How
to troubleshoot the one-way audio encountered by ONU (A) voice users because the broadband remote access server
(BRAS) incorrectly sets the canonical format indicator (CFI). Here you can
Fault Description
Network topology:
ONU(A) -> optical line terminal (OLT) -> SE800-> Huawei NE5000E
-> session border controller (SBC)
After dual-homing
migration is performed on an Huawei
OLT on a site, ONU(A) voice users encounter one-way audio. Specifically,
the ONU(A) voice users cannot hear the voice of the peer end. The ONU(B)
connected to the same OLT is functional.
The version of the
ONU(A) is V800R305C01B123.
The version of the
ONU(B) is V800R308C01SPC503.
Possible
Causes
- The SBC is faulty.
- Packet loss occurs on the network.
- The OLT is faulty.
- The ONU(A) is faulty.
Procedure
1.
Replace
the ONU(A) with a functional ONU(B) and perform the test again. One-way audio
does not occur. Therefore, the fault is not caused by an SBC fault, packet loss
on the network, or an OLT fault.
2.
Capture
packets on the uplink port of the ONU(A). The packets sent from the peer end
are detected, which indicates that the uplink port of the ONU(A) has received
the packets sent from the peer end. It is suspected that packets are lost on
the digital signal processing (DSP) drive side.
3.
Compare
the media packets sent from and received by the uplink port. It is found that
the CFI is 1 in the VLAN tag of the received packets, while the CFI is 0 in the
VLAN tag of the sent packets. It is confirmed that the ONU(A) sends the packets
from the peer end to the DSP chip for processing. The DSP chip determines that
the CFI with the value 1 is invalid and discards the packets. As a result, the
fault occurs on the ONU(A). The packet processing flow on the ONU(B) is
different from that on the ONU(A). Specifically, the ONU(B) processes the
packets in Real-Time Transport Protocol (RTP) mode and sends the packets to the
DSP chip for processing. Therefore, the voice service of the ONU(B) is
functional.
4.
Use
access control list (ACL) rules to determine the location where the CFI is set
to 1 segment by segment. Collect downstream packets from the voice gateway on
the OLT to check whether the packets received by the OLT are correct.
huawei(config)#acl 5002
huawei(config-acl-user-5002)#rule permit 02003b04 ffffffff 6 07c8 ffff 10 81001fa1 ffff1fff 12 ipoe
//Map
the packets with the following configurations: Source MAC address is the MAC
address of the voice gateway,
VLAN
ID is 4001, and CFI is 1.
huawei(config-acl-user-5002)#rule permit 02003b04 ffffffff 6 07c8 ffff 10 81001fa1 ffff1fff 12 ipoe
//Map
the packets with the following configurations: Source MAC address is the MAC
address of the voice gateway,
VLAN
ID is 4001, and CFI is 0.
huawei(config-acl-user-5002)#quit
huawei(config)#traffic-statistic
inbound user-group 5002 port 0/19/1
//Configure
the ACL on the uplink port of the OLT to collect statistics for downstream
packets on the network side.
huawei(config)#display
qos-info traffic-statistic port 0/19/1
Inbound:
Matches: Acl 5002 rule 5 running
27983 packets //The CFI of the packets received
on the OLT is 1.
Matches: Acl 5002 rule 10 running
0 packet
Based on the terminal
display, the CFI in the VLAN tag of the voice gateway packets received on the
uplink port of the OLT is set to 1. Therefore, the CFI with value 1 is not set
on the OLT.
5.
The
BRAS connects to the Layer 3 network, where packets do not have a VLAN tag. It
is confirmed that the BRAS (SE800) sets the CFI in the VLAN tag to 1, which
causes the one-way audio. Change the CFI to 0. The fault is rectified.
The CFI in a VLAN tag must be set
to 0. Otherwise, exceptions will occur.
The more
information about technical support you can consult with our technician - Bill,
and his e-mail address is as below:
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