12-13-2023 02:52 AM - edited 12-13-2023 02:53 AM
I am having an issue that does not look uncommon for 4331's
We have taken over a circuit in an office and this circuit will connect fine to other types of router or modem.
They will pick up the dhcp but perminent assigned IP address with no issue, as they are both different makes of box I assume the ISP is somehow just sending the single dhcp IP down this circuit and not statically assigning it in their DHCP server to a mac address
The only thing the remote tech told me is that they have to set the WAN as VLAN 20.
I have tried both as gig0/0/0 and 0/0/0.10 with dot1q encap
I have just a really basic config on the router right now, just enough to try and bring up the WAN
!
interface GigabitEthernet0/0/0
ip address dhcp
negotiation auto
!
ip route 0.0.0.0 0.0.0.0 dhcp
!
I have also tried with 'access-list 101 permit udp any any eq bootpc' applied to the interface
*Dec 13 11:04:39.676: DHCP: Waiting for 60 seconds on interface GigabitEthernet0/0/0
*Dec 13 11:05:10.247: DHCP: QScan: Purging entry
*Dec 13 11:05:10.247: DHCP: deleting entry 7F7DCD47F840 0.0.0.0 from list
*Dec 13 11:05:10.247: Temp IP addr: 0.0.0.0 for peer on Interface: GigabitEthernet0/0/0
*Dec 13 11:05:10.247: Temp sub net mask: 0.0.0.0
*Dec 13 11:05:10.247: DHCP Lease server: 0.0.0.0, state: 10 Purging
*Dec 13 11:05:10.247: DHCP transaction id: 10
*Dec 13 11:05:10.247: Lease: 0 secs, Renewal: 0 secs, Rebind: 0 secs
*Dec 13 11:05:10.247: No timer running
*Dec 13 11:05:10.247: Retry count: 0 Client-ID: cisco-00aa.6ea7.3b00-Gi0/0/0
*Dec 13 11:05:10.247: Client-ID hex dump: 636973636F2D303061612E366561372E
*Dec 13 11:05:10.247: 336230302D4769302F302F30
*Dec 13 11:05:39.676: DHCP: Try 15 to acquire address for GigabitEthernet0/0/0
*Dec 13 11:05:39.679: DHCP: No configured hostname - not including Hostname option
*Dec 13 11:05:39.679: DHCP: allocate request
*Dec 13 11:05:39.679: DHCP: new entry. add to queue
*Dec 13 11:05:39.679: DHCP: SDiscover attempt # 1 for entry:
*Dec 13 11:05:39.679: Temp IP addr: 0.0.0.0 for peer on Interface: GigabitEthernet0/0/0
*Dec 13 11:05:39.679: Temp sub net mask: 0.0.0.0
*Dec 13 11:05:39.679: DHCP Lease server: 0.0.0.0, state: 3 Selecting
*Dec 13 11:05:39.679: DHCP transaction id: 11
*Dec 13 11:05:39.679: Lease: 0 secs, Renewal: 0 secs, Rebind: 0 secs
*Dec 13 11:05:39.679: Next timer fires after: 00:00:04
*Dec 13 11:05:39.679: Retry count: 1 Client-ID: cisco-00aa.6ea7.3b00-Gi0/0/0
*Dec 13 11:05:39.679: Client-ID hex dump: 636973636F2D303061612E366561372E
*Dec 13 11:05:39.679: 336230302D4769302F302F30
*Dec 13 11:05:39.679: DHCP: SDiscover placed class-id option: 636973636F706E70
*Dec 13 11:05:39.680: DHCP: SDiscover: sending 299 byte length DHCP packet
*Dec 13 11:05:39.680: DHCP: SDiscover 299 bytes
*Dec 13 11:05:39.680: B'cast on GigabitEthernet0/0/0 interface from 0.0.0.0
*Dec 13 11:05:43.258: DHCP: SDiscover attempt # 2 for entry:
*Dec 13 11:05:43.258: Temp IP addr: 0.0.0.0 for peer on Interface: GigabitEthernet0/0/0
*Dec 13 11:05:43.258: Temp sub net mask: 0.0.0.0
*Dec 13 11:05:43.258: DHCP Lease server: 0.0.0.0, state: 3 Selecting
*Dec 13 11:05:43.258: DHCP transaction id: 11
*Dec 13 11:05:43.258: Lease: 0 secs, Renewal: 0 secs, Rebind: 0 secs
*Dec 13 11:05:43.258: Next timer fires after: 00:00:04
*Dec 13 11:05:43.258: Retry count: 2 Client-ID: cisco-00aa.6ea7.3b00-Gi0/0/0
*Dec 13 11:05:43.258: Client-ID hex dump: 636973636F2D303061612E366561372E
*Dec 13 11:05:43.258: 336230302D4769302F302F30
*Dec 13 11:05:43.258: DHCP: SDiscover placed class-id option: 636973636F706E70
*Dec 13 11:05:43.259: DHCP: SDiscover: sending 299 byte length DHCP packet
*Dec 13 11:05:43.259: DHCP: SDiscover 299 bytes
*Dec 13 11:05:43.259: B'cast on GigabitEthernet0/0/0 interface from 0.0.0.0
*Dec 13 11:05:47.262: DHCP: SDiscover attempt # 3 for entry:
*Dec 13 11:05:47.262: Temp IP addr: 0.0.0.0 for peer on Interface: GigabitEthernet0/0/0
*Dec 13 11:05:47.262: Temp sub net mask: 0.0.0.0
*Dec 13 11:05:47.262: DHCP Lease server: 0.0.0.0, state: 3 Selecting
*Dec 13 11:05:47.262: DHCP transaction id: 11
*Dec 13 11:05:47.262: Lease: 0 secs, Renewal: 0 secs, Rebind: 0 secs
*Dec 13 11:05:47.262: Next timer fires after: 00:00:04
*Dec 13 11:05:47.262: Retry count: 3 Client-ID: cisco-00aa.6ea7.3b00-Gi0/0/0
*Dec 13 11:05:47.262: Client-ID hex dump: 636973636F2D303061612E366561372E
*Dec 13 11:05:47.262: 336230302D4769302F302F30
*Dec 13 11:05:47.263: DHCP: SDiscover placed class-id option: 636973636F706E70
*Dec 13 11:05:47.263: DHCP: SDiscover: sending 299 byte length DHCP packet
*Dec 13 11:05:47.263: DHCP: SDiscover 299 bytes
*Dec 13 11:05:47.263: B'cast on GigabitEthernet0/0/0 interface from 0.0.0.0
*Dec 13 11:05:51.265: DHCP: QScan: Timed out Selecting state%Unknown DHCP problem.. No allocation possible
12-13-2023 03:02 AM - edited 12-13-2023 03:03 AM
Interface g0/0/0.20
encap dot1q 20 <- if it SP need vlan 20 tag
Ip add dhcp
Then
Interface g0/0/0
No shut
That sould work
MHM
12-13-2023 03:04 AM - edited 12-13-2023 03:05 AM
Hello @Richard Tapp
Ensure that the VLAN configuration on the router matches the VLAN configuration expected by the ISP. Since the remote tech mentioned setting the WAN as VLAN 20, make sure the VLAN configuration is correct.
This assumes VLAN 20 is the correct VLAN for your WAN.
12-13-2023 03:42 AM
First i would connect my Laptop and check is the ISP able to give IP addressto PC and woking as expected before i configured on the router, once PC working i make a note of IP address - so we know ISP able to give IP address to PC.
If ISP says VLAN 20 then you should follow once PC testing done (so this will save time)
I have tried both as gig0/0/0 and 0/0/0.10 with dot1q encap - you have not tagged to VLAN 20, that may be reason that failing, try below tagging with VLAN 20 (Hope that should work ?)
interface GigabitEthernet0/0/0
no ip address
no shutdown
!
interface GigabitEthernet0/0/0.20
ip address dhcp
encapsulation dot1q 20
no shutdown
12-15-2023 02:15 AM
I got this to work with gig0/0/0.10 and an access-group that allowed bootpc in then end
12-15-2023 02:20 AM
I totally forget there is two parts of dhcp bootpc and bootps
You need to allow both
permit udp any eq bootpc any eq bootps
MHM
12-15-2023 03:16 AM
Good to know you able to resolve the issue.
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