E_LMI technical white paper

huajiazi

E_LMI technical white book

1、E_LMI introduction        2
2、configuration specification        13
2.1  global configuration        13
2.1.1 configure ELMI protocol status        13
2.1.2 configure Elmi mode        14
2.1.3 configure Elmi Evc ID        14
2.2  EVC relevant configuration        14
2.2.1 configure EVC bandwidth performance        14
2.2.2 configure UNI numbers that EVC can bind        15
2.3  relevant interface configuration        15
2.3.1 configure interface protocol status        15
2.3.2 configure interface UNI ID        15
2.3.3 configure interface UNI mapping type        15
2.3.4 configure interface UNI pooling time        16
2.3.5 configure interface UNI pooling checking time        16
2.3.6 configure interface UNI pooling counter        16
2.3.7 configure interface UNI status counter        16
2.3.8 configure interface UNI bandwidth performance        17
2.4  service attribute and configuration on interface        17
2.4.1 configure definite service of interface binding with EVC        18
2.4.2 add vlan for definite service on interface        18
2.4.3 delete vlan for definite service on interface        18
3、display and debug        18
3.1 show Elmi global information        18
3.2 show Elmi Evc detail        18
3.3 show Elmi Evc summary        19
3.4 show Elmi Uni summary        19
3.5 show Uni detail        20
3.6 show Elmi Uni data statistics        20
3.7 error information debugging        20
3.8 timer debugging        20
3.9 event debugging        20
3.10 information debugging for received and sent packet        21
3.11 status information debugging        21
3.12 interface debugging switch        21
4、configuration instance        21


1、E_LMI introduction
As a technology about MAN and WAN, Ethernet promotes a series of market requirements about operation, management, maintenance and configuration protocol (OAM&P). Usually, the telecom carriers network are larger-scale and complex network with abundant customers, which needs a lot of operators to work for it so as to provide P2P service. Since the enterprise terminal customer need higher service availability, the telecom carrier must shorten MTTR to improve service availability. The feature of Ethernet OAM&P solved these problem, so telecom carrier can provide carrier-class service.
The standard OAM&P tools in telecom industry are including 802.1ag connection fault management and Ethernet local management interface (E-LMI) protocol. 802.1ag provides monitoring and troubleshooting tools for P2P Ethernet, so telecom carriers can check out the problems of P2P connection and network isolation, identifying the customers with network problem. E-LMI protocol is developed by MEF, providing advantage for telecom carrier and terminal customer. E-LMI support telecom carrier to auto-configure customer-edge device according to service. This auto-configuration simplify service operation and ease the work between telecom carriers and enterprise customer.
MEF reference frame relay local management interface rule (FR-LMI), have defined Ethernet local management interface (E-LMI). E-LMI is located in customer ultimate network interface (UNI)’s OAM protocol, which is mainly working between use edge device and provider edge device. E-LMI can make service provider auto-configure CE with the service. CE can auto-receive mapping information from VLAN to EVC and related bandwidth and QoS by E-LMI. The function of auto-configuration reduce the work of creating service, also ease the harmonizing work between service provider and enterprise customer. Therefore, the enterprise customer need not know CE configuration, all configuration are provided by service provider, avoiding the risk of human error. Moreover, E-LIMI provides EVC status for CE. If EVC fault is discovered (such as discovered by 802.1ag), the service provider edge device will notify CE fault so as to quickly switch accessing route.
Figure 1 describes working scope of LMI, we can see it working between customer edge device (CE) and provider edge device UNI.

Figure 1 – E-LMI scope


Figure 2 – E-LMI terminal function components
Shown as Figure 2，LMI protocol can operate between two logical ports of P2P, one end is user side of UNI, the other end is network side of UNI.
L-EMI main usage :
        Notify EVC adding or deleting to CE；
        Notify EVC available status (active, non-active, partial active) to CE;
        Mutual notification with CE about UNI and EVC feature.  

LMI protocol frame format is conforming to Ethernet 2 standard，destination MAC is 01-80-C2-00-00-07，Ethernet protocol type is 0x88EE，is untagged type.

LMI message types:
        Status enquiry message
        Status message

LMI message type
        Protocol Version
        Message Type
        Report Type Information Element
        Sequence Numbers Information Element
        CE-VLAN ID/EVC Map Information Element
        UNI Status Information Element
        EVC Status Information Element
        Data Instance (DI) Information Element
        Bandwidth Profile Sub-information Element
        EVC Map Entry Sub-information Element
        UNI Identifier Sub-information Element
        EVC Identifier Sub-information Element
        EVC Parameters Sub-information Element

LMI procedure：
        System parameters
        Periodic Polling
        Sequence Numbers
        Full Status
        Full Status Continued
        Asynchronous Status
        Data Instance Triggered Update
•        UNI-C Procedures
•        UNI-N Procedures
        Reporting a New EVC
        Error Procedures
•        UNI-N Operation
•        UNI-C Operation
•        Examples of Error Procedures
        Handling of Error Conditions
•        Protocol Version Error
•        Message too short
•        Message type errors
•        General information element errors (6 types)
•        E-LMI Operational Status Determination
        UNI-C Procedures
        UNI-N Procedures

LMI data stream analysis—timing pooling:
1、        UNI-C startup，send Full Status Enquiry，UNI-N will have status response of full status  or full status continue；
2、        UNI-C T391 pooling timer（5－30 seconds，default is 10 second）timeout, send status enquiry, for these enquiry, UNI-C will make account by polling Counter（N391）, every N391 accounting period（1－65K，default 360）, UNI-C send status enquiry type is Full Status Enquiry, the rest status enquiry is E-LMI Check;
3、        After UNI-N received status enquiry, reset Polling Verification Timer, this timer is T392, for Full Status enquiry from UNI-C, UNI-N will respond Full Status, this Full Status should include one EVC status at least. If Full Status responded by UNI-N is beyond Ethernet frame length, then send multi Full Status Continued.
4、        After UNI-C received Full Status or Full Status Continued from UNI-N, analyze the message, and update with EVC, maybe add or delete or update under demand. If received Full Status Continued, then immediately send Full Status Continued, and restart T391 timer, after T391 timer is timeout, then send Full Status Continued enquiry until Full Status is received.