📄 ipx_theory.htm
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<p><b><font size="4" color="#008000" face="Arial">IPX Overview</font></b></p>
<p><b><font color="#008000" face="Arial" size="4">Background</font><br>
</b><font face="Arial">Internetwork Packet eXchange (IPX) was developed by Novell in the mid 1980's
and is based on the XNS protocol developed by Xerox. The IPX protocol was the
dominate LAN protocol in the late 80's and early 90's.</font></p>
<p><font face="Arial"><b><font color="#008000" size="4">IPX Addressing</font><br>
</b>IPX has an 80-bit address. The first 32-bits represent the network
address and the last 48-bits represent the node address. The network
address is selected by the administrator. The node address is borrowed
from the interfaces MAC address. For a serial interface, the node address
is borrowed from the first LAN interface. <br>
An IPX address is hexadecimal. <br>
The format is: network.node.node.node</font></p>
<p><font face="Arial">Examples:</font></p>
<p><font face="Times New Roman">5c.0000.0ca1.4567 (network portion is 5c)<br>
1ace99.0000.0c23.1231 (network portion is 1ace99)<br>
4001231.0002.0D12.1241 (network portion is 4001231)</font></p>
<p><font face="Arial"><b><font color="#008000" size="4">IPX Routing</font><br>
</b>
The three primary IPX routing protocols are IPX RIP, IPX EIGRP, and NLSP (Novell
Link-Services Protocol). For the CCNA we need to understand IPX RIP.
IPX RIP is a distance vector routing protocol that advertises the entire routing
table every 60 seconds. The metric has two parts: ticks then hops.
Ticks are about 1/18 of a second and measure the delay. A serial link is 6
ticks, and an Ethernet link is 1 tick. The path with the lowest number of
ticks is used. In the event of a tie, hop count is the tie-breaker.
IPX RIP is automatically enabled with the </font><font size="2" face="Terminal">ipx routing</font><font face="Arial"> command and simply
places a network address on an interface.</font><p><font face="Arial"><b>
<font color="#008000" size="4">IPX Load Balancing</font><br>
</b>If a Cisco router has two equivalent paths to a destination, by default it
will only select ONE of these paths. This differs from IP which load
balances by default. To enable IPX load balancing so the router will
balance the number of packets sent across equal cost paths use the <b>ipx
maximum-paths</b> command to specify how many paths it will load balance
across. </font><p><font face="Arial"><b><font size="4" color="#008000">IPX
Service Advertising Protocol (SAP)<br>
</font>
</b>Netware compatible devices use SAPs to broadcast the name and type of
resources they have to share every 60 seconds. A single Netware server can
have multiple SAPs, for example one for file-sharing (type 4) and one for
printer-sharing (type 7). Cisco routers can be configured to generate SAPs
as well.</font><p><font face="Arial"><b><font size="4" color="#008000">IPX Encapsulation or Frame types</font><br>
</b>IPX is a layer-3 protocol that is wrapped in a layer 2 frame before being
released onto the network. The type of layer 2 frame or encapsulation can
vary. The default encapsulation type on serial links is HDLC. It is
possible to have more than one encapsulation type on an interface. This
chart shows shows the Ethernet Encapsulation types.</font><p><br>
<table border="0" cellpadding="0" cellspacing="0">
<tr>
<td bgcolor="#FFFF00"><b>Encapsulation Type<br>
Cisco Name</b></td>
<td bgcolor="#FFFF00"><b>Encapsulation Type<br>
Novell Name</b></td>
<td bgcolor="#FFFF00"><b>When is it used?</b></td>
</tr>
<tr>
<td>novell-ether***</td>
<td>802.3</td>
<td>Old Novell. Version 3.11 or earlier</td>
</tr>
<tr>
<td>sap</td>
<td>802.2</td>
<td>New Novell. Version 3.12 or later</td>
</tr>
<tr>
<td>arpa</td>
<td>ethernet_II</td>
<td>rarely</td>
</tr>
<tr>
<td>snap</td>
<td>snap</td>
<td>IPX for Macintosh</td>
</tr>
<tr>
<td>*** default on Ethernet</td>
<td></td>
<td></td>
</tr>
</table><p align="left"><font face="Arial"><b><font size="4" color="#008000">Sub-interfaces</font><br>
</b>There may be times when you have more than one encapsulation type running on
a segment. This can happen when you have an old Netware server and a
newer one. To enable the router to talk to both of these encapsulation
types, you must create a sub-interface for each. A sub-interface is a
logical interface. You can have multiple sub-interfaces for each physical
interface. To create or configure a sub-interface, follow the physical
interface name with a period and the sub-interface number like interface
ethernet 0.2. </font>
<p align="left"><b><font size="4" face="Arial" color="#008000">IPX Configuration</font></b><p>
<font face="Arial">Basic IPX is
very easy to configure. Remember, you do not need to configure the node
address because the router borrows the MAC address for that.</font><p>
<font face="Arial" size="4" color="#008000"><b>Basic IPX
Config</b></font><p><font face="Arial">1. Enable IPX Routing on the router</font><p>
<font face="Terminal" size="2">Router(config)#ipx routing</font><p>
<font face="Arial">2.
Enable IPX on the Interface by assigning the network number and, optionally,
then encapsulation type (on same line or different line)</font><p>
<font face="Terminal" size="2">Router(config)#interface ethernet 0<br>
Router(config-if)#ipx network 6F encapsulation arpa<b><br>
</b>or<br>
Router(config)#interface ethernet 0<br>
Router(config-if)#ipx network 6F<br>
Router(config-if)#ipx encapsulation arpa</font><font face="Times New Roman"><b><br>
</b></font><p><b><font face="Arial" size="4" color="#008000">Viewing
your IPX information:</font></b><p><font face="Arial">1. View the interfaces information</font><p>
<font face="Terminal" size="2">Router#show ipx interface<br>
Router#show ipx interface brief</font><p><font face="Arial">2. View the IPX routing
information</font><p><font face="Terminal" size="2">Router#show ipx route</font><font face="Arial"><br>
</font>
<p><font face="Arial" size="2"><span class="724482219-24092001">Copyright (c)
1998-2003 Boson Software, Inc. All Rights Reserved.</span></font></p>
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