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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

IP Switching / Tag Switching

한국외국어대학교

한 치 문


Ipsilon s ip switching

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


Major components of an ip switch

: 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


Atm switch

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.


Ip switching controller

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


Hop by hop layer 3 forwarding between ip switch controllers

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


First phase in establishing a switched flow

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


Second phase in establishing a switched flow

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.


The ip switch can support

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.


Traffic in each direction is treated as a separate flow

Upstream

Downstream

(IFMP Redirect)

Upstream

Traffic in Each Direction is Treated as a Separate Flow


Ipsilon s general switch management protocol gsmp

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


Five basic types gsmp messages

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


Five basic types gsmp messages1

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


Ifmp redirect message

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


Ifmp flow identifiers

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


Structure of an ifmp redirect message

Structure of an IFMP Redirect Message


Tag switch introduction

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


Tag switching elements

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


Tag switch introduction1

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


Ip switching tag switching

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


Tag switching components

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


Tag switching components1

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


Tag switching components2

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


Ip switching tag switching

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


Tag encapsulations

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


Ip switching tag switching

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


Destination based routing

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


Tag allocation and tib management

Tag Allocation and TIB management

  • Downstream Tag Allocation

  • Downstream-on-Demand Tag Allocation

  • Upstream tag Allocation


Downstream tag allocation

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


Downstream on demand tag allocation

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


Tag distribution protocol

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


Tag switching operation

Tag Distribution Protocol (TDP) builds a Tag Information Base (TIB) in Tag-Edge Routers and Tag Switches

Tag Switching Operation

Tag Switching Operation Overview


Tag switching operation1

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


Tag switching operation2

Core Tag Switches, switch Packets based on Tags and perform Tag Swapping

Tag Switching Operation

Tag Switching Operation Overview


Tag switching operation3

Tag-Edge Router at Egress removes Tag and delivers Packet

Tag Switching Operation

Tag Switching Operation Overview


Tag switching operation4

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


Hierarchical ip routing

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


Hierarchical ip routing1

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


Tag switching benifits

  • 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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