Login
- Table of Contents
-
- 10-High Availability Configuration Guide
- 00-Preface
- 01-Ethernet OAM configuration
- 02-CFD configuration
- 03-DLDP configuration
- 04-RRPP configuration
- 05-ERPS configuration
- 06-Smart Link configuration
- 07-Monitor Link configuration
- 08-VRRP configuration
- 09-BFD configuration
- 10-Track configuration
- 11-Process placement configuration
- Related Documents
-
| Title | Size | Download |
|---|---|---|
| 02-CFD configuration | 191.07 KB |
Restrictions and guidelines: CFD configuration
Configuring basic CFD settings
Configuring MIP auto-generation rules
Configuring CFD
About CFD
Connectivity Fault Detection (CFD), which conforms to IEEE 802.1ag Connectivity Fault Management (CFM), is an end-to-end per-VLAN link layer OAM mechanism. CFD is used for link connectivity detection, fault verification, and fault location.
Basic CFD concepts
Maintenance domain
A maintenance domain (MD) defines the network or part of the network where CFD plays its role. An MD is identified by its MD name.
Maintenance association
A maintenance association (MA) is a part of an MD. You can configure multiple MAs in an MD as needed. An MA is identified by the MD name + MA name.
An MA serves the specified VLAN or no VLAN. An MA that serves a VLAN is considered to be carrying VLAN attribute. An MA that serves no VLAN is considered to be carrying no VLAN attribute.
Maintenance point
An MP is configured on a port and belongs to an MA. MPs include the following types: maintenance association end points (MEPs) and maintenance association intermediate points (MIPs).
MEPs define the boundary of the MA. Each MEP is identified by a MEP ID.
MEPs include inward-facing MEPs and outward-facing MEPs:
· An outward-facing MEP sends packets to its host port.
· An inward-facing MEP does not send packets to its host port. Rather, it sends packets to other ports on the device.
A MIP is internal to an MA. It cannot send CFD packets actively, but it can handle and respond to CFD packets. MIPs are automatically created by the device. By cooperating with MEPs, a MIP can perform a function similar to ping and traceroute.
MEP list
A MEP list is a collection of local MEPs allowed to be configured and the remote MEPs to be monitored in the same MA. It lists all the MEPs configured on different devices in the same MA. The MEPs all have unique MEP IDs. When a MEP receives from a remote device a continuity check message (CCM) carrying a MEP ID not in the MEP list of the MA, it drops the message.
The local device must send CCM messages carrying the Remote Defect Indication (RDI) flag bits. Otherwise, the peer device cannot sense certain failures. When a local MEP has not learned all remote MEPs in the MEP list, the MEPs in the MA might not carry the RDI flag bits in CCMs.
CFD levels
MD levels
To accurately locate faults, CFD introduces eight levels (from 0 to 7) to MDs. The bigger the number, the higher the level and the larger the area covered. Domains can touch or nest (if the outer domain has a higher level than the nested one) but cannot intersect or overlap.
MD levels facilitate fault location and make fault location more accurate. As shown in Figure 1, MD_A in light blue nests MD_B in dark blue. If a connectivity fault is detected at the boundary of MD_A, any of the devices in MD_A, including Device A through Device E, might fail. If a connectivity fault is also detected at the boundary of MD_B, the failure points can be any of Device B through Device D. If the devices in MD_B can operate correctly, at least Device C is operational.
CFD exchanges messages and performs operations on a per-domain basis. By planning MDs correctly in a network, you can use CFD to rapidly locate failure points.
MA and MP levels
The level of an MA equals the level of the MD to which the MA belongs.
The level of a MEP equals the level of the MD to which the MEP belongs.
The level of a MIP is defined by its generation rule and the MD to which the MIP belongs. MIPs are generated on each port automatically according to the following MIP generation rules:
· Default rule—If no lower-level MIP exists on an interface, a MIP is created on the current level. A MIP can be created even if no MEP is configured on the interface.
· Explicit rule—If no lower-level MIP exists and a lower-level MEP exists on an interface, a MIP is created on the current level. A MIP can be created only when a lower-level MEP is created on the interface.
If a port has no MIP, the system will check the MAs in each MD (from low to high levels), and follow the procedure as described in Figure 2 to create or not to create MIPs at the current level.
Figure 2 Procedure of creating MIPs
CFD grading example
Figure 3 demonstrates a grading example of the CFD module. Four levels of MDs (0, 2, 3, and 5) are designed. The bigger the number, the higher the level and the larger the area covered. MPs are configured on the ports of Device A through Device F. Port A of Device B is configured with the following MPs:
· A level 5 MIP.
· A level 3 inward-facing MEP.
· A level 2 inward-facing MEP.
· A level 0 outward-facing MEP.
Packet processing of MPs
For an MA carrying VLAN attribute, MPs of the MA send packets only in the VLAN that the MA serves. The level of packets sent by an MP equals the level of the MD to which the MP belongs.
For an MA not carrying VLAN attribute, MPs of the MA can only be outward-facing MEPs. The level of packets sent by an outward-facing MEP equals the level of the MD to which the MEP belongs.
A MEP forwards packets at a higher level without any processing and only processes packets of its level or lower.
A MIP forwards packets of a different level without any processing and only processes packets of its level.
CFD functions
CFD functions, which are implemented through the MPs, include:
· Continuity check (CC).
· Loopback (LB).
· Linktrace (LT).
· Alarm indication signal (AIS).
· Loss measurement (LM).
· Delay measurement (DM).
· Test (TST).
Continuity check
Connectivity faults are usually caused by device faults or configuration errors. Continuity check examines the connectivity between MEPs. This function is implemented through periodic sending of CCMs by the MEPs. A CCM sent by one MEP is intended to be received by all the other MEPs in the same MA. If a MEP fails to receive the CCMs within 3.5 times the sending interval, the link is considered as faulty and a log is generated. When multiple MEPs send CCMs at the same time, the multipoint-to-multipoint link check is achieved. CCM frames are multicast frames.
Loopback
Similar to ping at the IP layer, loopback verifies the connectivity between a source device and a target device. To implement this function, the source MEP sends loopback messages (LBMs) to the target MEP. Depending on whether the source MEP can receive a loopback reply message (LBR) from the target MEP, the link state between the two can be verified.
LBM frames are multicast and unicast frames. The device can send and receive unicast LBM frames, and can receive multicast LBM frames but cannot send multicast LBM frames. LBR frames are unicast frames.
Linktrace
Linktrace is similar to traceroute. It identifies the path between the source MEP and the target MP. The source MEP sends the linktrace messages (LTMs) to the target MP. After receiving the messages, the target MP and the MIPs that the LTM frames pass send back linktrace reply messages (LTRs) to the source MEP. Based on the reply messages, the source MEP can identify the path to the target MP. LTM frames are multicast frames and LTRs are unicast frames.
Protocols and standards
· IEEE 802.1ag, Virtual Bridged Local Area Networks Amendment 5: Connectivity Fault Management
Restrictions and guidelines: CFD configuration
When you configure CFD, follow these restrictions and guidelines:
· Configure CC before you use the MEP ID of the remote MEP to configure other CFD functions. This restriction does not apply when you use the MAC address of the remote MEP to configure other CFD functions.
· Do not configure a Layer 2 aggregate interface as an IPP if the following conditions exist:
¡ The Layer 2 aggregate interface exists between an inward-facing MEP and a remote MEP.
¡ The MAC address of the remote MEP is used for CFD functions.
For information about IPPs, see DRNI configuration in Layer 2—LAN Switching Configuration Guide.
· Typically, a port blocked by the spanning tree feature cannot receive or send CFD messages except in the following cases:
¡ The port is configured as an outward-facing MEP.
¡ The port is configured as a MIP or inward-facing MEP, which can still receive and send CFD messages except CCM messages.
For more information about the spanning tree feature, see Layer 2—LAN Switching Configuration Guide.
CFD tasks at a glance
To configure CFD, perform the following tasks:
1. Configuring basic CFD settings
a. Enabling CFD
b. Configuring service instances
d. Configuring MIP auto-generation rules
b. (Optional.) Configuring LB
c. (Optional.) Configuring LT
Prerequisites for CFD
For CFD to work correctly, design the network by performing the following tasks:
· Grade the MDs in the entire network, and define the boundary of each MD.
· Assign a name for each MD. Make sure the devices in the same MD use the same MD name.
· Define the MA in each MD according to the VLAN you want to monitor.
· Assign a name for each MA. Make sure that the devices in the same MA in the same MD use the same MA name.
· Determine the MEP list of each MA in each MD. Make sure devices in the same MA maintain the same MEP list.
· At the edges of MD and MA, MEPs must be designed at the device port. MIPs can be designed on devices or ports that are not at the edges.
Configuring basic CFD settings
Enabling CFD
1. Enter system view.
system-view
2. Enable CFD.
cfd enable
By default, CFD is disabled.
Configuring service instances
About service instances
Before configuring the MEPs and MIPs, you must first configure service instances. A service instance is a set of service access points (SAPs), and belongs to an MA in an MD.
The MD and MA define the level attribute and VLAN attribute of the messages handled by the MPs in a service instance. The MPs of the MA that carries no VLAN attribute do not belong to any VLAN.
Procedure
1. Enter system view.
system-view
2. Create an MD.
cfd md md-name [ index index-value ] level level-value [ md-id { dns dns-name | mac mac-address subnumber | none } ]
3. Create a service instance.
cfd service-instance instance-id ma-id { icc-based ma-name | integer ma-num | string ma-name | vlan-based [ vlan-id ] } [ ma-index index-value ] md md-name [ vlan vlan-id ]
Configuring MEPs
About MEPs
CFD is implemented through various operations on MEPs. As a MEP is configured on a service instance, the MD level and VLAN attribute of the service instance become the attribute of the MEP.
Restrictions and guidelines
· You can specify an interface as the MEP for only one of the non-VLAN-specific MAs at the same level. In addition, the MEP must be outward facing.
· If a MEP in a non-VLAN-specific MA does not receive a CCM message within 3.5 CCM intervals from a remote MEP, the local MEP sets its interface to link down state. This behavior of the local MEP facilitates fast switchover for RRPP or Smart Link.
Prerequisites
Before you configure MEPs, you must configure service instances.
Procedure
1. Enter system view.
system-view
2. Configure a MEP list.
cfd meplist mep-list service-instance instance-id
The created MEP must be included in the configured MEP list.
3. Enter Layer 2 Ethernet interface view or Layer 2 aggregate interface view.
interface interface-type interface-number
4. Create a MEP.
cfd mep mep-id service-instance instance-id { inbound | outbound }
Configuring MIP auto-generation rules
About MIP auto-generation rules
As functional entities in a service instance, MIPs respond to various CFD frames, such as LTM and LBM frames. You can configure MIP auto-generation rules for the system to automatically create MIPs.
Any of the following events can cause MIPs to be created or deleted after you have configured the cfd mip-rule command:
· Enabling or disabling CFD.
· Creating or deleting MEPs on a port.
· Changes occur to the VLAN attribute of a port.
· The rule specified in the cfd mip-rule command changes.
Restrictions and guidelines
· An MA carrying no VLAN attribute is typically used to detect direct link status. The system cannot generate MIPs for such MAs.
· For an MA carrying VLAN attribute, the system does not generate MIPs if the same or a higher level MEP exists on the interface.
Procedure
1. Enter system view.
system-view
2. Configure MIP auto-generation rules.
cfd mip-rule { default | explicit } service-instance instance-id
By default, no rules for generating MIPs are configured, and the system does not automatically create any MIP.
Configuring CFD functions
Configuring CC
About CC
After the CC function is configured, MEPs in an MA can periodically send CCM frames to maintain connectivity.
You must configure CC before you use the MEP ID of the remote MEP to configure other CFD functions. This restriction does not apply when you use the MAC address of the remote MEP to configure other CFD functions.
When the lifetime of a CCM frame expires, the link to the sending MEP is considered disconnected. When setting the CCM interval, use the settings described in Table 1.
Table 1 CCM interval field encoding
|
CCM interval field |
Transmission interval |
Maximum CCM lifetime |
|
1 |
10/3 milliseconds |
35/3 milliseconds |
|
2 |
10 milliseconds |
35 milliseconds |
|
3 |
100 milliseconds |
350 milliseconds |
|
4 |
1 second |
3.5 seconds |
|
5 |
10 seconds |
35 seconds |
|
6 |
60 seconds |
210 seconds |
|
7 |
600 seconds |
2100 seconds |
|
|
NOTE: · The value range for the interval field is 1 to 7. If you set the value to 1, the continuity check might work incorrectly due to hardware restrictions. · The CCM messages with an interval field value of 1 to 3 are short-interval CCM messages. The CCM messages with an interval field value of 4 to 7 are long-interval CCM messages. |
Restrictions and guidelines
When you configure the CCM interval, follow these restrictions and guidelines:
· Configure the same CCM interval field value for all MEPs in the same MA.
· After the CCM interval field is modified, the MEP must wait for another CCM interval before sending CCMs.
Procedure
1. Enter system view.
system-view
2. (Optional.) Set the CCM interval field.
cfd cc interval interval-value service-instance instance-id
By default, the interval field value is 4.
3. Enter Layer 2 Ethernet interface view or Layer 2 aggregate interface view.
interface interface-type interface-number
4. Enable CCM sending on a MEP.
cfd cc service-instance instance-id mep mep-id enable
By default, CCM sending is disabled on a MEP.
Configuring LB
To verify the link state between the local MEP and the remote MEP, execute the following command in any view:
cfd loopback service-instance instance-id mep mep-id { target-mac mac-address | target-mep target-mep-id } [ number number ]
Configuring LT
About LT
LT can trace the path between source and target MEPs, and can locate link faults by automatically sending LT messages. The two functions are implemented in the following way:
· Tracing path—The source MEP first sends LTM messages to the target MEP. Based on the LTR messages in response to the LTM messages, the path between the two MEPs is identified.
· LT messages automatic sending—If the source MEP fails to receive CCM frames from the target MEP within 3.5 times the transmission interval, it considers the link faulty. The source MEP then sends LTM frames, with the TTL field set to the maximum value 255, to the target MEP. Based on the returned LTRs, the fault source is located.
Prerequisites
Before you configure LT on a MEP in an MA carrying VLAN attribute, create the VLAN to which the MA belongs.
Procedure
1. Identify the path between a source MEP and a target MEP.
cfd linktrace service-instance instance-id mep mep-id { target-mac mac-address | target-mep target-mep-id } [ ttl ttl-value ] [ hw-only ]
This command is available in any view.
2. Enter system view.
system-view
3. Enable LT messages automatic sending.
cfd linktrace auto-detection [ size size-value ]
By default, LT messages automatic sending is disabled.
Display and maintenance commands for CFD
Execute display commands in any view and reset commands in user view.
|
Task |
Command |
|
Display LTR information received by a MEP. |
display cfd linktrace-reply [ service-instance instance-id [ mep mep-id ] ] |
|
Display the content of the LTR messages received as responses to the automatically sent LTMs. |
display cfd linktrace-reply auto-detection [ size size-value ] |
|
Display MD configuration information. |
display cfd md |
|
Display the attribute and running information of the MEPs. |
display cfd mep mep-id service-instance instance-id |
|
Display MEP lists in a service instance. |
display cfd meplist [ service-instance instance-id ] |
|
Display MP information. |
display cfd mp [ interface interface-type interface-number ] |
|
Display information about a remote MEP. |
display cfd remote-mep service-instance instance-id mep mep-id |
|
Display service instance configuration. |
display cfd service-instance [ instance-id ] |
|
Display CFD status. |
display cfd status |
CFD configuration examples
Example: Configuring CFD
Network configuration
As shown in Figure 4:
· The network comprises five devices and is divided into two MDs: MD_A (level 5) and MD_B (level 3). All ports belong to VLAN 100, and the MAs in the two MDs all serve VLAN 100. Assume that the MAC addresses of Device A through Device E are 0010-FC01-6511, 0010-FC02-6512, 0010-FC03-6513, 0010-FC04-6514, and 0010-FC05-6515, respectively.
· MD_A has three edge ports: HundredGigE 1/0/1 on Device A, HundredGigE 1/0/3 on Device D, and HundredGigE 1/0/4 on Device E. They are all inward-facing MEPs. MD_B has two edge ports: HundredGigE 1/0/3 on Device B and HundredGigE 1/0/1 on Device D. They are both outward-facing MEPs.
· In MD_A, Device B is designed to have MIPs when its port is configured with low level MEPs. Port HundredGigE 1/0/3 is configured with MEPs of MD_B, and the MIPs of MD_A can be configured on this port. You must configure the MIP generation rule of MD_A as explicit.
· The MIPs of MD_B are designed on Device C, and are configured on all ports. You must configure the MIP generation rule as default.
· Configure CC to monitor the connectivity among all the MEPs in MD_A and MD_B. Configure LB to locate link faults.
· After the status information of the entire network is obtained, use LT to detect link faults.
Procedure
|
|
IMPORTANT: By default, interfaces on the device are disabled (in ADM or Administratively Down state). To have an interface operate, you must use the undo shutdown command to enable that interface. |
1. Configure a VLAN and assign ports to it:
On each device shown in Figure 4, create VLAN 100 and assign ports HundredGigE 1/0/1 through HundredGigE 1/0/4 to VLAN 100.
2. Enable CFD:
# Enable CFD on Device A.
<DeviceA> system-view
[DeviceA] cfd enable
# Configure Device B through Device E in the same way Device A is configured. (Details not shown.)
3. Configure service instances:
# Create MD_A (level 5) on Device A, and create service instance 1 (in which the MA is identified by a VLAN and serves VLAN 100).
[DeviceA] cfd md MD_A level 5
[DeviceA] cfd service-instance 1 ma-id vlan-based md MD_A vlan 100
# Configure Device E in the same way Device A is configured. (Details not shown.)
# Create MD_A (level 5) on Device B, and create service instance 1 (in which the MA is identified by a VLAN and serves VLAN 100).
[DeviceB] cfd md MD_A level 5
[DeviceB] cfd service-instance 1 ma-id vlan-based md MD_A vlan 100
# Create MD_B (level 3), and create service instance 2 (in which the MA is identified by a VLAN and serves VLAN 100).
[DeviceB] cfd md MD_B level 3
[DeviceB] cfd service-instance 2 ma-id vlan-based md MD_B vlan 100
# Configure Device D in the same way Device B is configured. (Details not shown.)
# Create MD_B (level 3) on Device C, and create service instance 2 (in which the MA is identified by a VLAN and serves VLAN 100).
[DeviceC] cfd md MD_B level 3
[DeviceC] cfd service-instance 2 ma-id vlan-based md MD_B vlan 100
4. Configure MEPs:
# On Device A, configure a MEP list in service instance 1, and create inward-facing MEP 1001 in service instance 1 on HundredGigE 1/0/1.
[DeviceA] cfd meplist 1001 4002 5001 service-instance 1
[DeviceA] interface hundredgige 1/0/1
[DeviceA-HundredGigE1/0/1] cfd mep 1001 service-instance 1 inbound
[DeviceA-HundredGigE1/0/1] quit
# On Device B, configure a MEP list in service instances 1 and 2.
[DeviceB] cfd meplist 1001 4002 5001 service-instance 1
[DeviceB] cfd meplist 2001 4001 service-instance 2
# Create outward-facing MEP 2001 in service instance 2 on HundredGigE 1/0/3.
[DeviceB] interface hundredgige 1/0/3
[DeviceB-HundredGigE1/0/3] cfd mep 2001 service-instance 2 outbound
[DeviceB-HundredGigE1/0/3] quit
# On Device D, configure a MEP list in service instances 1 and 2.
[DeviceD] cfd meplist 1001 4002 5001 service-instance 1
[DeviceD] cfd meplist 2001 4001 service-instance 2
# Create outward-facing MEP 4001 in service instance 2 on HundredGigE 1/0/1.
[DeviceD] interface hundredgige 1/0/1
[DeviceD-HundredGigE1/0/1] cfd mep 4001 service-instance 2 outbound
[DeviceD-HundredGigE1/0/1] quit
# Create inward-facing MEP 4002 in service instance 1 on HundredGigE 1/0/3.
[DeviceD] interface hundredgige 1/0/3
[DeviceD-HundredGigE1/0/3] cfd mep 4002 service-instance 1 inbound
[DeviceD-HundredGigE1/0/3] quit
# On Device E, configure a MEP list in service instance 1.
[DeviceE] cfd meplist 1001 4002 5001 service-instance 1
# Create inward-facing MEP 5001 in service instance 1 on HundredGigE 1/0/4.
[DeviceE] interface hundredgige 1/0/4
[DeviceE-HundredGigE1/0/4] cfd mep 5001 service-instance 1 inbound
[DeviceE-HundredGigE1/0/4] quit
5. Configure MIPs:
# Configure the MIP generation rule in service instance 1 on Device B as explicit.
[DeviceB] cfd mip-rule explicit service-instance 1
# Configure the MIP generation rule in service instance 2 on Device C as default.
[DeviceC] cfd mip-rule default service-instance 2
6. Configure CC:
# On Device A, enable the sending of CCM frames for MEP 1001 in service instance 1 on HundredGigE 1/0/1.
[DeviceA] interface hundredgige 1/0/1
[DeviceA-HundredGigE1/0/1] cfd cc service-instance 1 mep 1001 enable
[DeviceA-HundredGigE1/0/1] quit
# On Device B, enable the sending of CCM frames for MEP 2001 in service instance 2 on HundredGigE 1/0/3.
[DeviceB] interface hundredgige 1/0/3
[DeviceB-HundredGigE1/0/3] cfd cc service-instance 2 mep 2001 enable
[DeviceB-HundredGigE1/0/3] quit
# On Device D, enable the sending of CCM frames for MEP 4001 in service instance 2 on HundredGigE 1/0/1.
[DeviceD] interface hundredgige 1/0/1
[DeviceD-HundredGigE1/0/1] cfd cc service-instance 2 mep 4001 enable
[DeviceD-HundredGigE1/0/1] quit
# Enable the sending of CCM frames for MEP 4002 in service instance 1 on HundredGigE 1/0/3.
[DeviceD] interface hundredgige 1/0/3
[DeviceD-HundredGigE1/0/3] cfd cc service-instance 1 mep 4002 enable
[DeviceD-HundredGigE1/0/3] quit
# On Device E, enable the sending of CCM frames for MEP 5001 in service instance 1 on HundredGigE 1/0/4.
[DeviceE] interface hundredgige 1/0/4
[DeviceE-HundredGigE1/0/4] cfd cc service-instance 1 mep 5001 enable
[DeviceE-HundredGigE1/0/4] quit
Verifying the configuration
1. Verify the LB function when the CC function detects a link fault:
# Enable LB on Device A to check the status of the link between MEP 1001 and MEP 5001 in service instance 1.
[DeviceA] cfd loopback service-instance 1 mep 1001 target-mep 5001
Loopback to MEP 5001 with the sequence number start from 1001-43404:
Reply from 0010-fc05-6515: sequence number=1001-43404 time=5ms
Reply from 0010-fc05-6515: sequence number=1001-43405 time=5ms
Reply from 0010-fc05-6515: sequence number=1001-43406 time=5ms
Reply from 0010-fc05-6515: sequence number=1001-43407 time=5ms
Reply from 0010-fc05-6515: sequence number=1001-43408 time=5ms
Sent: 5 Received: 5 Lost: 0
2. Verify the LT function after the CC function obtains the status information of the entire network:
# Identify the path between MEP 1001 and MEP 5001 in service instance 1 on Device A.
[DeviceA] cfd linktrace service-instance 1 mep 1001 target-mep 5001
Linktrace to MEP 5001 with the sequence number 1001-43462:
MAC address TTL Last MAC Relay action
0010-fc05-6515 63 0010-fc02-6512 Hit
