IP Transmission Technologies

transcript

Hourglass of TCP/IP Protocols

email WWW phone...

SMTP HTTP RTP...

TCP UDP…

ethernet PPP…

CSMA async sonet...

copper fiber radio...

Transmission Technologies

Ethernet (10Mbps – 1Gbps) Copper Fiber Wireless Satellite

Leased Line (64Kbps – 2Mbps)Frame Relay (64Kbps – 2Mbps)Packet Over Sonet (155Mbps – 2.4Gbps)ATM (155Mbps – 2.4Gbps)Access: DSL, CATV, ISDN, GPRS, Dial-up

Some Issues:•service discovery•security•management•spectrum coexistence

Wireless data everywhere

SatelliteExample (Digital Video Broadcast:

DVB-RCS)

Types of Point to Point Protocols

SLIP over async Very simple IP only Unreliable - no checksum

HDLC over sync various proprietary versions frames have checksum

Leased Line

SDTE DTEDCE DCE

Flag Address Control Proprietary Data FCS Flag

Cisco HDLC

PPPFlag Address Control Protocol LCP FCS Flag

Link Control Protocol (LCP)

Code Identifier Length Data

V.35V.35

“SLIP done right”Used for synchronous and

asynchronous transmissionExtended negotiation mechanismMultiple protocol support

PPP and OSI model

Synchronous or Asynchronous Physical Media

LCP - Link Control Protocol

PPP Network Control Protocol

IPCP IPXCP others

Physical Layer

Data Link Layer

Network Layer

LCP Configuration Options

Feature Protocol

Authentication PAP, CHAP

Compression Stacker, ..

Error Detection Quality

Multilink MPPP

PAP/CHAP

PAP Password required Unencrypted password sent via the link Allows storage of encrypted passwords

CHAP Challenge handshake No passwords sent via the link Need for storing unencrypted secrets

Passwords sent in cleartextPeer in control of attempts

Selecting a PPP Authentication Protocol

Remote Router(SantaCruz)

Central-Site Router (HQ)

Hostname: santacruzPassword: boardwalk

username santacruzpassword boardwalk

PAP 2-Way Handshake

"santacruz, boardwalk"

Accept/Reject

Selecting a PPP Authentication Protocol

Remote Router(SantaCruz)

Central-Site Router (HQ)

Hostname: santacruzPassword: boardwalk

username santacruzpassword boardwalk

CHAP3-Way Handshake

Challenge

Response

Accept/Reject

Use “secret” known only to authenticator and peer

Multilink PPP

Combining physical links into one logical bundle

Result: higher speed and lower latency MPPP / Bonding

MPPP assembles/disassembles frames on the Data Link Layer

MPPP used for synchronous and asynchronous physical links

Bonding assembles/disassembles on the bit level

ISDN Call setup and Teardown

Corresponds with output from debug isdn q931

Show ppp multilink

Show that both B channels are involved with the connection

Frame Relay

s0.2-DLCI=110

s0.3-DLCI=120

s0.1-DLCI=120

s0.2-DLCI=130

s0.1-DLCI=110

s0.3-DLCI=130RTR2

Packet Over Sonet (POS)

OC-1 STS-1 51.84

OC-3 STS-3 STM-1 155.52

OC-9 STS-9 STM-3 466.56

OC-12 STS-12 STM-4 622.08

OC-18 STS-18 STM-6 933.12

OC-24 STS-24 STM-8 1244.16

OC-36 STS-36 STM-12 1866.24

OC-48 STS-48 STM-16 2488.32

SONET/SDHOS

SONETES

Link Rate Mbps

ATM AAL5

MPLS VPNs

MPLS Forwarding and/ or LDP

Traffic Engineering(TE)

DiffServ-aware Traffic Engineering

(DS-TE)

Managed VPN Services(MPLS/ BGP VPNs)

Any Transport over MPLS(AToM)

Inter-Provider

Connectivity(I-AS)

Carrier Supporting

Carrier (CSC)

Multicast over MPLS VPNs

InterInter--Area TEArea TE

Layer 2 VPN Services(L2VPN)

Quality of Service(DiffServ QoS)

MPLS Forwarding and/ or LDP

Traffic Engineering(TE)

DiffServ-aware Traffic Engineering

(DS-TE)

Managed VPN Services(MPLS/ BGP VPNs)

Any Transport over MPLS(AToM)

Inter-Provider

Connectivity(I-AS)

Carrier Supporting

Carrier (CSC)

Multicast over MPLS VPNs

InterInter--Area TEArea TE

Layer 2 VPN Services(L2VPN)

Quality of Service(DiffServ QoS)

Layer 3 VPNs = BGP/MPLS VPNs

(RFC 2547 bis)

Layer 2 VPNs & AToM (Any Transport over MPLS)

Layer 2 Vs. Layer 3 VPNs:

Depending on the type of customer payload, a VPN can be classified as L2 or L3 VPNs: Examples of L2VPN:

ATM LAN Emulation (LANE),Ethernet over MPLS (Idraft-Martini, Idraft-

KKompella, VPLS: Idraft-Lasserre-VKompella, IPLS: Idraft-Shah)

Examples of L3VPN:RFC 1577: Classical IP over ATM IPSec Tunneling modeRFC 2547: BGP/MPLS-based VPNsIdraft-Declercq: BGP/IPSec VPNsIdraft-Knight: Virtual Router Based VPNs

Encapsulation of Customer Ethernet Frames in a L2 PPVPN

Untagged or Tagged Ethernet Untagged or TaggedCustomer Ethernet over MPLS Customer Ethernet Frames over Ethernet Frames

UserEnet

MPLS-Domain

UserEnet

VLANVLAN

UserEnet

ORMPLS MPLS

MPLSMPLS

Enet Enet

Provider NetworkSupporting L2PPVPN

Customer or Other Ethernet Access Network

Customer or OtherEthernet Access Network

VC Label

Tunnel Label

Single Customer VLAN Domain

Customer A L2 Network, e.g. Ethernet

Customer BL2 Network, e.g. Ethernet

Ethernet Frames with or without

VLAN tags

2 MPLS LABELS per frame:Tunnel Label = Outer Label for delivery to dest. PE

VC Label = Inner Label to identify L2VPN end-pts ;

802.1q VLANs

MPLS LSP MESH

Example of a L2 PPVPN (VPLS)

Customer A L2 Network, e.g. Ethernet

Customer B L2 Network, e.g. Ethernet

802.1q VLANs

Customer LAN switch

Provider Network

Customer A Network

Customer BNetwork

CustomerIP packets carrying possibly Private IP

addresses

2 MPLS LABELS per frame:Tunnel Label = Outer Label for delivery to dest. PE

VC Label = Inner Label to identify L2VPN end-pts ;

MPLS LSP MESH

Example of a L3 PPVPN (RFC2547bis)

Customer ANetwork

Customer B Network

Customer Edge Router

Provider Network

Ethernet over MPLS

MPLS Network

Enterprise LAN

Point to Point, Metro Ethernet Service

Distributed NAP

Based on draft-martiniVCs to VLANs => VCid maps to VLAN id

Ethernet 802.1q VLAN Transport

VLAN 41

VLAN 56

PE1 1.0.0.4

PE1 1.0.0.8

802.1q to 802.1q VLAN Transport

Customer Site

Interface GigabitEthernet0/0.2

encapsulation dot1q 41

mpls l2transport route 1.0.0.8 312 <sequencing>

Interface GigabitEthernet1/0.2

encapsulation dot1q 56

mpls l2transport route 1.0.0.8 313 <sequencing>

AToM - MTU Considerations

PE2PE1

Egress MTU Signalled using LDP

Incoming PDU dropped if MTU exceeded

Ingress PE checks Egress PE outbound interface MTU AND egress interface into MPLS backbone

NO mechanism to check backbone MTU

Provider MUST dictate MTU or direct traffic away from low MTU links

Customer Site

MPLS VPNs for Multiple Transport Types

MPLS VPNs for Multiple Networks

MPLS VPNs for Single Networks

•Carrier Supporting Carrier•Inter AS•VPN ID

Cisco’s MPLS VPNs L3 (rfc2547)

Strategy for MPLS VPNs

Layer 2 VPNs –Using AToMOptical VPNs

•ATM (AAL5) over MPLS•Ethernet over MPLS•Frame Relay over MPLS•PPP over MPLS•HDLC over MPLS•Cell Relay over MPLS

Introduction –IETF DiffServ Architecture (RFC-2475)

• The idea: different service levels for packets• The service: some significant characteristics of packet

transmission in one direction across the networkExamples: bandwidth and latency

Type-of-Service (RFC791)

Version Length Total Length

80 15 31

Precedence UnusedD T R

D Normal Delay Low Delay

T Normal Throughput High Throughput

R Normal Reliability High Reliability

ToS Field …

IP Precedence Values

111 Network Control

110 Internetwork Control

101 Critical

100 Flash Override

011 Flash

010 Immediate

001 Priority

000 Routine

Network-Layer BWM

Bandwidth Management functions classification, shaping discarding, queuing

Queuing Disciplines

First-In-First-Out (FIFO) no classes fast, easy to implement

Priority Queuing all traffic in a high-priority class is sent before

any in a lower priority one

Class-based Queuing (CBQ) a number of bytes is sent from each class

before going to the next class

Priority Queuing

Class-Based Queuing

Queuing Disciplines (cont.)

Weighted Fair Queuing traffic is divided into a number of flows each flow is given a share of the traffic

(based on its weight) small packets are given priority over

large ones (interactive and control traffic gets more priority)

Weighted Fair Queuing

Token Bucket Model

Token Bucket main parameters: Token Arrival Rate - v Bucket Depth - Bc Time Interval – tc Link Capacity - C Overflow Tokens

Tokens

Incoming

packetsConform

Exceed

Token Bucket characterizes traffic source

tc = Bc/v

Excess Burst (Be)Cisco Implementation

CARallows RED like behavior:

traffic fitting into Bc always conforms traffic fitting into Be conforms with probability

proportional to amount of tokens left in the bucket traffic not fitting into Be always exceeds

CAR uses the following parameters: t – time period since the last packet arrival Current Debt (Dcur) – Amount of debt during current time

interval Compound Debt (Dcomp) – Sum of all Dcur since the last drop Actual Debt (Dact) – Amount of tokens currently borrowed

Excess Burst (Be)Cisco Implementation

CAR AlgorithmPacket of length

L arrived

Bccur – L > 0ConformAction

Dcur = L - Bccur

Bccur = 0Dcomp = Dcomp + Dcur

Dact = Dact + Dcur

Dact > BeY

ExceedAction

Dcomp > BeY

Dcomp = 0

Bccur = Bccur – L

Policing Configuration Sample

ip cef

interface serial 2/1

ip unnumbered loopback 0

rate-limit output access-group 100 64000 8000 16000 conform-action transmit excess-action drop

interface serial 2/2

rate-limit input 128000 16000 32000 conform-action transmit excess-action drop

access-list 100 permit tcp host 10.0.0.1 any eq http

CAR Based

Random Early Detection (RED)

Starts randomly dropping packets before actual congestion occurs

Keeps average queue depth lowIncreases average throughput

Developed by Van Jacobson in 1993

10mbps Ethernet 10mbps Ethernet

Voice 1500 Data Bytes Voice Voice 1500 Data Bytes Voice Voice 1500 Data Bytes Voice

56kb WAN

~214ms Serialization Delay

Voice Packet60 bytes

Every 20 ms

Every >214 ms

Benefit: reduce the jitter in voice calls

• Implemented via Multilink PPP (MLP) over FR, ATM, and leased lines • Fragments are interleaved with the real-time packets, reducing the

Serialization delay experienced by Voice packets

Cisco AutoQoS Framework –MLPPP Link Fragmentation & Interleaving

Problem: large packets “freeze out” voice

Link Fragmentation and Interleaving (LFI)

VoicePacket

Jumbogram

64 kbps

1500 bytes 190ms

For links < 128kbps

Link Fragmentation and Interleaving (LFI)

64 kbps

Supported interfaces: Multilink PPP Frame Relay DLCI ATM VC

LFI Configuration Sample

interface virtual-template 1

ppp multilink

ppp multilink interleave

ppp multilink fragment-delay 30

ip rtp interleave 16384 1024 512

MLP version

Dynamic Host Configuration ProtocolBased on old BootP protocol for

diskless workstationsDHCP server on Router or Network

Serverip dhcp pool soho network 10.0.0.0 255.0.0.0 default-router 10.0.0.1 dns-server 195.13.160.52 195.122.1.59

IP Transmission Technologies

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