WO2009149892A1 - Method for populating a forwarding information base of a router and router - Google Patents
Method for populating a forwarding information base of a router and router Download PDFInfo
- Publication number
- WO2009149892A1 WO2009149892A1 PCT/EP2009/004128 EP2009004128W WO2009149892A1 WO 2009149892 A1 WO2009149892 A1 WO 2009149892A1 EP 2009004128 W EP2009004128 W EP 2009004128W WO 2009149892 A1 WO2009149892 A1 WO 2009149892A1
- Authority
- WO
- WIPO (PCT)
- Prior art keywords
- router
- prefix
- dfz
- forwarding information
- information base
- Prior art date
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Classifications
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
- H04L45/00—Routing or path finding of packets in data switching networks
- H04L45/02—Topology update or discovery
- H04L45/04—Interdomain routing, e.g. hierarchical routing
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
- H04L45/00—Routing or path finding of packets in data switching networks
- H04L45/02—Topology update or discovery
Definitions
- the present invention relates to a method for populating a forwarding information base of a router of an autonomous system (AS) in the Internet's Default Free Zone (DFZ), wherein the forwarding information base contains a multitude of entries, each entry mapping a destination prefix to at least one route to reach said destination prefix.
- AS autonomous system
- DFZ Default Free Zone
- the present invention relates to a router for deployment in autonomous systems (AS) in the Internet's Default Free Zone (DFZ), comprising a forwarding information base and/or a routing table, wherein the forwarding information base and/or the routing table contain a multitude of entries, each entry mapping a destination prefix to at least one route to reach said destination prefix.
- AS autonomous systems
- DFZ Internet's Default Free Zone
- Today's Internet comprises thousands of autonomous systems (AS), each of which is one or a collection of networks under the control of a single administrative entity.
- AS autonomous systems
- each network interface is identified by means of an IP address which is, in case of IPv4 a 32-bit number.
- IP addresses are aggregated into contiguous blocks. Such blocks are called prefixes and consist of an IP address and a mask, the latter one indicating the number of leftmost contiguous significant bits.
- the prefix notation 61.14.192.0/18 refers to a prefix with a mask length of 18-bits and thus leaves 14-bits to be used by the owning organization including further assignment of sub-prefixes to customers.
- FIB forwarding information base
- FIB forwarding information base
- Both routing tables and forwarding information bases have experienced a steeply increasing number of entries over the past years. This development is to be regarded as extremely critical, in particular with respect to the Internet's Default Free Zone (DFZ).
- the DFZ is the Internet's core and, in the context of Internet routing, refers to the entirety of all ASes in the Internet, where the global routing states accumulate. Thus, routers of an AS belonging to the DFZ do not require a default route to route a packet to any destination. For instance, tier-1 Internet providers are part of the DFZ.
- AS autonomous systems
- TE inbound traffic engineering
- the aforementioned object is accomplished by a method comprising the features of claim 1.
- a method comprising the features of claim 1.
- such a method is characterized in that for each prefix advertised to said router, the autonomous system (AS) the advertisement was received from is determined, and that a decision is made whether to include the prefix into the forwarding information base of said router or not, wherein in said decision the autonomous system (AS) and/or predefined characteristics of the autonomous system (AS) said prefix is learned from is/are considered.
- a router comprising the features of independent claim 7.
- the router further comprises inspection means for determining for each advertised prefix the autonomous system (AS) the advertisement was received from, and processing means for including the prefix into said forwarding information base and/or into said routing table, said processing means being configured to make a decision of whether to include the prefix into said forwarding information base and/or said routing table or not, and to depend said decision on the autonomous system (AS) and/or predefined characteristics of the autonomous system (AS) said prefix is learned from.
- the router according to the invention includes appropriate inspection means.
- the information regarding the AS the prefix is learned from is used for making a decision of whether to include the prefix into the forwarding information base of the router or not.
- the router according to the invention includes appropriate processing means being configured to make such decision.
- the decision of whether to include the prefix into the routing table of the router or not is based on the prefix advertisement originating AS and/or on predefined characteristics thereof.
- the size of routing tables and forwarding information bases in the Default Free Zone of the Internet is reduced, thus reducing the associated churn.
- the method and the router according to the invention do not require any changes to the routing protocol itself, i.e. protocol messages and headers do not need to be touched.
- a check is performed for each prefix advertised to the router, whether the advertisement was received from a non-DFZ autonomous system or from a DFZ autonomous system.
- the different prefix treatment can be based on a specific characteristic of the AS the prefix was received from, namely whether it belongs to the DFZ or whether it does not belong to the DFZ.
- a non-DFZ AS can be regarded as customer AS, whereas a DFZ AS functions as peering or transit AS.
- different prefix treatment may be realized on the basis of checking whether the AS the prefix was learned from is a customer AS or whether the advertisement comes from a peering or transit AS through the DFZ.
- advertised prefixes originating from non-DFZ autonomous systems may be included into the router's forwarding information base.
- prefixes learned from non-DFZ ASes may be treated exactly as they are in the current Internet.
- advertised prefixes learned from DFZ ASes may be included into the router's forwarding information base only if the prefix is shorter than the prefix of an existing entry. The included shorter prefix will then replace the existing longer prefix.
- the amount of prefixes populating the forwarding information bases is significantly reduced while still satisfying the traffic engineering needs of customers. Only a subset of Internet routers needs to change their local decision algorithm. This involves modifying the algorithm that populates the forwarding information base. The configuration needed for this is minimal as it is a per-BGP peer decision, i.e. it can be applied to a whole BGP session.
- edge ASes still achieve their goals but the Internet DFZ is relieved of considerable stress, what cannot be achieved with simple aggregation. Furthermore, this means is conceptually elegant with potentially huge gains. It is expected that it would be applicable to -50% of the prefixes in the DFZ at the tier-1 level.
- packets that travel through the DFZ will still adhere to the traffic engineering goals of autonomous systems at the edge of the Internet as the AS that has the destination AS of a packet as a customer still keeps the full disaggregated routing information.
- DFZ ASes that do not have the destination AS as a customer only keep an aggregate of the disaggregated prefixes. In other words, a fraction of the more specific prefixes in the DFZ is filtered.
- complex filter and policy rules which are common today, are not required.
- consecutive prefixes learned from DFZ ASes are aggregated to larger ones, thereby further reducing the amount of entries in the forwarding information bases.
- ASes that provide transit i. e. are part of the DFZ
- BGP inter-domain routing protocol
- the mechanism described for populating a router's forwarding information base can be applied in the same way for populating also a router's routing table.
- Fig. illustrates schematically the principal structure of the Internet including a router in the Internet's DFZ according to an embodiment of the present invention.
- the Internet constitutes of a multitude of autonomous systems AS which can be divided into DFZ ASes, i.e. ASes belonging to the DFZ of the Internet, and into non-DFZ ASes, i,e. ASes outside the DFZ located in the edge regions of the Internet. Additionally, from each AS's perspective directly connected ASes can be classified as customers, peers or transit ASes.
- DFZ ASes i.e. ASes belonging to the DFZ of the Internet
- non-DFZ ASes i,e. ASes outside the DFZ located in the edge regions of the Internet.
- ASes from each AS's perspective directly connected ASes can be classified as customers, peers or transit ASes.
- three DFZ (tier- 1) ASes are depicted, AS3356, AS701 , and AS1239.
- a total of five non-tier-1 ASes are depicted, which are referred to as AS9299, AS6648, AS4775, AS
- the method according to the invention targets the routers in the Default Free Zone of the Internet, in other words, routers that locally know a route to every destination in the Internet.
- routers' forwarding information bases FIBs
- FIBs forwarding information bases
- the router performs a longest-prefix match, meaning that it will use the FIB entry that matches the packet's address and has the longest prefix; this algorithm allows basic inbound traffic engineering in the current Internet.
- longest- prefix matching also results in the global routing tables growing rapidly if disaggregation becomes common place for traffic engineering purposes.
- the method according to the invention aims at populating the FIB differently.
- the differentiated FIB population is based on whether a prefix was learned from a customer AS or from a non-customer AS. Prefixes learned from customers ASes are treated exactly as they are in the current Internet. However, a route learned from non- customer ASes will only be included in the FIB if it has a shorter prefix than an existing entry, reducing the amount of prefixes learned while still satisfying the traffic engineering needs of customers.
- routers of AS1239 will only populate theirs FIBs with routes learned from AS3356 and AS701 representing shortest prefixes. This action will specifically filter out very small, disaggregated prefixes such as /24s which cause much of the global routing table churn.
- packets that travel through the DFZ will still adhere to the traffic engineering goals of ASes at the edge of the Internet: the AS that has the destination AS as a customer still keeps the full, disaggregated routing information.
- AS1239 still maintains all the routes advertised by AS6163 as the ASes it receives the advertisement from (AS9229, AS6646 and AS4775) are all customers.
- DFZ ASes that do not have the destination AS as a customer i.e. AS3356 and AS701 only keep an aggregate of the disaggregated prefixes (i.e. the /18).
- the method filters a fraction of the more specific prefixes in the DFZ. Additionally, for prefixes learned from non-customer ASes, consecutive prefixes are aggregated to larger ones, further reducing the amount of state. Referring to the Fig. and considering the prefixes 61.14.192.0/21 and 61.14.200.0/21 , if they were received from another DFZ AS, these would be aggregated into a /20, but again, only if they came from a non-customer or peering AS in the tier-1 case. This means that there are no complicated filtering rules necessary based on known prefixes but it applies to, for example, whole BGP sessions.
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- Engineering & Computer Science (AREA)
- Computer Networks & Wireless Communication (AREA)
- Signal Processing (AREA)
- Data Exchanges In Wide-Area Networks (AREA)
Abstract
Description
Claims
Priority Applications (5)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
JP2011506615A JP5097854B2 (en) | 2008-06-13 | 2009-06-09 | Method for registering router in forwarding information base and router |
CN2009801189709A CN102047617A (en) | 2008-06-13 | 2009-06-09 | Method for populating a forwarding information base of a router and router |
EP09761455A EP2286557A1 (en) | 2008-06-13 | 2009-06-09 | Method for populating a forwarding information base of a router and router |
KR1020107028455A KR101241619B1 (en) | 2008-06-13 | 2009-06-09 | Method for populating a forwarding information base of a router and router |
US12/990,692 US20110044342A1 (en) | 2008-06-13 | 2009-06-09 | Method for populating a forwarding information base of a router and router |
Applications Claiming Priority (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
EP08010800 | 2008-06-13 | ||
EP080108004 | 2008-06-13 |
Publications (1)
Publication Number | Publication Date |
---|---|
WO2009149892A1 true WO2009149892A1 (en) | 2009-12-17 |
Family
ID=41010365
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
PCT/EP2009/004128 WO2009149892A1 (en) | 2008-06-13 | 2009-06-09 | Method for populating a forwarding information base of a router and router |
Country Status (6)
Country | Link |
---|---|
US (1) | US20110044342A1 (en) |
EP (1) | EP2286557A1 (en) |
JP (1) | JP5097854B2 (en) |
KR (1) | KR101241619B1 (en) |
CN (1) | CN102047617A (en) |
WO (1) | WO2009149892A1 (en) |
Families Citing this family (4)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US20120078683A1 (en) * | 2010-09-28 | 2012-03-29 | Alcatel-Lucent Usa Inc. | Method and apparatus for providing advice to service provider |
CN102957606B (en) * | 2011-08-30 | 2017-02-08 | 中兴通讯股份有限公司 | Routing information announcement method and device |
US9282026B2 (en) * | 2013-03-11 | 2016-03-08 | Dell Products L.P. | System and method for improved routing in autonomous systems |
US10091105B2 (en) * | 2013-10-25 | 2018-10-02 | Yaoqing Liu | Efficient forwarding information base caching system and method |
Family Cites Families (6)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US7161897B1 (en) * | 2000-11-27 | 2007-01-09 | Nortel Networks Limited | Communications system, apparatus and method therefor |
US6865611B1 (en) * | 2000-11-27 | 2005-03-08 | Nortel Networks Limited | Communications system, apparatus and method therefor |
CN100384142C (en) * | 2004-10-22 | 2008-04-23 | 中国人民解放军国防科学技术大学 | Route between fields abnormity detecting method based on multi view |
US7894433B2 (en) * | 2005-08-08 | 2011-02-22 | Cisco Technology, Inc. | Default gateway router supplying IP address prefixes ordered for source address selection by host device |
JP4630225B2 (en) * | 2006-05-15 | 2011-02-09 | 富士通株式会社 | Communication control system |
US9521063B2 (en) * | 2006-08-23 | 2016-12-13 | Avaya Inc. | Method and system for enhanced internet protocol address aggregation |
-
2009
- 2009-06-09 WO PCT/EP2009/004128 patent/WO2009149892A1/en active Application Filing
- 2009-06-09 KR KR1020107028455A patent/KR101241619B1/en active IP Right Grant
- 2009-06-09 US US12/990,692 patent/US20110044342A1/en not_active Abandoned
- 2009-06-09 EP EP09761455A patent/EP2286557A1/en not_active Withdrawn
- 2009-06-09 CN CN2009801189709A patent/CN102047617A/en active Pending
- 2009-06-09 JP JP2011506615A patent/JP5097854B2/en not_active Expired - Fee Related
Non-Patent Citations (1)
Title |
---|
NARTEN IBM T: "Routing and Addressing Problem Statement; draft-narten-radir-problem- statement-02.txt", 15 April 2008, IETF STANDARD-WORKING-DRAFT, INTERNET ENGINEERING TASK FORCE, IETF, CH, ISSN: 0000-0004, XP015056785 * |
Also Published As
Publication number | Publication date |
---|---|
US20110044342A1 (en) | 2011-02-24 |
JP5097854B2 (en) | 2012-12-12 |
KR20110020267A (en) | 2011-03-02 |
EP2286557A1 (en) | 2011-02-23 |
KR101241619B1 (en) | 2013-03-11 |
JP2011519236A (en) | 2011-06-30 |
CN102047617A (en) | 2011-05-04 |
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