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New Member

BOOTP/DHCP Printers Connected to Cataylst 4000 Series Sup II

I have an issue with printers connected to a newly placed Catalyst 4006 with SUP II. We also have PC's and IP Phones connected to this same switch and they have no issue getting DHCP to work. Printers however that are set to use BOOTP/DHCP are not able to renew or get address assignments after putting in this switch.

Here is the basic config:


set system name LAF-SWITCH


#frame distribution method

set port channel all distribution mac both



set snmp community read-only routers##

set snmp community read-write routers++



set vtp domain TSG

set vtp mode client



set interface sc0 1

set interface sl0 down

set interface me1 down

set ip route



set ip dns server primary

set ip dns server

set ip dns domain




set spantree backbonefast enable

#vlan <VlanId>

set spantree priority 28672 1

set spantree priority 28672 2

set spantree fwddelay 15 1003

set spantree maxage 20 1003

set spantree priority 28672 1003



set logging level cops 2 default



set ntp client enable

set ntp server

set timezone CST -6 0

set summertime enable


#set boot command

set boot config-register 0x2102

set boot system flash bootflash:cat4000.6-3-5.bin


#module 1 : 2-port 1000BaseX Supervisor

set port name 1/1 LAF-4503-M

set port name 1/2 LAF-3550-S3

set trunk 1/1 on dot1q 1-1005

set trunk 1/2 on dot1q 1-1005

This is pretty pressing and urgent and any help would be appreciated.

New Member

Re: BOOTP/DHCP Printers Connected to Cataylst 4000 Series Sup II

it seems that the printers are not negotiating with the catalyst4006 switch. see the port speeds.


New Member

Re: BOOTP/DHCP Printers Connected to Cataylst 4000 Series Sup II

I'd bet your problem is due to the fact that a switch unlike a hub does a span tree check before allowing packets to enter the port. This by default takes 60 Sec. So when a PC/Printer/Whatever is connected to the switch the switch will not pass it's packets for 60 sec's by default. On most Cisco switches this is shown with an Amber color LED on the switch port.

Novell used to have major problmes with this and so did Vines. You can fix this delay by enabling portfast on the switch ports.

What portfast does is delays the spantree blocking of the port and runs the loop check later. Thus allowing every packet from the first to the last thought the port.

There is a major thing to remember here. When enabling portfast you could bring down your network if you create a loop. spanning tree protects from having loops. when you say portfast enable you've opened your self up for loops and therefore you could take down your network.

Portfast will run spantree later and block the port if a loop is found. but by that time it could be 2 late.

you'll only want to do this on the ports your printer are connected to. Lets say your printers are on ports 2/22 and 3/22...

never do this on ports where 2 switches are connected together.

here's the commands to enable portfast..

set spantree portfast 2/22 enable

set spantree portfast 3/22 enable

or i think this would work

set spantree portfast 2/22,3/22 enable


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