Hey Guys,
I've been a member of Cisco for a long time, but have yet to use the forums. I've used other networking forums where I would provide help, but no-one would help me when I had an issue. My Goal is to give just as much as I take. Hopefully I can make Cisco forums my home!
Now for my problem! On my home network I'm trying to get DHCP snooping to work correctly. The network clients are able to receive addresses from the DHCP server (3640 Router) and access resources and search the internet with no problem , but the DHCP snooping database bindings are not being entered (In 3550 with Layer 3 disabled). I need them to be entered to be able to utilize DAI and ISG. What is going on? I think it may be because my router is the DHCP server, and the database is not being passed on to the switch. How would I be able to accomplish this? I know if I were to move the DHCP configuration from the router to the switch it would work, but I don't want to go down the simple route and ignore problems that I come across.
Relevant configuration is as below:
Switch:
ip dhcp snooping vlan 100,200,300
ip dhcp snooping
LAN_SWITCH#show cdp neighbors
Capability Codes: R - Router, T - Trans Bridge, B - Source Route Bridge
S - Switch, H - Host, I - IGMP, r - Repeater, P - Phone
Device ID Local Interface Holdtme Capability Platform Port ID
Mckibbin_LAN.Daniels_Wireless Fas 0/2 165 T AIR-AP350 Fas 0
Internet_Router Fas 0/1 128 R S I 3640-A Eth 1/1
interface FastEthernet0/2
switchport trunk encapsulation dot1q
switchport trunk allowed vlan 100,200,300
switchport mode trunk
spanning-tree portfast trunk
ip dhcp snooping trust
!
interface FastEthernet0/1
switchport trunk encapsulation dot1q
switchport trunk allowed vlan 100,200,300
switchport mode trunk
duplex full
ip dhcp snooping trust
end
The routers interface is set up for router on a stick with subinterfaces for each vlan.
Router
no ip dhcp use vrf connected
ip dhcp excluded-address 172.16.1.1
ip dhcp excluded-address 172.16.2.2
ip dhcp excluded-address 172.16.1.33
ip dhcp excluded-address 172.16.1.2
ip dhcp excluded-address 172.16.1.3
ip dhcp excluded-address 172.16.1.4
!
ip dhcp pool wireless
import all
network 172.16.1.0 255.255.255.224
default-router 172.16.1.1
domain-name Daniels_Wireless
!
ip dhcp pool wired
import all
network 172.16.1.32 255.255.255.224
default-router 172.16.1.33
domain-name Daniels_Wired
!
Debug Output From Switch:
*Mar 7 16:44:11.932: DHCPSN: Found ingress pkt on Fa0/2 VLAN 200
*Mar 7 16:44:11.932: DHCPSN: DHCP packet being sent to PI snooping process
*Mar 7 16:44:11.932: DHCP_SNOOPING: received new DHCP packet from input interfa
ce (FastEthernet0/2)
*Mar 7 16:44:11.932: DHCP_SNOOPING: process new DHCP packet, message type: DHCP
REQUEST, input interface: Fa0/2, MAC da: 000d.28e2.c692, MAC sa: 4c0f.6e8f.a311,
IP da: 172.16.1.1, IP sa: 172.16.1.9, DHCP ciaddr: 172.16.1.9, DHCP yiaddr: 0.0
.0.0, DHCP siaddr: 0.0.0.0, DHCP giaddr: 0.0.0.0, DHCP chaddr: 4c0f.6e8f.a311
*Mar 7 16:44:11.932: DHCP_SNOOPING_SW: bridge packet send packet to port: FastE
thernet0/1, vlan 200.
*Mar 7 16:44:11.940: DHCPSN: Found ingress pkt on Fa0/1 VLAN 200
*Mar 7 16:44:11.940: DHCPSN: DHCP packet being sent to PI snooping process
*Mar 7 16:44:11.940: DHCP_SNOOPING: received new DHCP packet from input interfa
ce (FastEthernet0/1)
*Mar 7 16:44:11.940: DHCP_SNOOPING: process new DHCP packet, message type: DHCP
ACK, input interface: Fa0/1, MAC da: 4c0f.6e8f.a311, MAC sa: 000d.28e2.c692, IP
da: 172.16.1.9, IP sa: 172.16.1.1, DHCP ciaddr: 172.16.1.9, DHCP yiaddr: 172.16.
1.9, DHCP siaddr: 0.0.0.0, DHCP giaddr: 0.0.0.0, DHCP chaddr: 4c0f.6e8f.a311
*Mar 7 16:44:11.944: DHCP_SNOOPING: direct forward dhcp reply to output port: F
astEthernet0/2.
LAN_SWITCH#show ip dhcp snooping statistics
Packets Forwarded = 300
Packets Dropped = 1
Packets Dropped From untrusted ports = 0
LAN_SWITCH#
*Mar 7 16:48:49.364: DHCP_SNOOPING: checking expired snoop binding entries
LAN_SWITCH#show ip dhcp snooping b
LAN_SWITCH#show ip dhcp snooping binding
MacAddress IpAddress Lease(sec) Type VLAN Interface
------------------ --------------- ---------- ------------- ---- ----------
----------
Total number of bindings: 0
I would appreciate any help. Thanks!
Daniel M.
