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Taller Redes Emergentes
Taller Redes Emergentes
Taller Redes Emergentes
Taller Redes Emergentes
Taller Redes Emergentes
Taller Redes Emergentes
Taller Redes Emergentes
Taller Redes Emergentes
Taller Redes Emergentes
Taller Redes Emergentes
Taller Redes Emergentes
Taller Redes Emergentes
Taller Redes Emergentes
Taller Redes Emergentes
Taller Redes Emergentes
Taller Redes Emergentes
Taller Redes Emergentes
Taller Redes Emergentes
Taller Redes Emergentes
Taller Redes Emergentes
Taller Redes Emergentes
Taller Redes Emergentes
Taller Redes Emergentes
Taller Redes Emergentes
Taller Redes Emergentes
Taller Redes Emergentes
Taller Redes Emergentes
Taller Redes Emergentes
Taller Redes Emergentes
Taller Redes Emergentes
Taller Redes Emergentes
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Taller Redes Emergentes
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Taller Redes Emergentes
Taller Redes Emergentes
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Taller Redes Emergentes
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Taller Redes Emergentes
Taller Redes Emergentes
Taller Redes Emergentes
Taller Redes Emergentes
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Taller Redes Emergentes

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  • 1. Características y evolución de las redes LAN y WAN para ofrecer servicios de Comunicación UnificadaSession IDPresentation_ID © 2007 Cisco Systems, Inc. All rights reserved. Cisco Confidential 1
  • 2. Buenos Días a todos…! Systems Engineer Public Sector arprieto@cisco.comSession IDPresentation_ID © 2007 Cisco Systems, Inc. All rights reserved. Cisco Confidential 2
  • 3. The Elements of Unified CommunicationsVoice Mail/ Web /Audio/ XML LDAP UnifiedMessaging Video Phone Services Directory Applications Conferencing UC UC PSTN/IP MediaEndpoints Resources Processing Gateway UC Infrastructure Agents Gateway/ Comms MTP Survivable Endpoints GK Remote Xcode PSTN Conf Si IP WAN Si Branch Access WAN Router Switch Branch Access Distribution/ AggregationCampus Switch Core Switch Router Network Infrastructure Session ID Presentation_ID © 2007 Cisco Systems, Inc. All rights reserved. Cisco Confidential 3
  • 4. Network Infrastructure Agenda  Building a Campus Network  QoS in the Campus  QoS in the WAN  Qos in the Wireless LANsSession IDPresentation_ID © 2007 Cisco Systems, Inc. All rights reserved. Cisco Confidential 4
  • 5. Systems Architecture Bay Bridge: Golden Gate Bridge:  Original cost in 1936: $1.1 billion  Original cost to in 1937: (adjusted for today’s $) $446 million (adjusted for today’s $)  Estimated cost to expand: $6.2 billion… and climbing A Poorly Planned Architecture A Well Planned ArchitectureSession IDPresentation_ID © 2007 Cisco Systems, Inc. All rights reserved. Cisco Confidential 5
  • 6. Building a Campus Network Hierarchical Network Design Without a Rock Solid Foundation the Rest Doesn’t Matter • Offers hierarchy – each layer has specific Access role • Modular topology - building blocks • Easy to grow, understand, and Distribution troubleshoot Si Si • Creates small fault domains – Clear demarcations and isolation • Promotes load balancing and redundancy Core • Promotes deterministic traffic patterns Si Si • Incorporates balance of both Layer 2 and Layer 3 technology, leveraging the strength of both Distribution • Utilizes Layer 3 Routing for load Si Si balancing, fast convergence, scalability, and control Access • Sub second convergence possible Building BlockSession IDPresentation_ID © 2007 Cisco Systems, Inc. All rights reserved. Cisco Confidential 6
  • 7. Building a Campus Network—The Access Layer Feature Rich Environment—Not Just About Connectivity To Core Si Si Distribution Access VLANS do not span access switches  Aggregates network end-points  Catalyst® integrated security features  Layer 2/Layer 3 feature rich environment; 802.1x, Port security, DHCP snooping, convergence, HA, security, QoS, IP Dynamic ARP Insp, IP Source Guard, etc. multicast, etc  Automatic phone discovery, conditional trust  Intelligent network services: QoS, trust boundary, Power Over Ethernet, auxiliary boundary, broadcast suppression, IGMP VLAN, etc. snooping  Spanning tree toolkit: Portfast, UplinkFast,  Intelligent network services: Rapid BackboneFast, LoopGuard, BPDUGuard, PVST+, EIGRP, OSPF, DTP, PAgP, UDLD, BPDUFilter, RootGuard, etc.Session ID etc.Presentation_ID © 2007 Cisco Systems, Inc. All rights reserved. Cisco Confidential 7
  • 8. Campus Network—Access Layer Voice and Data VLANs Phone VLAN = 110 PC VLAN = 10 (VVID) (PVID) 802.1Q encapsulation Native VLAN (PVID) No with 802.1p Layer 2 Configuration Changes CoS Needed on PC  During initial CDP exchange phone is configured with a Voice VLAN ID (VVID)  Phone also supplied with QoS configuration via CDP TLV fields  Quality—Separation of broadcast domains i.e. phones and PCs are on separate subnets  Security—Different network policies for different subnets; WORM attacks can be contained to the PC VLANs.Session IDPresentation_ID © 2007 Cisco Systems, Inc. All rights reserved. Cisco Confidential 8
  • 9. Building a Campus Network—The Distribution Layer Policy, Convergence, QoS, and High Availability Distribution Si Si Si Si Access  Availability, load balancing, QoS and  EIGRP/ OSPF - Route summarization, provisioning are the important passive interfaces to access layer, sub considerations at this layer second convergence possible with timer  Aggregates wiring closets (access adjustment, redundant path load sharing layer) and uplinks to core  HSRP or GLBP to provide first hop  Use Layer 3 switching in the redundancy, sub second convergence distribution layer possible with timer adjustment  Protects core from high density  Spanning tree features ( Only if needed ): peering and problems in access layer Setting STP Root, Root Guard, Rapid PVST+—Per VLAN 802.1wSession IDPresentation_ID © 2007 Cisco Systems, Inc. All rights reserved. Cisco Confidential 9
  • 10. Building a Campus Network—The Core Layer Scalability, High Availability, and Fast Convergence Core Distribution Access  Backbone for the network—connects network building blocks  Performance and stability vs. complexity—less is more in the core  Aggregation point for distribution layer  Tune routing protocol timers for sub second convergence  Separate core layer helps in scalability during future growthSession ID  Use hardware accelerated services only to maintain performancePresentation_ID © 2007 Cisco Systems, Inc. All rights reserved. Cisco Confidential 10
  • 11. Campus Design Best Practices First Hop Redundancy  Used to provide a resilient default gateway/first hop 1st Hop Redundancy address to end stations  HSRP, VRRP, and GLBP Si Si Si Si Si Si alternatives  VRRP, HSRP and GLBP provide millisecond timers Layer 3 Equal Layer 3 Equal and excellent sub second Cost Link’s Si Si Cost Link’s convergence performance  VRRP if you need multi- vendor interoperability Si Si Si Si Si Si  GLBP facilitates uplink load balancing  Preempt timers need to WAN Data Center Internet be tuned to avoid black- holed trafficSession IDPresentation_ID © 2007 Cisco Systems, Inc. All rights reserved. Cisco Confidential 11
  • 12. Campus Design—Routed Access Layer  Tune CEF load balancing  Match CatOS/IOS Ether-channel settings and tune load balancing Si Si Core  Summarize routes towards core  Filter routes towards the access Distribution  Disable Ether-channel Si Layer 3 Si unless needed P-t-P Link  ―Set port host‖ on access layer ports: Disable Trunking Disable Etherchannel Access VLAN 20 Data VLAN 40 Data Enable PortFast 10.1.20.0/24 10.1.40.0/24 VLAN 120 Voice VLAN 140 Voice  RootGuard or BPDU-Guard 10.1.120.0/24 10.1.140.0/24  Use security featuresSession IDPresentation_ID © 2007 Cisco Systems, Inc. All rights reserved. Cisco Confidential 12
  • 13. Building a Campus Network Summary  Access layer Access Rapid Per-VLAN Layer 2 spanning-tree ( PSVT +) Rootguard Portfast Distribution Layer 3 UplinkFast Server Farm Layer 3 to the edge ? Core  Distribution Layer Layer 3 HSRP/GLBP with load balancing OSPF/EIGRP Distribution configured for fast Layer 3 convergence  Core Layer Access OSPF/EIGRP configured for fast Layer 2 convergence WAN Internet PSTN http://www.cisco.com/en/US/netsol/ns656/networking_solutions_design_guidances_list.html#anchor2Session IDPresentation_ID © 2007 Cisco Systems, Inc. All rights reserved. Cisco Confidential 13
  • 14. Network Infrastructure Agenda  Building a Campus Network  QoS in the Campus  QoS in the WAN  QoS in the Wireless LANsSession IDPresentation_ID © 2007 Cisco Systems, Inc. All rights reserved. Cisco Confidential 14
  • 15. Enabling QoS in the Campus Traffic Profiles and Requirements Voice Video-Conf Data  Smooth  Bursty  Smooth/bursty  Benign  Greedy  Benign/greedy  Drop sensitive  Drop sensitive  Drop insensitive  Delay sensitive  Delay sensitive  Delay insensitive  UDP priority  UDP priority  TCP retransmitsBandwidth per Call IP/VC has the Same Traffic patterns forDepends on Codec, Requirements as VoIP, Data Vary AmongSampling-Rate, but Has Radically Applicationsand Layer 2 Media Different Traffic Patterns (BW Varies Greatly) Latency ≤ 150 ms  Latency ≤ 150 ms Data Classes: Jitter ≤ 30 ms  Jitter ≤ 30 ms Mission-Critical Apps Loss ≤ 1%  Loss ≤ 1% Transactional/Interactive AppsOne-Way Requirements One-Way Requirements Bulk Data Apps Best Effort Apps (Default)Session IDPresentation_ID © 2007 Cisco Systems, Inc. All rights reserved. Cisco Confidential 15
  • 16. Why QoS in the Campus Protect the Good and Punish the Bad  QoS does more than just protect Voice and Video  For "best-effort" traffic an implied "good faith" commitment that there are at least some network resources available is assumed  Need to identify and potentially punish out of profile traffic (potential worms, DDOS, etc.)  Scavenger class is an Internet-2 Draft Specification => CS1/CoS1 Access Distribution Core Voice Voice Data Data Scavenger ScavengerSession IDPresentation_ID © 2007 Cisco Systems, Inc. All rights reserved. Cisco Confidential 16
  • 17. Enabling QoS in the Campus Layer 2 Classification: 802.1p, CoS TAG Pream. SFD DA SA Type 4 Bytes PT Data FCS Ethernet FrameThree Bits Used for CoS (802.1p User Priority) PRI CFI VLAN ID 802.1Q/p Header CoS Application  802.1p user priority field also 7 Reserved called Class of Service (CoS) 6 Reserved  Different types of traffic are 5 Voice Bearer assigned different CoS values 4 Video Conferencing*  CoS six and seven are 3 Call Signaling reserved for network use 2 High Priority Data 1 Medium Priority Data * Including Audio and VideoSession ID 0 Best Effort DataPresentation_ID © 2007 Cisco Systems, Inc. All rights reserved. Cisco Confidential 17
  • 18. Enabling QoS in the Campus Layer 3 Classification: IP Precedence, DSCP Version ToS Length Byte Len ID Offset TTL Proto FCS IP SA IP DA Data IPv4 Packet 7 6 5 4 3 2 1 0 IP Precedence Unused Standard IPv4 DiffServ Code Point (DSCP) Flow Ctrl DiffServ Extensions  IPv4: three most significant bits of ToS byte are called IP precedence— other bits unused by IP precedence  DiffServ: six most significant bits of ToS byte are called Diff Serv Code Point (DSCP)—remaining two bits used for flow control  DSCP is backward-compatible with IP precedence  DSCP values correspond to Per Hop Behavior (PHB) designations  RFC 2474 provides more information on DSCP; also, see appendix in this presentationSession IDPresentation_ID © 2007 Cisco Systems, Inc. All rights reserved. Cisco Confidential 18
  • 19. IP Precedence and DSCP Compatibility Compatibility with current IP precedence usage (RFC 1812) Differentiates probability of timely forwarding: (xyz000) >= (abc000) if xyz > abc (that is, if a packet has DSCP value of 011000, it has a greater probability of timely forwarding than a packet with DSCP value of 001000)Session IDPresentation_ID © 2007 Cisco Systems, Inc. All rights reserved. Cisco Confidential 19
  • 20. Per-Hop Behaviors  DSCP selects PHB throughout the network: Default PHB (FIFO, tail drop) EF PHB AF PHB Class-selector PHB (IP precedence)Session IDPresentation_ID © 2007 Cisco Systems, Inc. All rights reserved. Cisco Confidential 20
  • 21. EF PHB EF PHB: Ensures a minimum departure rate Guarantees bandwidth—class guaranteed an amount of bandwidth with prioritized forwarding Polices bandwidth—class not allowed to exceed the guaranteed amount (excess traffic is dropped) DSCP value of 101110: Looks like IP precedence 5 to non-DiffServ- compliant devices: Bits 5 to 7: 101 = 5 (same 3 bits are used for IP precedence) Bits 3 and 4: 11 = No drop probability Bit 2: Just 0Session IDPresentation_ID © 2007 Cisco Systems, Inc. All rights reserved. Cisco Confidential 21
  • 22. AF PHB AF PHB: Guarantees bandwidth Allows access to extra bandwidth, if available Four standard classes: AF1, AF2, AF3, and AF4 DSCP value range of aaadd0: aaa is a binary value of the class dd is drop probabilitySession IDPresentation_ID © 2007 Cisco Systems, Inc. All rights reserved. Cisco Confidential 22
  • 23. AF PHB (Cont.) Each AF class uses three DSCP values. Each AF class is independently forwarded with its guaranteed bandwidth. Congestion avoidance is used within each class to prevent congestion within the class.Session IDPresentation_ID © 2007 Cisco Systems, Inc. All rights reserved. Cisco Confidential 23
  • 24. AF PHB (Cont.) Each AF class uses three DSCP values. Each AF class is independently forwarded with its guaranteed bandwidth. Congestion avoidance is used within each class to prevent congestion within the class.Session IDPresentation_ID © 2007 Cisco Systems, Inc. All rights reserved. Cisco Confidential 24
  • 25. DSCP SummarySession IDPresentation_ID © 2007 Cisco Systems, Inc. All rights reserved. Cisco Confidential 25
  • 26. Enabling QoS in the Campus Classification and Marking Cisco Marking Recommendations L3 Classification L2 Application IPP PHB DSCP CoS Routing 6 CS6 48 6 Voice 5 EF 46 5 Video Conferencing 4 AF41 34 4 Streaming Video 4 CS4 32 4 Mission-Critical Data 3 AF31* 26 3 Call Signaling 3 CS3* 24 3 Transactional Data 2 AF21 18 2 Network Management 2 CS2 16 2 Bulk Data 1 AF11 10 1 Scavenger 1 CS1 8 1Session ID Best Effort 0 0 0 0Presentation_ID © 2007 Cisco Systems, Inc. All rights reserved. Cisco Confidential 26
  • 27. Enabling QoS in the Campus Congestion Scenario: TCP Traffic Burst + VoIP Core Instantaneous Typical 4:1 Si Si Interface Data Over- CongestionSubscription Distribution Si SiTypical 20:1 Data Over-Subscription Access = Data = VoiceSession IDPresentation_ID © 2007 Cisco Systems, Inc. All rights reserved. Cisco Confidential 27
  • 28. Enabling QoS in the Campus Congestion Scenario: Data + VoIP IP Phone Enclosure Phone Voice Integrated Max. 80 Kbps 3-Port Switch P0 P P2 P1 Access Switch Data PC Max. 100 Mbps Potential Congestion Points During Data Traffic Bursts, Buffers Can Become Congested, Causing Voice Packets to Be DroppedSession IDPresentation_ID © 2007 Cisco Systems, Inc. All rights reserved. Cisco Confidential 28
  • 29. Enabling QoS in the Campus Scheduling in IP Phones IP Phone Enclosure P1 Untrusted: P Trusted: Phone Switch Phone Rewrites CoS = 0Switch Accepts incoming CoS Voice CoS = 5 CoS = 5 P0 P P2 P1 Access Data CoS = 0 Switch Priority Q PC Data Qs  Voice media traffic is marked with CoS 5/ DSCP EF (high priority)  Data traffic from the PC is remarked with CoS 0 (low priority) by the IP phone switch; this occurs if PC tags frames as 802.1p/Q; phone switch transparent if PC frames untaggedSession IDPresentation_ID © 2007 Cisco Systems, Inc. All rights reserved. Cisco Confidential 29
  • 30. Campus QoS Considerations Establishing Trust Boundaries Endpoints Access Distribution Core WAN Aggregators 1 Si Si 2 Si 3 Si Trust Boundary For scalability, classification should be done as close to the edge as possible The outermost trusted devices represent the trust boundary 1 Optimal Trust Boundary: Trusted Endpoint A device is trusted if it correctly classifies packets 2 Optimal Trust Boundary: Untrusted Endpoint 3 Suboptimal Trust Boundary Only use if access switch cannot perform classificationSession IDPresentation_ID © 2007 Cisco Systems, Inc. All rights reserved. Cisco Confidential 30
  • 31. Network Infrastructure Agenda  Building a Campus Network  QoS in the Campus  QoS in the WAN  Qos in the Wireless LANsSession IDPresentation_ID © 2007 Cisco Systems, Inc. All rights reserved. Cisco Confidential 31
  • 32. Enabling QoS in the WAN Factors That Negatively Affect Packet-Based Voice/Video Delay Loss Delay Variation (Jitter)Session IDPresentation_ID © 2007 Cisco Systems, Inc. All rights reserved. Cisco Confidential 32
  • 33. Types of Delay Processing Delay: The time it takes for a router to take the packet from an input interface, examine it, and put it into the output queue of the output interface Queuing Delay: The time a packet resides in the output queue of a router Serialization Delay: The time it takes to place the ―bits on the wire‖ Propagation Delay: The time it takes to transmit a packetSession IDPresentation_ID © 2007 Cisco Systems, Inc. All rights reserved. Cisco Confidential 33
  • 34. Processing and Queuing Delay Processing Delay: The time it takes for a router to take the packet from an input interface, examine it, and put it into the output queue of the output interface Queuing Delay: The time a packets resides in the output queue of a router Serialization Delay: The time it takes to place the ―bits on the wire‖ Propagation Delay: The time it takes to transmit a packetSession IDPresentation_ID © 2007 Cisco Systems, Inc. All rights reserved. Cisco Confidential 34
  • 35. Ways to Reduce Delay Upgrade the link; the best solution but also the most expensive. Forward the important packets first. Compress the payload of Layer 2 frames (it takes time). Compress IP packet headers.Session IDPresentation_ID © 2007 Cisco Systems, Inc. All rights reserved. Cisco Confidential 35
  • 36. Packet Loss Tail drops occur when the output queue is full. These are common drops, which happen when a link is congested. Many other types of drops exist, usually the result of router congestion, that are uncommon and may require a hardware upgrade (input drop, ignore, overrun, frame errors).Session IDPresentation_ID © 2007 Cisco Systems, Inc. All rights reserved. Cisco Confidential 36
  • 37. Ways to Prevent Packet Loss Upgrade the link; the best solution but also the most expensive. Guarantee enough bandwidth to sensitive packets. Prevent congestion by randomly dropping less important packets before congestion occurs.Session IDPresentation_ID © 2007 Cisco Systems, Inc. All rights reserved. Cisco Confidential 37
  • 38. Traffic Policing and Shaping Overview These mechanisms must classify packets before policing or shaping the traffic rate. Traffic policing typically drops or marks excess traffic to stay within a traffic rate limit. Traffic shaping queues excess packets to stay within the desired traffic rate.Session IDPresentation_ID © 2007 Cisco Systems, Inc. All rights reserved. Cisco Confidential 38
  • 39. Traffic Policing and Shaping Overview These mechanisms must classify packets before policing or shaping the traffic rate. Traffic policing typically drops or marks excess traffic to stay within a traffic rate limit. Traffic shaping queues excess packets to stay within the desired traffic rate.Session IDPresentation_ID © 2007 Cisco Systems, Inc. All rights reserved. Cisco Confidential 39
  • 40. Policing vs. Shaping • Incoming and outgoing directions. • Outgoing direction only. • Out-of-profile packets are dropped. • Out-of-profile packets are queued until • Dropping causes TCP retransmits. a buffer gets full. • Policing supports packet marking or • Buffering minimizes TCP retransmits. re-marking. • Marking or re-marking not supported. • Shaping supports interaction with Frame Relay congestion indication.Session IDPresentation_ID © 2007 Cisco Systems, Inc. All rights reserved. Cisco Confidential 40
  • 41. Enabling QoS in the WAN Link Fragmentation and Interleaving (LFI) Fragment-Size Recommendations Fragmentation Size Matrix Serialization Delay Matrix (Based on 10-msec Delay) 64 128 256 512 1024 1500 PVC Frag Bytes Bytes Bytes Bytes Bytes Bytes Speed Size 56 kbps 9 ms 18 ms 36 ms 72 ms 144 ms 214 ms 56 kbps 70 Bytes 64 kbps 8 ms 16 ms 32 ms 64 ms 128 ms 187 ms 64 kbps 80 Bytes128 kbps 4 ms 8 ms 16 ms 32 ms 64 ms 93 ms 128 kbps 160 Bytes256 kbps 2 ms 4 ms 8 ms 16 ms 32 ms 46 ms 256 kbps 320 Bytes512 kbps 1 ms 2 ms 4 ms 8 ms 16 ms 23 ms 512 kbps 640 Bytes 640 768 kbps 1000 Bytes X768 kbps 1.2 ms 2.6 ms 5 ms 10 ms 15 ms Used 1536 kbps 2000 BytesSession IDPresentation_ID © 2007 Cisco Systems, Inc. All rights reserved. Cisco Confidential 41
  • 42. Enabling QoS in the WAN Scheduling in the WAN PQ Packets Do not Go Through Fragmentation: on Low-Link Speeds, You Cannot put Large (i.e., Video) Packets in the PQ with Voice Packets Therefore video traffic not recommended for link speeds <768kbps Low Latency Queuing Link Fragmentation Police and Interleave Voice Video PQ TX Interleave Ring SignalingPackets Packets In Out Critical Data CBWFQ Fragment WFQ Best Effort Session ID Presentation_ID Layer 3 Queuing Subsystem © 2007 Cisco Systems, Inc. All rights reserved. Cisco Confidential Layer 2 Queuing Subsystem 42
  • 43. How Many Classes of Service Do I Need? Expanding the Number of Classes of Service over Time 4/5 Class Model 8 Class Model 11 Class Model Voice Voice Realtime Interactive-Video Video Streaming Video Call Signaling Call Signaling Call Signaling IP Routing Network Control Network Management Critical Data Mission-Critical Data Critical Data Transactional Data Bulk Data Bulk Data Best Effort Best Effort Best Effort Scavenger Scavenger Scavenger TimeSession IDPresentation_ID © 2007 Cisco Systems, Inc. All rights reserved. Cisco Confidential 43
  • 44. Enabling QoS in the WAN Provisioning Bandwidth with Compressed RTP (cRTP) VoIP Packet Voice RTP UDP Link IP Header Payload Header Header Header X Bytes 12 Bytes 8 Bytes 20 Bytes X Bytes  Compresses RTP + UDP + IP headers (40 bytes) down to cRTP 2–4 bytes Header ~2-4 Bytes  Enabled on a per-link basis ATM PPP Frame-Relay Codec 53 Bytes Cells with 6 Bytes of Header 4 Bytes of Header a 48-Byte Payload G.711 at 50 pps 68 kbps 85 kbps 67 kbps G.711 at 33 pps 66 kbps 84 kbps 65.5 kbps G.729A at 50 pps 12 kbps 21.2 kbps 11.2 kbps G.729A at 33 pps 10.5 kbps 14 kbps 10 kbpsSession IDPresentation_ID © 2007 Cisco Systems, Inc. All rights reserved. Cisco Confidential 44
  • 45. Enabling QoS in the WAN A Day in the Life of a VoIP Packet: Without cRTP Assumption: G.729, 20-ms Sample Payload (20) Payload = 20 Bytes Frame RelayPacket 78 78Size (Bytes) 64 60 Enet (14) Enet (14) 60 802.1Q (4) F/R (4) 802.1Q (4) IP (20) IP (20) IP (20) IP (20) IP (20) 20 UDP (8) UDP (8) UDP (8) UDP (8) UDP (8) 20 RTP (12) RTP (12) RTP (12) RTP (12) RTP (12) Payload Payload Payload Payload Payload Payload Payload (20) (20) (20) (20) (20) (20) (20)Session IDPresentation_ID © 2007 Cisco Systems, Inc. All rights reserved. Cisco Confidential 45
  • 46. Enabling QoS in the WAN A Day in the Life of a VoIP Packet: With cRTP Assumption: Payload cRTP Is not Free! G.729, 20-ms Sample Watch for CPU on (20) Payload = 20 Bytes WAN Edge Routers!!! Frame RelayPacket 78 cRTP Is 78Size (Bytes) Point to Enet (14) Point Enet (14) 60 60 802.1Q (4) 28 802.1Q (4) IP (20) IP (20) IP (20) IP (20) 20 UDP (8) UDP (8) UDP (8) UDP (8) 20 F/R (4) RTP (12) RTP (12) cRTP (4) RTP (12) RTP (12) Payload Payload Payload Payload Payload Payload Payload (20) (20) (20) (20) (20) (20) (20)Session IDPresentation_ID © 2007 Cisco Systems, Inc. All rights reserved. Cisco Confidential 46
  • 47. Network Infrastructure Agenda  Building a Campus Network  QoS in the Campus  QoS in the WAN  Qos in the Wireless LANsSession IDPresentation_ID © 2007 Cisco Systems, Inc. All rights reserved. Cisco Confidential 47
  • 48. WLAN and LAN  Wireless LAN (WLAN) as an extension to wired LANSession IDPresentation_ID © 2007 Cisco Systems, Inc. All rights reserved. Cisco Confidential 48
  • 49. WLAN QoS Queuing OverviewSession IDPresentation_ID © 2007 Cisco Systems, Inc. All rights reserved. Cisco Confidential 49
  • 50. WLAN QoS RF Backoff TimingSession IDPresentation_ID © 2007 Cisco Systems, Inc. All rights reserved. Cisco Confidential 50
  • 51. WLAN QoS Queuing OverviewSession IDPresentation_ID © 2007 Cisco Systems, Inc. All rights reserved. Cisco Confidential 51
  • 52. What We Have Built So Far Si IP WAN Si Branch Access WAN Router Switch Branch Access Distribution/ AggregationCampus Switch Core Switch Router Network Infrastructure Session ID Presentation_ID © 2007 Cisco Systems, Inc. All rights reserved. Cisco Confidential 52
  • 53. Session IDPresentation_ID © 2007 Cisco Systems, Inc. All rights reserved. Cisco Confidential 53

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