Cisco multi-channel STM-1 module function test

Cisco multi-channel STM-1 module function test

Abstract: At present, the method of using the CISCO multi-channel STM-1 module to consolidate multiple SDH 2Mbit / s dedicated lines has gradually been widely used. Used on the network. In order to have a more comprehensive understanding of the function of the module, in order to enable Beijing Communications to better provide services to users, we conducted this function experiment. The test method is to configure a multi-channel STM-1 module on a CISCO 7507 router, and use one of the 2Mbit / s channels to interconnect with a low-end router at a rate of 2Mbit / s via the SDH network; Two 64kbit / s time slots are bound in the 2Mbit / s channel and interconnected with another low-end router at 128kbit / s via SDH and DDN. The purpose of the experiment is to test whether the multi-channel module can communicate with the low-end router through the 2Mbit / s and 128kbit / s channels in the network layer. Through the test, the results show that the multi-channel STM-1 module split 2Mbit / s and N × 64kbit / s function is normal, the network communication is normal, can provide such services to users based on Beijing Communication Network.
Keywords: channelization; STM-1; multiplexing

1 Experimental background

With the development of information and communication technology, many users' demands for communication are increasing day by day, and higher demands are placed on the number and bandwidth of dedicated line circuits. When users need to rent multiple 2Mbit / s private lines to access a central point, the traditional method is to install a synchronous digital system (Synchronous Digital Hierarchy, SDH) at the central point if the number of 2Mbit / s circuits is large. ) Optical transceiver to provide N 2Mbit / s ports; if the number of 2Mbit / s circuits is small, the 2Mbit / s circuits will be extended to the central point through a high-rate digital subscriber loop (HDSL) modem ; Users need to configure a large number of E1 interfaces on the router to connect 2Mbit / s dedicated lines to the central network one by one. When a user leases a large number of 64kbit / s Digital Data Network (DDN) dedicated lines, multiple 64kbit / s DDN dedicated lines are also aggregated into multiple channelized E1 (CE1) circuits through DDN. SDH or HDSL bearer access to the user's central point.

It can be seen that when a large number of 2Mbit / s circuits are converged to the central point, if all routers are accessed by 2Mbit / s dedicated lines, then the router is required to provide a large number of E1 / CE1 interfaces, which will be affected The limitation of the board and the slot, and the large number of cables and jumpers will also cause inconvenience in maintenance and management, and the number of fault points will increase accordingly, and the obstacle rate will also increase. Therefore, when we design network solutions for users, we will avoid this networking method as much as possible, but recommend that users configure multi-channel STM-1 modules (MulTIChannel STM-1 Port Adapter, PA-MC-STM-1) on routers To complete the convergence access of multiple 2Mbit / s circuits.

At present, Cisco has officially launched the PA-MC-STM-1 module, and some users have successfully split multiple 2Mbit / s dedicated lines using this module, but no users have used its split N in Beijing. × 64kbit / s function. Therefore, in order to make our solution more practical, in order to provide users with a more secure and reliable network guarantee, and in order to improve the service quality of Beijing Communications, the System Integration Department is responsible for the organization, implementation and field testing. With the assistance of the dedicated network maintenance department, the transmission center of the network management department, the network supervision center and other relevant units, a test was conducted to split the 2Mbit / s and N × 64kbit / s functions of the Cisco multi-channel STM-1 module.

2 PA-MC-STM-1 module
2.1 Introduction to the module

PA-MC-STM-1 is an ideal solution for today's fast-growing wide-area interconnection needs. It adapts to different interconnection service needs and can provide access to dedicated line circuits and frame relay services at the same time. At the same time, users can use a STM-1 to achieve a large number of remote site access, but also users do not have to do too much consideration for what kind of router interface module should be configured.

PA-MC-STM-1 is a channelized module designed for interconnection of routers above CISCO 7200 series and SDH. It provides the ability to access 63 E1 circuits through a pair of optical fibers, instead of the traditional 63 The way that independent wire pairs access E1 circuit. This module reduces the complexity of wiring, and once the relevant data is configured, when the new E1 circuit is leased, the free channel can be used to realize "lease and use" without the need for hardware expansion and additional configuration Convenient. When a low-rate dedicated line is required, such as N × 64kbit / s, the module can support up to 256 channel groups, and the lowest 64kbit / s sub-rate circuit can be split.

2.2 Key features of the module

ï¿  One channelized STM-1 port;
ï¿  Support channelized E1, fracTIonal E1, and full-rate E1,

-Up to 256 channels can be configured in 63 E1,
-For each E1, you can choose internal clock or network clock,
-The minimum time slot of 64kbit / s can be split;

ï¿  Support frame relay, PPP, HDLC serial port encapsulation protocol; ï¿  Support IP, IPX network protocol;
ï¿  Support CRC-4 check;
ï¿  Support SDH 1 + 1 multiplex section protection.

2.3 Requirements for routers

For CISCO 7500 series routers, the requirements are:
ï¿  VIP4-80 (VersaTIle Interface Processor, general interface processor) or above;
ï¿  RSP4 (Route Switch Processor), RSP4 + or RSP8;
ï¿  CISCO IOS (Internet OperaTIon System, Internet Operating System) version 12.0 (14) S, 12.0 (16) S or 12.1 (5) E.

3 Experimental environment

The network connection for this test is shown in Figure 2.

Figure 2 Test network connection diagram

3.1 Laboratory room

On a CISCO 7507 router (hereinafter referred to as 7507) in the laboratory, we configured a multi-channel STM-1 module to provide an STM-1 single-mode optical interface. In this test, the module will test the function of splitting 2Mbit / s and 128kbit / s dedicated circuit at the same time.
At the same time, a Huawei 3640 router (hereinafter referred to as 3640) was also placed in the experimental computer room. The router was equipped with a CE1 module with interface type DB-25 (4E1). The first CE1 interface was used in this experiment. Through the conversion cable, it can provide 120Ω, G.703 interface.

3.2 Transmission room

A 4 × STM-1 optical interface tributary board was expanded on the LUCENT ADM16 / 1 (Add and Drop Multiplexer, Add and Drop Multiplexer) optical transceiver (hereinafter referred to as ADM16 / 1) in the transmission equipment room, and occupied one of the interfaces It is interconnected with the multi-channel STM-1 module of 7507 in the laboratory.

3.3 DDN computer room

In the DDN computer room, a CISCO 2611 router (hereinafter referred to as 2611) was placed, equipped with a synchronous serial port, connected to an I24 Modem and connected to DDN. Through network management configuration, the rate of I24 Modem is set to 128kbit / s.

3.4 Dedicated line circuit

We applied for two private lines, one is a 128kbit / s DDN private line, one end is connected to 2611 in the DDN computer room via the Modem; the other end is imported into a CE1 through the DDN node machine, and then mapped to a VC12 of STM-1 through ADM16 / 1 7507 router in the test room.

The other is a 2Mbit / s dedicated transmission line. One end is connected to the CE1 interface of 3640 in the experiment room; the other end is mapped to another 7507 in the test room through ADM16 / 1 mapped to another VC12 of STM-1.

4 Experimental content

1. First, the DDN network management configures the data and binds the first and second time slots of a CE1 to 128kbit / s (to configure the data on the DDN node machine, we first use the loop to make this dedicated line work normally), and then the transmission network management The configuration data maps this CE1 to AU-4 / 1 (indicating the first AU-4), TUG-3 / 1, and TUG-2 / 1 in VC12 / 1. Configure relevant data on the multi-channel STM-1 interface of 7507 and the serial port of C2611, observe whether the LINE and LINE PROTOCOL of this sub-interface are both UP, and perform PING test with each other to check whether the network is working properly.

2. The transmission network management configuration data maps a 2Mbit / s to the VC12 / 2 of AU-4 / 1, TUG-3 / 1, TUG-2 / 1, on the multi-channel STM-1 interface of 7507 and CE1 interface of 3640 Configure relevant data, observe whether the LINE and LINE PROTOCOL of the two sub-interfaces are both UP, and perform PING test with each other.

5 Experimental data configuration

Before giving the experimental configuration data, first introduce the multiplexing structure of PA-MC-STM-1, as shown in Figure 3.

Figure 3 PA-MC-STM-1 multiplexing structure

STM-1 is formed by multiplexing one AU-4 or 3 AU-3s. In this test, one AU-4 is multiplexed into one STM-1. Each AU-4 can have 3 TUG-3 transmission channels, each TUG-3 / AU-3 can be configured to carry 21 TU-12, each TU-12 can carry 1 channelized E1 frame, each E1 Frames can be split into N × 64kbit / s time slot combinations.

Each E1 can be set to the fractional E1 specified by CCITT / ITU G.704 and G.706. Fractional E1 is a subset of the entire E1, the rate grade can be N × 64kbit / s, and N is 1 ~ 31. The unused E1 channel cannot be accessed, and the idle information that can be set is transmitted (0x0 to 0xFF in hexadecimal, that is, 0 to 225 in decimal). At the same time, each E1 can also be configured as unframed E1 that does not contain any framing information. Unframed E1 is a special case of fractional E1.

According to the above multiplexing principle, the following configuration data is given:

1. CISCO 7507 router test data configuration:
Router (config) #Controller sonnet 1/1/0
Router (config-controller) #framing sdh
Router (config-controller) #clock source line
Router (config-controller) #aug mapping au-4
Router (config-controller) # au-4 1 tug-3 1
Router (config-controller-tug-3) #mode c-12
Router (config-controller-tug-3) # tug-2 1 e1 1 channel-group 1
timeslots 1-2
Router (config-controller-tug-3) # tug-2 1 e1 1 framing no crc4
Router (config-controller-tug-3) # tug-2 1 e1 2 unframed
Router (config-controller-tug-3) #idle pattern 0x0
Router (config-controller-tug-3) #exit
Router (config-controller) #exit
Router (config) #interface serial 1/1 / 0.1 / 1/1/1: 1
Router (config-if) #ip address 192.168.1.1 255.255.255.0
Router (config-if) #encapsulation hdlc
Router (config-if) #no shutdown
Router (config-if) #exit
Router (config) #interface serial 1/1 / 0.1 / 1/1/2: ​​0
Router (config-if) #ip address 192.168.2.1 255.255.255.0
Router (config-if) #encapsulation hdlc
Router (config-if) #no shutdown
Router (config-if) #end
Router # write
Router # sh run
controller SONET 1/1/0
framing sdh
!
au-4 1 tug-3 1
idle pattern 0x0
tug-2 1 e1 1 cannel- 1 timeshlots 1-2
tug-2 1 e1 1 framing no-crc4
tug-2 1 e1 2 unframed
!
interface Serial1 / 1 / 0.1 / 1/1/1: 1
ip address 192.168.1.1 255.255.255.0
encapsulation hdlc
!
interface Serial1 / 1 / 0.1 / 1/1/2: ​​0
ip address 192.168.2.1 255.255.255.0
encapsulation hdlc
!

2. CISCO 2611 router test data configuration:
Router # config t
Router (config) #interface serial 0/0
Router (config-if) #ip address 192.168.1.2 255.255.255.0
Router (config-if) #encapsulation hdlc
Router (config-if) #no shutdown
Router (config-if) #end

3. Huawei 3640 router test data configuration:
Router # config t
Router (config) #controller e1 0
Router (config-if-E1-0) #using e1
Router (config-if-E1-0) #clock line
Router (config-if-E1-0) #linecode hdb3
Router (config-if-E1-0) #no shutdown
Router (config-if-E1-0) #exit
Router (config) #interface s0: 0
Router (config-if-Serial0: 0) #ip address 192.168.2.2 255.255.255.0
Router (config-if-Serial0: 0) # encapsulation hdlc
Router (config-if-Serial0: 0) #no shutdown
Router (config-if-Serial0: 0) #end

6 Test process

In an experiment, the result is important, but the process is more important. Without a process, there is no result, and from the process we can grow a lot of knowledge, gain a lot of experience, and enrich the content of the results, providing a valuable reference for future practical applications. Below, I will give a rough description of the test process.

In the course of the experiment, we have done loop circuit tests on transmission and DDN equipment many times, using loop means to help locate and eliminate faults. In order to describe the loop test process more clearly, the position of the loop is marked with letters (A, B, C,) on the schematic diagram of FIG. 4.

Figure 4 Schematic diagram of loop test

After the network management has configured the relevant data, the physical lines are all connected, and the network devices are also connected, we first check the port and protocol status from the router and find that the LINE and LINE PROTOCOL of these two lines are DOWN, indicating that there is a problem with the line. So we roughly followed the steps below.

1. Because the LINE status of the sub-ports connecting the two lines is DOWN, the first thought is that the entire 155Mbit / s channel may not be connected. At the same time, we found that the RxCXR light on the multi-channel STM-1 module is not lit, which confirms that there must be a fault in the optical path from the optical interface of the ADM16 / 1 to the module. In general, most of these problems are caused by optical fibers, and rarely caused by equipment. So we replaced a pair of optical fibers, the fault phenomenon disappeared, and the LINE status of the sub-ports of the two lines became the UP status, indicating that not only the entire optical path has been normal, but also the section of the circuit from the router to ADM16 / 1 The configuration on the VC12 level is matched, and the 2Mbit / s physical path of this segment works normally.

2. After LINE UP, LINE PROTOCOL is still DOWN, so we started to check the 2Mbit / s dedicated line of VC12 / 2.

The state of the PA-MC-STM-1 LED indicator is shown in Table 1.

Table 1

(1) First, loop this 2 Mbit / s in the direction of 7507 at the ADM16 / 1 A position, and find that the LINE PROTOCOL UP of this E1 subport in the multi-channel STM-1 module is LOOPED, indicating that 7507 saw the loop. The 2M path from SDH to 7507 is normal. Then make a loop in the direction of 3640 at the A position and find that the LINE PROTOCOL status of the E1 interface of the 3640 is still DOWN. Therefore, we concluded that there should be a problem with the 2Mbit / s line between ATM16 / 1 and 3640.

(2) So we used a 2M meter to cross-connect the test at the DDF2 (Digital Distribution Frame) position. The test results show that the attenuation of the transmission line is very large, about 16DdB, indicating the direction of transmission from DDF2 to DDF1 Of the jumpers, there must be a jumper connector that is not properly connected. So we removed the DDF2 jumper and re-jumped, and tested it with a 2M meter, and found that the attenuation was still very large. We also removed the jumper at DDF1 and re-jumped, or the attenuation was large, so the fault range was narrowed. It's the last joint.

(3) We made an RJ45 plug at one end of the 2Mbit / s cable that jumped out of DDF1. In order to interconnect with the RJ45 plug of the 3640 E1 cable, we used an RJ45 socket-to-socket converter, connecting the 2Mbit / s jumper and E1 cable. The fault appears here. One of the RJ45 sockets and plugs are loosely connected, which results in poor connection of the line, so the entire 2Mbit / s line is attenuated too much. After treatment, the fault disappeared, the E1 sub-port LINE PROTOCOL status of the multi-channel STM-1 became UP, and this 2Mbit / s line was finally tuned.

3. After the 2Mbit / s line is connected, we begin to deal with the problem of 128kbit / s dedicated line, mainly through the following steps:

(1) We first made 2Mbit / s loops at 7507 and 2611 in the ADM16 / 1 A position, and found that the loops were detected by both parties, and the LINE PROTOCOL status became UP and LOOPED. This means that from the SDH side, all channels are normal. The 7507 can detect a 2Mbit / s loop, and the 2611 can also detect this loop after passing the DDN.

(2) Then, we make a loop on both sides of the CE1 trunk port (position B) of the DDN node machine. Similarly, the status of LINE PROTOCOL of 7507 and 2611 are both UP, indicating that we start from the trunk port of the DDN node machine Looking from both sides, all passages are normal.

(3) After the CE1 loop was completed, the problem could not be found, so we made a loop at the V35 port (C position) of the DDN node machine. At this time, it was found that the 2611 could detect the loop, LINE PROTOCOL UP, and the corresponding E1 subport of the channelized STM-1 module on the 7507 could not detect the loop, and the corresponding LINE PROTOCOL status was still DOWN.

(4) After finding the problem, we conducted a cross-over test at DDF2 using the 2Mbit / s table, and found that there is no alarm in the 2M sending direction, the path is normal, and the REMOTE alarm in the receiving direction, that is, the remote from 7505 End (advice) alarm. At the same time, when we disconnected the 7507 optical fiber and looped the optical fiber toward the ADM16 / 1 in the ODF1 (Optical Fiber Distribution Frame, optical fiber distribution frame), we then tested the 2Mbit / s receiving direction with the 2M meter and found that the REMOTE alarm disappeared , 2Mbit / s transmission and reception are normal.

(5) According to the above test phenomena, after an in-depth and detailed analysis, we finally believe that the multi-channel STM-1 module does not completely match the parameters of the DDN node machine in the configuration of certain parameters, and it is Parameters related to frame format. The reasons are as follows:

From the test results of the 2M table, the reason why the REMOTE alarm will appear in the 2Mbit / s receiving direction, and the alarm will disappear after disconnecting 7507, the reason should be when the 7505 receives the 2Mbit / s information frame assembled and sent by the DDN node machine When the frame format is not correct, a REMOTE alarm is sent back, indicating that it does not match the remote device (DDN node machine) and cannot correctly identify the 2Mbit / s information frame.

From the DDN loop test results, when the loop is performed on the CE1 trunk port (position B) of the DDN node machine, the status of the E1 subport of the 7507 is UP, and the DDN node machine does not reset the 2Mbit / s at this time. Framing. When looping from the DDN node machine V35 port (C position), because the 2Mbit / s frame is sent to 7507 after reassembly by the DDN node machine, the frame format may not match the frame format set by 7507, so E1 The LINE PROTOCOL status of the subport is DOWN.

(6) After the above analysis and positioning of the problem, we decided to start with the parameters, carefully check the parameters of the DDN node machine and the parameters of 7507, and check them one by one. The CE1 parameter of the DDN node machine is relatively simple, generally defaults to 1 ~ 31 slot frame format, CRC4 DISABLE. The corresponding E1 subport on the channelized STM-1 is also set to use 1 ~ 31 time slots to transmit data, but the default value of the CRC4 parameter is ENABLE, which is inconsistent with the DDN node machine. Therefore, we changed the CRC4 parameter of the router to "NO CRC4", and regenerated a 128kbit / s circuit on the DDN network management, so the 128kbit / s circuit was finally debugged, and the LINE PROTOCOL state became UP .

So far, the two dedicated lines have been tuned up and the test was successful.

7 Prone problems

Through this period of testing, we have summarized some faults that are prone to occur and the corresponding treatment methods for reference.

1. Fiber failure and failure phenomenon: The RxCXR LED indicator on the PA-MC-STM-1 panel is off, and the LINE status of all sub-ports is DOWN.
· Cause of failure: The optical fiber is disconnected.
· Troubleshooting: Check and clean the fiber connector or replace the fiber.

2. 2Mbit / s physical line failure · Fault phenomenon: For E1 dedicated line circuit, the LINE status of PA-MC-STM-1 E1 sub-port is UP, LINE PROTOCOL status is DOWN, and the LINE status of the peer router E1 port is DOWN; The 2M meter measures excessive attenuation or detects open circuit (LOS).
· Fault reason: 2Mbit / s jumper connector is not connected properly, jumper jumper connection error.
· Troubleshooting: Check the jumper connector or change the jumper.

3. Parameter configuration issues and symptoms: For N × 64kbit / s dedicated line circuits, loops are detected on the DDN CE1 port, both routers can detect loops, and loops from the DDN V35 port, and low-end routers can detect loops. The high-end router cannot detect the 2Mbit / s loop.
· Cause of failure: The parameters between the router and the DDN do not match.
· Troubleshooting: Check the framing format (1 ~ 31 time slot) and CRC-4 parameters.

8 Experimental conclusion

Through experiments, it is confirmed that the function of PA-MC-STM-1 to split 2Mbit / s and N × 64kbit / s is normal, and such services can be provided to users based on Beijing Communications ’DDN and SDH networks.

9. Suggestions for business opening

When users first apply for N × 64kbit / s to import into CE1 and then into STM-1 service, it is recommended that before the formal opening of the dedicated line service, a certain amount of time should be set aside for the telecommunication maintenance department to cooperate with the user in circuit commissioning and operation observation Make sure to open in batches after running for a period of time without problems in order to provide users with highly reliable and high-quality services.

The telecommunication maintenance department should cooperate closely with the users when troubleshooting the dedicated line. This type of dedicated line has many intermediate links and involves different maintenance departments, which brings certain difficulties to troubleshooting. At the same time, when dealing with obstacles, users also need to cooperate to check the status of their network equipment and lines. Therefore, we should be anxious for users to worry about, think about what users think, work closely with users to solve problems for users as soon as possible, and show the high-tech and high-level corporate image of Beijing Communications.

10 Management and maintenance of PA-MC-STM-1

The following are the maintenance management commands for the PA-MC-STM-1 of the CISCO 7507 router, which are often used in daily maintenance.

· Check the router system hardware configuration, interface type number, IOS software version number, name Router # show version (or "show hardware")

· View PA-MC-STM-1 port errors and performance data Router # show controller sonnet slot / port-adapter / port [brief | tabular]

View the error and performance data of PA-MC-STM-1 subport Router # show controller sonnet slot / port-adapter / port.au-4-number / tug-3-
number / tug-2-number / e1-number [brief | tabular]

· View PA-MC-STM-1 subport status and statistics Router # show interface serial slot / port-adapter / port.au-4-number / tug-3- /

number / tug-2-number / e1-number: channel-group-number

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