From: ccie2be (ccie2be@nyc.rr.com)
Date: Thu Oct 14 2004 - 17:33:06 GMT-3
Hey Ken,
It doesn't give out 163.3.6.128/25 because dhcp is smart enough to know that
with a /25 mask that address is the address of the subnet itself rather than
a host address.
Therefore, my way of configuring the address pool can't be correct because
163.3.6.128 is explicitly mentioned as the first address that dhcp should
have in it's pool of host addresses.
Thanks and keep those bricks handy. I often need to be hit over the head
with one. :-)
Tim
----- Original Message -----
From: "Kenneth Wygand" <KWygand@customonline.com>
To: "ccie2be" <ccie2be@nyc.rr.com>; "Group Study" <ccielab@groupstudy.com>
Sent: Thursday, October 14, 2004 4:07 PM
Subject: RE: DHCP
Tim,
Yes, this is correct in that your solution will give out /25 addresses.
However, what is the first address your solution will distribute?
<SNIP>
Router>show run
!
!
ip dhcp pool ADDRESSES
network 163.3.6.128 255.255.255.128
!
!
interface Ethernet2/0
ip address 163.3.6.150 255.255.255.128
!
!
00:14:51: DHCPD: DHCPDISCOVER received from client 0100.028a.4fff.18 on
interface Ethernet2/0.
00:14:51: DHCPD: requested address 10.0.0.1 is not on subnet
163.3.6.128.
00:14:53: DHCPD: assigned IP address 163.3.6.129 to client
0100.028a.4fff.18.
00:14:53: DHCPD: Sending DHCPOFFER to client 0100.028a.4fff.18
(163.3.6.129).
00:14:53: DHCPD: child pool: 163.3.6.128 / 255.255.255.128 (ADDRESSES)
00:14:53: DHCPD: pool ADDRESSES has no parent.
00:14:53: DHCPD: child pool: 163.3.6.128 / 255.255.255.128 (ADDRESSES)
00:14:53: DHCPD: pool ADDRESSES has no parent.
00:14:53: DHCPD: creating ARP entry (163.3.6.129, 0002.8a4f.ff18).
00:14:53: DHCPD: unicasting BOOTREPLY to client 0002.8a4f.ff18
(163.3.6.129).
00:14:53: DHCPD: DHCPREQUEST received from client 0100.028a.4fff.18.
00:14:53: DHCPD: Sending DHCPACK to client 0100.028a.4fff.18
(163.3.6.129).
00:14:53: DHCPD: child pool: 163.3.6.128 / 255.255.255.128 (ADDRESSES)
00:14:53: DHCPD: pool ADDRESSES has no parent.
00:14:53: DHCPD: child pool: 163.3.6.128 / 255.255.255.128 (ADDRESSES)
00:14:53: DHCPD: pool ADDRESSES has no parent.
00:14:53: DHCPD: creating ARP entry (163.3.6.129, 0002.8a4f.ff18).
00:14:53: DHCPD: unicasting BOOTREPLY to client 0002.8a4f.ff18
(163.3.6.129).
</SNIP>
Hmm... the first address it gave out is 163.3.6.129. Why didn't it give
out 163.3.6.128, since that was part of the question's requirements?
Kenneth E. Wygand
Systems Engineer, Project Services
CCIE #13720, CISSP #37102, CCNP/DP, ACSP,
Cisco IPT Design Specialist, MCP, CNA, Network+, A+
Custom Computer Specialists, Inc.
"Failure only occurs at the point in which one stops trying."
-Anonymous
Custom Computer Specialists, Inc.
"Celebrating 25 Years of Excellence"
-----Original Message-----
From: ccie2be [mailto:ccie2be@nyc.rr.com]
Sent: Thursday, October 14, 2004 2:29 PM
To: Kenneth Wygand; Group Study
Subject: Re: DHCP
Hey Ken,
Thanks for getting back to me on this.
I looked again at the command reference for the dhcp network command and
it
says that this command specifies what subnet and MASK should be
distributed
to dhcp clients.
So, I think the problem with my config is this. If the mask should
255.255.255.0 and not 255.255.255.128, then my answer is wrong because
I'm
assigning the wrong subnet mask. However, if the subnet mask should be
/25,
then I think my answer is correct. Do you agree?
In this case, the task didn't explicitly state what subnet mask should
be
used, but the official answer indicates that they expected a /24 subnet
mask.
Am I understanding this correctly?
Tim
----- Original Message -----
From: "Kenneth Wygand" <KWygand@customonline.com>
To: "ccie2be" <ccie2be@nyc.rr.com>; "Group Study"
<ccielab@groupstudy.com>
Sent: Thursday, October 14, 2004 2:07 PM
Subject: RE: DHCP
Tim,
Upon re-reading your question, there's another "tidbit" that makes your
answer incorrect, even if the question does not state the subnet mask
that is to be assigned to the clients.
Say you issued the following commands:
ip dhcp pool ADDRESSES
network 163.3.6.128 255.255.255.128
What will be the _first_ IP address assigned through this pool? What
will be the last? To see this a little easier, perhaps determine what
the first and last IP addresses distributed by the "network 163.3.6.0
255.255.255.0" configuration (assuming nothing is statically excluded).
Keep in mind that the router has a little bit of brains behind it when
you configure these network statements and knows what should or should
not be valid when you configure this.
Let me know if this starts to make a little sense.
Kenneth E. Wygand
Systems Engineer, Project Services
CCIE #13720, CISSP #37102, CCNP/DP, ACSP,
Cisco IPT Design Specialist, MCP, CNA, Network+, A+
Custom Computer Specialists, Inc.
"Failure only occurs at the point in which one stops trying."
-Anonymous
Custom Computer Specialists, Inc.
"Celebrating 25 Years of Excellence"
-----Original Message-----
From: nobody@groupstudy.com [mailto:nobody@groupstudy.com] On Behalf Of
Kenneth Wygand
Sent: Thursday, October 14, 2004 1:56 PM
To: ccie2be; Group Study
Subject: RE: DHCP
Tim,
Here's a clue. You didn't mention what you wanted the subnet mask to be
on your clients: 255.255.255.0 or 255.255.255.128 or something else.
Does the question state this?
If so, how does the DHCP server (which is a router, in your case) know
what subnet mask to distribute to a client's request? This is a field
that must be distributed in the server's "DHCP offer" packet to a
clients "DHCP Request" packet.
Once you have the answer to this, you answered your own question. ;-)
Kenneth E. Wygand
Systems Engineer, Project Services
CCIE #13720, CISSP #37102, CCNP/DP, ACSP,
Cisco IPT Design Specialist, MCP, CNA, Network+, A+
Custom Computer Specialists, Inc.
"Failure only occurs at the point in which one stops trying."
-Anonymous
Custom Computer Specialists, Inc.
"Celebrating 25 Years of Excellence"
-----Original Message-----
From: nobody@groupstudy.com [mailto:nobody@groupstudy.com] On Behalf Of
ccie2be
Sent: Thursday, October 14, 2004 1:42 PM
To: Group Study
Subject: DHCP
Hi guys,
I need to configure dhcp to meet these requirements:
Assign ip addresses from 163.3.6.128 thorugh 163.3.6.250
Exclude ip address: 163.3.6.130
My solution was like this:
ip dhcp excluded-address 163.3.6.251 163.3.6.255
ip dhcp excluded-address 163.3.6.130
!
ip dhcp pool ADDRESSES
network 163.3.6.128 255.255.255.128 <-- Is this allowed?
However, the "official" solution was like this:
ip dhcp excluded-address 163.3.6.251 163.3.6.255
ip dhcp excluded-address 163.3.6.130
ip dhcp excluded-address 163.3.6.0 163.3.6.127
ip dhcp pool ADDRESSES
network 163.3.6.0 255.255.255.0
So, the only difference between my solution and the official solution
was that
I used a different subnet and mask and therefore shouldn't need to
exclude
host ip addresses from 0 to 127.
I can't test this, so I was wondering if my solution would work OK.
Thanks, Tim
This archive was generated by hypermail 2.1.4 : Sat Nov 06 2004 - 17:11:48 GMT-3