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IP Transmission Technologies

IP Transmission Technologies. email WWW phone... SMTP HTTP RTP... TCP UDP… IP ethernet PPP… CSMA async sonet... copper fiber radio. Hourglass of TCP/IP Protocols. Transmission Technologies. Ethernet (10Mbps – 1Gbps) Copper Fiber Wireless Satellite

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IP Transmission Technologies

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  1. IP Transmission Technologies

  2. email WWW phone... SMTP HTTP RTP... TCP UDP… IP ethernet PPP… CSMA async sonet... copper fiber radio... Hourglass of TCP/IP Protocols

  3. 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

  4. Wireless data everywhere • Some Issues: • service discovery • security • management • spectrum coexistence

  5. Satellite • Example (Digital Video Broadcast: DVB-RCS)

  6. 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

  7. Link Control Protocol (LCP) Code Identifier Length Data PPP Flag Address Control Protocol LCP FCS Flag Cisco HDLC Flag Address Control Proprietary Data FCS Flag S S S S S DCE DTE S DTE DCE Leased Line V.35 V.35

  8. PPP • “SLIP done right” • Used for synchronous and asynchronous transmission • Extended negotiation mechanism • Multiple protocol support

  9. PPP and OSI model Network Layer IPCP IPXCP others PPP Network Control Protocol Data Link Layer LCP - Link Control Protocol Synchronous or Asynchronous Physical Media Physical Layer

  10. LCP Configuration Options

  11. 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

  12. Selecting a PPP Authentication Protocol PAP 2-Way Handshake Remote Router (SantaCruz) Central-Site Router (HQ) "santacruz, boardwalk" Accept/Reject • Passwords sent in cleartext • Peer in control of attempts username santacruz password boardwalk Hostname: santacruz Password: boardwalk

  13. Selecting a PPP Authentication Protocol CHAP 3-Way Handshake Remote Router (SantaCruz) Central-Site Router (HQ) Challenge Response Accept/Reject • Use “secret” known only to authenticator and peer username santacruz password boardwalk Hostname: santacruz Password: boardwalk

  14. 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

  15. ISDN Call setup and Teardown • Corresponds with output from debug isdn q931

  16. Show ppp multilink • Show that both B channels are involved with the connection

  17. RTR2 RTR3 Frame Relay s0.1-DLCI=110 s0.2-DLCI=110 s0.3-DLCI=130 RTR1 s0.3-DLCI=120 s0.2-DLCI=130 s0.1-DLCI=120

  18. SONET ES SDH ES SONET/SDH OS Link Rate Mbps 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 Packet Over Sonet (POS)

  19. ATM

  20. ATM AAL5

  21. MPLS VPNs Layer 2 VPNs & AToM (Any Transport over MPLS) Layer 3 VPNs = BGP/MPLS VPNs (RFC 2547 bis)

  22. 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 mode • RFC 2547: BGP/MPLS-based VPNs • Idraft-Declercq: BGP/IPSec VPNs • Idraft-Knight: Virtual Router Based VPNs

  23. 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 User Enet User Enet User Enet User Enet User Enet User Enet VLAN VLAN VLAN VLAN VLAN VLAN MPLS MPLS OR Enet Enet User Enet User Enet User Enet User Enet User Enet User Enet MPLS MPLS VC Label Enet Enet Tunnel Label Customer or Other Ethernet Access Network Provider Network Supporting L2PPVPN Customer or Other Ethernet Access Network MPLS-Domain Single Customer VLAN Domain

  24. PE PE PE PE Example of a L2 PPVPN (VPLS) 802.1q VLANs 802.1q VLANs Provider Network Customer LAN switch Customer A L2 Network, e.g. Ethernet Customer B L2 Network, e.g. Ethernet MPLS LSP MESH 2 MPLS LABELS per frame: Tunnel Label = Outer Label for delivery to dest. PE VC Label = Inner Label to identify L2VPN end-pts ; Customer A L2 Network, e.g. Ethernet Customer B L2 Network, e.g. Ethernet Ethernet Frames with or without VLAN tags

  25. PE PE PE PE Example of a L3 PPVPN (RFC2547bis) Provider Network Customer Edge Router Customer A Network Customer B Network MPLS LSP MESH 2 MPLS LABELS per frame: Tunnel Label = Outer Label for delivery to dest. PE VC Label = Inner Label to identify L2VPN end-pts ; Customer A Network Customer B Network Customer IP packets carrying possibly Private IP addresses

  26. Ethernet over MPLS Point to Point, Metro Ethernet Service ISP C MPLS Network ISP A Enterprise LAN ISP B PE PE ISP 2 PE PE ISP 1 PE PE Enterprise LAN ISP 3 Distributed NAP Based on draft-martini VCs to VLANs => VCid maps to VLAN id

  27. Ethernet 802.1q VLAN Transport 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> VLAN 56 MPLS Customer Site PE1 1.0.0.8 PE1 1.0.0.4 VLAN 41 VLAN 41 VLAN 56 Customer Site Customer Site Customer Site 802.1q to 802.1q VLAN Transport

  28. AToM - MTU Considerations Ingress PE checks Egress PE outbound interface MTU AND egress interface into MPLS backbone Customer Site Customer Site Egress MTU Signalled using LDP PE1 PE2 PDU NO mechanism to check backbone MTU Incoming PDU dropped if MTU exceeded Provider MUST dictate MTU or direct traffic away from low MTU links

  29. Strategy for MPLS VPNs MPLS VPNs for Single Networks MPLS VPNs for Multiple Networks MPLS VPNs for Multiple Transport Types Layer 2 VPNs –Using AToM Optical VPNs • ATM (AAL5) over MPLS • Ethernet over MPLS • Frame Relay over MPLS • PPP over MPLS • HDLC over MPLS • Cell Relay over MPLS • Carrier Supporting Carrier • Inter AS • VPN ID Cisco’s MPLS VPNs L3 (rfc2547) Time

  30. 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 network Examples: bandwidth and latency

  31. Type-of-Service (RFC791) Precedence D T R Unused Version Length ToS Field Total Length … 0 8 15 31

  32. IP Precedence Values

  33. Network-Layer BWM • Bandwidth Management functions • classification, shaping • discarding, queuing

  34. 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

  35. Priority Queuing

  36. Class-Based Queuing

  37. 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)

  38. Weighted Fair Queuing

  39. Tokens v Bc Overflow Tokens C Incoming packets Conform Exceed Token Bucket Model Token Bucket characterizes traffic source Token Bucket main parameters: • Token Arrival Rate - v • Bucket Depth - Bc • Time Interval – tc • Link Capacity - C tc = Bc/v

  40. Excess Burst (Be)Cisco Implementation CAR allows 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 exceedsCAR 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

  41. Excess Burst (Be)Cisco Implementation Packet of lengthL arrived CAR Algorithm Y ConformAction Bccur – L > 0 Bccur = Bccur – L N Dcur = L - Bccur Bccur = 0 Dcomp = Dcomp + Dcur Dact = Dact + Dcur +v·t Y ExceedAction Dact > Be N Y Dcomp = 0 Dcomp > Be N

  42. Policing Configuration Sample CAR Based 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

  43. Random Early Detection (RED) Developed by Van Jacobson in 1993 • Starts randomly dropping packets before actual congestion occurs • Keeps average queue depth low • Increases average throughput

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