CN1265592C - Processing method for super long message in two layered virtual special network - Google Patents

Abstract

The present invention belongs to the technical field of computer networks, and relates to a method for processing a super-long message in a two-layer virtual private network. The present invention comprises that supplier peripheral equipment (PE) segments a super-long message into fragmentation messages at the inlet of the virtual private network (VPN), and adds a multiprotocol label switching (MPLS) head respectively to each fragmentation message and sends each fragmentation message; PE at the outlet of the VPN recombines all received fragmentation messages into a complete message according to the content of the MPLS head, and sends the complete message to user equipment. The present invention has the advantages of saving the expenses of users, reducing the management difficulties of user networks, reducing risks brought by completely reforming all equipment, reducing the costs of network operators, etc.

Description

The processing method of overlength message in the Layer 2 virtual private network

Technical field

The invention belongs to technical field of the computer network, particularly in Multi-Protocol Label Switch (MPLS) Layer 2 virtual private network (VPN) to the processing method of overlength message.

Background technology

Multi protocol label exchange (MPLS-MultiProtocol Label Switch) Layer 2 virtual private network (VPN-Virtual Private Network) is a kind of new VPN technologies, it is transparent to another website by the MPLS network with the link layer message of a website of user, simulate a kind of virtual circuit (VC-Virtual Circuit), thereby realize that two layers of the different websites of user are interconnected.The mode that user site inserts can be Ethernet, ATM (Asynchronous Transfer Mode), peer-peer protocol (PPP-Point to Point Protocol), frame relay (FR-FrameRelay) etc.For example: the user respectively has a branch in Beijing and Shenzhen, and these two branches are linked into the MPLS two-layer VPN network of certain telco service provider respectively in the Ethernet mode.By the MPLS two-layer VPN, imperceptible two the geographic distances of branch of user, two branches directly couple together by Ethernet, form the local area network (LAN) of an enterprises, and its networking mode is as shown in Figure 1.In MPLS two-layer VPN model, the equipment that user side links to each other with carrier network is called user side edge device (CE-Custom Edge), the equipment that links to each other with user network in the carrier network is called supplier edge device (PE-Provider Edge), does not become vendor equipment (P-Provider) with the equipment that the user directly links to each other in the carrier network.

Aspect forwarding, the link layer message that PE transmits CE (comprising the link layer head) is stamped the MPLS head, sends by the MPLS network then.If what CE transmitted is an internet protocol (IP-Internet Protocol) message, before sending, message content is as shown in table 1, comprises link layer header, MPLS head, link layer header and IP message itself.

Table 1

Link layer header

The MPLS head

Link layer header

The IP message

The link layer message maximum transmitted length (MTU) of Ethernet protocol definition is 1518.Generally speaking, the maximum IP message transmissions length (MTU-Max Transmit Unit) of user network equipment is 1500.These messages are coupled with the ethernet link layer head of 14 bytes when sending by Ethernet, length is less than 1518, so can normally send.Length is greater than 1518 if add up, and then the network equipment can also be provided with according to the MTU of oneself message is carried out burst when the IP layer is handled, and reassembles into complete IP message then again in the destination.So in any case, the IP message can normally transmit on Ethernet.

But after introducing MPLS two-layer VPN technology, there is following problem:

If the interface between CE and the PE is an Ethernet interface, the interface between PE and the P also is an Ethernet interface.Then will comprise two Ethernet heads, MPLS head and IP message itself in the message that PE sends.

Suppose that the IP message length that CE sends remains 1500, be coupled with two Ethernet heads and a MPLS head (for two-layer VPN at PE equipment, 8 bytes normally), then length is: 1500+14 * 2+8=1536, maximum message segment length 1518 much larger than Ethernet protocol, then these messages will be abandoned, and can not normally arrive another website of user.So just can not proper communication between two websites of user.

At present, the MTU problem that solves above-mentioned MPLS two-layer VPN has two kinds of methods:

1, limited subscriber side sends the length of message in tolerance interval.For example: the IP message that requires the user is all less than 1482.After adding two Ethernet heads and MPLS head like this, length is less than 1518, can be on Ethernet normal transmission.

Realize that this method is with two kinds of technical schemes:

A) need all devices and the main frame of configure user network;

Will inevitably increase network management personnel's workload like this, increase the management cost of Virtual network operator, and be not easy to realize at short notice.

B) device upgrade that user network is linked to each other with carrier network is a three-layer equipment, is come the IP message that surpasses prescribed level is carried out burst by this equipment.

Can increase user's cost like this, be unfavorable for the popularization of this business.

2, the equipment in the modernization overlay MPLS network makes all devices can both transmit the Ethernet message that surpasses 1518 sizes.

The modernization overlay network equipment can increase the cost of operator; In addition, carrier network may adopt the equipment of a plurality of producers, thereby also can be owing to inconsistent being difficult to of device fabrication manufacturer realizes.

Summary of the invention

The objective of the invention is to propose the processing method of overlength message in a kind of two-layer virtual private network, have the spending of saving the user, reduce the management difficulty of user network for overcoming above-mentioned the deficiencies in the prior art; The risk that minimizing modernization overlay all devices brings and the plurality of advantages of carrier network cost.

The present invention proposes the processing method of overlength message in a kind of Layer 2 virtual private network, it is characterized in that, may further comprise the steps:

1) the inlet supplier edge device PE at VPN (virtual private network) VPN is divided into fragment message with the overlength message, and each fragment message is stamped multi protocol label exchange MPLS head respectively;

2) set up the burst sign of this message, the tick lables of each fragment message and the sequence number of fragment message at multi protocol label exchange MPLS head, send then;

3) whole fragment messages that will receive according to the content of multi protocol label exchange MPLS head at the export supply merchant edge device PE place of VPN (virtual private network) VPN are reassembled as complete message, send to subscriber equipment.

The tick lables of described fragment message can be divided into burst starting position sign, two kinds of burst end position signs at least.Also can comprise the third middle burst tick lables.

The sequence number of described fragment message can adopt the continuous integral number array of a circulation, the maximum burst number that the length of this array can be divided into greater than a message at least.

Determination methods in that whole bursts of an above-mentioned message are all received can specifically may further comprise the steps:

51) after receiving a fragment message, judge whether the sequence that paid-in a plurality of fragment message is formed meets the following conditions;

(a) the location sign comprises that at least the burst starting position indicates, the fragment message of burst end position sign in this fragment message sequence;

(b) and the sequence number of all fragment messages of this fragment message sequence can be arranged in continuously or continuously and the integer ordered series of numbers of circulation;

52) if satisfy, then all bursts of this message are all received, otherwise explanation also has some fragment messages not receive, then repeats the 51st) step.

The present invention has following advantage:

1, any equipment that does not need the user is done any special processing to the MTU of overlength message, thereby has saved user's spending, has reduced the management difficulty of user network;

2, only need the processing of the PE equipment of Layer 2 virtual private network to the MTU of overlength message, other equipment of MPLS network must not transformed,, reduced risk and operator's cost that the modernization overlay all devices brings.

Description of drawings

Fig. 1 is multi protocol label exchange Layer 2 virtual private network networking mode schematic diagram.

Fig. 2 is a method overall procedure block diagram of the present invention.

Fig. 3 is the Processing Example FB(flow block) of entry PE of the present invention.

Fig. 4 is an outlet PE Processing Example FB(flow block) of the present invention.

Embodiment

The processing method of a kind of MPLS two-layer VPN MTU that the present invention proposes in conjunction with the embodiments and accompanying drawing be described in detail as follows;

Method general steps of the present invention may further comprise the steps as shown in Figure 2:

1) will be divided into fragment message above predetermined maximum transmitted length (MTU) message at the entry PE place of VPN, each fragment message will be stamped MPLS head and transmission respectively;

2) whole fragment messages that will receive according to the content of MPLS head at the outlet PE place of VPN are reassembled as complete message, send to subscriber equipment.

Set up following content in the MPLS head of fragment message of the present invention:

A) the burst sign of fragment message.It is a plurality of fragment messages that the overlength message that message length is surpassed MTU at VPN porch PE is divided into a plurality of parts, then each fragment message is carried out MPLS encapsulation and send, so just need in the MPLS head, add a sign and be message fragment information so that whether burst of message to be described;

B) tick lables of fragment message.A message may be divided into a plurality of bursts.In order correctly to discern these bursts in outlet PE and they to be reassembled as original message, just need indicate the position of each burst in former message in entry PE.For example: a message is divided into three bursts, then first burst is stamped burst starting position sign, illustrates that this is first burst of a message, and it will form same message with the burst of next receiving; Second burst stamped middle burst tick lables, illustrate that this message is not the end of burst; The 3rd message stamped burst end position sign, illustrate that this burst is last burst of a message;

C) sequence number of fragment message.Because the route that each MPLS message is walked may be different, like this, outlet PE receive message order may to send the order of message different with entry PE, so may make a mistake when outlet is recombinated to burst, this just need distribute a sequence number to satisfy the demand for each burst in entry PE.For example use the continuous integral number of one group of circulation, the maximum burst number that the length of this group number can be divided into greater than a message at least.First fragment message that virtual connection sends uses the sequence number of the first digit of ordered series of numbers as oneself, and the sequence number of later fragment message then adds one for the sequence number of a last fragment message.If a last sequence number adds the maximum that one result has surpassed this group integer, then reuse the sequence number of first digit as oneself.

Like this, outlet PE can combine the tick lables of burst and sequence number, thereby guarantees the correct original message that recovers.

The processing method embodiment of entry PE of the present invention may further comprise the steps as shown in Figure 3:

1, receives a message from user side;

2, judge that whether message surpasses predetermined length, if message does not surpass predetermined length, then directly stamps the MPLS head, and sends;

3 otherwise message content is divided into two or more fragment messages, each fragment message all is no more than said predetermined length;

4, each fragment message is stamped the MPLS head, send respectively then;

MPLS head in each fragment message that is partitioned into is set up following information:

1) burst sign: each fragment message is stamped the burst sign, so that distinguished with common message;

2) sequence number: the sequence number of each fragment message is a numeral in the continuous integral number sequence of setting;

3) tick lables: be used for indicating the position of this burst at whole message, the sign that present embodiment adopts is divided into burst starting position sign, middle burst tick lables (if this message only is divided into two, then this sign need not), three kinds of burst end position signs.In order to first burst of distinguishing message, middle burst, or last burst.

Outlet PE processing method embodiment of the present invention may further comprise the steps as shown in Figure 4:

1, receives a two-layer VPN message from the MPLS network;

2, according to whether having the burst sign to judge whether message is fragment message, if message is not a fragment message, then directly removes the MPLS head, sends to the user;

If 3 messages are fragment messages, judge again whether other bursts of this fragment message are all received, if all receive, then all these bursts are reassembled into a complete message, send to the user, otherwise fragment message is preserved, waited for after other fragment messages arrive and recombinating again.

Judge that the method whether whole bursts of a message are all received may further comprise the steps:

1) after receiving a fragment message, judges whether the sequence that paid-in a plurality of fragment message (comprising a fragment message of just having received) is formed meets the following conditions;

(a) tick lables that exists in this fragment message sequence comprises the fragment message of burst starting position sign, burst end position sign at least;

(b) and the sequence number of all fragment messages of this fragment message sequence can be arranged in continuously or continuously and the integer ordered series of numbers of circulation;

2) if satisfy, then all bursts of this message are all received, otherwise explanation also has some fragment messages not receive, then repeats the 1st) step.

Claims (5)

1, the processing method of overlength message in a kind of Layer 2 virtual private network is characterized in that, may further comprise the steps:

1) the inlet supplier edge device PE at VPN (virtual private network) VPN is divided into fragment message with the overlength message, and each fragment message is stamped multi protocol label exchange MPLS head respectively;

2) set up the burst sign of this message, the tick lables of each fragment message and the sequence number of fragment message at multi protocol label exchange MPLS head, send then;

3) whole fragment messages that will receive according to the content of multi protocol label exchange MPLS head at the export supply merchant edge device PE place of VPN (virtual private network) VPN are reassembled as complete message, send to subscriber equipment.

2, the processing method of overlength message in the two-layer virtual private network as claimed in claim 1 is characterized in that, the tick lables of described fragment message is divided into burst starting position sign, two kinds of burst end position signs at least.

3, the processing method of overlength message in the two-layer virtual private network as claimed in claim 2 is characterized in that, the tick lables of described fragment message also comprises the third middle burst tick lables.

4, the processing method of overlength message in the two-layer virtual private network as claimed in claim 1, it is characterized in that, described fragment message sequence number adopts the continuous integral number array of a circulation, the maximum burst number that the length of this array can be divided into greater than a message at least.

5, the processing method of overlength message in the two-layer virtual private network as claimed in claim 2 is characterized in that, the determination methods that whole bursts of a described message are all received specifically may further comprise the steps:

51) after receiving a fragment message, judge whether the sequence that paid-in a plurality of fragment message is formed meets the following conditions:

(a) tick lables that exists in this fragment message sequence comprises burst starting position sign, burst end position sign at least;

(b) and the sequence number of all fragment messages of this fragment message sequence can be arranged in continuously or continuously and the integer ordered series of numbers of circulation;

52) if satisfy, then all bursts of this message are all received, otherwise explanation also has some fragment messages not receive, then repeats the 51st) step.

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