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One-Way Audio Occurs After the New QoS Policy is Added Due to the Insufficient Understanding on the NE80E QoS Feature

Publication Date:  2013-09-30 Views:  41 Downloads:  0
Issue Description
Networking:
UA5000--------(G8/0/19)NE80E(P1/0/0)------NE5000E-------M320-------------Soft3000/TMG8010
Symptom:
The voice service on the G8/0/19 ports of NE80E is one-way audio. Users under the UA5000 can hear the voice of the peer party, but the peer party cannot hear the local user.
Handling Process

1. Under the UA5000, perform the ping test to check  whether packet loss occurs on each device.

2. The UA5000 and Soft3000/TMG8010 are checked to be normal after the analysis on the access network and core network.

3. It is realized that the fault occurs after the user delivers the QoS policy on the port. In addition, the problem disappears after the policy is removed. The configuration information is shown as follows:
interface GigabitEthernet8/0/19
qos car cir 10000 cbs 2000000 pbs 0 green pass red discard inbound
qos car cir 10000 cbs 2000000 pbs 0 green pass red discard outbound
port-queue af4 wfq weight 15 shaping shaping-percentage 10 outbound
traffic policy guanjian-QOS-4 inbound
#
traffic classifier biaoji
if-match any
#
traffic behavior guanjian-4
remark ip-precedence 4
#
traffic policy guanjian-QOS-4
classifier biaoji behavior guanjian-4

4. The CAR policy is delivered on the port. Check whether there are CAR discards on the port and a lot of packets are found to be discarded.
[NE80E]dis car st in gi 8/0/19 in
Interface GigabitEthernet8/0/19
Inbound
Committed Access Rate:
CIR 10000(Kbps), PIR 0(Kbps), CBS 2000000(byte), PBS 0(byte)
Conform Action: pass
Yellow Action: pass
Exceed Action: discard
Passed: 48094130615 bytes, 222725069 packets
Dropped: 460706594 bytes, 2116817 packets
Last 30 seconds passed rate: 85864 bps, 49 pps
Last 30 seconds dropped rate: 0 bps, 0 pps

5. Replicate the problem in the lab. The problem cannot be replicated in the lab even though th econfigurtaion in th elab is the same as that on the live network.
6. Capture packets on the upstream port of the UA5000. It is found that the TOS domain of the packets sent by the UA5000 is not 0 but 101100. The problem is replicated in the lab when the packets with the TOS domain 101100 is used for the traffic test.

7. It is confirmed that when the NE80E performs remark IP-precedence, only the first three most significant bits are remarked and other fields are unchanged. In this way, the value of the DSCP domain becomes 100100 (36 in decimal notation). Based on the mapping relationship of the diffserv domain: ip-dscp-inbound 36 phb af4 yellow, the packet color after it is remarked is yellow. However, yellow packets are discarded when single bucket CAR is configured on the LPUG board.
Root Cause
The packets are yellow and yellow packets are discarded when single bucket CAR is configured on the LPUG board.
Solution
Configure double bucket CAR or change "remark ip-precedence" to "remark dscp".
Suggestions
None

END