IP over ATM Networks

1
IP over ATM Networks

• IP over ATM

2
Overview

• Applicable Standards
• Network Topologies
• Network Configurations
• Performance Studies
• Future Direction

3
Applicable Standards

• Data Encapsulation
• RFC 1483 Data Encapsulation
• Classical IP
• RFC 2225 Classical IP and ARP over ATM
• RFC 2226 IP Broadcast over ATM Networks
• NHRP - Next Hop Resolution Protocol
• RFC 2332 - NBMA Next Hop Resolution Protocol
  (NHRP)
• RFC 2333 - NHRP Protocol Applicability Statement
  
• RFC 2335 - NHRP Using SCSP
• RFC 2336 - Classical IP and ARP over ATM to NHRP
  Transition
• RFC 2583- Guidelines for Next Hop Client (NHC)
  Developers
• MPOA Multi-protocol Over ATM
• RFC 2684- Multi-protocol Encapsulation over ATM
  Adaptation Layer 5

4
Data Encapsulation

• RFC 1483 Defines the 2 modes of encapsulating
  IP Datagrams
• VC Based Multiplexing
• Data is encapsulated into the CPCS-PDU field by
  the AAL5
• One Virtual Channel Connection per Protocol
• LLC Encapsulation
• An IP packet is prefixed with an IEEE 802.2 LLC
  header before being encapsulated in the AAL5
  frame
• When used with Permanent Virtual Channels
• Multiple protocols in one connection

5
Classical IP

• RFC 2225 - Classical IP over ATM
• Defines requirements for configuration of IP
  hosts over an ATM LAN
• The term Classical refers to the treatment of
  the ATM host adapter as an interface to the
  LAN-based stack
• RFC 2226 - IP Broadcast over ATM

6
Next Hop Resolution Protocol

• RFC 2332 - NBMA Next Hop Resolution Protocol
  (NHRP)
• RFC 2333 - NHRP Protocol Applicability Statement
  
• RFC 2335 - NHRP Using SCSP
• RFC 2336 - Classical IP and ARP over ATM to NHRP
  Transition
• RFC 2583- Guidelines for Next Hop Client (NHC)
  Developers

7
Multi Protocols over ATM

• RFC 2684- Multi-protocol Encapsulation over ATM
  Adaptation Layer 5
• IETF Draft Multi Protocol Label Switching
  (MPLS)

8
Network Topologies

• LANE LAN Emulation over ATM
• Simulates LAN protocols like Ethernet and Token
  Ring
• Allows current IP-based applications to run
  without modification
• LIS Logical IP Sub-networks
• Required by Classical IP Configuration

9
Network Topologies
10
Classical IP over ATM

• Runs within the LIS Topology
• One Logical IP subnet is used for many hosts and
  routers
• Each VC directly connects two IP host within the
  same LIS
• IP addresses are resolved to ATM addresses by use
  of an ATMARP Server within the LIS
• An ATM address is either encoded as an NSAP form
  ATM End System Address (AESA) or is an E.164
  Public-UNI address.

11
Network Configuration

• All IP hosts must have the same IP prefix and
  mask
• Each LIS must have at least one ATM-ARP Server
  with LIS scope
• Inter LIS communication is done via Routers
• All IP hosts must be connected with a fully
  meshed topology

12
ATM Specific Configuration

• ATM parameters that must be implemented
• ATM Hardware Address (atmha) - the ATM address
  of the individual IP host
• ATMARP Request Address list (atmarp-req-list)
  contains one or more ATM addresses of individual
  ATMARP servers
• This list will be NULL if used with PVC
• Routers must maintain configuration information
  for each LIS is connected to

13
Protocol Summary

• Clients Register its ATM Address
• Sending Data
• Sender Request ARP service (ATMARP) and AMT-ARP
  Replies with ATM address
• VC is setup between Sender and Receiver and IP
  packet is sent
• Receiver Requests ARP service (InATMARP) and
  AMT-ARP Replies with IP address
• AAL5 passes IP packet up the stack
• Clients must refresh information at least once
  every 15 minutes

14
Network Topologies
15
ATMARP/InATMARP Packet Encapsulation

• The format of the AAL5 CPCS-SDU payload field for
  ATMARP/InATMARP PDUs is
• LLC (0xAA-AA-03 SNAP)
• OUI (0x00-00-00 following is EtherType)
• EtherType (0x08-06 ARP)
• ATMARP/InATMARP Packet

16
ATMARP and InATMARP Fields

• arhrd 16 bits Hardware type
• arpro 16 bits Protocol type ( IP is 0x0800 )
• arshtl 8 bits Type length (TL) of source ATM
  number (q)
• arsstl 8 bits Type length (TL) of source ATM
  subaddress (r)
• arop 16 bits Operation code (request and reply
  including Inv., or NAK)
• arspln 8 bits Length of source protocol address
  (s) (IPv4 arspln is 4)
• arthtl 8 bits Type length (TL) of target ATM
  number (x)
• artstl 8 bits Type length (TL) of target ATM
  subaddress (y)
• artpln 8 bits Length of target protocol address
  (z)
• arsha qoctets of source ATM number
• arssa roctets of source ATM subaddress
• arspa soctets of source protocol address
• artha xoctets of target ATM number
• artsa yoctets of target ATM subaddress
• artpa zoctets of target protocol address

17
Performance

• Affected by IP packet size -already discussed in
  class
• Affected by the Topology

• Can you tell why performance suffers?

18
Performance Improvements

• NHRP
• Caches AMT-ARP from other LIS
• Allows creation of a shortcut

19
Performance Improvements

• MPOA
• Caches AMT-ART from other ELANs
• Allows creation of a shortcut

20
Performance

• ARP Testing over WAN
• no major problems are expected - ATM
  Experiments for Advanced Backbone Services ,
  Michael H. Behringer
• Smaller buffers can lead to more TCP window
  dynamic, which reduces throughput and adds delay
  due to packet loss - IETF August 1997
  Proceedings, Ross Callon

21
Performance Study

• Under a Mobile IP over ATM
• Case 1 Uses existing IP Routing
• Case 2 Shortcut with ARP
• Case 3 Shortcut without ARP
• Performance Evaluation of Scheme Integration
  Mobile IP and NHRP over ATM Byun, Kim, Han

22
Performance Study

• Under a Mobile IP over ATM
• Case 1 Uses existing IP Routing
• Case 2 Shortcut with ARP
• Case 3 Shortcut without ARP

23
Performance Study

• LANE versus MPOA
• Throughput showed on Table 1.
• Multi-Protocol over ATM(MPOA) Performance Tests
  Vatiainem, Harju, Koivisto

24
Future Direction

• MPLS Multiprotocol Label Switching
• Within the context of IP over ATM it will gain
  performance by using Virtual Paths
• Did MPOA achieve its objective? -Hommes, Pless,
  Zier TERENA Networking Conference 2000Lisbon,
  Portugal 22-25 May 2000

25
Questions and Answers
26
IP over ATM Networks

• Bibliography

27
References

• ARP
• http//www.networkdictionary.com/protocols/arp.php
  ?PHPSESSIDc2a79111d168faf
• http//archive.dante.net/ten-34/tf-ten/inet97/
• MOA
• http//www.mfaforum.org/education/4.shtml
• http//rfc.sunsite.dk/rfc/rfc2684.html
• http//www.javvin.com/protocol/rfc2684.pdf
• MPLS
• http//www.terena.nl/events/archive/tnc2000/procee
  dings/3B/3b3.ppt487,20,MPLS - an Alternative
  Approach to MPOA?
• Mobile IP - Performance
• http//springerlink.metapress.com/(ufhkhf55cx4i1jm
  njgzghqb2)/app/home/contribution.asp?referrerpare
  ntbacktoissue,52,77journal,1059,3333linkingpub
  licationresults,1105633,1
• http//springerlink.metapress.com/media/g1jhygmhur
  vcex22ta5x/contributions/x/h/f/v/xhfvaky2v3ebfm5v.
  pdf
• LANE
• http//docs.hp.com/en/B1056-90008/ch04s02.html
• Summary
• http//sunsite.uakom.sk/sunworldonline/swol-09-199
  7/swol-09-connectivity.html
• http//www.cra.org/Policy/NGI/papers/20FinkWP

28
References

• http//www.linktionary.com/c/cip_atm.html
• http//docs.hp.com/en/B1056-90008/ch03s01.html
• http//www.rajjain.com/cis788-97/ftp/ip_over_atm/i
  ndex.htm
• ftp//ftp.rfc-editor.org/in-notes/rfc2336.txt
• ftp//ftp.rfc-editor.org/in-notes/rfc2333.txt
• http//www3.ietf.org/proceedings/97aug/transit97au
  g-54.htm
• http//www.atm.tut.fi/faster/mpoa/eunice-final.pdf
  
• http//www.networkdictionary.com/protocols/nhrp.ph
  p?PHPSESSIDc2a79111d168faf
• ftp//ftp.rfc-editor.org/in-notes/rfc2332.txt
• NHRP
• ftp//ftp.rfc-editor.org/in-notes/rfc2583.txt
• http//rfc.net/rfc2583.html
• ftp//ftp.rfc-editor.org/in-notes/rfc2335.txt