Gigabit%20Ethernet%20Vs%20Asynchronous%20Transfer%20Mode

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Gigabit EthernetVs Asynchronous Transfer Mode
John A.Clark Bay Networks Technical Account
Manager John.Clark_at_Anixter.Com
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Not a Desktop Debate

• Industry analysis shows 10/100 Ethernet is the
  clear choice for the desktop technology

• Token Ring important in vertical markets
• ATM to-the-desk for niche applications

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Not a Protocol Debate

• IP has emerged as the protocol of choice - most
  organisations have a migration plan

• Few networks are IP only - other protocols e.g.
  IPX, NetBEUI, SNA are still important on existing
  LANs

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Its a Backbone Issue

• What Technology/Business Factors Should be
  Considered?

• Network Speed/distance
• Standards Status
• Network Resilience
• Routing/Layer 3 switching
• Supported Applications
• Network Management
• Investment/Ease of Use

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Network Speed/Distance

• Gigabit Ethernet
• 1000BaseCX 25m copper
• 1000BaseSX 550m on 50 micron MM fibre, 220m on
  62.5 micron (DMD)
• 1000BaseLX 550m all MM fibre , 3km SM fibre -
  Long reach 50km proprietary
• 1 Gbps limit - 10 Gbps ?
• 200m network diameter restrictions - CSMA/CD as
  shared media

• ATM
• 25Mbps Cat V UTP
• 155Mbps - OC/3 fibre
• 622Mbps - OC/12 fibre
• 800m on MM, 15km on SM
• 2.4Gbps - OC/48, 10 Gbps - OC/192 ...no
  theoretical limit
• DWDM - multiple OC/192
• ATM/SDH WAN (e.g. BT Cellstream)
• No max network diameter

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Standards Status

• Gigabit Ethernet
• 802.3z OK
• 802.3ab 1000baseT tba
• 802.3x flow control
• 802.1P priority OK
• 802.1Q VLAN tag OK
• RSVP, RTPDiffserv tba

• ATM
• Anchorage Accord combined standard
• IISP
• PNNI OK
• LANE 2.0 OK
• MPOA 1.0 OK
• NHRP OK

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Network Resilience

• Gigabit Ethernet
• Proprietary H/W or Spanning Tree
• ST stability /convergence issues?
• No standards based load-sharing -proprietary MLT
• Use of OSPF / RIP with Layer 3 switching

• ATM
• Inherently highly redundant technology
• Standards based NNI
• Parallel load-sharing links for resilience
  aggregate bandwidth
• Highly meshed topologies - PNNI multi peer groups

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Routing/Layer 3 Switching

• Gigabit Ethernet
• IP/IPX Routing via high 100/1000 Mbps links
• One Arm router using 802.1Q VLAN trunks
• Layer 3 hardware routing switches with n Mbps
  throughout/ n usec latency

ATM Routing via high speed 100/1000 Mbps
Ethernet links VLAN trunks with ATM VNR
proven Layer 3 switching via ATM Forum MPOA -
initially IP - then IPX
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Supported Applications

• Gigabit Ethernet
• LAN/MAN Technology
• Data only traffic - but optimised for IP .VoIP,
  video etc.
• Enough Bandwidth to support everything
• QoS (ToS/priority) from 802.1P, RSVP, Diffserv
  etc.
• Switch-to-switch 802.3x flow control - source
  quench pause frames

• ATM
• LAN / MAN / WAN
• Traffic Types Data, Voice, Video
• APIs use QoS and optimise traffic for specific
  applications
• Sophisticated QoS UBR, CBR,VBR(rt/nrt), ABR
  policed traffic contract - peak, mean, burst etc.
  
• End-to-end flow control, traffic shaping queues,
  CLP bit discard

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Network Management

• Gigabit Ethernet
• Simple adaptation of Ethernet MIBs
• Compatibility with existing management
  applications

• ATM
• ATM Forum MIBs and proprietary MIBs in current
  use
• WAN MIBs to be finalised
• ATM VC connectionless complexity introduces
  network management challenges

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Investment/Ease of Use

• ATM
• Solid proven technology - many reference
  installations
• Anchorage Accord simplified ATM forum standards -
  new standards, new features
• Some Administrative Training Costs

• Gigabit Ethernet
• Plain old Ethernet? - frame format - actually
  technical differences
• Low risk / low lostfeeling - 10gt100gt1000 Mbps
• Not many new skills required for support - low
  training costs

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Thank You - Questions?
John A.Clark Bay Networks Technical Account
Manager John.Clark_at_Anixter.Com