Novell IPX

1
Novell IPX

• Roy H. John
• Cisco Networking Academy
• Youngstown State University

2
Why IPX when Novell has already gone to IP?

• Two reasons

• A huge installed base of IPX (legacy networks)
• The requirement that networking professionals
  deal with a variety of protocols.
• With more than 5 million networks and more than
  50 million clients, Novell has the largest share
  of the NOS market. Until Novell's NetWare 5.0
  release in 1998, all NetWare networks used IPX.

3
Novell IPX protocol suite

• IPX, a connectionless layer 3 protocol, that does
  not require an acknowledgment for each packet and
  defines the network and and node addresses
• Novell Routing Information Protocol (RIP)-which
  is different from IP RIP-to facilitate the
  exchange of routing information
• Service Advertising Protocol (SAP) to advertise
  network services
• NetWare Core Protocol (NCP) to provide
  client-to-server connections and applications
• Sequenced Packet Exchange (SPX) service for Layer
  4 connection-oriented services

4
IPX Key Features

• It is used in a client/server environment
• It uses the network.node IPX (80 bit) addressing
  structure
• Its logical address contains an interface MAC
  address
• IPX interface configuration supports multiple
  data-link encapsulations
• Novell RIP uses the distance-vector metrics of
  ticks and hops
• Service advertisement protocol (SAP) and Get
  Nearest Server (GNS) broadcasts connect clients
  and servers

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Key Features - continued

• IPX uses distance-vector routing (such as RIP) or
  link-state routing (such as NetWare Link Services
  Protocol NLSP).
• IPX RIP sends routing updates every 60 sec.
• RIP uses ticks (network delay) and hop count as
  its routing metrics and is limited to a maximum
  of 16 hops.

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IPX Addressing

• Structure of IPX addresses
• Has 2 parts
• The 32 bit network address (like an IP address)
• A 48 bit node (physical) address
• (often the MAC address is used).

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Multiple Novell Encapsulations

• Ethernet 802.3 is also called raw Ethernet and is
  the default for NetWare versions 2 through 3.11.
• Ethernet 802.2 or SAP (also called Novell
  Ethernet_802.2 or 802.3) is the standard IEEE
  frame format, including an 802.2 LLC header. With
  the release of NetWare 3.12 and 4.x, this
  encapsulation became Novell's new standard frame
  format and is also used for OSI routing.
• Ethernet II or ARPA (also called Novell
  Ethernet_II or Ethernet Version II) uses the
  standard Ethernet Version II header and is used
  with TCP/IP.
• Ethernet SNAP or snap (also called Novell
  Ethernet_SNAP or snap) extends the IEEE 802.2
  header by adding a Subnetwork Access Protocol
  (SNAP) header, which provides an "encapsulation
  type" code similar to that defined in the
  Ethernet Version II specification and used with
  TCP/IP and AppleTalk.

Important Chart
8
IOS encapsulation names

• Four different ways to frame Ethernet in Novell
  networks exist

• Their Cisco IOS names are

• novell-ether
• sap
• arpa
• snap

Important Chart

• Attention must be paid to using the correct
  encapsulation type when configuring IOS for a
  NetWare network.

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Multiple Encapsulation

• Multiple encapsulations are supported on a single
  LAN interface, allowing older and newer NetWare
  nodes to coexist on the same LAN segment as long
  as you configure multiple logical networks.
• Multiple IPX-encapsulation support reduces
  equipment expense, minimizes configuration
  complexity, and eases migration from one IPX
  encapsulation method to another.

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IPX packet format
An IPX packet has more fields. They are, in Bytes

• Checksum (2)
• Packet Length (2)
• Transport Control (1)
• Packet Type (1)
• Destination network (4)
• Destination node (6)
• Destination socket (2)
• Source network (4)
• Source node (6)
• source socket (2)
• data (variable)

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Novell RIP

• Novell RIP is a distance-vector routing protocol,
  Routing table updates are sent at 60-second
  intervals.
• It uses two metrics to make routing decisions
  ticks (a time measure) and hop count (a count of
  each router transversed).
• Novell RIP checks its two distance-vector metrics
  by first comparing the ticks for alternate paths.
  By utilizing ticks as a metric this provides a
  better measurement of the speed of the link. If
  two or more paths have the same tick value,
  Novell RIP compares the hop count.
• If two or more paths have the same hop count, the
  router load shares. Load sharing is the use of
  two or more paths to route packets to the same
  destination evenly among multiple routers to
  balance the work and improve network performance.
  

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Service Advertising Protocol (SAP)

• All the servers on NetWare networks can advertise
  their services and addresses.
• All versions of NetWare support SAP broadcasts to
  announce and locate registered network services.
• SAP updates are sent every 60 seconds.
• Workstations do not keep SAP tables -only routers
  and servers keep SAP tables.
• All servers and routers keep a complete list of
  the services available throughout the network in
  SAP tables

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SAP -
continued

• Each SAP service is an object type identified by
  a number. The following are examples
• Number SAP Service
• 4 NetWare file server
• 7 Print server
• 24 Remote bridge server (router)

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Get Nearest Server Protocol (GNS)

• NetWare clients automatically discover available
  network services because of a SAP broadcasts.
• One type of SAP advertisement is GNS, which
  enables a client to quickly locate the nearest
  server for login.
• If a NetWare server is located on the segment, it
  responds to the client request. The Cisco router
  does not respond to the GNS request.
• If there are no NetWare servers on the local
  network, the Cisco router responds with a server
  address from its own SAP table.

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GNS -
continued

• In responding to GNS requests, Cisco IOS software
  can also distribute clients evenly among the
  available servers.
• By supporting serverless LAN segments and
  distributing clients evenly among available
  servers, Cisco IOS software provides
  network-based load sharing, improves application
  availability, and minimizes the need to configure
  and manage large numbers of local servers,
  assuming that the servers are identical.

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Review

• What type of protocol is IPX?
• Where do you get the node number (host ) using
  Novell's IPX addressing scheme?
• Which metrics does Novell RIP use?
• What occurs when a router running Novell RIP has
  two equal paths to a network?
• Where does the response to a GNS request come
  from if there is both a Cisco router and a
  NetWare server on the same LAN?