CN1194508C

CN1194508C - Multicasting messag transmission method base on two layer exchange device

Info

Publication number: CN1194508C
Application number: CNB02117802XA
Authority: CN
Inventors: 张群
Original assignee: Huawei Technologies Co Ltd
Current assignee: Huawei Technologies Co Ltd
Priority date: 2002-05-15
Filing date: 2002-05-15
Publication date: 2005-03-23
Anticipated expiration: 2022-05-15
Also published as: CN1458771A

Abstract

The present invention discloses a multicast message forwarding method based on a two-layer exchange device. In the method, firstly, an internet group management protocol (IGMP) message is received from an access port by the two-layer exchange device, and whether a visual local area network (VLAN) head exists in the message is judged, and if not, a visual local area network identification (VLANID) of the access port is added to the message to form a VLAN head; then, a mapping relation table for the VLANID of the access port and a media access control (MAC) address of multicast to a physical port which receives the IGMP message is generated, and a mapping relation table for the VLANID of an uplink port and the MAC address of the multicast to the physical port which receives the IGMP message is generated; finally, according to the mapping relation tables, the multicast message is forwarded. With the adoption of the proposal, the problem that a multicast data message without a VLAN head received by the uplink port of the two-layer exchange device can not be effectively forwarded can be solved, and the waste of network resources can be avoided.

Description

A kind of method for forwarding multicast message based on two-layer switching equipment

Technical field

The present invention relates to the message forwarding method in the communication network, relate in particular to method for forwarding multicast message based on two-layer switching equipment.

Background technology

In broadband network, user terminal can pass through the two-layer switching equipment access network usually at present, and wherein common two-layer switching equipment is an Ethernet Layer 2 switch (LANSWITCH) of supporting the 802.1Q agreement.Be the forwarding of example explanation multicast message below with LANSWITCH.All messages that sent by the user terminal of LANSWITCH access network all will be coupled with a special mark that is used for user terminal identification, in the reality, this mark is generally VLAN (VLAN:Virtual Local Area Network) label, this VLAN label can unique identification this user terminal insert the particular physical interface of LANSWITCH, promptly the message of the ethernet format sent from access interface of user all will add the port position that a VLAN head inserts with identifying user through this switch.LANSWITCH is as follows for all message forwarding methods of receiving: search two-layer retransmitting table according to the VLANID in target MAC (Media Access Control) address in the message and the VLAN head, it is MAC Address and VLANID mapping table to physical port, if find occurrence, then message is forwarded from corresponding physical port; If do not find occurrence, then all physical ports of the VLANID correspondence of message in the VLAN head are transmitted, be equivalent to broadcast type and send.Because two-layer retransmitting table is according to source MAC in the message and VLANID and receives that the physical port of this message generates, because can not being used as the unicast mac address of marking terminal equipment, uses multicast mac address, what therefore multicast message used is can not control the target MAC (Media Access Control) address of the multicast mac address of (MAC) address appearance as message as the source media interviews, if do not do special processing, LANSWITCH can't generate two-layer retransmitting table for multicast mac address, LANSWITCH can only take to send to the mode of all of the port with broadcasting for multicast message, has greatly wasted the system bandwidth resource and has had a strong impact on the performance of LANSWITCH.In order to improve the processing of LANSWITCH to multicast message, LANSWITCH intercepts and captures user's Internet Group Management Protocol (IGMP) message, with the VLAN sign (VLANID) of the port of receiving this IGMP message and multicast mac address generation two-layer retransmitting table about this multicast mac address, after in case LANSWITCH has generated two-layer retransmitting table about multicast mac address, for the multicast data message of receiving later, transmit with regard to can equally searching two-layer retransmitting table according to common message fully, thereby avoid LANSWITCH that the broadcasting of multicast message is transmitted.

By above-mentioned LANSWITCH in the processing of message as can be seen, when LANSWITCH receives that one can be given this message expansion a VLAN head during not with the message of VLAN head automatically, and this VLAN head is that VLANID with the port of receiving this message constructs.When LANSWITCH generates two-layer retransmitting table about multicast mac address, its VLANID uses is the VLANID of access interface that receives the user side of this IGMP message, and when the LANSWITCH uplink port is received the multicast data message of not being with the VLAN head (in the reality, multicast program is all at network side, multicast data message all sends from the LANSWITCH uplink port), LANSWITCH can add the VLAN head that the VLANID of uplink port constitutes for this message, and the VLANID of user-side port and upstream side port is inequality, therefore this will cause generating about the two-layer retransmitting table of multicast mac address for the LANSWITCH uplink port receive not like water off a duck's back with the multicast data message of VLAN head, LANSWITCH still can be used as broadcasting packet to multicast message and handle, transmit according to VLANID corresponding physical port, will waste a large amount of Internet resources.

Summary of the invention

The object of the present invention is to provide a kind of method for forwarding multicast message of avoiding network resources waste based on two-layer switching equipment.

For achieving the above object, the method for forwarding multicast message based on two-layer switching equipment provided by the invention comprises:

(1) described two-layer switching equipment is from access interface receiving internet igmpinternet IGMP message;

(2) judge in the described IGMP message whether the virtual LAN VLAN head is arranged,, change step (3), otherwise the VLAN ID VLANID that adds the above access interface for this IGMP message constitutes the VLAN head if having;

(3) generate the VLAN ID VLANID of described access interface and multicast media access control MAC address mapping relations table, and the VLAN ID of generation uplink port and multicast Media Access Control Address are to the mapping relations table of the physical port of receiving this IGMP message to the physical port of receiving this IGMP message;

(4) carry out the forwarding of multicast message according to above-mentioned two kinds of mapping relations tables, promptly

When described two-layer switching equipment receives the multicast message of band VLAN head, to the mapping relations table of the physical port of receiving this IGMP message, described multicast message is forwarded to this physical port according to the VLAN ID VLANID of access interface and multicast media access control MAC address;

When described two-layer switching equipment receives the multicast message of not being with the VLAN head, automatically add the VLAN head that the VLANID of uplink port constitutes for this multicast message, according to the VLANID and the mapping relations table of corresponding multicast mac address of uplink port, this multicast message is forwarded to this physical port then to the physical port of receiving this IGMP message.

The present invention has used the VLANID of the uplink port of LANSWITCH when generating the multicast two-layer retransmitting table, increased the VLANID of uplink port of a LANSWITCH and multicast mac address mapping relations table to the physical port of receiving this IGMP message, because setting up two when generating the multicast two-layer retransmitting table transmits: the VLANID in transmitting uses the VLANID that receives the user-side port that IGMP joins message, VLANID during another is transmitted uses the VLANID of the uplink port of LANSWITCH, thereby solved the problem that can't effectively not transmit that the LANSWITCH uplink port is received, therefore adopted the method for the invention to transmit the IGMP multicast message and can avoid network resources waste with the multicast data message of VLAN head.

Description of drawings

Fig. 1 is the embodiment flow chart of the inventive method.

Embodiment

The present invention is described in further detail below in conjunction with accompanying drawing.

Usually, the multicast message of handling through two-layer switching equipment has two kinds: IGMP message and multicast data message.This is two kinds of different messages, though they use multicast mac address as target MAC (Media Access Control) address: the IGMP message is the signaling control message that user terminal advertised network equipment needs certain multicast services, the user is only at needs with when leaving certain multicast services, just can send corresponding IGMP message, and the target MAC (Media Access Control) address of the target MAC (Media Access Control) address of IGMP message and corresponding multicast data message adopts identical multicast mac address; And multicast data message is only the data message of real bear multicast service content.Therefore, two-layer switching equipment generates the multicast message two-layer retransmitting table needs the participation of IGMP message just may realize, utilizes two-layer retransmitting table to carry out the forwarding of multicast data message then.

Can realize with the VLAN head and do not transmit in order to make two-layer switching equipment with the non-broadcast type of the multicast message of VLAN head, the present invention sets up a two-layer retransmitting table more when generating the multicast two-layer retransmitting table, can realize with the VLAN head with not with the non-broadcast type forwarding of the multicast message of VLAN head by two two-layer retransmitting tables like this.Be example explanation the present invention below by Ethernet Layer 2 switch (LANSWITCH).

Fig. 1 is the embodiment flow chart of the inventive method.According to Fig. 1, realize that the present invention has 5 steps.At first, LANSWITCH is in step 1, from access interface receiving internet igmpinternet (IGMP) message, judge in step 2 whether the Virtual Local Area Network head is arranged in this message then, if have, change step 4, otherwise the VLAN ID (VLANID) of adding access interface for this message in step 3 constitutes the VLAN head, for example, the IGMP message that sends for the user terminal of not supporting the 802.1Q agreement does not have the VLAN head, therefore the VLAN head of IGMP message is all added automatically by LANSWITCH, and is that VLAN ID (VLANID) with access interface constitutes; Change step 4 then; In step 4, the VLAN ID (VLANID) of generation access interface and multicast medium access control (MAC) address (being the target MAC (Media Access Control) address of IGMP message) are to the mapping relations table of the physical port of receiving this IGMP message, generate this table and be the function of traditional LANSWITCH, do like this is for compatible with tradition, because if when the upper layer device that connects on the LANSWITCH was supported the 802.1Q agreement, it can send the multicast data message of the VLANID that has access interface; Generate the VLAN ID of uplink port and multicast Media Access Control Address (being the target MAC (Media Access Control) address of IGMP message) mapping relations table simultaneously to the physical port of receiving this IGMP message; In step 5, carry out the forwarding of multicast data message at last according to above-mentioned mapping relations table.

When the LANSWITCH uplink port is received the multicast data message of not being with the VLAN head, LANSWITCH can add the VLAN head that the VLANID of uplink port constitutes for this message automatically, LANSWITCH is according to the multicast mac address in the message then, be that the target MAC (Media Access Control) address of multicast data message and the VLANID of uplink port search two-layer retransmitting table, because step 3 has generated the VLANID and the mapping relations table of corresponding multicast mac address to the physical port of receiving this IGMP message of uplink port, LANSWITCH directly is forwarded to this physical port to multicast data message, guaranteed that the user who sends the IGMP message can receive multicast data message, obtained multicast services.

Claims

1, a kind of method for forwarding multicast message based on two-layer switching equipment comprises:

(2) judge in the described IGMP message whether the virtual LAN VLAN head is arranged,, change step (3), otherwise the VLAN ID VLANID that adds the above access interface for described IGMP message constitutes the VLAN head if having;

2, method for forwarding multicast message according to claim 1 is characterized in that: described two-layer switching equipment is a layer 2 ethernet switch.