Pnp startup vlan problem

[JPvisltgb]

Hi All,

I have some problems regarding getting dhcp config for switch.

I have topology:  DHCP server (192.168.1.50) <-- GRE over IPsec--> Router  <--------> Switch.

Router config:

interface GigabitEthernet0/0/1.99

description Mgmt

encapsulation dot1Q 99

vrf forwarding VRF-NAME

ip address X.X.1.1 255.255.255.248

ip helper-address global 192.168.1.50

no ip redirects

no ip proxy-arp

pnp startup-vlan 99.

When switch booted Pnp creating configuration:

vlan 99

interface vlan 99

ip address dhcp

interface GigabitEthernet1/0/1

switchport access vlan 99

macro description CISCO_SMI_EVENT

Switch is not getting IP from DHCP.

I tried to configure dhcp server locally on router:

ip dhcp pool SW_Provisioning

vrf VRF

network XXX.XXX.1.0 255.255.255.248

default-router XXX.XXX.1.1

option 43 ascii "5A1N;B2;K4;IXXX.XXX.XXX.XXX;J80"

And got same result - fail.

Switch which I'm using is - 2960X Version 15.2(2)E6.

One thing that I'm aware of is that switchport access vlan 99 shouldn't be on the switch trunk port, it should be something like switchport mode trunk because router subinterface is tagged.

Any suggestions?

[aradford · Accepted solution]

Routers do not support DTP.

You will need to make vlan 99 the native vlan on the interface as the switch will be in access mode.

The reason it works differently if there was a switch up stream is that DTP creates a trunk dynamically.

Adam

[JPvisltgb]

I got it, thank you.

[JPvisltgb]

I changed router configuration :

interface GigabitEthernet0/0/1.99

description Mgmt

encapsulation dot1Q 99 native

vrf forwarding VRF-NAME

ip address X.X.1.1 255.255.255.248

ip helper-address global 192.168.1.50

no ip redirects

no ip proxy-arp

But after boot switch didn't get vlan 99 configuration.  It just got IP from DHCP to Vlan 1

Switch#show ip interface brief

Interface              IP-Address      OK? Method Status                Protocol

Vlan1                  XXX.XXX.1.5      YES DHCP   up                    up

[aradford]

sorry, I should have been clearer.

The way i do this on routers is

- remove the pnp  startup vlan

- configure the management vlan as native

this means the switch will connect via vlan1 on it's uplink and into vlan 99

In the config i download to the switch, I then "switchover" to shutdown vlan 1 (make sure you do this first) and enable vlan 99 on the switch with either a static or dynamic ip.

Gotcha-s.

- make sure you use VTP transparent so you can define vlan 99 in the config (or the vlan will not be present on a new switch)

- make sure you shut down vlan1 before creating and assigning vlan 99 otherwise you will have two interfaces with the same IP network

- make sure you add a default route if you use a static IP

Adam