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PXE with DHCP Issues - 7600 Router to 3650 Switches with VLANs

ElikCyber
Level 1
Level 1

Hello folks,

   I figures i post on here to pick on your brains to see if there is a solution to the problem I am having.  Basically, I have setup the PXE server that is located on 3650G Switch, and it is under VLAN10 which is on the private LAN network of 10.1.1.0.  However, the issue I found is that while hte VLAN10 is default network thoughout the network with additional VLANs on it, it seems the forwarding is not enabled til around 38 to 45 seconds later, which is pretty too long for the PXE to initialize on the server to access the DHCP and then fetch the bootloader.  One note, I did searched though the previous discussions and none of whwt I found have worked so far on resolving the issue I am facing here for it.  Plus, the VLAN 199 is able to ping and access Ips on VLAN10 which is set for PXE environment.

    Here is the setup I have from the CIsco 7600 with Upstream Routes and BGP information removed along few other sections:

ATLcore7609-01#show running-config

Building configuration...

Current configuration : 12896 bytes

!

! Last configuration change at 23:35:20 EDT Thu Oct 13 2011 by russ

! NVRAM config last updated at 16:19:09 EDT Wed Oct 5 2011 by cterry

!

version 12.2

service timestamps debug datetime localtime

service timestamps log datetime localtime

service password-encryption

service counters max age 10

!

hostname ATLcore7609-01

!

boot-start-marker

boot-end-marker

!

no aaa new-model

!

!

!

clock timezone EST -5

clock summer-time EDT recurring

firewall module 7 vlan-group 8,10,199

firewall vlan-group 10  10

ip source-route

!

!

no ip domain lookup

ip domain name micfo.com

ip dhcp smart-relay

ip dhcp excluded-address 10.1.1.1 10.1.1.200

!

ip dhcp pool PXE-VLAN

   network 10.1.1.0 255.255.255.0

   bootfile pxelinux.0

   next-server 10.1.1.200

   domain-name micfo.com

   default-router 10.1.1.1

   dns-server 10.1.1.200

!

!

mls flow ip interface-full

no mls flow ipv6

mls cef error action reset

multilink bundle-name authenticated

!

!

spanning-tree mode pvst

spanning-tree extend system-id

!

!

vlan internal allocation policy ascending

vlan access-log ratelimit 2000

!

interface Loopback23

ip address 192.168.23.1 255.255.255.0

interface GigabitEthernet1/10

description RACK 2 SWITCH Giga 0/1

switchport

switchport trunk native vlan 10

switchport mode trunk

!

interface GigabitEthernet1/11

description RACK 2 SWITCH-PrivateLAN 0/1

switchport

switchport trunk native vlan 10

switchport mode trunk

!

!

interface Vlan1

no ip address

shutdown

!

!

interface Vlan10

ip dhcp relay information trusted

ip address 10.1.1.1 255.255.255.0

ip helper-address 10.1.1.200

interface Vlan199

description ARIN/Micfo

ip address 199.189.248.1 255.255.248.0

!

Switch 3650G - 2nd Rack

ATLtor2-3560#show running-config

Building configuration...

Current configuration : 7096 bytes

!

version 12.2

no service pad

service timestamps debug datetime localtime

service timestamps log datetime localtime

service password-encryption

!

hostname ATLtor2-3560

!

clock timezone EST -5

clock summer-time EDT recurring

system mtu routing 1500

ip subnet-zero

ip domain-name micfo.com

!

!

no file verify auto

spanning-tree mode pvst

spanning-tree extend system-id

!

vlan internal allocation policy ascending

!

!

interface FastEthernet0/1

switchport access vlan 8

switchport trunk native vlan 8

!

interface FastEthernet0/2

switchport access vlan 67

switchport trunk native vlan 67

!

interface FastEthernet0/3

switchport access vlan 67

switchport trunk native vlan 67

!

interface FastEthernet0/4

switchport access vlan 74

switchport trunk encapsulation dot1q

switchport trunk native vlan 74

switchport mode trunk

!

interface FastEthernet0/5

switchport access vlan 192

switchport trunk native vlan 192

!

interface FastEthernet0/6

switchport access vlan 199

switchport trunk native vlan 199

!

interface FastEthernet0/7

switchport access vlan 206

switchport trunk encapsulation dot1q

switchport trunk native vlan 206

switchport mode trunk

!

interface FastEthernet0/8

switchport access vlan 209

switchport trunk native vlan 209

!

interface FastEthernet0/9

switchport access vlan 210

switchport trunk native vlan 210

!

interface FastEthernet0/10

switchport access vlan 210

switchport trunk native vlan 210

!

interface FastEthernet0/11

switchport access vlan 75

switchport trunk encapsulation dot1q

switchport trunk native vlan 75

switchport mode trunk

!

interface FastEthernet0/12

switchport access vlan 207

switchport trunk encapsulation dot1q

switchport trunk native vlan 207

switchport mode trunk

!

interface FastEthernet0/13

switchport access vlan 208

switchport trunk encapsulation dot1q

switchport trunk native vlan 208

switchport mode trunk

!

interface FastEthernet0/14

switchport access vlan 216

switchport trunk native vlan 216

!

interface FastEthernet0/15

switchport access vlan 199

switchport trunk native vlan 199

!

interface FastEthernet0/16

switchport access vlan 199

switchport trunk native vlan 199

!

interface FastEthernet0/17

switchport access vlan 199

switchport trunk native vlan 199

!

interface FastEthernet0/18

switchport access vlan 199

switchport trunk native vlan 199

!

interface FastEthernet0/19

switchport access vlan 199

switchport trunk native vlan 199

!

interface FastEthernet0/20

switchport access vlan 199

switchport trunk native vlan 199

!

interface FastEthernet0/21

switchport access vlan 199

switchport trunk native vlan 199

!

interface FastEthernet0/22

switchport access vlan 10

!

interface FastEthernet0/23

switchport access vlan 10

!

interface FastEthernet0/24

switchport access vlan 10

!

interface FastEthernet0/25

switchport access vlan 10

!

interface FastEthernet0/26

switchport access vlan 10

!

interface FastEthernet0/27

switchport access vlan 10

!

interface FastEthernet0/28

switchport access vlan 10

!

interface FastEthernet0/29

switchport access vlan 10

!

interface FastEthernet0/30

switchport access vlan 10

!

interface FastEthernet0/31

switchport access vlan 10

!

interface FastEthernet0/32

switchport access vlan 10

!

interface FastEthernet0/33

switchport access vlan 10

!

interface FastEthernet0/34

switchport access vlan 10

!

interface FastEthernet0/35

switchport access vlan 10

!

interface FastEthernet0/36

switchport access vlan 10

!

interface FastEthernet0/37

switchport access vlan 10

!

interface FastEthernet0/38

switchport access vlan 10

!

interface FastEthernet0/39

switchport access vlan 10

!

interface FastEthernet0/40

switchport access vlan 10

!

interface FastEthernet0/41

switchport access vlan 10

!

interface FastEthernet0/42

switchport access vlan 10

!

interface FastEthernet0/43

switchport access vlan 10

!

interface FastEthernet0/44

switchport access vlan 10

!

interface FastEthernet0/45

switchport access vlan 10

!

interface FastEthernet0/46

switchport access vlan 10

!

interface FastEthernet0/47

switchport access vlan 199

!

interface FastEthernet0/48

switchport access vlan 199

!

interface GigabitEthernet0/1

switchport trunk encapsulation dot1q

switchport trunk native vlan 10

switchport mode trunk

!

interface GigabitEthernet0/2

!

interface GigabitEthernet0/3

!

interface GigabitEthernet0/4

!

interface Vlan1

no ip address

!

interface Vlan10

ip dhcp relay information trusted

ip address 10.1.1.12 255.255.255.0

ip helper-address 10.1.1.200

!

ip default-gateway 10.1.1.1

ip classless

ip http server

ip http secure-server

end

ATLtor2-3560#

When I tested it with other switch with nohting configured on it as far VLAN or anything else, just straight dumb switch, it was able to boot by PXE quickly without any problems.  Just it seems that from Router's DHCP or by Linux/WIndows DHCP over the VLAN10/VLAN199, it does not pick it up at all due to port forwarding not enabled in time for the server to get the DHCP Welcome message to start booting.


So is there any solution on this problem here, since I read somehwere that it might be due to Spanning Tree issue and the long initializion for port to be initialized when it detect connection.

4 Replies 4

Reza Sharifi
Hall of Fame
Hall of Fame

Hi,

So, the PIX server is in vlan 10, and the PIX clients are in vlan 199?

What happens when you put both clients are server in the same vlan?

If I remember corretly, the clients and server have to be in the same subnet

HTH

Hello,

  It is not blocked as far the DHCP is concerned, or even across the VLANs itself.  Just when the server is booted up, it have 20 seconds to get the DHCP response, to connect and fetch the boot file.  However, it seems that from what I can tell, the port don't seems to be activated and active when the server is booted up til around 38 to 45 seconds later, which is beyond the PXE Boot up time period.

kunkelta
Level 1
Level 1

It sounds like you do not have portfast enabled on your server ports. You will get a 40 second or so delay if you don't enable portfast on the ports.

Sent from Cisco Technical Support iPhone App

Hello,

  Thanks.  With that comment, plus few others, I am able to get it working properly now.  I had to add few lines to the ports on the 3650G to have it reduced down to 10 secs for DHCP bootup with this configuration:

interface FastEthernet0/22

switchport access vlan 10

switchport mode access

switchport nonegotiate

spanning-tree portfast

   Since I found out that having DTP enabled caused the delay along with the no setting of portfast.  So after setting the switchport mode access and then switchport nonegotiate and then spanning-tree portfast, it works properly as it should be for it.  Thanks guys for all the help here.  I appreciate it.