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NE40 Suddenly Fails to Learn the ARP Entry of the Peer Routing Device

Publication Date:  2012-07-27 Views:  62 Downloads:  0
Issue Description
NE40 GE6/0/2 (LPUB)---Non-Huawei routing devices mulitple fibers directly conceted on the local
The NE40 fails to learn the ARP entry of the peer device, but the OSPF neighbor is not interrupted. The peer device can learn the ARP of the NE40 and the OSPF neighbor is not interrupted either.
<r1-c-xy>disp ospf peer

Area 0.0.0.0 interface 221.11.71.17(GigabitEthernet6/0/2)’s neighbor(s)
RouterID: 221.11.71.15 Address: 221.11.71.18
State: Full Mode: Nbr is Slave Priority: 1
DR: 221.11.71.18 BDR: 221.11.71.17
Dead timer expires in 39s
Neighbor comes up for 1Y02M23D
When the fault occurs, the status of interfaces at two ends is Up.
There are incoming packets but no outgoing packets on GE 6/0/2 of the NE40.
<r1-c-xy>disp int gi 6/0/2
GigabitEthernet6/0/2 current state: up
Line protocol is up
Hardware is WAN-GigabitEthernet,
Address is 00e0-fc1c-ee5c
Description: "NE40-S6506B GE1" (To_S6506B_G2/0/5)
Internet address is:
221.11.71.17/30 Is-Primary
The Maximum Transmit Unit is 1500 bytes, the BandWidth is 1000000 Kbits
Send-frame-type is Ethernet_II, loopback not set
Negotiation disabled, full-duplex, 1000Mbps
Flow control disabled, urpf disabled
This port works as a Router
Statistics last cleared: 2007-05-20 00:59:19
Traffic statistics:
Last 5 minutes input rate 1433021 bytes/sec, 2997 packets/sec
Last 5 minutes output rate 34 bytes/sec, 0 packets/sec
The fault lasts for 10 minutes and recovers automatically (It occurs once again and recovers automatically.) 
 
Alarm Information
Null 
Handling Process
Configure the static ARP on the peer device. After a period of time, the fault does not reoccur, so it is certain that the problem appears because the peer device does not send the ARP Response packets. 
 
Root Cause
The interface information shows that input packets appear on the interface G6/0/2 and the output packets on the GE 6/0/2 contain no unicast packets but broadcast and multicast packets.
The hello packet of the OSPF can be sent, which ensure the connection of the OSPF neighbors.
Broadcast packets can be sent, which implies that ARP Request packets can also be sent. Learning the ARP fails may be because no ARP Response packets are received.
The incoming packets on the interface indicate that the peer can receive the ARP Request packets from the device and learn the ARP entry. Therefore, the peer device will send unicast packets.
The NE40 fails to learn the ARP entry. The NE40 may not receive the ARP Response packets sent by the peer or the peer may not respond to the ARP Response packets.
<r1-c-xy>disp int gi 6/0/2
GigabitEthernet6/0/2 current state: up
Line protocol is up
Statistics last cleared: 2007-05-20 00:59:19
Traffic statistics:
Last 5 minutes input rate 1427549 bytes/sec, 2999 packets/sec
Last 5 minutes output rate 35 bytes/sec, 0 packets/sec

Input: 0 shorts, 4 jumbos, 0 giants, 0 pauses
780953980969 unicasts, 88413274 multicasts, 537296787
Output: 0 shorts, 0 jumbos, 0 giants
1276910129223 unicasts, 6239583 multicasts, 65108374 broadcasts 0 MulticastOctets, 0 MulticastPkts
<r1-c-xy>disp int gi 6/0/2
GigabitEthernet6/0/2 current state: up
Line protocol is up
Output: 0 shorts, 0 jumbos, 0 giants
1276910129223 unicasts, 6239585 multicasts, 65108375 broadcasts

Do as follows for further confirmation.
1. Check whether the peer device is configured with the static ARP.
2. When the fault reappears, enable ARP debugging and mirror and capture packets on the interface to check whether the peer sends the ARP Response packets. 
 
Suggestions
Null 

END