MSTP networking should focus on five key issues

With the full arrival of the 3G era, the MSTP service has gradually risen to a relatively higher position. The current WCDMA network as the SDH equipment for RNC-NodeB transmission routing has completely used Ethernet boards for related business up and down and business convergence. MSTP networking puts forward higher requirements. According to the current situation and specific technical requirements, it is necessary to discuss the MSTP networking, and discuss and solve the misunderstandings and problems in the networking process.

According to experience, there are currently five major problems in the MSTP networking process. The following will analyze these problems.

Confused by "user port" and "system port"

The structure of the MSTP board is completely based on the switch chip, but the loaded software is different. The Ethernet port of the switch includes 8, 16, 24, 48 and above. There is no difference between all ports. The MSTP board is also the same, that is, there is no difference between the user port and the system port. What the user port can achieve For any function, the system port can also be implemented without difference, and the performance index is also the same. The only difference is the physical firmware that the user port can be externally connected. For a more visual description, the user port can be called the external port and the system port as the internal port. Therefore, the system port mode that is generally not modified during the networking process can fully support all supported modes of the user port: access mode, trunk mode, TLS access mode, transparent transmission mode, etc., as long as this point is recognized, the MSTP group can be reduced The complexity of the network improves the performance of the network and improves the efficiency of troubleshooting. For example, in the WCDMA network, the application of SDH equipment is to access the SFE4 board of the S320 device of the ring ring to converge to the GE layer of the SEC board of the convergence layer. SFE4 corresponds to the system port. The GE port is divided into the same VLAN. The SFE4 single-board user port is set to access mode, the system port is not changed, the SEC single-board system port is not changed, the user port is set to trunk mode, and the RNC terminates the VLAN. Form an effective business. However, when we understand that there is no difference between the user port and the system port, we can set SFE4 to transparent transmission, and set the SEC single-board system port to access mode, GE port trunk mode, and RNC terminates the VLAN to form an effective service. Changes can find that the networking is simpler, there are fewer failure points, and the transmission efficiency has been improved accordingly.

MAC address learning method cannot be used smoothly

As mentioned above, only the SEC board can support the IVL mode, and other models only support the SVL mode. The difference between the SVL and IVL methods for packet processing is that the SVL method first reads the source MAC address in the packet header, and records these MAC addresses and corresponding ports in their own MAC address table, and then reads the packet header. The destination MAC address, and find the corresponding port in the MAC address table. If it finds (non-incoming port), it sends the data frame to the corresponding port; if it cannot find it, it sends it to all ports in this VLAN; IVL method first reads the source MAC address and the outermost VLAN ID in the packet header Value, and record these MAC addresses, the outermost VLAN ID value and the corresponding port in their MAC address table, and then read the destination MAC address and the outermost VLAN ID value in the packet header, according to the read MAC For address and VLAN ID values, look up the corresponding port in the MAC address table. If it is found, the data frame is sent to the corresponding port; if it is not found, it is sent to all ports in the outermost VLAN ID domain; if the received message contains the source MAC address and the destination MAC address of the port The same, the Ethernet frame is discarded. For multicast frames and broadcast frames, the switching module broadcasts to all ports except the source port in the VLAN domain where the outermost VLAN frame is located. In addition, the data packet forwarding in transparent transmission mode has nothing to do with MAC address and VLAN information.

Port mode of specific conditions cannot be effectively mastered

Access mode: The Ethernet frames expected to be received by the port do not carry any VLAN tag. After receiving such a frame, the frame will be tagged with a VLAN tag, whose VLAN ID is the PVID set later; if received Frames that already contain VLAN tags will be discarded. When forwarding frames from other ports, the port first checks whether the VLAN ID is the same as the VLAN ID of the VLAN to which the port belongs. If it matches, it strips off its VLAN tag and forwards it; if it does not match, it discards it.

Trunk mode: The Ethernet frames expected to be received by the port are all tagged with VLAN tags. After receiving such frames, the outermost VLAN tag will be checked. If the VLAN ID belongs to one of the configured VLAN IDs on this port, then directly Forward, if not, discard it.

TLS access mode: Whether the port receives a frame without any VLAN tag or a frame with one or more VLAN tags, it will add another VLAN tag to it, and its VLAN ID is the PVID set later ; When forwarding frames from other ports, first check the outermost VLAN ID, if it is the same as the VLAN ID of the VLAN to which this port belongs, strip the outermost VLAN tag and forward, if it is inconsistent, discard it.

Transparent transmission mode: indicates that the port forwards any frame directly without any processing. The transparent transmission ports need to be set in pairs.

On the basis of mastering the above modes, there are also board differences. ZTE SEC boards and other boards need to modify the TPID value to 88A8 when using the TLS access mode to transfer services. Otherwise, they will not communicate normally.

The network can not view the entire network

In MSTP networking, not only the characteristics of the SDH device board, but also whether the device connected to the SDH device can support data service standards, such as whether it can support QinQ (802.1Q standard), etc., understand that these can increase MSTP Networking flexibility.

A board is SEC board, user ports 1 and 2 are FE ports, B board is SEC board, user port 1 is GE port, B board user port 1 is connected to BAS, and A board user port 1 2 Connect to two DSLAMs respectively. BAS equipment supports QinQ, DSLAM does not support, only supports VLAN division, two DSLAMs (each containing 2000 VLANs) are aggregated through the A board user port 1, 2 to the B board GE port, when you understand the other data equipment Feature networking can set the board connected to DSLAM to transparent transmission mode, SEC board system port to TLS access mode, GE port to trunk mode, BAS and SEC board VLAN are the same, and the termination VLAN, so that business is smooth . Failure to fully understand the processing capabilities of other devices for VLANs will cause great difficulties in networking and business smoothing, which will affect service provisioning.

Problems with the connection of devices from different manufacturers

The matters needing attention when connecting MSTP networking with other manufacturers are as follows: whether the logical sequence of time slots is consistent; whether the data encapsulation type is consistent; whether the cost setting is consistent; whether the port rate is consistent with the duplex mode; on the basis of the above matters, avoid business In a loop, normal interconnection is generally possible.

Only after handling the above problems can we be invincible in the MSTP network, and we can make progress towards more complex and special requirements. The ever-changing MSTP network requires continuous improvement. The types of failures are endless and require our specific treatment. But the changes are inseparable. As long as you have mastered the L2 switching principle and board characteristics, combined with alarms and performance values, you can use them flexibly It can achieve perfect networking and ensure smooth business.

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Silicon TVS / TSS

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