CN1909471A - Method for realizing failure detection of IP transfer plane between areas - Google Patents
Method for realizing failure detection of IP transfer plane between areas Download PDFInfo
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- CN1909471A CN1909471A CN 200510087706 CN200510087706A CN1909471A CN 1909471 A CN1909471 A CN 1909471A CN 200510087706 CN200510087706 CN 200510087706 CN 200510087706 A CN200510087706 A CN 200510087706A CN 1909471 A CN1909471 A CN 1909471A
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Abstract
The invention relates to a method for checking the accidence of inter-domain IP transfer plane, which comprises: at the inter-domain node, via expanding OPEN report of BGP, obtaining the bidirectional transfer check BFD mark and BFD ability instruct informant; said method can be used in single-jump or multi-jump IBGP/EBGP; then between said inter-domain nodes, based on the BFD mark and the BFD ability instruct information, starting BFD checking function to check the accidence of inter-domain transfer plane. The invention can use BFD to check the accidence of transfer plane, between the transfer paths of BGP neighbors, to improve the reliability, while it can avoid error check.
Description
Technical field
The present invention relates to network communications technology field, relate in particular to a kind of implementation method that detects the IP transfer plane between areas fault.
Background technology
In draft draft-ieft-bfd-base-02.txt, BFD has very big advantage as a kind of detection method of link or node or interface fault of underloading for the fault that detects data plane.Having defined BFD in draft draft-ietf-bfd-base-02.txt is used for the state machine of detection failure and is used to set up the BFD session and safeguards some necessary parameters of BFD session, and the formal representation with data load comes out, for variety of protocol, when adopting BFD as the datum plane fault detection mechanism, use in various media as data load.
But,, how to encapsulate the BFD data load under the variety of protocol situation, and how to start the BFD session because BFD itself is not defined in various media.Therefore, if adopt BFD as the datum plane fault detection mechanism, must stipulate accordingly for concrete application scenarios.
In draft draft-ietf-bfd-mpls-01.txt, defined and how in MPLS (multiprotocol label switching) network, to have adopted BFD as LSP (label switched path) fault detection method.Specifically, stipulated the method for packing of BFD load in MPLS, locate to adopt the corresponding Iabel (label) of detected LSP FEC (forwarding equivalence class of LSP) to encapsulate BFD at ingress LSR (inlet LSR), if multilayer Iabel is arranged, then internal layer Iabel TTL (label survival value) is set to 1, and this is the demand when needing egress LSR (outlet LSR) key-course to handle for some specific FEC (forwarding equivalence class).For MPLS PW (MPLS virtual circuit), then adopt and carry special control word in the data message and show that this data message is the BFD message.
Simultaneously, for the BFD session initiation, in draft draft-ietf-bfd-mpls-01.txt, use the BOOT strapping Protocol of MPLS Ping (a kind of method that detects MPLS LSP datum plane fault) as BFD, hold at ingress LSR (inlet LSR), at＜MPLS LSP, FEC〉the unique identifier of distribution, sign as the ingress LSR BFD of place session, in MPLS Pingrequest message, carry corresponding to＜MPLS LSP FEC〉the BFD Session ID, hold at egressLSR (outlet LSR), also at＜MPLS LSP, FEC〉distribute unique identifier, as the sign of this BFD session of engress LSR place, among the back message using MPLS Ping echo, carry corresponding to this＜MPLS LSP, FEC〉the BFD Session ID.The BFD session is just set up at ingress LSR and egress LSR place like this, and the identifier at two ends is as unique identifier of BFD session.
LSP is specifically as follows interior LSR A of Domain A (territory A) and the path between the LSR B as shown in Figure 1 in the corresponding detected territory.LSP is specifically as follows LSR A between Domain A (territory A) and the Domain B (territory B) and the path between the LSR B as shown in Figure 2 between corresponding detected territory.
Be not difficult to find out that technique scheme is to use a kind of method of BFD as fault detect at MPLS LSP, does not consider to use the detection method of BFD as fault of forwarding plane between the IP territory.
In addition, in draft draft-ietf-bfd-v4v6-1hop-02.txt and draft-ietf-bfd-multihop-02.txt, also use BFD to transmit the datum plane fault detection mechanism at direct adjacency of IP and multi-hop IP forward-path respectively as IP, as a kind of replacement that IGP Hello (webmaster protocol handshake in the territory) message is detected, as shown in Figure 3, at realizing in the territory between Router A and the Router B that BFD detects, but the testing result of BFD has only reference value to IGP (intradomain gateway agreement), can not force the IGP agreement to use the foundation of the testing result of BFD as subsequent action.
All having defined BFD payload in these two draft encapsulates in the IP message as the UDP load.
IP directly in abutting connection with the time, during BFD session (BFD session) initialization, with the different BFD session of port binding or protocol binding identification.
During multi-hop with out-of-band signalling such as MPLS ping mode initialization BFD session or only move a BFD session between the source/destination arbitrarily.
For single-hop or multi-hop IP forward-path, during as Routing Protocol, can adopt the hello packet of Routing Protocol to start BFD session with OSPF or ISIS.
When in these two draft, also having described OSPF/ISIS Graceful Restart and the relation between BFD Session.If BFD session does not influence BFD session because of control aspect down by C bit statement among the payload, then when BFD session just in time detects fault and IGP graceful restart (IGP is steadily restarted) and is carrying out, should end the graceful restart process of IGP, because fault has also taken place data plane, should carry out system this moment and restart.If BFD C bit statement BFDsession and control aspect are associated, then can be not influential to the graceful restart process of IGP, because this moment, BFD session and control aspect were associated, no matter Forwarding plane fault whether, BFDsession should fail this moment.
This technical scheme is at using the detection method of BFD as the forward-path fault in the IP territory, still not considering the detection method of fault of forwarding plane between the IP territory.
Summary of the invention
In view of above-mentioned existing in prior technology problem, the purpose of this invention is to provide a kind of implementation method that detects the IP transfer plane between areas fault, thereby can utilize BFD to detect the fault of IP transfer plane between areas easily, realize effective maintenance at network.
The objective of the invention is to be achieved through the following technical solutions:
The invention provides a kind of implementation method that detects the IP transfer plane between areas fault, comprising:
A, obtain two-way forwarding in the territory intermediate node and detect the BFD identifier;
Start the BFD measuring ability according to described BFD identifier information between B, described territory intermediate node, Forwarding plane between the territory is carried out fault detect.
Described steps A comprises:
Between the intermediate node of territory, transmit described BFD identifier.
Described steps A also comprises:
Transmit the BFD capability indication information between the territory, described BFD capability indication information is used to represent whether local terminal supports the BFD function.
Described steps A comprises:
OPEN message by borde gateway control protocol BGP transmits described BFD identifier and BFD capability indication information between the territory;
Described steps A comprises:
With expanding the capability code that is used to represent the BFD capability indication information in the capability option in the parameter options in the described OPEN message, transmit the BFD capability indication information by described capability code.
Described steps A comprises:
In the BFD identifier information between the static configuration territory on the intermediate node of territory.
Described step B comprises:
Between the intermediate node of territory, carry the BFD message, and transmitting the detection that realizes fault of forwarding plane between the territory between the intermediate node of territory by User Datagram Protoco (UDP) UDP.
Described step B also comprises:
When the OPEN message by BGP starts the BFD function, then after starting the BFD function, set up bgp session or BFD and bgp session again and independently set up respectively.
Described step B also comprises:
C bit in the BFD message is used to state whether the BFD session is relevant with the control aspect, and the peer node measure that the BFD session should be taked when determining the steady restarting process of control aspect BGP according to described C bit information.
As seen from the above technical solution provided by the invention, realization of the present invention makes and can promptly use BFD to detect fault of forwarding plane between the forward-path of bgp neighbor, to improve the reliability that fault of forwarding plane detects between the intermediate node of IP territory.The flase drop that may occur when simultaneously, the present invention can also avoid using BFD as detection forward-path fault under some situation between the IP territory is surveyed situation.
Description of drawings
Fig. 1 is a LSP schematic diagram in the detected territory;
Fig. 2 is a LSP schematic diagram between detected territory;
Fig. 3 is an IP forward-path schematic diagram in the detected territory;
Fig. 4 is an IP forward-path schematic diagram between detected territory;
Fig. 5 is the process chart of method of the present invention.
Embodiment
Core of the present invention is in the detection that utilizes the fault of forwarding plane between BFD function realization territory, to improve the reliability that fault of forwarding plane detects.
For realizing that the problem that the present invention need solve mainly comprises: use BFD as between the territory during fault detect of IP forward-path, how to start BFD session (BFD session), promptly how to start the BFD function on the node; The described problem that need to solve also comprise BFD session how and between the territory IP routing protocol graceful restart (steadily restarting) cooperate and the foundation of the foundation of BFD session and BGP syntople between sequencing problem.
Among the present invention, use the declaration of BGP OPEN information capability declaration function whether to possess the BFD disposal ability and carry BFD session identifier mydiscriminator when mainly adopting BFD to detect the IP transfer plane between areas fault; Use static configuration BFDsession identifier as the method that starts BFD session when perhaps, adopting BFD to detect the IP transfer plane between areas fault.
The invention provides the method for utilizing BFD Function detection IP transfer plane between areas fault, between the territory that method of the present invention is used the IP forward-path as shown in Figure 4, the specific implementation of described method specifically comprises as shown in Figure 5:
Step 51: between the intermediate node of territory, transmit the BFD identifier information that is used to carry out the BFD detection, detect so that carry out BFD by described BFD identifier information guiding BFD measuring ability;
Between the intermediate node of territory, transmit described BFD identifier information and specifically comprise dual mode:
(1) in the OPEN of BGP message, expands capabilities option among its option parameters, increase new Capability Code coding (BFD capability indication information) and indicate whether to have the BFD disposal ability, and carry BFD session identifier.The form of concrete OPEN message is as described below:
Capability Code (1 octet): concrete encoded radio is undetermined;
Capability Length (1 octet): capable field length is 4;
Capability Value (variable): ability value is a variable, is specially actual BFDsession identifier information, i.e. BFD identifier information, and this field also can be called mydiscriminator (identifier) field;
Above-mentioned implementation can not exert an influence to the BGP message format, only need increase new coding in original ability declaration function and get final product;
When making when starting BFD session in this way, on the intermediate node of territory, opposite end, can effectively avoid the flase drop under the particular case to survey according to described BFD capability indication information;
For example, when Router A and Router B were bgp neighbor, if forward-path is transmitted for the UDP message fault is arranged between A and the B, transmitting for TCP (transmission control protocol) message did not have fault, for the BFD message forwarding path fault is arranged so, normal for the BGP message forwarding path.If do not adopt the declaration of BGP OPEN ability declaration function whether to possess the BFD disposal ability, BFD otherwise starts (as static configuration), can cause the BFD session failure between Router A and the Router B so.This moment, for bgp protocol, the opposite end did not support the BFD disposal ability to distinguish in this failure scenarios and the BGP adjacency, may cause BGP to think that forward-path is normal, continues normal operation when datum plane has fault because bgp information is transmitted normally.
(2) can also adopt the mode of static configuration to start BFD among the present invention, be specially the corresponding BFD identifier information of configuration on the intermediate node of territory, the territory intermediate node just can start BFD testing process between the territory according to described BFD identifier, at this moment, need not execution in step 51, only need direct execution in step 52 to get final product.
Step 52: utilize the BFD testing process between the BFD identifier information startup node that obtains between the intermediate node of territory;
Step 53: between the intermediate node of IP territory, carry out the encapsulation and the transmission of BFD message;
The packaged type of described BFD message specifically comprises:
The BFD message, promptly BFD payload (BFD load) adopts the carrying of UDP message; UDP source port number and destination slogan are undetermined, can be by the unified distribution of IANA (internet address is assigned mechanism) tissue.If operation IPv4/IPv6 agreement between the bgp neighbor, bgp neighbor is direct-connected, promptly has only a jumping, then TTL in the IP message (life span value) is set to 255, prevents to utilize the BFD message to cheat.If multi-hop IBGP/EBGP, suggestion prevents that with the authentication function of BFD itself the BFD message from cheating.
Step 54: the failure condition of determining the Forwarding plane between the IP territory according to the BFD message that transmits between the intermediate node of IP territory;
Concrete BFD testing process offers some clarification in the BFD agreement, so locate no longer to describe in detail.
Among the present invention, the ordinal relation between BFD session foundation and BGP session foundation also needs to follow following principle:
If in the process that BGP session sets up, start BFDsession by BGP OPEN information, if not considering BFD session, whether do not set up BGP session, this moment, BFD may just begin to set up after BGP.If promptly BFD is in up (activation) state, may cause bgp protocol just to set up in some cases, just the situation that need restart.For example, promptly normal if forward-path is transmitted for the TCP message and do not had fault between A and the B when Router A and Router B are bgp neighbor to the BGP message forwarding path, the message such as the UDP message of other protocol types broken down.Can detect the malfunction of forward-path at this moment at datum plane by certain methods, may cause system to restart like this.If bgp session waited for that before setting up BFD session sets up, just can not duplicate startup.Because BFD session can not UP in these cases, BGP also is in non-establish state always so.
For this reason, if when BGP session sets up, when starting BFDsession by BGP OPEN information, the foundation of the foundation of BGP session and BFD session connects, after promptly waiting BFDsession to be in the up state, BGP session enters established (foundation) state again, can avoid above-mentioned problem to take place like this.Wait in the process of BFD session foundation at BGP session, need make particular processing to the Hold time (maintenance) of BGP session, for example can not refresh, BGP session can be not overtime like this, avoids causing BGP session to fail because of overtime.
In actual application, specifically can be according to actual conditions decisions whether with the procedure correlation of setting up of BGP session and BFD session.
In addition, the relation between BFD session among the present invention and the BGP graceful restart then can adopt following processing mode to consider:
If BFD session is by C bit (Control Plane Independent among the payload, control plane independently) statement is not because control aspect down influences BFD session, then when BFDsession just in time detects fault and BGP graceful restart and is carrying out, should end the graceful restart process of BGP, because fault has also taken place data plane, should carry out system this moment and restart.If be associated at the C of BFD message bit statement BFD session and control aspect, then can be not influential to the graceful restarting process of BGP, because this moment, BFD session and control aspect were associated, no matter Forwarding plane fault whether, BFD session should fail this moment.
In sum, the present invention can use BFD to detect fault of forwarding plane between the forward-path of bgp neighbor, and the flase drop that can avoid may occurring when use BFD is as detection forward-path fault under some situation between the IP territory is surveyed situation.
The above; only for the preferable embodiment of the present invention, but protection scope of the present invention is not limited thereto, and anyly is familiar with those skilled in the art in the technical scope that the present invention discloses; the variation that can expect easily or replacement all should be encompassed within protection scope of the present invention.Therefore, protection scope of the present invention should be as the criterion with the protection range of claim.
Claims (9)
1, a kind of implementation method that detects the IP transfer plane between areas fault is characterized in that, comprising:
A, obtain two-way forwarding in the territory intermediate node and detect the BFD identifier;
Start the BFD measuring ability according to described BFD identifier information between B, described territory intermediate node, Forwarding plane between the territory is carried out fault detect.
2, the implementation method of detection IP transfer plane between areas fault according to claim 1 is characterized in that, described steps A comprises:
Between the intermediate node of territory, transmit described BFD identifier.
3, the implementation method of detection IP transfer plane between areas fault according to claim 2 is characterized in that, described steps A also comprises:
Transmit the BFD capability indication information between the territory, described BFD capability indication information is used to represent whether local terminal supports the BFD function.
4, according to the implementation method of claim 2 or 3 described detection IP transfer plane between areas faults, it is characterized in that described steps A comprises:
OPEN message by borde gateway control protocol BGP transmits described BFD identifier and BFD capability indication information between the territory.
5, the implementation method of detection IP transfer plane between areas fault according to claim 4 is characterized in that, described steps A comprises:
With expanding the capability code that is used to represent the BFD capability indication information in the capability option in the parameter options in the described OPEN message, transmit the BFD capability indication information by described capability code.
6, the implementation method of detection IP transfer plane between areas fault according to claim 1 is characterized in that, described steps A comprises:
In the BFD identifier information between the static configuration territory on the intermediate node of territory.
7, according to the implementation method of claim 1,2,3 or 6 described detection IP transfer plane between areas faults, it is characterized in that described step B comprises:
Between the intermediate node of territory, carry the BFD message, and transmitting the detection that realizes fault of forwarding plane between the territory between the intermediate node of territory by User Datagram Protoco (UDP) UDP.
8, the implementation method of detection IP transfer plane between areas fault according to claim 7 is characterized in that, described step B also comprises:
When the OPEN message by BGP starts the BFD function, then after starting the BFD function, set up bgp session or BFD and bgp session again and independently set up respectively.
9, the implementation method of detection IP transfer plane between areas fault according to claim 7 is characterized in that, described step B also comprises:
C bit in the BFD message is used to state whether the BFD session is relevant with the control aspect, and the peer node measure that the BFD session should be taked when determining the steady restarting process of control aspect BGP according to described C bit information.
Priority Applications (4)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN 200510087706 CN1909471A (en) | 2005-08-05 | 2005-08-05 | Method for realizing failure detection of IP transfer plane between areas |
| EP06753099A EP1921809A4 (en) | 2005-08-05 | 2006-07-04 | A method for achieving fault detection of ip forwarding plane |
| PCT/CN2006/001563 WO2007016841A1 (en) | 2005-08-05 | 2006-07-04 | A method for achieving fault detection of ip forwarding plane |
| US11/526,567 US7664044B2 (en) | 2005-08-05 | 2006-09-26 | Method of failure detection in an IP forwarding plane |
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| Application Number | Priority Date | Filing Date | Title |
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| CN 200510087706 CN1909471A (en) | 2005-08-05 | 2005-08-05 | Method for realizing failure detection of IP transfer plane between areas |
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| CN1909471A true CN1909471A (en) | 2007-02-07 |
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| CN 200510087706 Pending CN1909471A (en) | 2005-08-05 | 2005-08-05 | Method for realizing failure detection of IP transfer plane between areas |
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