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The BFD Session Set up Between an NE40E and a Non-Huawei Device Fails to Go Up Because the Non-Huawei Device Sends BFD P

Publication Date:  2013-01-08 Views:  39 Downloads:  0
Issue Description

An NE40E running V600R003 is connected to a device from Z supplier using the External Border Gateway Protocol (EGBP). The EBGP neighbor relationship is established between the two devices. However, after a BFD session is set up to monitor the EBGP neighbor relationship, the BFD session cannot go Up.

Handling Process

1.         The on-site Huawei technical support personnel check the configuration on the NE40E and find no fault. An example configuration is shown as follows.

[NE40E-bgp]dis this

#

bgp 64606

 router-id 110.89.224.2

 timer keepalive 30 hold 90

 group CMS external

 peer CMS as-number 65130

 peer CMS ebgp-max-hop 2

 peer CMS connect-interface LoopBack0

 peer CMS bfd min-tx-interval 150 min-rx-interval 150

 peer CMS bfd enable

 peer CMS password cipher %$%,_A%GUK@terminal debugging

2.         Then they enable the debugging function of BFD on the NE40E (If the interval at which BFD packets are sent is very short, the time for debugging is also very short). They find that the NE40E sends BFD packets only. The following example shows the debugging information on the NE40E.

debugging bfd packet:

Aug 28 2012 16:31:18.830.1 NE40E BFD/7/Packet:Slot=4;

 16:04614: Send BFD Packet :

TTL(253) DstPort(3784)

Ver(1) Diag(0) State(1) P(0) F(0) C(0) A(0) D(0) R(0)

Detect Mult(3) Length(24) My Discr(8219) Your Discr(0)

Min TX Interval(14500) Min RX Interval(14500) Min Echo RX Interval(0)

Aug 28 2012 16:31:33.460.1 NE40E BFD/7/Packet:Slot=4;

 16:04614: Send BFD Packet :

TTL(253) DstPort(3784)

Ver(1) Diag(0) State(1) P(0) F(0) C(0) A(0) D(0) R(0)

Detect Mult(3) Length(24) My Discr(8219) Your Discr(0)

Min TX Interval(14500) Min RX Interval(14500) Min Echo RX Interval(0)

Aug 28 2012 16:31:47.930.1 NE40E BFD/7/Packet:Slot=4;

 16:04614: Send BFD Packet :

TTL(253) DstPort(3784)

Ver(1) Diag(0) State(1) P(0) F(0) C(0) A(0) D(0) R(0)

Detect Mult(3) Length(24) My Discr(8219) Your Discr(0)

Min TX Interval(14500) Min RX Interval(14500) Min Echo RX Interval(0)

Aug 28 2012 16:32:02.530.1 NE40E BFD/7/Packet:Slot=4;

 16:04614: Send BFD Packet :

TTL(253) DstPort(3784)

Ver(1) Diag(0) State(1) P(0) F(0) C(0) A(0) D(0) R(0)

Detect Mult(3) Length(24) My Discr(8219) Your Discr(0)

Min TX Interval(14500) Min RX Interval(14500) Min Echo RX Interval(0)

Aug 28 2012 16:32:17.50.1 NE40E BFD/7/Packet:Slot=4;

 16:04614: Send BFD Packet :

TTL(253) DstPort(3784)

Ver(1) Diag(0) State(1) P(0) F(0) C(0) A(0) D(0) R(0)

Detect Mult(3) Length(24) My Discr(8219) Your Discr(0)

Min TX Interval(14500) Min RX Interval(14500) Min Echo RX Interval(0)

Aug 28 2012 16:32:31.650.1 NE40E BFD/7/Packet:Slot=4;

 16:04614: Send BFD Packet :

TTL(253) DstPort(3784)

Ver(1) Diag(0) State(1) P(0) F(0) C(0) A(0) D(0) R(0)

Detect Mult(3) Length(24) My Discr(8219) Your Discr(0)

Min TX Interval(14500) Min RX Interval(14500) Min Echo RX Interval(0)

3.         Based on the debugging information, the NE40E sends BFD packets but does not receive the BFD packets from the non-Huawei device.

When the BFD session is Down, a BFD packet is sent every 10 to 15s. The interval at which the BFD packets are transmitted is 14500 ms as shown in the preceding debugging information, which is proper. This indicates that the interval at which BFD packets are sent may not be a configured value, but a randomly assigned value ranging from 10000 to 15000 (in milliseconds) when the BFD session is Down. The subsequent negotiation of the BFD session status uses the configured interval.

4.         Based on the symptoms of the problem, the non-Huawei device fails to send BFD packets as expected.

Root Cause

The cause for the problem lies in that the non-Huawei device cannot send the BFD packets as expected. The NE40E does not receive the BFD packets from the non-Huawei device for session negotiation. As a result, the BFD session cannot go Up.

Solution
When a BFD session between an NE40E and a non-Huawei device fails to go Up, select either of the following operations to locate the problem: 1) If background traffic is not sent during the process, collect interface statistics after clearing the historical statistics on the interface to check whether a fault occurs in BFD packet transmission. 2) If background traffic is sent during the process, enable the debugging function of BFD within a short time to locate the problem.
Suggestions
When a BFD session between an NE40E and a non-Huawei device fails to go Up, select either of the following operations to locate the problem: 1) If background traffic is not sent during the process, collect interface statistics after clearing the historical statistics on the interface to check whether a fault occurs in BFD packet transmission. 2) If background traffic is sent during the process, enable the debugging function of BFD within a short time to locate the problem.The command is "debugging bfd packet"

END