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IP Switching / Tag Switching

IP Switching / Tag Switching. 한국외국어대학교. 한 치 문. Ipsilon's IP Switching. Ipsilon Networks company founded in October 1994 , in Sunnyvale, CA, URL: http://www.ipsilon.com/ IP router software over ATM hardware RFC 1953 Ipsilon Flow Management Protocol Specification for IPv4

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IP Switching / Tag Switching

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  1. IP Switching / Tag Switching 한국외국어대학교 한 치 문

  2. Ipsilon's IP Switching • Ipsilon Networks company • founded in October 1994 , in Sunnyvale, CA, URL: http://www.ipsilon.com/ • IP router software over ATM hardware • RFC 1953 Ipsilon Flow Management Protocol Specification for IPv4 • RFC 1954 Transmission of Flow Labelled IPv4 on ATM Data Links • RFC 1987 Ipsilon's General Switch Management Protocol Specification

  3. : Control Signal : Information Signal IFMP IFMP Routing Protocol Routing Protocol Major Components of an IP Switch • ATM switch, IP switch controller, • Specialized management protocols(GSMP, IFMP) http://www.3com.com/technology/tech_net/white_papers/500636b.html#IP

  4. ATM Switch • all of the software above AAL-5 has been removed • software supporting LAN Emulation servers, address resolution servers, ATM signaling protocols, and all routing protocols are removed from the ATM control processor. • "slave" portion of a protocol is installed • General Switch Management Protocol (GSMP) • permit the ATM switch hardware to accept commands from the IP switching controller.

  5. IP Switching Controller • managing routing protocol updates with its neighbors • constructing the IP routing table • making Layer 3 forwarding decisions • supporting standard routing policies and control functions • identifies packets by examining the contents of a packet's headers (source IP address, destination IP address, source port number, destination port number) • Port-Pair Flow Type • Host-Pair Flow type • performs flow classification (packet forwarding method --> ATM Switch, ATM Controller) • The decision of each IP switch to classify packets as part of a traffic flow is a local policy decision • Application을 identify하는 Source 혹은 Destination Port Number 조사 • 주어진 시간에서 각 Flow에 속하는 Packet 수를 계산

  6. Hop-by-Hop Layer 3 Forwarding Between IP Switch Controllers • When an IP switch is first initialized • Establishes a default ATM forwarding channel (VPI/VCI) on each of its physical links • This default channel allows neighboring IP switch controllers to exchange routing information and perform connectionless hop-by-hop Layer 3 routing

  7. IFMP Redirect (FlowID, VPI/VCI=A, Lifetime) First Phase in Establishing a Switched Flow • IP Controller는 Flow를 수신하면서 Input Port(Port 1)의 Label 공간으로 부터 Free Label(VPI/VCI=A)과, Control Port(Port C)에서 Free Label (VPI/VCI=Z)를 선택함 • IP Switch Controller는 GSMP Protocol를 이용하여 Switch Input Port의 Translation Table에 Entry를 기입한 후, IFMP Redirection Message를 Upstream으로 보냄 • Redirection Message는 Flow ID와 동일한 Header Field를 갖는 모든 패킷은 VPI/VCI=A의 채널로 전송되도록 요구함

  8. IP Switch Controller Upstream Direction Downstream Direction Port C IFMP Redirect (FlowID, VPI/VCI=A, Lifetime) IFMP Redirect (FlowID, VPI/VCI=B, Lifetime) Default VPI/VCI=A Default VPI/VCI=B Port 1 Port 0 Second Phase in Establishing a Switched Flow • Downstream Node가 Flow를 특정 VPI/VCI로 Redirection할 때,Switching의 이점이 존재하며, Flow Labelling Process는 각 링크에서 독립적으로 수행됨. Flow Classification Policy는 Administrative Domain내에서 일관성을 가짐. 따라서 Downstream Node는 거위 동일한 시간에 Flow를 redirect함 • 트래픽이 Switched Path에서 Cut Over 되면, Packet Misordering이 발생할 가능성이 있음. Switched Path 설정을 Source를 향해 Network를 통해 설정하도록 Destination에서 이루어지도록함.

  9. The IP Switch can support • IP multicast employing • the standard Internet Group Management Protocol (IGMP) • multicast routing protocols such as the Distance Vector Multicast Routing Protocol (DVMRP) • Flow classification may include a QOS determination based on the contents of the IP header (type of service, application), the qualities of the underlying ATM hardware, or RSVP.

  10. Upstream Downstream (IFMP Redirect) Upstream Traffic in Each Direction is Treated as a Separate Flow

  11. IP Switch Controller Request Response ATM Switch Ipsilon's General Switch Management Protocol (GSMP) • GSMP : • IP Switch Controller가 ATM Switch를 제어하는데 필요한 프로토콜임 • GSMP는 VPI=0, VCI=15로 동작 • 모든 Meaage는 AAL-5 LLC/SNAP로 Encapsulation됨 • 대부분 한 개의 Cell 크기로 구성 • 특징: • GSMPSlave의 특성은 초당 1,000개 커넥션이 가능 • GSMP Protocol Code Size는 약 1,000 Line 정도 • 서로 상이한 8개의 ATM Switch에서 구현

  12. Five basic types GSMP messages • Configuration request-response messages • Switch configuration msg : manufacturer , 48-bit IEEE 802 MAC address • A port configuration message returns information a switch port: • min/ max values of dynamically assigned incoming VPIs and VCIs, • bandwidth of the port measured in cells per second, • port status (available, unavailable, internal /external/ bothway loopback) • line status of the port (up, down, or test), • Connection management request-response messages • message types: Add Branch, Delete Branch, Delete Tree, Verify Tree, Delete All, and Move Branch

  13. Five basic types GSMP messages • Port management request-response messages • seven port management functions: Bring Up, Take Down, Internal Loopback, External Loopback, Bothway Loopback, Reset Input Port, Reset Event Flags • Statistics request-response messages • gather information from the port and VC-specific traffic and error counters • Event message(비 주기적으로 스위치가 Controller에 Report함) • five types of event messages: Port Up, Port Down, Invalid VPI/VCI, New Port, and Dead Port

  14. IFMP Redirect Message • IFMP 프로토콜은IFMP peer들 사이를 접속하는 IP Switch Network 내의 각 링크에서 독립적으로 이루어짐 • Default Virtual Channel(VPI=0, VCI=15)를 이용 • IFMP의 목적은 특정한 Flow에 대해 특정 VPI/VCI 채널로 전송하도록 송신단에 알려주눈것임. 이때 VPI/VCI 값은 수신 단에 의해 선택됨

  15. IFMP Flow Identifiers • Port-Pair Flow Type • 동일한 Source 및 Destination IP Address에서 동일한 Source 및 Destination TCP/UDP 단자 사이를 흐르는 트래픽 • Host-Pair Flow Traffic • 동일한 Source 및 Destination IP Address 사이를 흐르는 트래픽

  16. Structure of an IFMP Redirect Message

  17. IP ATM Tag Edge Tag Switch + = or Routing Switching Tag Switch (Introduction) • Tag Switching • Scaleable Integration of Switching and Routing Cisco Systems Confidential 0029_08F8_c1 25

  18. ATM Tag Switches ATM TSRs LS1010, StrataCom BPX Frame Tag Switches TSRs C7500, C7200 Tag Edge Routers TERs C7500, C7200 Tag Switch Controller ATM TSC C7200 TSR - Tag Switching Router Tag Switch (Introduction) Tag Switching Elements

  19. Tag Bindings • Per destination prefix • Multiple address ranges per tag • Specified paths for traffic engineering • Per QoS class • Per source/destination flow Tag Switch (Introduction) • Tag Edge Routers • Full-function Layer 3 routers • Security • Quality of service (QOS) • Traffic management • NetFlow switching • Apply tags to packets based on Tag Information Base (TIB) • Variety of binding options • Variety of link types • Packet-over-SONET, HSSI • ATM • Future FE/Gb Ethernet • Cisco IOS upgrade for existing Cisco routers

  20. Tag Switch (Introduction) Switching on Tags • Simplified lookup on tag • Tag label swap on forwarding • Switching done in software or hardware Tag Switches Routers or ATM switches Switches are Layer 3 routing peers Multiple routing protocols OSPF, IS-IS, EIGRP, BGP QoS and traffic engineering support

  21. Tag Switching Components • Tag Switching Components • Forwarding component • Based on label-swapping paradigm • The tag is used as an index • VPI/VCI, ATM and DLCI, Frame Relay • Control component • Responsible for binding of tags to Layer 3 routes • Distribution and maintenance of tags amongst TSRs • Separation allows for modularity • Accommodates new and emerging requirements TSR - Tag Switching Router

  22. Tag Switching Components Forwarding Component Forwarding table(FIB) populated by routing protocols OSPF, IGRP, BGP, IS-IS The Tag Forwarding Information Base(TFIB) is used in forwarding tagged packets Contains the incoming tag, outgoing tag, exit interface and outgoing link- level information Forwarding is based on exact match algorithm FIB - Forwarding Information Base

  23. Tag Switching Components Forwarding Component Forwarding algorithm: Extract tag from a packet Find TFIB entry with incoming tag = tag from packet Replace tag in packet with: outgoing tag and new MAC address Send packet on outgoing interface Forwarding is simple enough to allow for a straightforward hardware implementation TFIB - TagForwarding Information Base

  24. Tag Switching Components • Control Component • Responsible for creating and distributing and maintaining tag bindings • Bindings are driven by control traffic • Bindings are NOT driven by data traffic • The Tag Distribution Protocol (TDP) is used for binding tags to IP prefixes • Other binding options; BGP, RSVP RSVP - Resource reSerVation Protocol RSVP - Resource reSerVation Protocol

  25. PPP: Extra Tag Header PPP Header Tag Layer 3 Header Ethernet: Similar Ethernet Hdr Tag Layer 3 Header IPv6 Flow Label Field Ver Prio Flow Label ?? Tag ATM Cell Header GFC VPI VCI PTI CLP HEC DATA Tag Tag Encapsulations Tag Encapsulations Tag is independent of MAC layer and L3, but can fit in convenient places in L2 and L3 headers

  26. 0 1 2 3 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | TAG |RES|CoS|S| TTL | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Tag Encapsulations • Tag Header Format S = Bottom of stack TTL = Time to live CoS = Class of Service RES = Reserved • Can be used over Ethernet, 802.3, or PPP links • Requires two new Ethertypes/PPP PIDs for unicast (8847), one for multicast (8848) • Four octets in length

  27. Destination-Based Routing • Destination-Based Routing AddressPrefix Exit Interface AddressPrefix Exit Interface AddressPrefix Exit Interface 128.89 0 128.89 1 128.89 0 1 171.69 1 171.69 ... ... ... 128.89 0 128.89.25.4 Data 0 128.89.25.4 Data 1 1 128.89.25.4 Data 128.89.25.4 Data 171.69 Router builds FIB from Router Table and makes a Forwarding Decision based on Destination Address FIB - Forwarding Information Base

  28. Tag Allocation and TIB management • Downstream Tag Allocation • Downstream-on-Demand Tag Allocation • Upstream tag Allocation

  29. Downstream Tag Allocation • Frame-Based Tag Switching AddressPrefix Out Tag AddressPrefix Out Tag AddressPrefix Out Tag 128.89 - 128.89 9 128.89 4 171.69 171.69 171.69 ... ... ... R_1 TSR_2 R_3 Downstream Tag BINDING Downstream Tag BINDING TDP Session TDP Session Tags are created and bound by the Switch at the Downstream End of the Link, with respect to the Flow of Data 43

  30. Tag BIND_REQUEST Tag BIND_REQUEST 1 2 Conservative Mode 1 -- 2 -- 3 -- 4 Optimistic Mode 1 -- 4 -- 2 -- 3 ATM-TSR_2 R_1 R_3 TDP (VPI/VCI 0/32) TDP (VPI/VCI 0/32) Downstream Tag BINDING Downstream Tag BINDING 4 3 Tags are only allocated and distributed by the Downstream Switch when requested by the Upstream Switch Downstream-on-Demand Tag Allocation • Cell-Based Tag Switching

  31. Tag BIND_REQUEST Tag BIND_REQUEST Tag BINDING Tag BINDING Router 1 Router 2 Tag Distribution Protocol Tag Distribution Protocol Provides the mechanism for binding and distributing tags Binds tags/labels to IP prefixes Creates a Tag Information Base (TIB) One of several tag-binding mechanisms

  32. Tag Distribution Protocol (TDP) builds a Tag Information Base (TIB) in Tag-Edge Routers and Tag Switches Tag Switching Operation Tag Switching Operation Overview

  33. Ingress Tag-Edge Router receives Packet, performsLayer 3 Value-Added Services (Filtering, Encryption, Etc.) and applies Tag to Packets or Cells Tag Switching Operation Tag Switching Operation Overview

  34. Core Tag Switches, switch Packets based on Tags and perform Tag Swapping Tag Switching Operation Tag Switching Operation Overview

  35. Tag-Edge Router at Egress removes Tag and delivers Packet Tag Switching Operation Tag Switching Operation Overview

  36. In Tag Address Prefix OutInterface OutTag In Tag Address Prefix OutInterface OutTag In Tag Address Prefix OutInterface Out Tag 128.89 1 4 X 4 128.89 0 9 9 128.89 0 X 5 X 171.69 1 5 5 171.69 1 7 X 171.69 2 ... ... ... ... ... ... ... ... ... ... ... ... 128.89 0 0 128.89.25.4 Data 1 9 128.89.25.4 Data 2 Data 4 128.89.25.4 Data 1 Router performs Longest match lookup, Adds TAG Subsequent routers forward on TAGs 171.69 128.89.25.4 Tag Switching Operation Tag Switching Example: How Tag Switching Works

  37. Hierarchical IP Routing Two-Level Tags Isolate interdomain and intradomain routing Improving stability One level of tags for the interior IGP routes maintained by interior nodes Reduces interior table size Second level of tags for the exterior Only edge nodes run BGP Improves BGP scaling

  38. Border Router Addr Btg Addr Btg Interior Routers Itg Itg Addr Btg Itg Addr Btg Key IGP Tag Itg Addr Btg Btg BGP Tag • Decouples interior and exterior routing information • Allows for aggregation, (stacks of tags) Hierarchical IP Routing Two-Level Tags

  39. Without Tag Switching • Layer 2, Layer 3 overlay • All routers are neighbors to all others • High number of routing adjacencies • One link failure = N (squared) peer failures • Signaling performance issues • Scalability is limited • With Tag Switching • Tag switches are routing peers • Routers know all links • Integrated routing, addressing, management • Minimizes signaling overhead • Increased scalability Tag Switching Benifits IP over ATM vs. Tag Switching

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