(c) all rights reserved by professor wen-tsuen chen1 ä interior gateway routing protocol í a...

(C) All rights reserved by Professor (C) All rights reserved by Professor Wen-Tsuen ChenWen-Tsuen Chen

11

Interior Gateway Routing ProtocolInterior Gateway Routing Protocol A Routing Protocol within an autonomous systeA Routing Protocol within an autonomous syste

m (AS).m (AS). OSPF (Open Shortest Path First) RFC 1247 (VOSPF (Open Shortest Path First) RFC 1247 (V

ersion 1), RFC 1583 (Version 2).ersion 1), RFC 1583 (Version 2). Exterior Gateway Routing ProtocolExterior Gateway Routing Protocol

A Routing Protocol between ASes.A Routing Protocol between ASes. BGP (Border Gateway Protocol) RFC 1654.BGP (Border Gateway Protocol) RFC 1654.

Internet Routing ProtocolInternet Routing Protocol


22

OSPF Routing ProtocolOSPF Routing Protocol

Support a variety of distance metrics, Support a variety of distance metrics, including physical distance, delay, etc.including physical distance, delay, etc.

Support routing based on type of service.Support routing based on type of service. Load balancing: splitting the load over Load balancing: splitting the load over

multiple lines.multiple lines. Support for hierarchical systems: dividing Support for hierarchical systems: dividing

an AS into number areas.an AS into number areas.


33

Graph representation in OSPFGraph representation in OSPF

OSPF computes the shortest path from every router to every other OSPF computes the shortest path from every router to every other router.router.


44

AS as a hierarchical systemAS as a hierarchical system An area is a network or a set of contiguous networks.An area is a network or a set of contiguous networks. Every AS has a Every AS has a backbonebackbone area, called area o. area, called area o.

Internal Routers, Internal Routers, Area Border Routers,Area Border Routers,Backbone Routers,Backbone Routers,AS boundary RoutersAS boundary Routers


55

Within an area, each router runs the same shortest Within an area, each router runs the same shortest path algorithm to calculate the shortest path to evepath algorithm to calculate the shortest path to every other router in the area.ry other router in the area.

Handle type of service routing with multiple graphHandle type of service routing with multiple graphs, one labeled with costs of the type of service.s, one labeled with costs of the type of service.

For routing within an AS, need intra-area and inteFor routing within an AS, need intra-area and inter-area routers.r-area routers.


66

OSPF uses link state routing algorithms:OSPF uses link state routing algorithms: A designated router in a LAN. Exchange information A designated router in a LAN. Exchange information

only with designated routers.only with designated routers.


77

BGP Routing ProtocolBGP Routing Protocol BGP1 in 1989, current version BGP4 in 1993.BGP1 in 1989, current version BGP4 in 1993. BGP is fundamentally a distance vector protocol.BGP is fundamentally a distance vector protocol. Each BGP keeps track of the exact path used.Each BGP keeps track of the exact path used.

After all the paths come in from the neighbors, the best can be determined.After all the paths come in from the neighbors, the best can be determined.Since each router keeps the exact routes used, the count-to-infinite problem can Since each router keeps the exact routes used, the count-to-infinite problem can be easily solved.be easily solved.BGPs uses TCP as its transport protocol (port 179). for reliable transmission.BGPs uses TCP as its transport protocol (port 179). for reliable transmission.


88

Internet MulticastingInternet Multicasting IP supports multicasting using class D addresses.IP supports multicasting using class D addresses. Permanent addresses and temporary addresses.Permanent addresses and temporary addresses.

Permanent addressesPermanent addresses 224.0.0.1 all systems on a LAN224.0.0.1 all systems on a LAN 224.0.0.2 all routers on a LAN224.0.0.2 all routers on a LAN 224.0.0.5 all OSPF routers on a LAN224.0.0.5 all OSPF routers on a LAN 224.0.0.6 all designated routers on a LAN224.0.0.6 all designated routers on a LAN

A multicast router uses the IGMP (Internet Group A multicast router uses the IGMP (Internet Group Management Protocol) to group hosts the groups their Management Protocol) to group hosts the groups their processes currently belong to.processes currently belong to.

IGMP in RFC 1112.IGMP in RFC 1112.

Multicast routing uses spanning trees.Multicast routing uses spanning trees.


99

IP Mobility SupportIP Mobility Support

Each mobile host is able to use its home IP Each mobile host is able to use its home IP address anywhere.address anywhere.

Home agent vs. foreign agent.Home agent vs. foreign agent.


1010

IPv6IPv6

A modified combined version of Deering and FranA modified combined version of Deering and Francis proposals. SIPP (Simple Internet Protocol Plucis proposals. SIPP (Simple Internet Protocol Plus).s).

RFC 1752 issued in Jan 1995,RFC 1883, 1884, 18RFC 1752 issued in Jan 1995,RFC 1883, 1884, 1886,1887,1809,…86,1887,1809,…

Longer addresses.Longer addresses. Simplification of headers.Simplification of headers. Support for options.Support for options. Security and authentication.Security and authentication. Type of services.Type of services.


1111

IPv6 HeaderIPv6 Header


1212

Priority: 0~7 for transmissions possibly slowed down in Priority: 0~7 for transmissions possibly slowed down in case of congestion. 8~15 for real-time traffic.case of congestion. 8~15 for real-time traffic.

Flow label: for setting up a pseudo connection with Flow label: for setting up a pseudo connection with particular properties and requirements.particular properties and requirements.

Payload length: information bytes following the 40 byte Payload length: information bytes following the 40 byte header. 64 K bytes maximum.header. 64 K bytes maximum.

Next header: specify which of the (currently six) extension Next header: specify which of the (currently six) extension headers, if any, follows the header. If the header is the last headers, if any, follows the header. If the header is the last IP header, the Next header specifies the transport protocol IP header, the Next header specifies the transport protocol handler.handler.

Hop limit: for limiting packet lifetime.Hop limit: for limiting packet lifetime.


1313

IPv6 addressesIPv6 addresses


1414

No packet fragmentationNo packet fragmentation All IPv6 conformant hosts and router must support All IPv6 conformant hosts and router must support

packets of 576 bytes.packets of 576 bytes. The router that is unable to forward a large packet The router that is unable to forward a large packet

sends back an error message, to tell the host to sends back an error message, to tell the host to fragment future packets.fragment future packets.

No header checksum.No header checksum. No IHL because IPv6 header has a fixed length.No IHL because IPv6 header has a fixed length.


1515

IPv6 Data UnitIPv6 Data Unit

IPv6 HeaderIPv6 Header Extension HeaderExtension Header ...... Extension HeaderExtension Header Transport DUTransport DU

40 octets40 octets 0 or more0 or more


1616

IPv6 Extension HeadersIPv6 Extension Headers


1717

The hop-by-hop header should be examined The hop-by-hop header should be examined by all routers along the path.by all routers along the path.

Jumbograms are large datagrams exceeding Jumbograms are large datagrams exceeding 65,536 bytes. 65,536 bytes.

Hop-by-Hop Extension HeaderHop-by-Hop Extension Header


1818

Routing Extension HeadersRouting Extension Headers


1919

Routing Extension Headers (cont.)Routing Extension Headers (cont.)

List one or more routers that must be visited.List one or more routers that must be visited. Next address starts at 0 and is incremented as starts at 0 and is incremented as

each address is visited.each address is visited. Bit map tells whether each address must be tells whether each address must be

visited directly after the one before it (strict visited directly after the one before it (strict source routing) , or whether other routers source routing) , or whether other routers may come in between (loose source routing).may come in between (loose source routing).


2020

ATM Layer in ATM networksATM Layer in ATM networks Connection-oriented.Connection-oriented. No acknowledgements.No acknowledgements. Cells arriving destinations in order.Cells arriving destinations in order. Tow-level connection hierarchy.Tow-level connection hierarchy.


2121

Payload TypePayload Type


2222

ATM Cell HeaderATM Cell Header


2323

Connection Setup/ReleaseConnection Setup/Release


2424


2525

ATM RoutingATM Routing

To route on the VPI field except at the final hop.To route on the VPI field except at the final hop.


2626


2727


2828

Quality of Service CategoriesQuality of Service Categories


2929


3030

QoS Parameters: CLP, CTD, CDVQoS Parameters: CLP, CTD, CDV CBR: CDV, CTD, CLPCBR: CDV, CTD, CLP rt-VBR: CDV, CTD, CLPrt-VBR: CDV, CTD, CLP nrt-VBR: CLPnrt-VBR: CLP

Traffic Parameters:Traffic Parameters: CBR: PCR, CDVTCBR: PCR, CDVT rt-VBR: PCR, CDVT, SCR, MBSrt-VBR: PCR, CDVT, SCR, MBS nrt-VBR: PCR, CDVT, SCR, MBSnrt-VBR: PCR, CDVT, SCR, MBS

UBR: PCR, CDVTUBR: PCR, CDVT ABR: PCR, CDVT, MCRABR: PCR, CDVT, MCRwhere MBS is the maximum burst size.where MBS is the maximum burst size.


3131


3232

Traffic contractTraffic contract

A traffic contract specifies the negotiated characteristics of A traffic contract specifies the negotiated characteristics of a connection.a connection.

Traffic contract specification consists ofTraffic contract specification consists of A connection traffic descriptor.A connection traffic descriptor. A set of QoS parameters for each direction of the connection.A set of QoS parameters for each direction of the connection. The definition of a compliant.The definition of a compliant.

Connection traffic descriptor includesConnection traffic descriptor includes A set of traffic parameter of the ATM source.A set of traffic parameter of the ATM source. The CDVT.The CDVT. The conformance definition that specifies the conforming cells of The conformance definition that specifies the conforming cells of

the connection.the connection.


3333

The Generic Cell Rate Algorithm(GCRA)

The Generic Cell Rate Algorithm(GCRA)

GCRA (I, L)GCRA (I, L) Where I: IncrementWhere I: Increment L: LimitL: Limit


3434


3535

Traffic PolicingTraffic PolicingCell

t1

t1

t1

t1

t2

t2

Maximal caseCell 2 arrives T sec after Cell 1

Slow sender.Cell 2 arrives > T sec after Cell 1

Fast sender.Cell 2 arrives up to L sec early

Very fast sender.Cell 2 arrives prior to t1 + T - L.Cell is nonconforming

Cell 3 expected at t1 + T



Cell 3 expected at t2 + 2T

T


3636

Traffic Contract Conformance DefinitionTraffic Contract Conformance Definition

Traffic Management specification,Version 4.0Traffic Management specification,Version 4.0 CBR Service:CBR Service:

GCRA (1/PCR, CDVT)GCRA (1/PCR, CDVT)

VBR ServicesVBR Services GCRA (1/PCR, CDVT)GCRA (1/PCR, CDVT) GCRA (1/SCR, BT+CDVT), GCRA (1/SCR, BT+CDVT),

where BT = (MBS-1)(1/SCR-1/PCR)where BT = (MBS-1)(1/SCR-1/PCR)

UBR ServicesUBR Services PCRPCR

ABRABR DGCRADGCRA 321

111 ,,,,, ICRPCRMCR

The ATM Forum, April 1996The ATM Forum, April 1996


3737

Congestion ControlCongestion Control

Admission Control with resource reservation.Admission Control with resource reservation. Rate-based Congestion Control for ABR traffic.Rate-based Congestion Control for ABR traffic.

The sender has a current cell rate ACR (Actual Cell Rate), The sender has a current cell rate ACR (Actual Cell Rate), MCRMCRACRACRPCR. PCR.

ACR is reduced, if congestion occurs.ACR is reduced, if congestion occurs. For each RM-cell, ER (Explicit Rate) is set by the source to a requested rate For each RM-cell, ER (Explicit Rate) is set by the source to a requested rate

(such as PCR) and may be subsequently reduced by any network element in (such as PCR) and may be subsequently reduced by any network element in the path to a value that the element can sustain. ER is then used to limit the the path to a value that the element can sustain. ER is then used to limit the source ACR to a specific value.source ACR to a specific value.


3838

ATM LAN EmulationATM LAN Emulation

LES: LAN Emulation ServerLES: LAN Emulation Server BUS: Broadcast/Unknown ServerBUS: Broadcast/Unknown Server

(c) all rights reserved by professor wen-tsuen chen1 ä interior gateway routing protocol í a...

Documents

ospf routers

designated routers

professor wentsuen chen4

professor wentsuen chen5

professor wentsuen chen6

area border routers

ospf ospf

multicast routing