DHCP and ambiguous VLANS

[mike-stevenson]

Hi,

I have an ASR9001 running 5.1.3.  is it possible to configure an interface using "encapsulation ambiguous dot1q any second any" , and have DHCP requests forwarded to a DHCP server.

I have a need where I have a large number of DHCP clients that do not need to be authenticated/accounted etc, but are delivered on random QinQ combinations.  I would like to treat these clients as straight dhcp clients vs. BNG (i.e. licensed) clients.

I have configured up 

dhcp ipv4

profile VOICE proxy
  class DHCP-loopback203
   helper-address vrf voice 10.10.10.1 giaddr 10.203.0.1
   helper-address vrf voice 10.10.10.2 giaddr 10.203.0.1

interface Bundle-Ether203.1 proxy profile VOICE

interface Bundle-Ether203.1
 vrf voice
 ipv4 point-to-point
 ipv4 unnumbered Loopback203
 encapsulation ambiguous dot1q any second-dot1q any

I can see the DHCP request coming in, however the debug dhcp proxy says that the discovery packets are being dropped.

RP/0/RSP0/CPU0:Oct 30 11:41:19.893 : dhcpd[1082]: DHCPD PROXY: TP1955: FSM called for chaddr d054.2d69.d16f with event PACKET_DISCOVER state INIT
RP/0/RSP0/CPU0:Oct 30 11:41:19.893 : dhcpd[1082]: DHCPD PROXY: TP1903: Process packet event in INIT state called for chaddr d054.2d69.d16f
RP/0/RSP0/CPU0:Oct 30 11:41:19.894 : dhcpd[1082]: DHCPD PROXY: TP1955: FSM called for chaddr d054.2d69.d16f with event DPM_SUCCESS state INIT_DPM_WAIT
RP/0/RSP0/CPU0:Oct 30 11:41:19.894 : dhcpd[1082]: DHCPD PROXY: TP1665: Proxy process client request packet failed for chaddr d054.2d69.d16f
RP/0/RSP0/CPU0:Oct 30 11:41:19.894 : dhcpd[1082]: DHCPD PROXY: TP2739: Dropping DISCOVER for d054.2d69.d16f received on ambiguous VLAN interface for standalone proxy

Any help would be appreciated.  If i have to use a BNG license for each of these clients, my 32K sessions will be effectively halved..

many thanks

[xthuijs]

hi mike,

yeah you need a BNG configuration also in order to use the amb vlans for dhcp proxy.

the bng piece of it keeps track of the vlan combo and helps dhcp to provide the proper

encapsulation when the dhcp messages are sent back and forth.

For that, you'll need the bng pie, and subscriber control policy configuration and bng is indeed a licensed feature...

regards

xander

[manoj.karmacharya]

Failed to enable ambiguous VLAN on interface Gi0/0/0/1. Configured BNG in the following way:

RP/0/RP0/CPU0:vBNG#show configuration running-config interface GigabitEthernet 0/0/0/1

Mon Aug 20 15:27:46.431 UTC

interface GigabitEthernet0/0/0/1

 ipv4 point-to-point

 ipv4 unnumbered Loopback1

 arp learning disable

 service-policy type control subscriber IPSUBSCRIBER

 ipsubscriber ipv4 l2-connected

  initiator dhcp

 !

!

policy-map type control subscriber IPSUBSCRIBER

 event session-start match-first

  class type control subscriber DHCPv4 do-until-failure

   10 activate dynamic-template IPSUBSCRIBER

   20 authorize aaa list default format USERNAME password cisco

  ! 

 ! 

 end-policy-map

! 

class-map type control subscriber match-any DHCPv4

 match protocol dhcpv4 

 end-class-map

! 

dhcp ipv4

 profile DHCP-SERVER server

  lease 0 0 10

  pool IPv4-POOL-01

  dns-server 192.168.6.60

 !

 interface GigabitEthernet0/0/0/1 server profile DHCP-SERVER

!

pool vrf default ipv4 IPv4-POOL-01

 network 10.10.37.0/24 default-router 10.10.37.1

!