ping Specify ping parameters used by DHCP
pool Configure DHCP address pools
relay DHCP relay agent parameters
smart-relay Enable Smart Relay feature
Set your primary DHCP router to ping say once or twice before handing an
address out, but set the secondary to one more than the primary. The
secondary will then always respond a second or two slower, while the client
will have already registered with the primary. These pings are to guarantee
that the router doesn't hand out an address in use.
Chuck Church
Sr. Network Engineer
CCIE #8776, MCNE, MCSE
US Tennis Association
70 W. Red Oak Lane
White Plains, NY 10604
914-696-7199
-----Original Message-----
From: nobody@groupstudy.com [mailto:nobody@groupstudy.com]On Behalf Of
CCIE-Maillist
Sent: Thursday, May 23, 2002 7:02 AM
To: ccielab@groupstudy.com
Subject: Cisco IOS DHCP primary/secondary server on same VLAN
With the Cisco IOS DHCP server feature, is there some way to have one server
as the primary server and another as the backup, on the same vlan, with an
automatic "failover", such that clients go to one Cisco router DHCP server
and
if that one goes down, the second one answers?
(this is WITHOUT using a product like Cisco Network Registrar)
I know that I could configure two Cisco IOS DHCP servers on the same vlan
with
different scopes and that would make two servers available. The first one to
answer the broadcast for DHCP services would provide the service to the
client. BUT, how would I have one server be preferred over the other in that
situation, or another one that someone can come up with?
*** Does this command do that or is this just for TFTP download?
next-server
To configure the next server in a Dynamic Host
Configuration Protocol
(DHCP)
client's boot process, use the next-server DHCP pool
configuration
command.
Use the no form of this command to remove the boot
server list.
next-server address [address2...address8]
no next-server address
Syntax Description
address
Specifies the IP address of the next server in the
boot process, which
is
typically a Trivial File Transfer Protocol (TFTP)
server. One IP
address is
required, although you can specify up to eight
addresses in one command
line.
Defaults
If the next-server command is not used to configure a
boot server list,
the
DHCP server uses inbound interface helper addresses as
boot servers.
Command Modes
DHCP pool configuration
Usage Guidelines
This command first appeared in Cisco IOS Release
12.0(1)T.
You can specify up to eight servers in the list.
Servers are listed in
order
of preference (address1 is the most preferred server,
address2 is the
next
most preferred server, and so on).
Examples
The following example specifies 10.12.1.99 as the IP
address of the
next
server in the boot process:
next-server 10.12.1.99
Related Commands
bootfile
ip dhcp pool
ip helper-address
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