IP Transmission Technologies
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Transcript of IP Transmission Technologies
IP Transmission Technologies
Hourglass of TCP/IP Protocols
email WWW phone...
SMTP HTTP RTP...
TCP UDP…
IP
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
PPP
Leased Line
S S
SSS
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
PPP
“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
RTR1
s0.2-DLCI=110
s0.3-DLCI=120
s0.1-DLCI=120
s0.2-DLCI=130
RTR3
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
SDHES
Link Rate Mbps
ATM
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
Untagged or Tagged Ethernet Untagged or TaggedCustomer Ethernet over MPLS Customer Ethernet Frames over Ethernet Frames
UserEnet
VLAN
UserEnet
VLAN
UserEnet
VLAN
MPLS-Domain
UserEnet
VLAN
UserEnet
VLANVLAN
UserEnet
UserEnet
UserEnet
UserEnet
UserEnet
UserEnet
UserEnet
ORMPLS MPLS
MPLSMPLS
Enet
Enet Enet
Provider NetworkSupporting L2PPVPN
Customer or Other Ethernet Access Network
Customer or OtherEthernet Access Network
VC Label
Tunnel Label
Enet
Single Customer VLAN Domain
Customer A L2 Network, e.g. Ethernet
Customer A L2 Network, e.g. Ethernet
PEPE
PE
Customer BL2 Network, e.g. Ethernet
Customer BL2 Network, e.g. Ethernet
PE
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 A L2 Network, e.g. Ethernet
Customer B L2 Network, e.g. Ethernet
Customer B L2 Network, e.g. Ethernet
802.1q VLANs
Customer LAN switch
Provider Network
Customer A Network
Customer A Network
PEPE
PE
Customer BNetwork
Customer BNetwork
PE
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 ANetwork
Customer B Network
Customer B Network
Customer Edge Router
Provider Network
Ethernet over MPLS
PE PE
MPLS Network
PE PE
Enterprise LAN
ISP 1
Enterprise LAN
PE PE
ISP 2
ISP A
ISP 3
ISP B
ISP C
Point to Point, Metro Ethernet Service
Distributed NAP
Based on draft-martiniVCs to VLANs => VCid maps to VLAN id
Ethernet 802.1q VLAN Transport
MPLS
VLAN 41
VLAN 41
VLAN 56
VLAN 56
PE1 1.0.0.4
PE1 1.0.0.8
802.1q to 802.1q VLAN Transport
Customer Site
Customer Site
Customer Site
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
PDU
Provider MUST dictate MTU or direct traffic away from low MTU links
Customer Site
Customer Site
Time
MPLS VPNs for Multiple Transport Types
MPLS VPNs for Multiple Networks
MPLS VPNs for Single Networks
•Carrier Supporting Carrier•Inter AS•VPN ID
•Carrier Supporting Carrier•Inter AS•VPN ID
Cisco’s MPLS VPNs L3 (rfc2547)
Cisco’s MPLS VPNs L3 (rfc2547)
Strategy for MPLS VPNs
Layer 2 VPNs –Using AToMOptical 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
•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
0 1
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
Bc
v
C
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
Y
Dcur = L - Bccur
Bccur = 0Dcomp = Dcomp + Dcur
Dact = Dact + Dcur
+v·t
N
Dact > BeY
N
ExceedAction
Dcomp > BeY
N
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
ip unnumbered loopback 0
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
Voice Packet60 bytes
Every >214 ms
Voice Packet60 bytes
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
ip unnumbered loopback 0
ppp multilink
ppp multilink interleave
ppp multilink fragment-delay 30
ip rtp interleave 16384 1024 512
…
MLP version
DHCP
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
VoIP: