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The NE40E IPoE Terminal Is Slow in Obtaining IP Addresses

Publication Date:  2019-07-03 Views:  193 Downloads:  0

Issue Description

Device model: NE40E-X8
Software version: V600R009C20SPC600
Symptom: An IPoE terminal is slow in obtaining IP addresses, taking over 20 minutes.


Handling Process

1.Log in to the NE40E to check the cause of the user online failure. It is found that the DCHP server times out in waiting for packets sent from DHCP clients.
https://support.huawei.com/enterprisecase/product/images/286a2a57cd394183bbfcffe55c91c5b4

2. Enable full message tracing on the terminal to analyze the tracing information.
Mar 13 2018 16:48:21.900.2 BTRC/7/BTRC_TraceInfo:[objectID=1][slotID=1][DHCPA][user info:
  MAC Address    : XXXX-XXXX-F00E
  Interface      : Eth-TrunkXX.XX41
  PE VLAN ID     : 2024
  CE VLAN ID     : 1171
  Access Mode    : IPoE ]
[trace info:
DHCPA receive a packet.
DHCPA receive a DISCOVER pkt 
---Discovery packets are received.
  ----
Mar 13 2018 16:48:21.900.14 BTRC/7/BTRC_TraceInfo:[objectID=1][slotID=0][AAA][user info:   
  MAC Address    : XXXX-XXXX-F00E
  IP Address     : 255.255.255.255 
  Interface      : Eth-TrunkXX.XX41
  PE VLAN ID     : 2024
  CE VLAN ID     : 1171
  User Name      : X-NE40E--01231202401171@X]
[trace info: User authentication success] 
---The authentication succeeds.
----

Mar 13 2018 16:48:21.900.30 BTRC/7/BTRC_TraceInfo:[objectID=1][slotID=0][AM][user info:
  MAC Address    : XXXX-XXXX-F00E
  IP Address     : 255.255.255.255 
  Interface      : Eth-TrunkXX.XX41
  PE VLAN ID     : 2024
  CE VLAN ID     : 1171
  User Name      : X-NE40E--01231202401171@X]
[trace info:
[AM]Allocate IP address for DHCPS successfully.] 
---The IP address is successfully allocated.
----

Mar 13 2018 16:48:21.900.40 BTRC/7/BTRC_TraceInfo:[objectID=1][slotID=0][DHCPACC][user info:  
  MAC Address    : XXXX-XXXX-F00E
  IP Address     : 10.46.4.47 
  Interface      : Eth-TrunkXX.XX41
  PE VLAN ID     : 2024
  CE VLAN ID     : 1171
  Access Mode    : IPoE 
  Circuit ID     : 0021F-1171-TRUNK 
  Remote ID      : huawei-0021F-1171-TRUNK ]
[trace info:
DHCPACC send a packet to client. 
---An Offer message is sent to the client.
DHCPACC proc a OFFER pkt
Giaddr:0A2E0001 Yiaddr:0A2E042F
DhcpaccIndex:244131, DhcpaIndex:65535, cib:254486, state:3(DHCPACC_DIS_WAIT_SERVER_OFFER), DownReason:255]

Mar 13 2018 16:48:24.890.2 BTRC/7/BTRC_TraceInfo:[objectID=1][slotID=1][DHCPA][user info:
  MAC Address    : XXXX-XXXX-F00E
  Interface      : Eth-TrunkXX.XX41
  PE VLAN ID     : 2024
  CE VLAN ID     : 1171
  Access Mode    : IPoE ]
[trace info:
DHCPA receive a packet.
DHCPA receive a DISCOVER pkt
----DHCP Request messages are not received from the client after 3s, and the user online fails. The client re-initiates the sending of DHCP Discovery messages, but the problem persists.

3. Mirror packets on the upstream and downstream interfaces on the S77. Connect the PC for packet header obtaining. Analyze the packet header obtaining information.
https://support.huawei.com/enterprisecase/product/images/6b158b9cab8b4538ab68c14143fb3f74
https://support.huawei.com/enterprisecase/product/images/b531348232ae4350994836ecc4e9533f
---DHCP Offer messages are obtained, and the MAC address of the client is correct. The dhcp-broadcast configuration exists on the BAS interface. Therefore, the DHCP Offer messages are broadcast packets.

4. Check the OLT. It is found that all the upstream interfaces on the OLT are configured with the broadcast suppression level of 3.
https://support.huawei.com/enterprisecase/product/images/e889c43d758841879235183f105f28a6
---All the broadcast packets can be transmitted at a minimum rate of 24 kbps and a maximum rate of 48 pps. The upstream broadcast packets on the NE40 are discarded frequently.

Root Cause

The dhcp-broadcast configuration on the BAS interface allows the device to send DHCP unicast packets as broadcast packets.
In addition, all the uplink interfaces on the OLT are configured with a broadcast suppression level of 3, allowing packets to be transmitted at a minimum rate of 24kbps and a maximum rate of 48 pps. The downstream broadcast packets on the NE40 are discarded frequently.

Solution

1.Run the following command on the OLT to change the broadcast suppression level of interfaces:
MA5680T-1(config-if-giu-0/19)#
MA5680T-1(config-if-giu-0/19)#traffic-suppress 
{ all<K>|portid<U><0,1> }:all 
{ broadcast<K>|multicast<K>|unicast<K> }:broadcast  
{ value<K> }:value  
{ value<L><1,13> }:7

  Command:
          traffic-suppress all broadcast  value  7

MA5680T-1(config-if-giu-0/19)#quit
MA5680T-1(config)#interface  giu  0/20
MA5680T-1(config-if-giu-0/20)#traffic-suppress all broadcast value 7
MA5680T-1(config-if-giu-0/20)#
MA5680T-1(config-if-giu-0/20)#
MA5680T-1(config-if-giu-0/20)#quit


2. Delete the dhcp-broadcast configuration from the BAS interface.

END