Operation Manual – MPLS OAM
H3C S9500 Series Routing Switches Table of Contents
i
Table of Contents
Chapter 1 MPLS OAM Configuration...........................................................................................1-1
1.1 MPLS OAM Overview........................................................................................................1-1
1.1.1 MPLS OAM Background.........................................................................................1-1
1.1.2 MPLS OAM Packet Types and Formats.................................................................1-2
1.1.3 MPLS OAM Capabilities..........................................................................................1-5
1.1.4 References..............................................................................................................1-7
1.2 MPLS OAM Configuration .................................................................................................1-7
1.2.1 MPLS OAM Configuration Task List .......................................................................1-7
1.2.2 Configuring MPLS OAM Basic Capability...............................................................1-7
1.2.3 Configuring a Protection Group...............................................................................1-9
1.3 Displaying and Debugging MPLS OAM Basic Capability................................................1-10
1.4 Typical MPLS OAM Configuration Example....................................................................1-11
1.5 Troubleshooting MPLS OAM...........................................................................................1-16
1.5.1 Failure to Enable OAM on the Ingress Node........................................................1-16
1.5.2 Failure to Enable OAM on the Egress Node.........................................................1-16
1.5.3 Abnormal Verification Occurs on the Egress Node...............................................1-17
1.5.4 The Defect State of the Ingress Node is Different from that of the Egress Node..........1-17
1.5.5 The Defects of the Ingress Node cannot Trigger Protection Switching................1-18
1.5.6 The Primary LSP Recovered from a Defect, but the Protection Group cannot Switch
back................................................................................................................................
1-19
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Chapter 1 MPLS OAM Configuration
When configuring MPLS OAM, go to these sections for information you are interested
in:
z MPLS OAM Overview
z MPLS OAM Configuration
z Displaying and Debugging MPLS OAM Basic Capability
z Typical MPLS OAM Configuration Example
z Troubleshooting MPLS OAM
Note:
Currently the H3C S9500 series routing switches do not support the FFD.
1.1 MPLS OAM Overview
Operation, administration and maintenance (OAM) is a tool designed for monitoring
and troubleshooting network problems. It provides an effective way of reducing network
maintenance costs. MPLS OAM is intended for the operation, administration and
maintenance on the MPLS layer.
1.1.1 MPLS OAM Background
MPLS supports multiple Layer 2 and Layer 3 protocols like IP, ATM, and Ethernet. To
enable the following features on the user plane of MPLS, MPLS needs to provide an
OAM mechanism fully independent of any upper layer or lower layer:
z LSP connectivity.
z Protection switching so that services can be provided in compliance with the
service level agreements (SLAs) signed with customers in the presence of link
defects (or failures).
With this MPLS OAM mechanism employed, you can effectively pinpoint defects in an
MPLS network, report defects and take corresponding measures, and provide a
triggering mechanism for protection switching in case of failures.
For detailed information about MPLS OAM background, refer to ITU-T
Recommendation Y.1710.
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1.1.2 MPLS OAM Packet Types and Formats
MPLS OAM packets fall into four types: connectivity verification (CV), fast failure
detection (FFD), forward defect indication (FDI) and backward defect indication (BDI).
The following sections present a description of their formats.
I. OAM CV packets
The LSP connectivity is verified by checking that the egress node of an LSP has
received the OAM CV packets sent from the ingress node.
Figure 1-1 shows the format
of the OAM CV packet.
Padding (all 00Hex)
(18 octets)
BIP16 (2 octets)
Function type (01Hex) Reserved (all 00Hex)
LSP Trail Termination Source Identifier
(20 octets)
07 31
Figure 1-1 OAM CV packet format
Table 1-1 describes the fields of the OAM CV packet.
Table 1-1 Description on the fields of the OAM CV packet
Field Description
Function type Packet type, with 0x01 being the CV packet
Reserved Reserved field
LSP Trail
Termination Source
Identifier
TTSI, uniquely identifying an LSP in a network. It consists of
16-byte ingress LSR ID and 4-byte LSP ID. For IPv4, the first
10 bytes of ingress LSR ID are padded with 0x00, the
following two bytes are padded with 0xFF, and the last four
bytes are IPv4 address.
Padding Padded field
BIP16 Packet checksum
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II. OAM FFD packets
Like CV packets, you also can verify the LSP connectivity by checking the OAM FFD
packets sent from the ingress node of an LSP arrive at the egress node.
Figure 1-2
shows the format of the OAM FFD packet.
Compared with a CV packet, a FFD packet has additional 1-byte frequency information.
The transmission frequency is set to 1 second for the CV packet. For the FFD packet,
multiple transmission frequencies are supported, including 10ms, 20ms, 50ms, 100ms,
200ms, and 500ms.
Padding (all 00Hex)
(17 octets)
BIP16 (2 octets)
Function type (07Hex) Reserved (all 00Hex)
LSP Trail Termination Source Identifier
(20 octets)
07 31
Frequency
Figure 1-2 OAM FFD packet format.
Table 1-2 describes the fields of the OAM FFD packet.
Table 1-2 Description on the fields of the OAM FFD packet
Field Description
Function type
Packet type, with 0x07 being the FFD
packet
Reserved Reserved field
LSP Trail Termination Source Identifier TTSI. Refer to Table 1-1.
Frequency Transmission frequency for FFD packet
Padding Padded field
BIP16 Packet checksum
III. OAM FDI packets
OAM FDI packets are used by the upstream node of an LSP to notify the egress node of
defect information. In addition, when auto protocol is enabled, the ingress node notifies
the egress node with OAM FDI packets that it should stop defect verification.
Figure 1-3
shows the format of the OAM FDI packet.
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Padding (all 00Hex)
(14 octets)
BIP16 (2 octets)
Function type (02Hex) Reserved (00Hex)
TTSI (optional, if not used set to all 00Hex)
(20 octets)
07 31
Defect location (4 octets)
Defect type
15
Figure 1-3 OAM FDI packet format
Table 1-3 describes the fields of the OAM FDI packet.
Table 1-3 Description on the fields of the OAM FDI packet
Field Description
Function type Packet type, with 0x02 being the FDI packet
Reserved Reserved field
Defect type Type of LSP defects
TTSI
LSP identifier, refer to
Table 1-1. Without TTSI, each byte of the
field is padded with 0x00.
Defect location Information about defect location
Padding Padded field
BIP16 Packet checksum
IV. OAM BDI packets
OAM BDI packets are used by the egress node to notify the ingress node of defect
information through a reverse channel after it finds LSP defects.
Figure 1-4 shows the
format of the OAM BDI packet.
The implications of the fields of the OAM BDI packet are the same as that of the OAM
FDI packet, as shown in Table 5-3.
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Padding (all 00Hex)
(14 octets)
BIP16 (2 octets)
Function type (03Hex) Reserved (00Hex)
TTSI (optional, if not used set to all 00Hex)
(20 octets)
07 31
Defect location (4 octets)
Defect type
15
Figure 1-4 OAM BDI packet format
1.1.3 MPLS OAM Capabilities
I. Basic capability
MPLS OAM basic capability refers to connectivity verification.
C
V
/
F
F
D
B
D
I
Ingress
Egress
LSR
LSR
C
V
/
F
FD
B
D
I
C
V
/
F
F
D
B
D
I
Ingress
Egress
LSR
LSR
C
V
/
F
FD
B
D
I
Figure 1-5 Networking diagram for MPLS OAM connectivity verification
As shown in
Figure 1-5, procedure of connectivity verification follows:
1) The ingress node sends CV/FFD packets through the LSP to be verified to the
egress node.
2) By comparing the received information such as packet type, frequency and TTSI
with the locally recorded values that should be received, the egress node checks
the packets are received properly, and takes statistics for the right packets and
wrong packets received in the verification period so as to monitor the LSP
connectivity.
3) Once it detects LSP defects, the egress node analyzes the types of LSP defects
and transmits the BDI packet with defect information to the ingress node through a
reverse channel. In this way, the ingress node can get the defect state
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immediately. If a protection group is configured properly, the corresponding
protection switching would also be triggered.
When configuring MPLS OAM basic capability, you need to bind a reverse channel to
the LSP to be verified. A reverse channel is an LSP which has an ingress node and an
egress node contrary to the LSP to be verified. There are two types of reverse
channels:
z Dedicated reverse channel: Each forward LSP has its own reverse channel. This
means is rather stable but may incur wasted resources.
z Shared reverse channel: Multiple forward LSPs have a reverse channel in
common. All the LSPs transmit BDI packets through this LSP. This means
reduces wasted resources. However, the shared reverse channel may be
congested when defects are detected on multiple forward LSPs at the same time.
Configuring additional acknowledgement information for BDI packets is required in
order for the ingress node to distinguish which forward LSP has defects depending
on the BDI packets received. For example, TTSI is configured for the MPLS OAM.
As a result, a BDI packet can carry the TTSI information of the LSP to be verified,
which is useful for checking the BDI packet is necessary.
II. Protection switching
Protection switching (PS) is designed to establish the corresponding protection LSP
(secondary LSP) for the primary LSP. The primary LSP and the secondary LSP
constitute a protection group. In protection switching mode, once the primary LSP fails,
data flows can be switched to the secondary LSP rapidly, significantly improving the
reliability of networks.
In real world, you also can manually input some switching commands as required to
switch from the primary LSP to the secondary LSP, or vice versa. Manual switching and
signaling switching are prioritized. For manual switching, the switching takes effect only
when its priority is higher than the priority of the current signaling.
For PS, four modes are supported: 1:1 protection, 1+1 protection, share mesh
protection and packet 1+1 protection.
z 1:1 protection: Two LSPs in primary/secondary mode are available between the
ingress node and the egress node. In general, data is transported over the primary
LSP; when the ingress node detects some defect on the primary LSP through
verification mechanism (for example, OAM) and needs to run protection switching,
it switches data to the secondary LSP and keeps on transmission.
z 1+1 protection: Two LSPs in primary/secondary mode are available between the
ingress node and the egress node. In general, the ingress node sends the same
data packets to these two LSPs at the same time; but the egress node only
receives the data from the primary LSP. When the egress node detects some
defect on the primary LSP, it stops receiving data from the primary LSP and
switches to the secondary LSP to receive data.
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z Share mesh protection: This protection mode is designed for saving bandwidth in
the mesh network topology. In short, an LSP is used as the secondary LSP for
multiple LSPs. When any LSP fails, data packets to be transported over the LSP
are switched to the secondary LSP. The triggering and switching mechanisms of
this mode are similar to 1:1 protection.
z Packet 1+1 protection: This protection mode is similar to 1+1 protection. The
difference between them is that for packet 1+1 protection, the ingress node sends
packets with order labels through the primary LSP and the secondary LSP to the
egress node. For the packets with the same order label, the egress node receives
the one arrived in advance and drops the other. This protection mode is rather
complex and difficult to control.
Now, only 1:1 protection is supported.
1.1.4 References
For more information about MPLS OAM, refer to:
z ITU-T Recommendation Y.1710: Requirements for Operation & Maintenance
functionality for MPLS networks
z ITU-T Recommendation Y.1711: Operation & Maintenance mechanism for MPLS
networks
z ITU-T Recommendation Y.1720: Protection switching for MPLS networks
1.2 MPLS OAM Configuration
1.2.1 MPLS OAM Configuration Task List
Task Remarks
Configuring MPLS OAM Basic Capability Required
Configuring a Protection Group Required
1.2.2 Configuring MPLS OAM Basic Capability
I. Configuration Prerequisites
1) Application environment
MPLS OAM basic verification capability is designed to monitor the connectivity state of
an MPLS network, and verify and pinpoint the defects in the MPLS network. To verify
the connectivity of the MPLS network, you should configure the MPLS OAM function for
LSPs.
2) Configuration preparation
To configure MPLS OAM basic capability, perform the following tasks:
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z Configure MPLS basic capabilities, refer to MPLS Configuration.
z Configure static LSPs, refer to MPLS Configuration.
3) Data preparation
To configure MPLS OAM basic capability, prepare the following data:
Table 1-4 Data preparation
Number Data
1 The static LSP to be verified
2
For ingress node, LSP ID of the static LSP to be verified
For egress node, the ingress LSR ID and LSP ID of the static LSP to
be verified
3 The static LSP of the reverse channel
4
MPLS OAM parameters, for instance, verification packet type and
FFD transmission frequency
If the ingress node adopts a shared reverse channel, the No. 3 data in the above table
is omitted.
II. Configuration Procedure
Follow these steps to configure MPLS OAM basic capability:
To do... Use the command... Remarks
Enter system view
system-view
—
Enable MPLS OAM
mpls oam
Required
Configure MPLS OAM
parameters for the
ingress node
mpls oam ingress lsp-name
lsp-name lsp-id lsp-id [ type { cv | ffd
[ frequency ffd-fre ] } ] [ backward-lsp
share | lsp-name rev-lsp-name ]
Required
Enable OAM for the
ingress node
mpls oam ingress enable { all |
lsp-name lsp-name }
Required
Configure MPLS OAM
parameters for the
egress node
mpls oam egress lsp-name
lsp-name lsr-id lsr-id lsp-id lsp-id
[ type { cv | ffd [ frequency ffd-fre ] } ]
[ backward-lsp rev-lsp-name [ private
| share ] ]
Required
Enable OAM for the
egress node
mpls oam egress enable { all |
lsp-name lsp-name }
Required
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Note:
z This operation also can be used for modifying MPLS OAM parameters.
z The configuration of MPLS OAM parameters takes effect only after the MPLS OAM
function is enabled. You must first enable the MPLS OAM function on the ingress
node and then on the egress node. Otherwise, the egress node will generate an
alert.
1.2.3 Configuring a Protection Group
I. Configuration Prerequisites
1) Application environment
In an environment with higher demand on network performance, a protection channel is
reserved so that transmission of data flows can be restored rapidly after the primary
LSP failed.
2) Configuration preparation
To configure a protection group, perform the following tasks:
z Enable MPLS;
z Create the primary static LSP and the secondary static LSP.
3) Data preparation
To configure a protection group, prepare the following data:
Table 1-5 Data preparation
Number Data
1 Protection group ID
2 Name of the primary LSP in the protection group
3 Name of the secondary LSP in the protection group
4
Protection group parameters, for instance, Hold off time, switch
back mode and WTR time
Note that:
1) This operation also can be used for modifying protection group parameters.
2) Switch back means that after the primary LSP recovered from a fault, data flows
are switched from the secondary LSP back to the primary LSP.
3) FIB entries are not updated when data flows are switched from the primary LSP to
the secondary LSP. By querying the primary and secondary LSPs and the
protection group, you can view the forwarding information of the current LSP (for
instance, next hop, outbounding interface).
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4) The data flow is on the primary LSP if both the primary and secondary LSPs in one
protection group fail.
z When the primary LSP is in the up/no-defect state and the secondary LSP is in the
down, in-defect, or down/in-defect state, the data flow is on the primary LSP. If the
primary LSP then turns into the down, in-defect, or down/in-defect state, no
switching will take place.
z When the primary LSP is in the down, in-defect or down/in-defect state and the
secondary LSP is in the up/no-defect state, the data flow is on the secondary LSP.
If the secondary LSP then turns into the down, in-defect, or down/in-defect state,
the data flow will be switched to the primary LSP though the latter is not
operational.
5) When you delete a protection group where the data flow is on the secondary LSP,
the data flow will be switched to the primary LSP before the group is deleted, even
if the primary LSP is not operational.
6) If no protection group is configured, the manually-configured secondary LSP will
not have a corresponding LSP forwarding entry.
II. Configuration Procedure
Follow these steps to configure a protection group:
To do... Use the command... Remarks
Enter system view
system-view
—
Configure a protection
group for the specified
primary LSP
mpls protect-switch protect-id
work-lsp lsp-name protect-lsp
lsp-name [ holdoff holdoff-time ]
[ mode revertive ] [ wtr wtr-time ]
mpls protect-switch protect-id
work-lsp lsp-name protect-lsp
lsp-name [ holdoff holdoff-time ]
mode non-revertive
Required
Enable external protection
switch
mpls protect-switch manual
{ protect-lsp | work-lsp } protect-id
Optional
Display information about
the protection group
display mpls protect-switch { all |
protect-id } [ verbose | brief ]
In any view
1.3 Displaying and Debugging MPLS OAM Basic Capability
To do… Use the command... Remarks
Display MPLS OAM
information on the ingress
node
display mpls oam ingress { all |
lsp-name lsp-name } [ slot slot-id |
verbose ]
Alailable in
any view
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To do… Use the command... Remarks
Display MPLS OAM
information on the egress
node
display mpls oam egress { all |
lsp-name lsp-name } [ slot slot-id |
verbose ]
Alailable in
any view
Display information about
OAM packets received on
the ingress node
display mpls oam ingress
receive-packet { all | bdi | error } slot
slot-id
Alailable in
any view
Display information about
OAM packets sent from
the ingress node
display mpls oam ingress
send-packet { all | ap-fdi | cv | error |
ffd } slot slot-id
Alailable in
any view
Display information about
OAM packets received on
the egress node
display mpls oam egress
receive-packet { all | ap-fdi | cv |
error | fdi | ffd } slot slot-id
Alailable in
any view
Display information about
OAM packets sent from
the egress node
display mpls oam egress
send-packet { all | bdi | error } slot
slot-id
Alailable in
any view
Clear the statistics of all
OAM packets on the
ingress node
reset mpls oam packet-statistics
ingress { all | lsp-name lsp-name }
Alailable in
user view
Clear the statistics of all
OAM packets on the
egress node
reset mpls oam packet-statistics
egress { all | lsp-name lsp-name }
Alailable in
user view
Clear the statistics of
OAM packets for the
specified interface card
reset mpls oam packet-statistics
slot slot-id
Alailable in
user view
Executing the above mentioned commands, you will view the following results:
z Basic LSP information, including LSP name, LSP state, ingress LSR ID;
z Basic OAM information, including LSP name, TTSI, verification packet type,
transmission frequency;
z OAM verification information, including type of the packets to be transmitted,
transmission period, verification state and defect state. When the LSP works
properly, the verification state is Start and the defect state is No-defect;
z OAM reverse channel information, including share type, configuration information;
z Statistics of OAM packets received/sent on the ingress node;
z Statistics of OAM packets received/sent on the egress node.
1.4 Typical MPLS OAM Configuration Example
I. Network requirements
As shown in Figure 1-6, two static LSPs (in primary/secondary mode) and a shared
reverse channel are available between Switch A and Switch B. Once it detects
connectivity defects on the primary LSP, the egress node Switch C notifies the ingress
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node Switch A of defect verification results, and switches data flows to the secondary
LSP.
In this case, only Switch A and Switch C need to support MPLS OAM, Switch B, Switch
D and Switch E do not.
1) Configuration preparation
z At least two static LSPs are available between the ingress node and the egress
node to constitute a protection group. At the same time, a reverse static LSP from
the egress node to the ingress node is available for the egress node to notify
connectivity defects.
z You need to configure a protection group, and specify the protection group ID,
protection switching delay, switch back mode and switch back wait time.
z You need to enable MPLS OAM globally on the ingress node and the egress node.
z You need to configure MPLS OAM parameters for the LSP to be verified and
enable the MPLS OAM function on the ingress node.
z You need to configure MPLS OAM parameters for the LSP to be verified and
enable the MPLS OAM function on the egress node
2) Data preparation
To complete the configuration, you need to specify the following data:
z IP addresses of VLAN interfaces of various switches and names of various static
LSPs, as shown in Figure 5-6.
z Static LSPs borrow the loopback addresses of various switches. The destination
IP address of the primary and secondary LSPs is 3.3.3.3/32 and the destination IP
address of the reverse channel is 1.1.1.1/32.
z In a protection group, the switch back delay is set to 10, that is, 1 second; the
switch back mode is revertive; the switch back wait time is 20, that is, 10 minutes.
z The type of verification packet to be sent is set to CV and the transmission period
is the defaulted 1 second.
z The reverse channel is set to share.
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II. Networking diagram
Loopback0
4.4.4.4/32
Loopback0
VLAN34
Loopback0
1.1.1.1/32
SwitchA
VLAN14
VLAN12
VLAN15
15.1.1.1/24
VLAN15
LspAtCp
2.2.2.2/32
Loopback0
5.5.5.5/32
VLAN34
34.1.1.1/24
34.1.1.1/24
Loopback0
3.3.3.3/32
VLAN23 VLAN23
VLAN53
53.1.1.1/24
VLAN53
53.1.1.1/24
23.1.1.1/24
23.1.1.2/24
Switch D
Switch E
Switch B
SwitchC
VLAN14
14.1.1.2/24
14.1.1.1/24
VLAN12
12.1.1.1/24
12.1.1.2/24
15.1.1.2/24
Lspid:200
LspAtCw
Lspid:100
LspCtA
Figure 1-6 Networking diagram for configuring OAM and PS basic capabilities
III. Configuration procedure
1) Configure IP addresses for various interfaces
As shown in
Figure 1-6, configure the IP addresses and masks of various interfaces,
including various loopback interfaces. The detailed configuration steps are omitted.
2) Configure the IGP protocol
Enable OSPF on all switches and advertise their own routes. The detailed configuration
steps are omitted.
After the above configurations are completed, switches should interoperate to each
other on the network layer. You can issue the display ip routing-table command on
switches to view the routing table.
3) Configure MPLS OAM and static LSPs
As shown in
Figure 1-6, configure the primary static LSP LspAtC and the secondary
static LSP LspAtCp on Switch A; configure a shared reverse channel LspCtA on Switch
C.
4) Configure MPLS OAM for Switch A
# Enable MPLS OAM globally.
<SwitchA> system-view
[SwitchA] mpls oam
# Configure OAM parameters for the ingress node.
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[SwitchA] mpls oam ingress lsp-name LspAtCw lsp-id 100
[SwitchA] mpls oam ingress lsp-name LspAtCp lsp-id 200
# Configure a protection group.
[SwitchA] mpls protect-switch 1 work-lsp lspAtCw protect-lsp lspAtCp holdoff
10 mode revertive wtr 20
Using the display mpls protect-switch all command, you will see the following
information:
[SwitchA] display mpls protect-switch all
-----------------------------------------------------------------------
Protection-Switching Information
-----------------------------------------------------------------------
PROTECT-ID Dft-W Dft-P Ctrl-W Ctrl-P SwitchRst
1 No-defect No-defect Up Up W
# Enable MPLS OAM on the ingress node.
[SwitchA] mpls oam ingress enable all
5) Configure MPLS OAM for Switch C
# Enable MPLS OAM globally.
<SwitchC> system-view
[SwitchC] mpls oam
# Configure OAM parameters for the egress node.
[SwitchC] mpls oam egress lsp-name lspAtCw lsr-id 1.1.1.1 lsp-id 100
backward-lsp lspCtA share
[SwitchC] mpls oam egress enable lsp-name lspAtCw
[SwitchC] mpls oam egress lsp-name lspAtCp lsr-id 1.1.1.1 lsp-id 200
backward-lsp lspCtA share
[SwitchC] mpls oam egress enable lsp-name lspAtCp
After completing the above configurations, you can view information about the current
LSP and OAM and statistics of OAM verification packets on Switch A and Switch C.
The following takes the display on Switch C as an example.
# Display configuration information about the current LSP and OAM.
<SwitchC> display mpls oam egress all verbose
--------------------------------------------------------------------------
Verbose information about the 1st OAM at egress
--------------------------------------------------------------------------
lsp basic information: oam basic information:
--------------------------------------------------------------------------
Lsp-name : lspAtCw Oam-Index : 1024
Lsp signal status : Up Oam select board : 2
Lsp incoming Label : 3 Enable-state : --
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Lsp ingress lsr-id : 1.1.1.1 Auto-protocol :Disable
Auto-overtime (s) : 0
Ttsi/lsr-id : 1.1.1.1
Ttsi/lsp-id : 100
oam detect information: oam backward information:
--------------------------------------------------------------------------
Type : CV Share attribute : Share
Frequency : 1 s Lsp-name : lspCtA
Detect-state : Start Lsp-state : Up
Defect-state : No-defect
--------------------------------------------------------------------------
Verbose information about the 2nd OAM at egress
--------------------------------------------------------------------------
lsp basic information: oam basic information:
--------------------------------------------------------------------------
Lsp-name : lspAtCp Oam-Index : 1025
Lsp signal status : Up Oam select board : 2
Lsp incoming Label : 3 Enable-state : --
Lsp ingress lsr-id : 1.1.1.1 Auto-protocol : Disable
Auto-overtime (s) : 0
Ttsi/lsr-id : 1.1.1.1
Ttsi/lsp-id : 200
oam detect information: oam backward information:
--------------------------------------------------------------------------
Type : CV Share attribute : Share
Frequency : 1 s Lsp-name : lspCtA
Detect-state : Start Lsp-state : Up
Defect-state : No-
d
efect
--------------------------------------------------------------------------
Total Oam Num: 2
Total Start Oam Num: 2
Total Defect Oam Num: 0
# Display the statistics of verification packets received on the egress node.
<SwitchC> display mpls oam egress receive-packet all slot 2
--------------------------------------------------------------------------
CV Packet FFD Packet FDI Packet AP-FDI Packet Error Packet
--------------------------------------------------------------------------
467 0 0 0 0
6) Verify the configuration
Shutdown interface VLAN12 of Switch B. At this point, the primary LSP on Switch A
detects a defect.
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1-16
Using the display mpls protect-switch all command on Switch A, you will see that
data flows are switched to the secondary LSP.
[SwitchA] display mpls protect-switch all
-----------------------------------------------------------------------
Protection-Switching Information
-----------------------------------------------------------------------
PROTECT-ID Dft-W Dft-P Ctrl-W Ctrl-P SwitchRst
1 Defect No-defect Up Up P
1.5 Troubleshooting MPLS OAM
1.5.1 Failure to Enable OAM on the Ingress Node
I. Symptom
When you execute the mpls oam ingress enable [ lsp-name lsp-name ] command on
the ingress node, the message “% Warning: Invalid LSP name.” displays.
II. Solution
According to the message, you will see that the OAM parameters for the ingress node
are not configured rightly. To solve the problem, you can:
z Execute the mpls oam ingress lsp-name lsp-name lsp-id lsp-id [ type { cv | ffd
[ frequency ffd-fre ] } ] [ backward-lsp share | lsp-name rev-lsp-name ]
command on the ingress node to configure OAM parameters for the LSP to be
verified.
z Execute the display mpls oam ingress [ all | lsp lsp-name ] command to display
the configured OAM parameters.
z Execute the mpls oam ingress enable [ all | lsp-name lsp-name ] command to
enable the MPLS OAM function.
1.5.2 Failure to Enable OAM on the Egress Node
I. Symptom
When you execute the mpls oam egress enable [ lspname lsp-name ] command on
the egress node, the message “% Warning: Invalid LSP name.” displays.
II. Solution
According to the message, you will see that the OAM parameters for the egress node
are not configured rightly. To solve the problem, you can:
z Execute the mpls oam egress lsp-name lsp-name lsr-id ingress-lsr-id lsp-id
lsp-id } type { cv | ffd [ frequency ffd-fre ] } ] [ backward-lsp rev-lsp-name
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H3C S9500 Series Routing Switches Chapter 1 MPLS OAM Configuration
1-17
[ private | share ] ] command on the egress node to configure OAM parameters
for the LSP to be verified.
z Execute the display mpls oam egress [ all | lspname lsp-name ] command to
display OAM parameters configured in step 1.
z Execute the mpls oam egress enable [ all | lsp-name lsp-name ] command to
enable the MPLS OAM function.
1.5.3 Abnormal Verification Occurs on the Egress Node
I. Symptom
The network works properly. When you execute the display mpls oam egress [ all |
lspname lsp-name ] verbose command on the egress node, the defect-sate field
displays dLocv or dUnknown.
II. Solution
The reason for this problem may come from:
z The ingress node does not enable OAM.
z The ingress LSR ID and LSP ID of the LSP to be verified are not configured rightly
on the ingress node and the egress node.
z OAM parameters like verification packet type and transmission frequency
configured on the ingress node and the egress node are not consistent.
To solve this problem, you can:
z When you execute the display mpls oam ingress [ all | lsp-name lsp-name ]
verbose command, the Enable-state field displays Manual disable, meaning that
the ingress node does not enable OAM. In this case, you should execute the mpls
oam ingress enable [ all | lsp-name lsp-name ] command to enable OAM on the
ingress node.
z If OAM is enabled on the ingress node, execute the display mpls oam ingress
[ all | lsp-name lsp-name ] verbose command and the display mpls oam egress
[ all | lspname lsp-name ] verbose command to display the OAM configuration for
the ingress node and the egress node respectively. If the ingress LSR ID and LSP
ID of the LSP to be verified, verification packet type and transmission frequency
are inconsistent, use the corresponding configuration command to configure them
properly and reenable OAM.
1.5.4 The Defect State of the Ingress Node is Different from that of the Egress
Node
I. Symptom
When you execute the display mpls oam egress [ all | lsp-name lsp-name ] verbose
command on the egress node, the Defect-sate field displays dLocv; while you execute
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1-18
the display mpls oam ingress [ all | lsp-name lsp-name ] verbose command on the
ingress node, the defect-sate field displays No-defect.
II. Solution
The reason for this problem may come from:
z The reverse channel is not configured or down. So the egress node cannot notify
the ingress node of defect verification results.
z The reverse channel specified by the ingress node is different from that specified
by the egress node.
To solve this problem, you can:
z Execute the display mpls oam egress [ all | lsp-name lsp-name ] verbose
command. If the lsp-name field is null in the oam backward information, which
means the reverse channel is not configured. In this case, you should use the
OAM configuration command to configure a reverse channel for the LSP to be
verified.
z Both nodes are configured with a reverse channel, but the lsp-state field is down in
the oam backward information. In this case, you should modify MPLS
configuration and make the reverse channel up, or reuse OAM configuration
commands to configure an up reverse channel for the LSP to be verified.
z The reverse channel of the egress node is up, but it is different from that
configured on the ingress node. In this case, you should configure the reverse
channel properly on the egress node and the ingress node.
1.5.5 The Defects of the Ingress Node cannot Trigger Protection Switching
I. Symptom
Protection switching is enabled. When you execute the display mpls oam ingress [ all
| lsp-name lsp-name ] verbose on the ingress node, the defect-state field displays In
defect; while you execute the display mpls protect-switch [ protect-id | all ] verbose
command through command line, the Switching Result field displays Working LSP.
II. Solution
The reason for this problem may come from:
z The primary LSP is not the one for OAM defect verification.
z The secondary LSP also has defects and data flows are not switched.
z Holdoff is not zero. You need to wait a period of time before triggering protection
switching.
z External switching command restricts the transmission of data flows to the primary
LSP.
To solve this problem, you can:
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z Execute the display mpls protect-switch [ all | protect-id ] verbose command. If
the Working LSP User Plane Status is No-defect, which means the primary LSP
configured in the protection group is not the one for OAM defect verification. In this
case, you should use OAM ingress node and egress node configuration
commands to configure OAM parameters for the primary LSP in the protection
group and restart defect verification, or use the protection group configuration
command to configure a protection group for the LSP for defect verification.
z If the Working LSP User Plane Status field is In defect and the Protect LSP User
Plane Status field is In defect, which means the secondary LSP in the protection
group has defects. In this case, you should use the protection group command to
configure another perfect LSP and the primary LSP to constitute a protection
group.
z If the above two conditions are not met, view the Holdoff field. If the Holdoff is not
zero, which means Holdoff does not expire. This is not a fault. When the primary
LSP fails, data flows are switched to the secondary LSP only when it is always
available after Holdoff time. To trigger protection switching immediately after the
primary LSP fails, you should use the protection group command to set Holdoff to
zero.
1.5.6 The Primary LSP Recovered from a Defect, but the Protection Group
cannot Switch back
I. Symptom
When you execute the display mpls protect-switch protect-id command, the Switch
Rst field is P. In this case, data flows are still transmitted over the secondary LSP, even
the primary LSP recovered from a defect.
II. Solution
The reason for this problem may come from:
z The protection group is in non-revertive mode.
z The switch back wait time is longer.
z The external switching command switches data flows to the secondary LSP for
transmission by force. It has a higher priority.
To solve this problem, you can:
z Execute the display mpls protect-switch [ protect-id | all ] verbose command. If
the Revertive Mode field is Non-revertive, the protection group is in non-revertive
mode. This is not a fault. To trigger switch back after the primary LSP recovered
from a defect, you should use the mpls protect-switch command to configure the
protection group as revertive mode.
z If the protection group is in revertive mode and the WTR field is not zero, which
means WTR does not expire. This is not a fault. After the primary LSP recovered
from a defect, data flows will be switched back to the primary LSP in WTR time. To
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