RE: DHCP

From: Edwards, Andrew M (andrew.m.edwards@boeing.com)
Date: Tue Nov 23 2004 - 20:28:08 GMT-3


it will get all gateways you list via DHCP in the order that you list
them. With windows and TCP/IP after 3 attempts or when ~1/4 of the
packets are no longer serviced by the first gateway it will switch to
the second defined gateway.

Try running netstat -nr when you dump a gateway and see the change for
the next hop on the 0.0.0.0 0.0.0.0 route.

andy

        -----Original Message-----
        From: gladston@br.ibm.com [mailto:gladston@br.ibm.com]
        Sent: Tuesday, November 23, 2004 12:20 PM
        To: Edwards, Andrew M
        Cc: ccielab@groupstudy.com
        Subject: RE: DHCP

        Thanks, but does I need something more in the case of Windows
clients or they will receive both default gateways from the DHCP server
(172.16.123.1 and 172.16.123.3) and use the first as default gateway by
default?

        Cordially,

------------------------------------------------------------------
        Gladston

"Edwards, Andrew M" <andrew.m.edwards@boeing.com>

23/11/2004 18:11

To
Alaerte Gladston Vidali/Brazil/IBM@IBMBR, <ccielab@groupstudy.com>
cc
Subject
RE: DHCP

        This is when you will use IRDP (ICMP router discovery protocol)
for the
        router (R2) such that it can act as a host.

        Under the gateway routers interface for the network segment you
will use
        the interface commands:

        Ip irdp
        Ip irdp address 172.16.123.1 preference 5
        Ip irdp address 172.16.123.3 preference 10

        And, Windoz hosts can use multiple default gateways. Try the
first in
        the list, if its not resonsive try second, etc.

        Also, don't forget the other static addresses within the DHCP
range that
        need to be excluded (e.g. dns servers, netbios name server, tftp
server,
        etc.)

        Here is a link from the doc cd on DHCP:

http://www.cisco.com/univercd/cc/td/doc/product/software/ios122/122cgcr/
        fipr_c/ipcprt1/1cfdhcp.htm

        HTH

        andy

        -----Original Message-----
        From: gladston@br.ibm.com [mailto:gladston@br.ibm.com]
        Sent: Tuesday, November 23, 2004 11:33 AM
        To: ccielab@groupstudy.com
        Subject: DHCP

        I am working on the following configuration:

        r1, r2 and r3 are connected to the same Vlan.
        r1 is dhcp server; r2 is dhcp client.

        ip dhcp excluded-address 172.16.123.1 172.16.123.3
        !
        ip dhcp pool Pooldhcp
        network 172.16.123.0 255.255.255.0
        dns-server 172.16.123.100
        netbios-name-server 172.16.123.150
        domain-name web.com
        default-router 172.16.123.1 172.16.123.3
        lease infinite

        I was expecting r2 to receive both default-routers, but it just
points
        to the first, even when I shutdown router r1.

        Is it the same behavior of Windows clients for dhcp client?

        r2#sh ip rou
        Default gateway is 172.16.123.1

        Host Gateway Last Use Total Uses
Interface
        ICMP redirect cache is empty



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