From: ccie2be (ccie2be@nyc.rr.com)
Date: Tue Mar 04 2003 - 15:48:36 GMT-3
Hi,
You are right about DHCP - it can be configured to exclude a single ip addr
or a range of addresses. It can also be set up such that given a particular
mac addr, it will assign a particular IP addr.
As far as configuring an interface on the 3550 to be a DHCP client, I'm not
aware that is possible. If it is, could you tell me how that is done.
My understanding from reading the config guide, is that the 3550, if it
doesn't have a configuration file ie. it's right out of the box, will use
DHCP when it's first powered on to get an IP addr which will be assigned to
management interface which by default is in vlan 1- the address to which you
telnet to configure the box.
I guess I'm confused because the documentation says the 3550 will
automatically use DHCP if it doesn't have a config file and you're telling
me that otherwise.
In trying to think this thru, I'm imagining a situation where 3550's are
being deployed remotely to offices which don't have any IT staff. So, to
make this process simple and be able to set up the 3550 remotely, someone in
the network dept. acquires the appropriate mac addr and maps it to an IP
addr in the DHCP server. When the 3550 is cabled up and turned on, it then
goes out, using DHCP, and gets it's ip addr. At this point, someone can
telnet to it and further configure it or if a config file has been set up on
a TFTP server the 3550 will go out and get it's config from there.
The only question is what mac addr is used when the DHCP server is being
configured. The base mac address might work but what you said also makes
sense - use the mac addr of the interface thru which the DHCP requests are
sent.
If I only had a 3550, I could test this, but unfortunately I don't.
Furthermore, since a cisco router can be configured to be a DHCP server,
it's not hard for me to imagine seeing something like this on the lab exam.
So, I want to be 100% sure.
Thanks, Jim
----- Original Message -----
From: "boby2kusa" <boby2kusa@hotmail.com>
To: "'ccie2be'" <ccie2be@nyc.rr.com>
Sent: Tuesday, March 04, 2003 12:47 PM
Subject: RE: 3550 & DHCP
> Hello,
>
> First of all, when you configure a switch or a router in the network you
> have to know which interface will be connected to what segment. With
> that, you should be able to tell what vlan this sgment will be, the 3550
> can be configured where the interface itself is a layer 3 port or you
> might have to configure an SVI or an interface vlan. When you configure
> this interface vlan it uses the base mac address as the other respondent
> pointed and I also included in this e-mail. So, the answer remains as
> it depends what kind of interface you are using. I hoe that is finally
> clear. Besides, I thought that on a DHCP you can exclude ip addresses
> that you don't want to assign, these includes gateway ip addresses. The
> 3550 will not automatically seek the DHCP for an IP address, you have to
> configure the interface first to get it's ip address through DHCP.
>
>
>
> sw1#sh ver
> Cisco Internetwork Operating System Software
> IOS (tm) C3550 Software (C3550-I5K2L2Q3-M), Version 12.1(12c)EA1a,
> RELEASE SOFTW
> ARE (fc1)
> Copyright (c) 1986-2002 by cisco Systems, Inc.
> Compiled Fri 27-Dec-02 11:06 by antonino
> Image text-base: 0x00003000, data-base: 0x00855450
>
> ROM: Bootstrap program is C3550 boot loader
>
> sw1 uptime is 17 hours, 9 minutes
> System returned to ROM by power-on
> System image file is
> "flash:c3550-i5k2l2q3-mz.121-12c.EA1a/c3550-i5k2l2q3-mz.121
> -12c.EA1a.bin"
>
> cisco WS-C3550-24 (PowerPC) processor (revision C0) with 65526K/8192K
> bytes of m
> emory.
> Processor board ID CAT0613Z07D
> Last reset from warm-reset
> Bridging software.
> Running Layer2/3 Switching Image
>
> Ethernet-controller 1 has 12 Fast Ethernet/IEEE 802.3 interfaces
>
> Ethernet-controller 2 has 12 Fast Ethernet/IEEE 802.3 interfaces
>
> Ethernet-controller 3 has 1 Gigabit Ethernet/IEEE 802.3 interface
>
> Ethernet-controller 4 has 1 Gigabit Ethernet/IEEE 802.3 interface
>
> 24 FastEthernet/IEEE 802.3 interface(s)
> 2 Gigabit Ethernet/IEEE 802.3 interface(s)
>
> The password-recovery mechanism is enabled.
> 384K bytes of flash-simulated non-volatile configuration memory.
> Base ethernet MAC Address: 00:09:43:B4:24:00
> Motherboard assembly number: 73-5700-08
> Power supply part number: 34-0966-02
> Motherboard serial number: CAT0612062U
> Power supply serial number: LIT060500CK
> Model revision number: C0
> Motherboard revision number: B0
> Model number: WS-C3550-24-EMI
> System serial number: CAT0613Z07D
> Configuration register is 0x10F
>
> sw1#sh mac ma
> sw1#sh mac mac
> sw1#sh mac ?
> access-group MAC access-group
> address-table MAC forwarding table
>
> sw1#sh mac add
> sw1#sh mac address-table
> Mac Address Table
> ------------------------------------------
>
> Vlan Mac Address Type Ports
> ---- ----------- ---- -----
> All 0009.43b4.2400 STATIC CPU
> All 0009.43b4.2401 STATIC CPU
> All 0009.43b4.2402 STATIC CPU
> All 0009.43b4.2403 STATIC CPU
> All 0009.43b4.2404 STATIC CPU
> All 0009.43b4.2405 STATIC CPU
> All 0009.43b4.2406 STATIC CPU
> All 0009.43b4.2407 STATIC CPU
> All 0009.43b4.2408 STATIC CPU
> All 0009.43b4.2409 STATIC CPU
> All 0009.43b4.240a STATIC CPU
> All 0009.43b4.240b STATIC CPU
> All 0009.43b4.240c STATIC CPU
> All 0009.43b4.240d STATIC CPU
> All 0009.43b4.240e STATIC CPU
> All 0009.43b4.240f STATIC CPU
> All 0009.43b4.2410 STATIC CPU
> All 0009.43b4.2411 STATIC CPU
>
>
>
> -----Original Message-----
> From: nobody@groupstudy.com [mailto:nobody@groupstudy.com] On Behalf Of
> ccie2be
> Sent: Monday, March 03, 2003 5:48 PM
> To: Group Study; boby2kusa
> Subject: Re: 3550 & DHCP
>
>
> Hi,
>
> Thanks for responding to my question. However, another person wrote
> that I should just do a "show version" and use that "base" mac address.
> Is that ever true? Sometimes true? or never true?
>
> Also, according to the 3550 config guide, the 3550 switch will
> automatically generate a DHCP request upon bootup if a config file isn't
> present. Although it didn't say anything about this, my assumption is
> that if there isn't any config file, then there's only the default vlan,
> and all interfaces are in their default state (whatever that is). Is
> that true? And, if so, what mac address do I use? Is it possible that
> there's more than 1 mac address that will work for this purpose?
>
> Also, suppose you're deploying a new Cat 3550 to a network that is using
> DHCP but you don't want the 3550 to use DHCP. What do you do then? Do
> you 1st have to config the 3550 before connecting it do the network?
>
> The config guide isn't very clear about the sequence. I'm not sure
> whether the switch will go into the set up program first or request data
> from a DHCP server.
>
> BTW, please forgive me for all these questions - I don't have a 3550 to
> test these different things.
>
> Thanks for your help. Jim
>
>
> ----- Original Message -----
> From: "boby2kusa" <boby2kusa@hotmail.com>
> To: "'ccie2be'" <ccie2be@nyc.rr.com>; "'Group Study'"
> <ccielab@groupstudy.com>
> Sent: Monday, March 03, 2003 7:51 PM
> Subject: RE: 3550 & DHCP
>
>
> > It depends, which interface will be getting the ip address through the
>
> > DHCP? If it's the SVI interface then show int vlan #, if it's a
> > physical interface that is configured to be layer 3 interface then
> > show int fa #/#. These outputs have layer 2 bia.
> >
> >
> >
> > -----Original Message-----
> > From: nobody@groupstudy.com [mailto:nobody@groupstudy.com] On Behalf
> > Of ccie2be
> > Sent: Monday, March 03, 2003 3:06 PM
> > To: Group Study
> > Subject: 3550 & DHCP
> >
> >
> > Hi,
> >
> > It just occurred to me as I was going thru the 3550 config guide that
> > since DHCP can be used to assign the 3550's mgmt IP address as well as
>
> > other info, it's necessary to know how to find the 3550's mac address
> > to set up the DHCP server. So, here's my question, what mac address
> > should be used for this and where can I find it?
> >
> > Thanks, Jim
This archive was generated by hypermail 2.1.4 : Sat Apr 05 2003 - 08:51:32 GMT-3