CN105991445B

CN105991445B - Setting method and device of link aggregation group

Info

Publication number: CN105991445B
Application number: CN201610201761.2A
Authority: CN
Inventors: 周孟韬; 祁正林; 修亦宏; 刘刀桂
Original assignee: Hangzhou H3C Technologies Co Ltd
Current assignee: Hangzhou H3C Technologies Co Ltd
Priority date: 2016-03-31
Filing date: 2016-03-31
Publication date: 2020-07-07
Anticipated expiration: 2036-03-31
Also published as: CN105991445A

Abstract

The invention provides a method and a device for setting a link aggregation group, which are applied to a control network bridge of an extended network bridge system, wherein the message forwarding method comprises the following steps: receiving a broadcast message from a first port expander through a first cascade port; determining an aggregation port associated with a receiving expansion port of the broadcast message based on the first cascade port and the identifier of the receiving expansion port of the broadcast message; and setting a source expansion port identifier of the broadcast message based on the identifier of the aggregation port associated with the receiving expansion port of the broadcast message, and transmitting the broadcast message to the first port through the first cascade port in an expansion mode.

Description

Setting method and device of link aggregation group

Technical Field

The present invention relates to the field of communications technologies, and in particular, to a method and an apparatus for setting a link aggregation group.

Background

An Extended Bridge (Extended Bridge) is composed of a Control Bridge (CB) and a Port Extender (PE). The controlling bridge may be a single bridge or a stack of bridges.

Fig. 1 provides an existing extended bridge architecture. In fig. 1, the upstream Port (upstream Port) of the Port expander is connected to the Cascade Port (Cascade Port) of the control bridge in a one-to-one correspondence, and the Extended Port (Extended Port) of the Port expander is connected to one terminal (End Station) in a one-to-one correspondence.

The control network bridge sends the downlink message carrying the E-TAG to a port expander, and the port expander sends the downlink message to a corresponding terminal according to an expansion port corresponding to an E-channel identifier (ECID) of an expansion virtual local area network TAG (ETAG, Extension VLAN TAG). For example, the downlink message is a downlink unicast message, and the port extender sends the downlink unicast message to a terminal through a unique extension port corresponding to the downlink unicast message ECID; the downlink message is a broadcast message, the port extender copies the downlink broadcast message, and sends the downlink broadcast message to a plurality of terminals through a plurality of extension ports corresponding to the ECID of the downlink broadcast message.

Disclosure of Invention

The invention aims to provide a message forwarding method and a message forwarding device, which can be used for forwarding a broadcast message accessed by a port expander of an expanded bridge through an aggregation port of a link aggregation group.

In order to achieve the above object, the present invention provides a message forwarding method, wherein the method comprises: receiving a broadcast message from a first port expander through a first cascade port; determining an aggregation port associated with a receiving expansion port of the broadcast message based on the first cascade port and the identifier of the receiving expansion port of the broadcast message; and setting a source expansion port identifier of the broadcast message based on the identifier of the aggregation port associated with the receiving expansion port of the broadcast message, and transmitting the broadcast message to the first port through the first cascade port in an expansion mode.

In order to achieve the above object, the present invention further provides a message forwarding apparatus, wherein the apparatus includes: a receiving unit, which receives the broadcast message through the first cascade port; the control unit is used for determining an aggregation port related to a receiving expansion port of the broadcast message based on the first cascade port and the identifier of the receiving expansion port of the broadcast message; setting a source expansion port identifier of the broadcast message based on an identifier of an aggregation port associated with a receiving expansion port of the broadcast message; and the forwarding unit transmits the data through the first cascade port.

The beneficial effects of the invention at least comprise: the control bridge of the extended bridge system executes forwarding on the broadcast message which is accessed to the extended bridge by the port extender through the aggregation port of the link aggregation group, and can also prevent the broadcast message which is accessed by the aggregation port of the link aggregation group from being sent back to the port extender.

Drawings

Fig. 1 is a schematic diagram of a conventional expansion bridge.

Fig. 2 is a flowchart illustrating a method for setting a link aggregation group according to an embodiment of the present invention.

Fig. 3A and 3B are schematic diagrams of an extended bridge according to an embodiment of the present invention.

Fig. 4 is a schematic structural diagram of an extended bridge according to an embodiment of the present invention.

Fig. 5 provides a schematic structural diagram of a message forwarding apparatus according to an embodiment of the present invention.

Detailed Description

The present application is described below by way of examples shown in the drawings.

The term "comprising" as that term is used is meant to include, but is not limited to; the term "comprising" means including but not limited to; the term "based on" means based on at least a portion thereof. Furthermore, the term "a" or "an" is intended to mean one of the particular constituent.

In fig. 2, the message forwarding method provided in the embodiment of the present invention includes the following steps:

step 201, receiving a broadcast message from a first port expander through a first cascade port;

step 202, determining an aggregation port associated with a receiving expansion port of the broadcast message based on the first cascade port and the identifier of the receiving expansion port of the broadcast message;

step 203, setting a source expansion port identifier of the broadcast message based on the identifier of the aggregation port associated with the receiving expansion port of the broadcast message, and sending the source expansion port identifier of the broadcast message to the first port expander through the first cascade port.

With the message forwarding method shown in fig. 2, the control bridge of the expansion bridge performs forwarding on the broadcast message that the port expander accesses the expansion bridge through the aggregation port of the link aggregation group, and can also prevent the broadcast message that the aggregation port of the link aggregation group accesses from being sent back to the port expander.

In fig. 3A,

port expanders

31 and 32 and control bridge 33 form expansion bridge 34. The uplink (upstream link) port 31-1 of the port expander 31 is connected with the Cascade (Cascade) port Cas33-1 of the control bridge 33 by a link; the uplink port 32-1 of the port expander 32 is connected to the cascade port Cas33-2 of the control bridge 33 by a link.

Port expander 31 sends an expanded Port setup request (Extended Port Create request) message to control bridge 33 for each of expansion ports 31-2-1 and 31-2-2. Port expander 31 sends the expanded port setup request message to controlling bridge 33 via uplink port 31-1.

Port expander 32 sends an expansion port setup request message to controlling bridge 33 for expansion ports 32-2 and 32-3, respectively. Port expander 32 sends these expansion port setup request messages through uplink port 32-1.

Control bridge 33 receives an expansion port setup request message from port expander 31 via cascade port Cas33-1 and an expansion port setup request message from port expander 32 via cascade port Cas 33-2.

The control bridge 33 establishes E-channels for the expansion ports 31-2-1 and 31-2-2, respectively, and assigns ECID-31-2-1 and ECID-31-2-2 for the expansion ports 31-2-1 and 31-2-2, respectively, according to the port namespace (namespace) of the cascade port Cas33-1, for identifying the E-channels established for the expansion ports 31-2-1 and 31-2-2, respectively. The control bridge 33 sets the virtual ports VP31-2-1 and VP31-2-2 for expansion ports 31-2-1 and 31-2-2, respectively, so that expansion ports 31-2-1 and 31-2-2 appear as virtual ports VP31-2-1 and VP31-2-2 on the control bridge 33.

The control bridge 33 establishes E-channels for the expansion ports 32-2 and 32-3, respectively, and assigns ECID-32-2 and ECID-32-3 to the expansion ports 32-2 and 32-3, respectively, according to the port namespace of the cascade port Cas33-2, for identifying the E-channels established for the expansion ports 32-2 and 32-3, respectively. The control bridge 33 sets the virtual ports VP32-2 and VP32-3 for expansion ports 32-2 and 32-3, so that expansion ports 32-2 and 32-3 appear at the control bridge 33 as virtual ports VP32-2 and VP32-3, respectively.

The controlling bridge 33 records the ECID and the virtual port corresponding to the cascade interface in the uplink table, as shown in table 1-1:

TABLE 1-1

The controlling bridge 33 records the ECID and the tandem port corresponding to the virtual port in the downlink table, as shown in table 2-1:

TABLE 2-1

Control bridge 33 sends an expansion port setup response (Extended port setup response) message through cascade port Cas33-1, informing port expander 31 of the allocated ECID-31-2-1 for expansion port 31-2-1 and the allocated ECID-31-2-2 for expansion port 31-2-2, respectively. The control bridge 33 sends an expansion port setup response message through the tandem port Cas33-2 informing the port expander 32 of the assigned ECID-32-2 for expansion port 32-2 and the assigned ECID-32-3 for expansion port 32-3.

The port expander 31 receives the expansion port establishment response message, records the expansion port corresponding to the ECID in the upstream table shown in the table 3-1, and records the expansion port corresponding to the ECID in the downstream table shown in the table 4-1.

Keywords (Key)	Result Value (Value)
		31-2-1	ECID-31-2-1
31-2-1	ECID-31-2-2

TABLE 3-1

Keywords (Key)	Result Value (Value)
		ECID-31-2-1	31-2-1
ECID-31-2-2	31-2-2

TABLE 4-1

The port expander 32 receives the expansion port establishment response message, records the expansion port corresponding to the ECID in the upstream table shown in the table 5-1, and records the expansion port corresponding to the ECID in the downstream table shown in the table 6-1.

Keywords (Key)	Result Value (Value)
		32-2	ECID-32-2
32-3	ECID-32-3

TABLE 5-1

Keywords (Key)	Result Value (Value)
		ECID-32-2	32-2
ECID-32-3	32-3

TABLE 6-1

Control bridge 33 controls expansion port 31-2-1 and expansion port 31-2-2 of port expander 31 to establish a link connection with terminal 35. Control bridge 33 controls expansion port 32-2 of port expander 32 to establish a link connection with terminal 36 and controls expansion port 32-3 to establish a link connection with terminal 37.

Control bridge 33 sets up link aggregation group 31-2, sets up aggregation port LAG31-2 of link aggregation group 31-2, and associates aggregation port LAG31-2 with expansion port 31-2-1 and expansion port 31-2-2, i.e., expansion port 31-2-1 and expansion port 31-2-1 are set up as two member ports of aggregation port LAG 31-2. Control bridge 33 sets virtual port VP31-2 of aggregation port LAG31-2 such that aggregation port LAG31-2 appears on control bridge 33 as virtual port VP 31-2. The controlling bridge 33 establishes an E-channel for aggregation port LAG 31-2. Control bridge 33 assigns ECID-31-2 to aggregation port LAG31-2 according to the port namespace of cascaded port Cas33-1 for identifying the E-channel established for aggregation port LAG 31-2.

The control bridge 33 replaces the virtual port VP31-2-1 corresponding to ECID-31-2-1 and the tandem port Cas33-1 in the upstream table with virtual port VP31-2 and the virtual port VP31-2-2 corresponding to ECID-31-2-2 and the tandem port Cas33-1 with virtual port VP31-2, as shown in Table 1-2:

tables 1 to 2

The control bridge 33 records the ECID-31-2 and the tandem port Cas33-1 corresponding to the virtual port VP31-2 in the downlink table, as shown in Table 2-2:

tables 2 to 2

Control bridge 33 sends a port extender Control and Status Protocol (PE CSP) message to port extender 31, where a type-length-value (T-L-V) field of the PE CSP message carries aggregation port LAG31-2, ECID-31-2 of aggregation port LAG31-2, and extension port 31-2-1 and extension port 31-2-2 associated with aggregation port LAG 31-2.

The port expander 31 receives the PE CSP message, records the aggregation port 31 corresponding to the ECID-31-2 in the downlink table, as shown in table 4-2:

keywords (Key)	Result Value (Value)
		ECID-31-2-1	31-2-1
ECID-31-2-2	31-2-2
		ECID-31-2	LAG31-2

TABLE 4-2

Port expander 31 records the expansion port corresponding to aggregation port LAG31-2 in the aggregation port table shown in table 7.

Keywords (Key)	Result Value (Value)
		LAG31-2	31-2-1，31-2-2

TABLE 7

The port expander 31 may determine the member port associated with each aggregation port according to the aggregation port table.

As shown in fig. 3B, controlling bridge 33 sets the two physical links connecting port expander 31 with terminal 35 as a link aggregation group, which improves the reliability of the link between port expander 31 and terminal 35.

The terminal 35 selects the link connected to the expansion port 31-2-1 from the two links connected to the port expander 31 based on a load sharing algorithm to transmit the ethernet broadcast message.

The port expander 31 receives the ethernet broadcast message through the expansion port 31-2-1, inserts the expansion port virtual local area network identifier (VID, Extended port vlan ID) into the ethernet broadcast message at the ECID-31-2-1 of the expansion port 31-2-1 looked up in the uplink table shown in table 3-2, and transmits the ethernet broadcast message through the uplink port 31-1.

The control bridge 33 receives the ethernet broadcast packet with the ETAG through the cascade port Cas33-1, finds the virtual port VP31-2 in the local uplink table (shown in table 1-2) based on the ECID-31-2-1 and the cascade port Cas33-1, and determines that the aggregation port LAG31-2 enters the ingress interface (ingress port) of the extension bridge 34 with the ethernet broadcast packet.

The controlling bridge 33 learns the MAC address table entries based on the source MAC address, VLAN and virtual port VP31-2 of the ethernet broadcast message. The controlling bridge 33 replicates the ethernet broadcast message. In the invention, the control bridge 33 sets the Source Extended Port virtual local area network identifier (SVID) field of ETAG of a copied Ethernet broadcast message to ECID-31-2, replaces VID of ETAG with broadcast ECID, and sends the broadcast ECID through the cascade Port Cas 33-1. In the present invention, the link aggregation group of the port expander 31 is connected to the terminal 35, and the control bridge 33 determines that the ingress interface is a member port associated with the aggregation port LAG31-2 according to the VID of the uplink ethernet broadcast packet, so that the control bridge 33 sets the ECID31-2 of the aggregation port LAG31-2 in the SVID of the downlink ethernet broadcast packet, thereby preventing the port expander 31 from transmitting the downlink unicast broadcast packet from the terminal 35 through the aggregation link group.

The controlling bridge 33 sets the VID of the ETAG of a duplicated ethernet broadcast packet to broadcast the ECID, and sends it through the cascade port Cas 33-2. If the controlling bridge 33 is also connected to one or more devices (e.g., terminals or switches) within the same VLAN, the switch controlling bridge 33 deletes the ETAG of the replicated ethernet broadcast packet(s) and broadcasts it via one or more physical ports of the same VLAN. When the control bridge sends the uplink Ethernet broadcast message received by one cascade port through the other cascade port, the control bridge does not need to copy the SVID of the ETAG of the downlink Ethernet broadcast message according to the VID field of the ETAG of the uplink Ethernet broadcast message.

The port expander 31 broadcasts the message through the ethernet received by the uplink port 31-1, where the VID of the ETAG is the broadcast ECID and the SVID is ECID-31-2. The port expander 31 finds that the port list of the broadcast ECID includes an aggregation port LAG31-2, and determines that the ECID-31-2 of the SVID field corresponds to the aggregation port LAG31-2 of the port list of the broadcast ECID, so that the broadcast message is not sent through the aggregation port LAG31-2 of the port list of the broadcast ECID.

The port expander 32 broadcasts the message via the ethernet received by the uplink port 32-1, where the VID of the ETAG is the broadcast ECID. Port expander 32 finds the list of ports that broadcast the ECID to include expansion port 32-2 and expansion port 32-3. The port expander removes the ETAG, copies the ethernet broadcast packet, expands the ports 32-2 and 32-3 to transmit the ethernet broadcast packet, and broadcasts the ethernet broadcast packet to the

terminals

36 and 37, respectively.

The terminal 37 sends an ethernet broadcast message. The port expander 32 receives the ethernet broadcast message through the expansion port 32-2, inserts ETAG with VID of the ECID-32-2 into the ethernet broadcast message based on the ECID-32-2 looked up by the expansion port 32-2 in the local uplink table (as shown in table 5-1), and transmits the ethernet broadcast message through the uplink port 32-1.

The control bridge 33 receives the ethernet broadcast message with the ETAG through the cascade port Cas33-2, finds the virtual port VP32-2 in the local uplink table (as shown in table 1-2) based on the ECID-32-2 and the cascade port Cas33-2, and learns the MAC address table entry according to the source MAC address, VLAN, and virtual port VP32-2 of the ethernet broadcast message. The controlling bridge 33 replicates the ethernet broadcast message. The control bridge 33 copies the ECID-32-2 of the VID field of the ETAG of a duplicated ethernet broadcast packet to the SVID field, replaces the VID of the ETAG with the broadcast ECID, and sends it over the cascade port Cas 33-2. In the present invention, the control bridge 33 determines that ECID-32-2 is the ECID of a single expansion port, and directly copies the ECID-32 of the VID field to the SVID, thereby avoiding the Ethernet broadcast message from being sent back to the terminal 37.

The controlling bridge 33 sets the VID of the ETAG of a duplicated ethernet broadcast packet to broadcast the ECID, and sends it through the cascade port Cas 33-1. The controlling bridge 33 deletes the ETAG of one or more replicated ethernet packets and broadcasts it to one or more terminals, switches, via one or more physical ports of the same VLAN.

The port expander 32 finds that the port list of the broadcast ECID includes the expansion port 32-2 and the expansion port 32-3 by using the VID of the ETAG of the ethernet broadcast packet received through the uplink port 32-1 as the broadcast ECID. Port expander 32 determines that ECID-32-2 of the SVID field corresponds to an expansion port 32-2 of the port list broadcasting the ECID. The port expander 32 removes the ETAG, transmits the ethernet broadcast packet through the expansion port 32-3, and broadcasts the ethernet broadcast packet to the terminal 36.

The port expander 31 finds that the port list of the broadcast ECID includes LAG31-2 by using the VID of the ETAG of the ethernet broadcast packet received through the uplink port 31-1 as the broadcast ECID. The port extender 31 removes the ETAG, selects the extension port 31-2-2 from the extension ports 31-2-1 and 31-2-2 associated with the aggregation port LAG31-2 shown in table 7 based on the load algorithm, transmits the ethernet broadcast packet through the extension port 31-2-2, and transmits the ethernet broadcast packet to the terminal 35.

The ethernet broadcast message may be a data message or a protocol message, such as an ARP request message. In fig. 3B, when the control bridge 33 receives the ethernet broadcast packet of the same VLAN from the external two-layer network, the control bridge 33 sends the downlink ethernet broadcast packet through the cascade ports Cas33-1 and 33-2, the port expander 31 sends the downlink ethernet broadcast packet through the link aggregation group, and the port expander 32 sends the downlink ethernet broadcast packet through the expansion ports 32-2 and 32-3, which please refer to the above description.

The terminal 37 sends an ethernet unicast message to the terminal 35, wherein the source MAC address is the MAC address of the terminal 37 and the destination MAC address is the MAC address of the terminal 35. The port extender 32 receives the ethernet unicast message through the extension port 32-2, finds the ECID-32-2 in the local uplink table (as shown in table 5-1) based on the extension port 32-2, inserts the ETAG with VID of the ECID-32-2 into the ethernet unicast message, and transmits the ethernet unicast message through the uplink port 32-1.

The control bridge 33 receives the ethernet unicast message with the ETAG through the cascade port Cas33-2, and finds out the matched virtual port VP32-2 based on the destination MAC address and VLAN lookup. That is, the control bridge determines that the aggregation port LAG32-2 corresponding to virtual port VP32-2 is an egress port (egress port) based on the learned MAC address.

The control bridge 33 looks up the ECID-31-2 and the tandem port Cas33-1 in a local downstream table (as shown in table 1-2) according to the virtual port VP32-2, modifies the VID of the ethernet unicast ETAG to ECID-31-2, and sends it through the tandem port Cas 33-1.

The VID of the ETAG of the ethernet unicast packet received by the port expander 31 through the uplink port 31-1 is ECID-31-2, and the LAG31-2 is found in the local downlink table (as shown in table 4-2) based on the ECID-31-2. Port expander 31 removes the ETAG, selects expansion port 31-2-1 from expansion ports 31-2-1 and 31-2-2 (as shown in table 7) associated with aggregation port LAG31-2 based on a load algorithm, transmits through expansion port 31-2-1, and unicast-forwards the ethernet to terminal 35.

The ethernet unicast message may be a data message or a protocol message, such as an ARP response message. In fig. 3B, in the extension bridge 34, when the control bridge 33 receives the ethernet unicast packet of the same VLAN from the external two-layer network, the control bridge 33 finds the corresponding virtual port VP31-2 according to the destination MAC address, and sends the downstream ethernet unicast packet through the cascade port Cas33-1, where the VID of the ETAG is ECID-31-2, and the port extender 31 sends the downstream ethernet unicast packet through the link aggregation group, which refers to the above description.

In fig. 4,

network devices

441 and 442 are linked by a stack and form a stack device 44, and

network devices

441 and 442 perform master election and network device 442 is elected as the master of stack device 44. The stack device 44 operates as a control bridge 44. The port expanders 41-43 and the control bridge 44 constitute an expansion bridge 45.

Control bridge 44 sets the three physical links of port expander 41 to terminal 46 as link aggregation group 41-2, improving the reliability of the links between port expander 41 and terminal 46.

Control bridge 44 assigns an ECID to aggregation port LAG41-2 of the link aggregation group according to the port namespace for the cascading ports of network device 441 connection port expander 41.

The manner in which the control bridge 44 sends the downlink ethernet broadcast packet and the downlink ethernet unicast packet is the same as that of the control bridge 33 in fig. 3B; the port extender 41 sends the downlink message and the uplink message in the same manner as the port extender 31 sends the downlink message (e.g., the downlink ethernet broadcast message and the downlink ethernet unicast message) and the uplink message (e.g., the downlink ethernet broadcast message and the downlink ethernet unicast message) in fig. 3B. This embodiment will not be described in detail.

Fig. 5 shows a message forwarding apparatus 50 provided in the present invention, where the apparatus 50 can be applied to a port expander of an extended bridge system. As shown in fig. 5, the message forwarding apparatus 50 includes: receiving section 501, control section 502, and forwarding section 503.

The receiving unit 501 receives a broadcast packet through a first cascade port. A control unit 502, configured to determine, based on the first cascade port and the identifier of the receiving expansion port of the broadcast packet, an aggregation port associated with the receiving expansion port of the broadcast packet; and setting the source expansion port identification of the broadcast message based on the identification of the aggregation port associated with the receiving expansion port of the broadcast message. The forwarding unit 503 sends the packet through the first cascade port.

The receiving unit 501 receives a first unicast packet through a first cascade port. The control unit 502 determines, based on the first cascade port and the identifier of the receiving expansion port of the first unicast packet, an aggregation port associated with the receiving expansion port of the first unicast packet. A forwarding unit 503, performing source address learning based on the source address of the first unicast message and the aggregation port associated with the receiving expansion port of the first unicast message; and sending the first unicast message based on the output port associated with the destination address of the first unicast message.

The receiving unit 501 receives the second unicast packet through the second cascade port. The forwarding unit 503 determines a sending aggregation port associated with the destination address of the second unicast packet. The control unit 502 determines the identifier of the sending aggregation port and the third concatenation port associated with the destination address of the second unicast message; and setting the extension port identifier of the second unicast message based on the identifier of the sending aggregation port associated with the destination address of the second unicast message. The forwarding unit 503 sends the packet through the third cascade port.

The receiving unit 501 receives the third unicast packet through the two-layer port. The forwarding unit 503 determines a sending aggregation port associated with the destination address of the third unicast packet. The control unit 502 determines the identifier of the sending aggregation port and the fourth concatenation port associated with the destination address of the third unicast message; and setting the extension port identifier of the fourth unicast message based on the identifier of the sending aggregation port associated with the destination address of the fourth unicast message. The forwarding unit 503 sends the third unicast packet through the fourth tandem port.

The above description is only for the purpose of illustrating the preferred embodiments of the present invention and is not to be construed as limiting the invention, and any modifications, equivalents, improvements and the like made within the spirit and principle of the present invention should be included in the scope of the present invention.

Claims

1. A message forwarding method is characterized in that the method comprises the following steps:

issuing a PE CSP message to a first port expander, wherein the PE CSP message comprises an expansion port associated with the identification of the aggregation port;

receiving a broadcast message from a first port expander through a first cascade port;

determining an aggregation port associated with a receiving expansion port of the broadcast message based on the first cascade port and the identifier of the receiving expansion port of the broadcast message; setting an identifier of a convergence port associated with a receiving expansion port of the broadcast message as a source expansion port identifier of the broadcast message, and sending the identifier to a first port expander through the first cascade port, so that the first port expander determines an expansion port associated with the identifier of the convergence port in the broadcast message according to the expansion port associated with the identifier of the convergence port in the PE CSP message, and filters the broadcast message, wherein the broadcast message is a downlink Ethernet broadcast message; wherein the aggregation port is associated with a plurality of expansion ports of the first port expander; wherein, the plurality of expansion ports are connected with the same terminal.

2. The method according to claim 1, characterized in that it comprises:

receiving a first unicast message from the first port expander through the first cascade port;

determining an aggregation port associated with a receiving expansion port of the first unicast message based on the first cascade port and the identifier of the receiving expansion port of the first unicast message;

performing source address learning based on the source address of the first unicast message and the aggregation port associated with the receiving expansion port of the first unicast message;

and sending the first unicast message based on an outlet port associated with the destination address of the first unicast message.

3. The method according to claim 1, characterized in that it comprises:

receiving a second unicast message from a second port expander through a second cascade port;

determining a sending aggregation port associated with a destination address of the second unicast message;

determining the identifier of the sending aggregation port and a third level connection port associated with the destination address of the second unicast message;

and setting an expansion port identifier of the second unicast message based on the identifier of the sending aggregation port associated with the destination address of the second unicast message, and sending the expansion port identifier of the second unicast message to a third port expander through the third cascade port.

4. The method according to claim 1, characterized in that it comprises:

receiving a third unicast message through a two-layer port;

determining a sending aggregation port associated with the destination address of the third unicast message;

determining the identifier of the sending aggregation port and a fourth concatenation port associated with the destination address of the third unicast message;

and setting an extension port identifier of the fourth unicast message based on the identifier of the aggregation sending port associated with the destination address of the fourth unicast message, and sending the third unicast message to a fourth port extender through the fourth cascade port.

5. A message forwarding apparatus, the apparatus comprising:

the issuing unit issues a PE CSP message to the first port expander, wherein the PE CSP message comprises an expansion port associated with the identification of the aggregation port;

a receiving unit, which receives the broadcast message through the first cascade port;

the control unit is used for determining an aggregation port related to a receiving expansion port of the broadcast message based on the first cascade port and the identifier of the receiving expansion port of the broadcast message; setting the identifier of the aggregation port associated with the receiving expansion port of the broadcast message as the identifier of the source expansion port of the broadcast message; wherein the aggregation port is associated with a plurality of expansion ports of the first port expander; the plurality of expansion ports are connected with the same terminal;

and the forwarding unit is used for sending the broadcast message through the first cascade port device so that the first port expander determines the expansion port associated with the identification of the aggregation port in the broadcast message according to the expansion port associated with the identification of the aggregation port in the PE CSP message, and filters the broadcast message, wherein the broadcast message is a downlink Ethernet broadcast message.

6. The apparatus of claim 5,

the receiving unit receives a first unicast message through the first cascade port;

the control unit determines an aggregation port associated with a receiving expansion port of the first unicast message based on the first cascade port and the identifier of the receiving expansion port of the first unicast message;

the forwarding unit learns the source address based on the source address of the first unicast message and the aggregation port associated with the receiving expansion port of the first unicast message; and sending the first unicast message based on an outlet port associated with the destination address of the first unicast message.

7. The apparatus of claim 5,

the receiving unit receives a second unicast message through a second cascade port;

the forwarding unit determines a sending aggregation port associated with a destination address of the second unicast message;

the control unit determines the identifier of the sending aggregation port and the third cascade port associated with the destination address of the second unicast message; setting an extension port identification of the second unicast message based on an identification of a sending aggregation port associated with a destination address of the second unicast message,

and the forwarding unit sends the data through the third cascading port.

8. The apparatus of claim 5,

the receiving unit receives a third unicast message through a two-layer port;

the forwarding unit determines a sending aggregation port associated with a destination address of the third unicast message;

the control unit determines an identifier of a sending aggregation port and a fourth concatenation port associated with a destination address of the third unicast message;

setting an extension port identifier of a fourth unicast message based on an identifier of a sending aggregation port associated with a destination address of the fourth unicast message;

and the forwarding unit sends a third unicast message through the fourth cascade port.