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AC6605 cannot deliver DHCP configs

Publication Date:  2018-03-06 Views:  109 Downloads:  0
Issue Description

Two AC6605 had configured with HSB VRRP and direct forwarding mode, however no DHCP configuration was sent to the STAs. The ACs are connected to a Switch and the AP are also connected to the same Switch.

 

Handling Process

Check Current configuration and diagnostic information of the AC.

 

DHCP server is external to the AC:

#

dhcp server group PSA-DHCP-SRV
dhcp-server 10.128.48.254 0

#

 

DHCP server was reachable through ping.

Verify that Service Vlan (448) is allowed  in Gi0/0/8 interface connected to switch

#

interface GigabitEthernet0/0/8
 description Uplink
 port link-type trunk
 undo port trunk allow-pass vlan 1
 port trunk allow-pass vlan 448 450 to 451

#

 

Check forwarding mode of the VAP profile:

 #

vap-profile name PPITOPS
forward-mode direct
service-vlan vlan-id 448

#

 

In AC the configuration is correct.

 

Check the Switch port connected to the AP

interface GigabitEthernet0/0/7
  port link-type trunk
 undo port trunk allow-pass vlan 1
 port trunk allow-pass vlan 448 450 to 451

 

Root Cause

DHCP information is delivered to STAs through Service VLAN (448). STAs are not able to process tagged frames (VLan tag).

pvid was not configured in the switch, pvid is used to define the default vlan of the port. The default vlan of a trunk port will have the vlan tag removed so end stations are able to process the frames.  

 

interface GigabitEthernet0/0/7
  port link-type trunk
 undo port trunk allow-pass vlan 1
 port trunk allow-pass vlan 448 450 to 451

 

 

Solution

Configure pvid to match the service VLAN  (448) and allow the frames from service vlan (448) to be forwarded without the vlan tag so STA can process such frames.

 

 <SwitchA>system view

[SwicthA]interface GigabitEthernet0/0/7

[SiwtchA-interface GigabitEthernet0/0/7]pvid 448

[SiwtchA-interface GigabitEthernet0/0/7]display this

interface GigabitEthernet0/0/7
 port link-type trunk
 undo port trunk allow-pass vlan 1

 pvid 448
 port trunk allow-pass vlan 448 450 to 451

 

 

 

END