CN104333510B - A kind of Tag switching retransmission method in name data network - Google Patents

Abstract

The invention discloses a label switching and forwarding method in a named data network. The method includes: (1) the area with the function of name label switching is called the name label switching (Name Label Switching, NLS) domain, establishes the NLS domain, and connects different named data networks to provide interest packets and data packet transmission services; (2) Add labels to the edge routers in the NLS domain to forward data instead of data names or delete labels and use traditional named data networks to forward data and cache data; (3) The core nodes in the NLS domain only use label switching to forward data and do not cache data . The present invention adopts the label switching mechanism in the named data network, creates a label switching core domain--name label switching domain similar to the multi-protocol label switching technology, and realizes label switching and forwarding, thereby reducing the total number of name searches and the single search time , to achieve fast and scalable packet forwarding.

Description

A Label Switching Forwarding Method in Named Data Network

technical field

The invention relates to the field of future Internet architecture, in particular to a label switching and forwarding method in a named data network.

Background technique

With the rapid development of Internet technology and applications, the Internet and telecommunications industries are faced with the problems of mass content transmission and quality assurance. There is a contradiction between the tens of billions of access needs and the computing, storage and transmission capabilities that the telecommunications industry infrastructure can provide. In order to solve various problems existing in the existing IP network, two ideas of "improvement" and "revolution" are proposed: those that do not change the main status of Internet IP belong to "improvement", while the concept of "revolution" needs to be redesigned. A new network architecture is used to solve various problems in the IP network, and to better adapt to increasingly rich services and diverse user needs. As a result, the design concept of "revolution" began to attract attention. Various research parties and various government research funds are constantly trying to design a new Internet architecture, and the content-centric future Internet architecture design is an important branch of it.

In the content-centric design scheme, Named Data Networking (NDN) proposed by Van Jacobson et al. has attracted much attention. In 2010, NDN-related research received key funding from the NSF Future Internet Architecture Project of the National Natural Science Foundation of the United States. NDN routes and forwards content requests based on content names rather than IP addresses, and all network devices on the forwarding path can cache content to reduce the transmission of duplicate content in the network.

Two types of protocol packets are designed in NDN—interest packets and data packets, which are used to find paths and receive data content. The node model defined in NDN mainly consists of three parts: Forwarding Information Base (FIB), Content Store (Content Store, CS) and Pending Interest Table (PIT). NDN uses the information stored in these three tables to implement routing and forwarding. NDN proposes to use named data instead of named hosts to realize the transformation from host-oriented to content-oriented networks. Therefore, content name lookup is a difficult problem in NDN.

In the process of forwarding each hop, the name in the interest packet will be checked three times at most, once for the longest prefix match, and twice for exact match; inspired by the MPLS (Multi-Protocol Label Switching) mechanism, the present invention uses labels in NDN The switching mechanism creates an MPLS-like label switching core domain—name label switching (Name Label Switching, NLS) domain, which realizes label switching and forwarding, thereby reducing the total number of name lookups and single lookup time to achieve fast scalability group forwarding.

Contents of the invention

The purpose of the present invention is to propose a forwarding method using label switching instead of name lookup in NDN, so as to reduce name lookup time and table lookup times, and realize fast forwarding.

For the above purpose, the present invention provides a method for label switching in NDN, which is characterized as follows:

(1) The area where NLS works is called the NLS domain, which is a network domain that connects different NDN networks and provides interest packet and data packet transmission services for them.

(2) The NLS domain consists of two types of nodes: edge nodes and core nodes. The edge node is also called the Name Label Edge Router (NLER), and adds a label to each interest packet or data packet entering the NLS domain according to the Forwarding Equivalent Class (FEC). When the marked interest packet or The label is removed when the data packet leaves the NLS domain; the core node is usually called a name label switching router (Name Label Switching Router, NLSR), which forwards interest packets or data packets based on label switching.

(3) The marked interest packets and data packets are transmitted on the name label switching path (Name Label Switching Path, NLSP) established by using the label distribution protocol (Label Distributed Protocol, LDP). There are two types of NLSP: ILSP (Interest LSP) and DLSP (Data LSP), which are used to transmit interest packets and data packets respectively.

(4) The data in the NLS domain is only cached at the edge nodes.

(5) The edge node may be an ingress node or an egress node, depending on the direction in which the interest packet is sent: the edge node that sends the interest packet to the NLS domain is called the ingress node; the edge node that sends the interest packet out of the NLS domain is called the egress node node.

(6) The structure of NLS domain edge nodes: the entry node of NLS contains three tables of PIT, CS, and Label Information Base (LIB), which have the functions of labeling interest packets and removing data packet labels; exit nodes contain FIB, PIT, CS, and LIB four tables, with the functions of labeling data packets and removing interest packet labels.

(7) Data forwarding process in the NLS domain: when the Interest packet sent by the Client reaches the entry node of the NLS domain, the node first checks whether there is matching data in the CS table, and if so, discards the Interest packet and returns the data packet; Otherwise, the node will look up the PIT table, and if there is a matching entry, the interface the Interest arrives at will be added to the interface entry; if there is no matching entry, the node will look up the LIB table, which consists of name prefix, input/output interface and It consists of labels distributed by LDP, and names, interfaces, and label values correspond one-to-one. If a matching entry is found in the LIB table, the Interest is marked and forwarded along the ILSP. When a data packet from the NLS domain arrives at NLER, NLER removes the label of the data packet. According to the Content Name field of the data packet, it first searches in the content cache, and discards the data packet if there is one; if not found, it searches in the PIT , if there is, it will be forwarded according to all the interfaces found, and then cached in the content cache; if there is no matching entry in the PIT, the packet will be discarded.

When the marked interest packet arrives at the exit node of NLS, the node first removes the label and checks whether there is matching data in CS; if there is, mark the data packet and forward it according to DLSP; otherwise, look for PIT, if PIT If there is a Content Name entry of the Interest packet in the PIT table, add the interface from which the Interest packet arrives, and discard the Interest packet; if there is no such entry in the PIT, then search for the FIB, if found in the FIB, follow the search All the interfaces to which the interest packet is forwarded are recorded in the PIT; if the Content Name entry does not exist in the FIB, the interest packet is discarded. When a data packet arrives at this node, according to the Content Name field of the data packet, it is first searched in the content cache, and if there is, the data packet is discarded; if not found, it is searched in the PIT, and if it is found, the LIB table is marked with a label The packet is forwarded through DLSP and then cached in the content cache; if there is no match in the PIT either, the packet is discarded.

Description of drawings

FIG. 1 is a schematic diagram of label switching in a named data network.

Fig. 2 is a schematic diagram of the NLER at the entrance of the NLS domain.

Fig. 3 is a schematic diagram of the egress NLER of the NLS domain.

detailed description

The specific implementation manners of the present invention will be further described in detail below in conjunction with the accompanying drawings and embodiments. The following examples are used to illustrate the present invention, but are not intended to limit the scope of the present invention.

FIG. 1 is a schematic diagram of NDN label switching in the present invention. The methods include:

(1) The area where NLS works is called the NLS domain, which is a network domain that connects different NDN networks and provides interest packet and data packet transmission services for them.

(2) The NLS domain consists of two types of nodes: edge nodes and core nodes. The edge node is also called the Name Label Edge Router (NLER), and adds a label to each interest packet or data packet entering the NLS domain according to the Forwarding Equivalent Class (FEC). When the marked interest packet or The label is removed when the data packet leaves the NLS domain; the core node is usually called a name label switching router (Name Label Switching Router, NLSR), which forwards interest packets or data packets based on label switching.

(3) The marked interest packets and data packets are transmitted on the name label switching path (Name Label Switching Path, NLSP) established by using the label distribution protocol (Label Distributed Protocol, LDP). There are two types of NLSP: ILSP (Interest LSP) and DLSP (Data LSP), which are used to transmit interest packets and data packets respectively.

(4) The data in the NLS domain is only cached at the edge nodes.

(5) The edge node may be an ingress node or an egress node, depending on the direction in which the interest packet is sent: the edge node that sends the interest packet to the NLS domain is called the ingress node; the edge node that sends the interest packet out of the NLS domain is called the egress node node.

(6) The structure of NLS domain edge nodes: the entry node of NLS contains three tables of PIT, CS, and Label Information Base (LIB), which have the functions of labeling interest packets and removing data packet labels; exit nodes contain FIB, PIT, CS, and LIB four tables, with the functions of labeling data packets and removing interest packet labels.

(7) Data forwarding process in the NLS domain: when the Interest packet sent by the Client reaches the entry node of the NLS domain, the node first checks whether there is matching data in the CS table, and if so, discards the Interest packet and returns the data packet; Otherwise, the node will look up the PIT table, and if there is a matching entry, the interface the Interest arrives at will be added to the interface entry; if there is no matching entry, the node will look up the LIB table, which consists of name prefix, input/output interface and It consists of labels distributed by LDP, and names, interfaces, and label values correspond one-to-one. If a matching entry is found in the LIB table, the Interest is marked and forwarded along the ILSP. When a data packet from the NLS domain arrives at NLER, NLER removes the label of the data packet. According to the Content Name field of the data packet, it first searches in the content cache, and discards the data packet if there is one; if not found, it searches in the PIT , if there is, it will be forwarded according to all the interfaces found, and then cached in the content cache; if there is no matching entry in the PIT, the packet will be discarded.

When the marked interest packet arrives at the exit node of NLS, the node first removes the label and checks whether there is matching data in CS; if there is, mark the data packet and forward it according to DLSP; otherwise, look for PIT, if PIT If there is a Content Name entry of the Interest packet in the PIT table, add the interface from which the Interest packet arrives, and discard the Interest packet; if there is no such entry in the PIT, then search for the FIB, if found in the FIB, follow the search All the interfaces to which the interest packet is forwarded are recorded in the PIT; if the Content Name entry does not exist in the FIB, the interest packet is discarded. When a data packet arrives at this node, according to the Content Name field of the data packet, it is first searched in the content cache, and if there is, the data packet is discarded; if not found, it is searched in the PIT, and if it is found, the LIB table is marked with a label The packet is forwarded through DLSP and then cached in the content cache; if there is no match in the PIT either, the packet is discarded.

Fig. 2 is a schematic diagram of the NLS domain entrance NLER of the present invention. Fig. 3 is a schematic diagram of the egress NLER of the NLS domain in the present invention. The node function is:

(1) Connect the NLS domain and the NDN domain;

(2) Add or remove labels: add labels according to the forwarding equivalence class when the interest packet or data packet arrives in the NLS domain, and remove the label when it leaves the NLS domain;

(3) Cache data: In the NLS domain, data is only cached on the NLER;

(4) Initiator of NLSP establishment process: Whenever new content is received and cached, NLER can initiate establishment of NLSP through LDP.

Claims (2)

1. a kind of Tag switching retransmission method named in data network, including：

(1) name tags switching domain NLS (Name Label Switching) is the different name data network NDN (Named of connection DataNetworking) and provided interest bag and packet delivery service network domains；

(2) NLS domains are made up of two kinds of nodes：Fringe node and core node；Fringe node is also referred to as name tags edge route Device NLER (Name Label Edge Router), according to forwarding equivalence class FEC (Forwarding Equivalent Class) Interest bag or packet addition label to each entrance NLS domains, go when labeled interest bag or packet leave NLS domains Fall label；Core node is commonly known as name tags TSR NLSR (Name Label Switching Router), Interest bag or packet forwarding are carried out based on Tag switching；

(3) labeled interest bag and packet are utilizing tag distribution protocol LDP (Label DistributedProtocol) Transmitted on the name tags switching path NLSP (Name Label Switching Path) of foundation；NLSP has two types： ILSP (Interest LSP) and DLSP (Data LSP), is respectively used to transmission interest bag and packet；

(4) data in NLS domains are only cached in fringe node；

(5) fringe node is divided into Ingress node and Egress node two types, the direction sent depending on interest bag：By interest bag It is sent to the fringe node referred to as Ingress node in NLS domains；The fringe node that interest bag is sent from NLS domains is referred to as outlet section Point；

(6) structure of NLS domains fringe node：NLS Ingress node includes PIT, CS, tag information base LIB (Label Information Base) three tables, mark interest bag with label and remove the function of packet tags；Egress node is included Tetra- tables of FIB, PIT, CS, LIB, with label flag data bag and the function of removing interest bag label；

(7) in NLS domains interest bag or packet Tag switching retransmission method, including：

When the interest bag that Client is sent reaches the Ingress node in NLS domains, the node first checks for whether having matching in CS tables Data, if so, then lose interest bag, return data bag；Otherwise, node will search PIT tables, emerging if there is the entry of matching The interface that interest bag is reached will be added in interface entry；If the entry not matched, node will search LIB tables, and the table is by name Word prefix, input/output interface and it is made up of the label that LDP distributes, name, interface and label value are corresponded；If in LIB Matching entry is found in table, then interest coating mark, is forwarded along ILSP；When the packet from NLS domains reaches NLER, NLER removes the label of packet, according to the Content Name fields of packet, is searched first in content caching, if Then abandon the packet；If do not found, searched in PIT, if then being forwarded according to the total interface found, Then it is buffered in content caching；If the entry also not matched in PIT, the packet is abandoned；

When reaching NLS Egress node with markd interest bag, the node removes label first, and checks in CS whether have The data of matching；If so, then flag data bag, and being forwarded according to DLSP；Otherwise, PIT is searched, if there is the interest in PIT The Content Name entries of bag, then add the interface that interest bag arrives, and lose interest bag in the entry of PIT tables；Such as There is no the entry in fruit PIT, then search FIB, if found in FIB, interest bag is forwarded according to the total interface found, And recorded in PIT；If the also not no Content Name entries in FIB, abandon the interest bag；When packet is reached During this node, according to the Content Name fields of packet, searched first in content caching, if then abandoning the data Bag；If do not found, search, if so, searching LIB tables label flag data bag, and forwarded by DLSP in PIT, Then it is buffered in content caching；If also do not matched in PIT, the packet is abandoned.

2. according to the method described in claim 1, it is characterised in that the function of the NLER includes：

(1) connection NLS domains and NDN domains；

(2) add or remove label：When interest bag or packet reach NLS domains according to forwarding equivalence class addition label, and It removes label when leaving NLS domains；

(3) it is data cached：In NLS domains, data are only cached on NLER；

(4) NLSP sets up the promoter of process：Whenever new content is received and is cached, NLER can initiate to set up by LDP NLSP。