12-14-2007 01:01 AM - edited 03-05-2019 08:00 PM
Hi,
I've got a question. I configured my cisco to give IP addresses automatically to other PC's on network. The problem is getting a new address or renewing takes a long of time. For example when I run my DHCP server on Linux then renewing and getting times of new addresses takes about few seconds. On Cisco it takes more than 20-30 seconds. Sometimes especially on OS's from Linux branch I've got timeouts and need to tune manually timeouts in dhcp-client.
Can I do something with it ? Are there any tips & tricks to tune dhcp server on Cisco ?
When I configure static IP for some PC's (f.e. servers) getting IP's times are the same.
p.s. Router is new and now it has basic configuration and for the present doesn`t have any ACL and firewall rules yet.
Solved! Go to Solution.
12-14-2007 12:49 PM
Is your dhcp client connected to a cisco switch? If so make sure port-fast is enabled on all ports that connect PCs. If this is not enabled their will be a delay until the DHCP discover packets are forwarded because the switchport is still going through all its STP timers.
12-14-2007 04:24 AM
Jaroslaw
Taking that long to assign DHCP addresses seems unusual. Perhaps a good place to start would be to post the entire config of the router so that we might see if there is some config reason that impacts operation of DHCP.
If that does not reveal the problem it might be helpful to run debug for DHCP and to post the debug output.
HTH
Rick
12-14-2007 05:04 AM
Hi, thank You for an answer.
Here is my entire running config.
hell#sh run
Building configuration...
Current configuration : 4032 bytes
!
version 12.4
service timestamps debug datetime msec
service timestamps log datetime msec
service password-encryption
!
hostname hell
!
boot-start-marker
boot-end-marker
!
logging buffered 51200 warnings
enable secret 5 xxxxxxxxxxxxxxxxx
!
no aaa new-model
!
!
ip cef
no ip dhcp use vrf connected
ip dhcp excluded-address 192.168.0.0
!
ip dhcp pool SERWER
host 192.168.0.10 255.255.255.0
hardware-address 001a.6449.a8d2
default-router 192.168.0.1
dns-server 192.168.1.1
!
ip dhcp pool LAN
network 192.168.0.0 255.255.255.0
dns-server 192.168.1.1
default-router 192.168.0.1
!
!
no ip domain lookup
!
multilink bundle-name authenticated
!
crypto pki trustpoint TP-self-signed-2576536838
enrollment selfsigned
subject-name cn=IOS-Self-Signed-Certificate-2576536838
revocation-check none
rsakeypair TP-self-signed-2576536838
!
!
crypto pki certificate chain TP-self-signed-2576536838
certificate self-signed 01
!!!!certificate here!!! quit
!
!
username xxxxxx privilege 15 secret 5 xxxxxxxxxxxxxx
!
!
!
!
!
!
interface FastEthernet0
ip address dhcp
ip nat outside
ip virtual-reassembly
duplex auto
speed auto
!
interface FastEthernet1
no ip address
shutdown
duplex auto
speed auto
!
interface BRI0
no ip address
encapsulation hdlc
shutdown
!
interface FastEthernet2
switchport access vlan 2
!
interface FastEthernet3
!
interface FastEthernet4
!
interface FastEthernet5
!
interface FastEthernet6
!
interface FastEthernet7
!
interface FastEthernet8
!
interface FastEthernet9
switchport access vlan 2
!
interface Vlan1
description $ETH-SW-LAUNCH$$INTF-INFO-FE 2$
ip address 10.10.10.1 255.255.255.248
ip tcp adjust-mss 1452
!
interface Vlan2
description LAN
ip address 192.168.0.1 255.255.255.0
ip nat inside
ip virtual-reassembly
!
ip route 0.0.0.0 0.0.0.0 192.168.1.1
ip route 192.168.0.0 255.255.255.0 Vlan2
ip route 192.168.1.0 255.255.255.0 FastEthernet0
!
!
ip http server
ip http access-class 23
ip http authentication local
ip http secure-server
ip http timeout-policy idle 60 life 86400 requests 10000
ip nat translation timeout 180
ip nat translation tcp-timeout 600
ip nat inside source list SIEC2NAT interface FastEthernet0 overload
!
ip access-list extended SIEC2NAT
permit ip 192.168.0.0 0.0.0.255 any
!
no cdp run
!
!
!
!
!
!
control-plane
!
banner login ^C
Sun Microsystem.
^C
!
line con 0
login local
line aux 0
line vty 0 4
access-class 23 in
privilege level 15
login local
transport input telnet ssh
line vty 5 15
access-class 23 in
privilege level 15
login local
transport input telnet ssh
!
end
12-14-2007 07:52 AM
Jaroslaw
Thank you for posting the config of the router. I do not see anything in it that would explain the delay in processing DHCP. Perhaps it would be helpful if your could run debug dhcp and debug ip dhcp server events and post the output.
HTH
Rick
12-14-2007 10:27 AM
The problem is the hostname on your router of 'hell.' Telling packets to go to 'hell' always causes an issue. Packets don't like to be told that...
Okay, seriously, like Rick said, post your debugs. :)
-brad
(please rate the post if this helps!)
12-14-2007 12:49 PM
Is your dhcp client connected to a cisco switch? If so make sure port-fast is enabled on all ports that connect PCs. If this is not enabled their will be a delay until the DHCP discover packets are forwarded because the switchport is still going through all its STP timers.
12-17-2007 12:37 AM
Hi,
I followed by your issues and the configuration shown below gives 100% success.
interface FastEthernet9
switchport access vlan 2
duplex full
speed 100
spanning-tree portfast
I specified also duplex mode and speed not to let router and PC negotiate that values. Now not many devices works on 10 MBits so the negotiation is not useful.
I have found an cisco webpage with manual where is described that kind of problem. I pasted it for anyone who would have a problem with it.
http://www.cisco.com/warp/public/473/12.html
Thanks anyone for help me :-).
Regards,
Jarek
p.s. ccbootcamp ;-)... yeah I wondered if that 'hell' hostname won`t be a problem and I had an idea to rename my router but I still belived that it can`t be a problem ;-). God loves us ;-).
12-17-2007 04:13 AM
Glad you fixed your prob. But I would still take a look at the debugs if I were you so you can understand what was happening with the packets a bit better. It's a great troubleshooting step you can utilize in the future. :)
-brad
(please rate the post if this helps!)
12-18-2007 04:52 AM
Hi :-).
I have watched on debug infos, but nothing special there I saw. Everything works fine for me now. I`m preparing device to work and we will see after new year how does it handle it on all PC's in company (about 60). If it won`t work I will not have time for play with it and will need to run alternate dhcp server on Linux until I will not find a problem.
Anyway I`m sure everything will work fine ;).
12-17-2007 07:46 AM
Jarek,
Not sure if you did this or not yet but:
I noticed that you hard coded the speed and duplex on the switch ports. In order to achieve maximum performance you'll have to hard code the speed and duplex on the workstations NIC's themselves or there will be a miss match.
Craig
12-18-2007 04:59 AM
Hmm.. I thought hard coding duplex mode and speed of switch port will give me maximum performance because when they will not need to negotiate that values but router enforces them to workstation, doesn't it ? The time should be shorter because negotiation process of that values will be hard coded. Anyway at the present NIC's don`t need to work in 10Mbps. The minimum value is 100Mbps.
From the other way to the swichport will be connected only server and the other switch which will connect all the other stations.
Regards,
Jarek
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