Intel ER8100STUS - Express 8100 Router User manual

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Intel Express 8100 Router
Reference Manual

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ii
Second edition April 1998
Copyright © 1998, Intel Corporation. All rights reserved.
Intel Corporation, 5200 NE Elam Young Parkway, Hillsboro, OR 97124-6497
Intel Corporation assumes no responsibility for errors or omissions in this manual. Nor does Intel make any commitment to update the infor-
mation contained herein.
* Other product and corporate names may be trademarks of other companies and are used only for explanation and to the owners’ benefit,
without intent to infringe.

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I
Contents
Part I LAN and WAN Links and Services
1 LAN and WAN Services in the Router . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
LAN Services . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
WAN Services . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2
WAN Services and Protocols Available . . . . . . . . . . . . . . . . . . . . . . . . . . 3
General Facilities for WAN Services . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
2 Leased Lines Links . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
Point-to-Point Protocol (PPP) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
Data Compression . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
Data Encryption . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
Peer Authentication using the Challenge Handshake Authentication
Protocol (CHAP) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
Peer Authentication using the Password Authentication Protocol (PAP) 15
3 Frame Relay Services . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
4 ISDN Services . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20
Integrated Services Digital Network (ISDN) in the Intel Express 8100
Router . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20
ISDN Concept . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21
ISDN Services . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22
ISDN Numbering and Addressing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24
BRA and PRA Numbering . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26
MSN (Multiple Subscriber Number) . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27
SUB (Sub-addressing) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27
DDI (Direct Dialing In) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27
Permanent ISDN . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28
ISDN Standards . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28
ISDN Network Interface Reference Configurations . . . . . . . . . . . . . . . . . . . 30
5 X.25 Services . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32
X.25 Characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32
X.25 Services and Features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34
X.25 Packets and Virtual Calls . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35
X.25 Addressing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37
6 PPP Multilinks . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39
7 Internet Tunnels . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41

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II
Contents
Part II IP, Novell IPX and Bridging Services
8 IP Routing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 47
IP Concept . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 47
IP Addresses Structure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 48
IP Subnets . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 49
Address Resolution . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 51
Internet Control Messages . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 52
IP Filters—Firewall Protection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 52
IP Filter Example . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 55
Network Address Translation (NAT) . . . . . . . . . . . . . . . . . . . . . . . . . . . . 57
Static Mapping . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 60
Dynamic Mapping . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 60
Examples of Use . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 62
Routing Information Protocol (RIP) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 64
RIP-1 and RIP-2 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 64
RIP Metrics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 66
Triggered RIP . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 67
Static Routes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 68
Static Routes Example . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 70
9 Novell IPX Routing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 71
Novell Routing Concept . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 71
Internetworking Packet Exchange (IPX) . . . . . . . . . . . . . . . . . . . . . . . . . . 72
Frame Types . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 72
Novell Addressing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 72
Novell Metrics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 73
Data Transmission . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 75
IPX over WAN Links . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 76
IPX WAN Protocol . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 76
IPX Watchdog Packets . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 77
IPX Serialization Packets . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 79
Sequenced Packet Exchange (SPX) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 79
IPX Data Filters . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 82
IPX Filters Example . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 84
Routing Information Protocol (RIP) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 85
RIP Filtering . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 86
Service Advertising Protocol (SAP) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 87
SAP Filtering . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 87
Static Routes and Services . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 88
Configuration Example—Cost-Reduced WAN . . . . . . . . . . . . . . . . . . . . . . . 91
10 WAN Bridging Services . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 93
Introduction to WAN Bridging . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 93
How Bridging Works . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 94
Forwarding Tables . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 95
Operation of the Bridge in the Intel Express 8100 Router . . . . . . . . . . . 101
Controlled Bridging . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 106

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III
Contents
Spanning Tree Algorithm . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 108
Bridging Loops . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 108
Spanning Tree Concept . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 109
Spanning Tree in the Intel Express 8100 Router . . . . . . . . . . . . . . . . . . . 111
Bridge Spoofing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 114
BPDU Spoofing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 114
Non-BPDU Spoofing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 115
Enabling Bridge Spoofing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 115
Appendices
A Protocol Bandwidth Overheads and Requirements . . . . . . . . . . . . . . . . 117
B TCP and UDP Port Numbers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 119
C Ethernet Type Codes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 121
D IP Frame Formats . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 126
E Novell IPX Frame Formats . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 127
F Novell IPX Service Types . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 130

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iv
Preface
Products covered The following products are covered in this manual:
■Express 8100 Router with Frame Relay
■Express 8100 Router with X.25
■Express 8100 Router with an ISDN S/T port
■Express 8100 Router with an ISDN U port
Acronyms BACP Bandwidth Allocation Protocol
BCP Bridging Control Protocol
BECN Backward Explicit Congestion Notification
BPDU Bridging Protocol Data Units
BRA Basic Rate Access
BRI Basic Rate Interface
CBC Cypher Block Chaining
CCITT Comité Consultatif International Télégraphique et Téléphonique
CCP Compression Control Protocol
CHAP Challenge Handshake Authentication protocol
CRC Cyclic Redundancy Check
DCE Data Communication-terminating Equipment
DE Discard Eligibility
DLCI Data Link Connection Identifier
DLCMI Data Link Connection Management Interface (also called LMI)
DN Directory Number
DTE Data Terminal Equipment
DVMRP Distance Vector Multicast Routing Protocol
ECP Encryption Control Protocol
FECN Forward Explicit Congestion Notification
FR Frame Relay
HDLC High-level Data Link Control
ICMP Internet Control Message Protocol
IGMP Internet Group Management Protocol
IP Internet Protocol
IPCP Internet Protocol Control Protocol
IPX Internetwork Packet Exchange
IPXCP Internetwork Packet Exchange Control Protocol
ISDN Integrated Services Digital Network
ITU International Telecommunication Union
LAN Local Area Network
LAPB Link Access Procedure Balanced
LAPF Link Access Procedure for Frame Relay
LCP Link Control Protocol
LSP Link State PDU
MIB Management Information Base

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NAT Network Address Translation
NCP Network Control Protocol
PAP Password Authentication Protocol
PING Packet InterNet Groper Function
PDN Public Data Network
PRA Primary Rate Access
PRI Primary Rate Interface
PSDN Packet Switched Data Network
PVC Permanent Virtual Circuit
RIP Routing Information Protocol
RSVP ReSerVation Protocol
SAP Service Advertising Protocol
SLIP Serial Link Internet Protocol
SNAP SubNetwork Access Protocol
SNMP Simple Network Management Protocol
SPX Sequenced Packet Exchange
SVC Switched Virtual Circuit
TCP Transmission Control Protocol
TFTP Trivial File Transfer Protocol
UDP User Data Protocol
WAN Wide Area Network
WWW World Wide Web
Related documents Novell NetWare Link Services Protocol Specification Rev 1.0.
Novell part No. 100-001708-002.
IPX Router Specification.
Novell part No. 107-000029-001
User Datagram Protocol (UDP).
RFC 768
Trivial File Transfer Protocol (TFTP) revision 2.
RFC 783
Internet Protocol (IP).
RFC 791
Internet Control Message Protocol (ICMP).
RFC 792
Transmission Control Protocol (TCP).
RFC 793
Ethernet Address Resolution Protocol (ARP).
RFC 826

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vi
Transmission of IP Datagrams Over Public Data Networks
RFC 877
Broadcasting Internet Datagrams.
RFC 919
Broadcasting Internet Datagrams in the Presence of Subnets.
RFC 922
Internet Standard Subnetting Procedure.
RFC 950
Bootstrap Protocol.
RFC 951
Using ARP to Implement Transparent Subnet Gateways.
RFC 1027
Serial Link Internet Protocol (SLIP).
RFC 1055
Routing Information Protocol (RIP).
RFC 1058
Simple Network Management Protocol (SNMP).
RFC 1155
Internet Numbers
RFC 1166
Concise MIB Definitions.
RFC 1212
Management Information Base for Network Management of TCP/IP-Based In-
ternets: MIB II.
RFC 1213
Internet Control Message Protocol (ICMP) Router Discovery Messages.
RFC 1256
Management Information Base for Frame Relay Data Terminal Equipment
(DTE), 1992.
RFC 1315
Internet Protocol Control Protocol (IPCP) for the Point-to-Point Protocol
(PPP).
RFC 1332

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vii
Password Authentication Protocol (PAP)
RFC 1334
Multiprotocol Interconnect on X.25
RFC 1356
Multiprotocol Interconnect over Frame Relay Data Terminal Equipment
(DTE), 1993.
RFC 1490
Definition of Managed Objects for Bridges.
RFC 1493
Internetwork Packet Exchange Protocol Control Protocol (IPXCP) for the
Point-to-Point Protocol (PPP).
RFC 1552
Point-to-Point Protocol (PPP) over Integrated Services Digital Networks (IS-
DN).
RFC 1618
Network Address Translation (NAT)
RFC 1631
Bridge Control Protocol (BCP) for the Point-to-Point Protocol (PPP).
RFC 1638
Link Control Protocol (LCP) for the Point-to-Point Protocol (PPP).
RFC 1661
Point-to-Point Protocol (PPP) over High-level Data Link Control (HDLC).
RFC 1662
Assigned Numbers.
RFC 1700
Multilink Point-to-Point Protocol (PPP)
RFC 1717
Routing Information Protocol (RIP) Version 2
RFC 1723
Requirements for IP Version 4 Routers — regarding subnetting.
RFC 1812
Point-to-Point Protocol (PPP) Data Compression
RFC 1962

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Point-to-Point Protocol (PPP) Encryption
RFC 1968
Point-to-Point Protocol (PPP) Stac Data Compression
RFC 1974
Point-to-Point Protocol (PPP) Multilink
RFC 1990
Challenged Handshake Authentication Protocol (CHAP)
RFC 1994
Triggered RIP
RFC 2091
High-level Data Link Control.
ISO/IEC 3309
Link Access Procedure, Balanced (LAPB)
ISO/IEC 7776
X.25 Packet Layer Protocol for Data Terminal Equipment (DTE).
ISO/IEC 8208
Frame Relay User-Network Interface, January 1992.
FRF.1
Frame Relay Multiprotocol Interconnect, December 1992.
FRF.3
Media Access Control (MAC) Bridges.
IEEE/ANSI 802.1D
IEEE/ANSI 802.1G
High-level Data Link Control (HDLC)
ISO 3309
Frame Relaying Bearer Service Architectural Framework and Service Descrip-
tion, 1990.
ANSI T1.606
Frame Relaying Bearer Service, Congestion Management Principles, 1991
Addendum 1.
ANSI T1.606
DSS1 — Signalling Specification for Frame Relay Bearer Service, 1991.
ANSI T1.617

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ix
DSS1 — Core Aspects of Frame Protocol for use with Frame Relay Bearer Ser-
vice, 1991.
ANSI T1.618
Frame Relay Bearer Services, 1991.
ITU-T (CCITT) Recommendation I.233.1
Congestion Management in Frame Relaying Networks, 1991.
ITU-T (CCITT) Recommendation I.370
Basic User-Network Interface — Layer 1 Specification, 1993.
ITU-T (CCITT) Recommendation I.430
Usage of Cause and location in the Digital Subscriber Signalling System No. 1
and the Signalling System No. 7 ISDN User Part, 1993.
ITU-T (CCITT) Recommendation Q.850
ISDN User-Network Interface-Data Link Layer Specification, 1993.
ITU-T (CCITT) Recommendation Q.921
ISDN Data Link Layer Specification for Frame Mode Bearer Services, 1992.
ITU-T (CCITT) Recommendation Q.922
ISDN User-Network Interface Layer 3 Specification for Basic Call Control,
1993.
ITU-T (CCITT) Recommendation Q.931
International Numbering Plan for Public Data Networks
ITU-T (CCITT) Recommendation X.121
Interface Between Data Terminal Equipment (DTE) and Data Circuit-termi-
nating Equipment (DTE) for Terminals Operating in the Packet Mode and
Connected to Public Data Networks by Dedicated Circuits.
ITU-T (CCITT) Recommendation X.25

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Part I
LAN and WAN Links and Services

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1
Chapter 1
LAN and WAN Services in the Router
In this chapter This chapter gives an introduction to the LAN and WAN services available in the
different Intel Express 8100 Router versions, and the common facilities available
of the different WAN services. WAN services include leased line, PPP, Frame
Relay, ISDN and X.25 services.
The different WAN services available in the Intel Express 8100 Router are de-
scribed in the following chapters.
LAN Services
Introduction Local Area Networks (LAN) are concerned with the interconnection of distribut-
ed computer systems whose physical location is confined to a localized group of
buildings. The main difference between a communication path established via a
LAN and connections made via Public Data Networks/Wide Area Networks
(WAN) is that connections via a LAN allow for higher transmission rates due to
the short physical distances.

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WAN Services
LAN and WAN Services in the Router
LAN Services concept The following illustration indicates how LAN Services are embedded in the Intel
Express 8100 Router.
Ethernet services Ethernet is a Local Area Network (LAN) hardware standard that is capable of
linking up to 1,024 nodes (stations) in a bus network. It uses a base-band (single-
channel) communication technique providing for a raw data transmission rate of
either 10 Mbps for 10Base-T or 100Mbps for 100Base-T. Ethernet uses carrier-
sense multiple-access/ collision-detection techniques (CSMA/CD).
WAN Services
Introduction Wide Area Network (WAN) services consist of links to remote sites via private
or Public Data Networks (PDNs).
ROUTING (TCP/IP & IPX) and Bridging
LAN SERVICES
Ethernet
0996
LAN Port
Protocol Identification
LAN Link Control

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3
WAN Services
LAN and WAN Services in the Router
WAN Services and Protocols Available
WAN services overview WAN services are private or public data networks (PDNs) available to subscrib-
ers for interconnecting remote sites. The Intel Express 8100 Router supports:
■Leased lines
■Switched (dial-up) connections
■Point-to-Point Protocol (PPP)—described in “Point-to-Point Protocol
(PPP)”, p. 8
■Frame Relay services—described in Chapter 3 “Frame Relay Services”, p.
17
■ISDN connections and services—described in Chapter 4 “ISDN Services”,
p. 20
■X.25 services—described in Chapter 5 “X.25 Services”, p. 32
■PPP Multilinks which combine a number of PPP links into a single route
between two sites—described in Chapter 6 “PPP Multilinks”, p. 39
■Internet Tunnels for routing data via the internet—described in Chapter 7
“Internet Tunnels”, p. 41
Number of WAN links
supported
The Intel Express 8100 Router supports up to 5 WAN links (Frame Relay, ISDN
or X.25).
Leased lines A leased line is a permanent physical connection between two Local Area Net-
works. The costs for the use of a leased line are fixed—that is, they are indepen-
dent of the amount of data transmitted. A leased line is normally used when there
is a need for constant data flow between two sites.
Dial-up links Dial-up links (also referred to as switched links or switched lines) are links that
are only established when data requires transmitting over the WAN link and are
similar in operation to a normal telephone connection. Dial-up WAN links re-
quire the use of a modem or other WAN connect device designed to establish this
type of connection.
The number for the dial-up WAN link is configured in the modem or WAN con-
nect device (not for ISDN and X.25 links). This is a prerequisite for V.11, V.24,
V.35 and V.36 WAN connections.
General Facilities for WAN Services
Introduction This section gives an overview and describes the WAN service features common
to all WAN link types available in the Intel Express 8100 Router.

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WAN Services
LAN and WAN Services in the Router
Data compression Data compression is available for all WAN link types to improve the throughput.
PPP and Frame Relay
For PPP links (leased lines, dial-up links and ISDN links) and Frame Relay links,
data compression rates of up to 4:1 can be achieved for text data.
X.25
For X.25 links, data compression rates of up to 4:1 can be achieved for text data.
Timecut mode for dial-
up (switched) links
Note Timecut mode should be selected for dial-up (switched) WAN links.
Operating costs can be excessive otherwise.
When a dial-up (switched) WAN link is in Timecut mode, the link is only acti-
vated when there is queued data. Timecut mode should be selected where trans-
mission costs are dependent on the data transferred, the number of data packets
sent or the duration for which the link is active. Timecut mode ensures that the
WAN link is only established when necessary.
Routing protocols such as RIP and IPX send various routing packets between de-
vices to continually assess the topology of the network. If the standard settings
are used for these settings (for example RIP packets are sent every 30 seconds),
timecut WAN links never get the chance to close down. Routing protocol settings
used on timecut WAN links should be set in accordance with this, and there are
other considerations to be made (for example Watchdog Spoofing and RIP and
SAP Filtering—see Chapter 9 “Novell IPX Routing”, p. 71).
Backup links Backup links are dial-up (switched) links that can be initialized if another link
should fail or has not been established within a defined time interval. Typically,
a primary WAN link is a 2 Mbps leased line connection, the backup WAN link
is a 64 kbps dial-up connection—the costs of the backup link is therefore depen-
dent on how much the link is used.
A WAN link in Backup mode is only used if the primary link should fail, or if a
connection to it was established from a remote source. Backup links can only be
closed down by the router that started the link.

Reference.bok : Chapter01 5 Wed Apr 22 10:58:08 1998
5
WAN Services
LAN and WAN Services in the Router
Timecut backup links
considerations
Timecut mode for backup links must only be used if the backup link runs in par-
allel to the primary WAN link, that is the main WAN link and the backup WAN
link must run between the same routers as shown in the figure below:
Timecut mode MUST NOT be selected for backup links that run via a different
router than the main WAN link as shown below. Problems otherwise occur when
using the backup WAN Link.
1476
LAN2LAN1
Primary WANLink
BackupWAN Link
(dial-up)
RouterA RouterB
LAN WAN1 WAN2 System
®
IntelExpress Router 9200
LAN WAN 1 WAN2 System
®
IntelExpress Router 9200
1475
TheBackupWANLink must Not use
timecutmode
LAN 2
LAN 2
LAN 3
LAN 1 LAN 1
Primary WAN
Link
BackupWAN
Link
Backup
WANLink
RouterA RouterA
RouterB
RouterC
RouterC
Primary WAN
Link
Primary WAN
Link
LAN WAN1 WAN2 System
®
IntelExpress Router 9200
LAN WAN1 WAN2 System
®
IntelExpress Router 9200
LAN WAN1 WAN2 System
®
IntelExpress Router 9200
LAN WAN1 WAN2 System
®
IntelExpress Router 9200
LAN WAN1 WAN2 System
®
IntelExpress Router 9200
LAN WAN1 WAN2 System
®
IntelExpress Router 9200
RouterB

Reference.bok : Chapter01 6 Wed Apr 22 10:58:08 1998
6
WAN Services
LAN and WAN Services in the Router
Multiple backup links For ISDN and X.25 services, it is possible to establish multiple backup links for
increased internetwork reliability. This can be a particularly useful feature in
X.25 networks where a number of Switched (dial-up) links can be available.
In the above example, link 4 is used if the primary link (link 2) should fail, link
5 is used if link 4 should fail and link 6 is used if link 5 should fail.
Timer Profiles The Intel Express 8100 Router implements Timer Profiles which offer extensive
facilities to restrict WAN link activity according to a user-defined time profile.
This may be done for security reasons or to reduce the operating costs of WAN
links.
Up to 16 user-defined timer profiles can be defined, any one of which can be se-
lected for use with a WAN link during configuration of the link. Each profile al-
lows you to define access rights on a weekly basis, with a half-hour resolution.
For each link, access can be blocked:
■for outgoing access from the router to the WAN link
■for both outgoing and incoming access (WAN link disabled outside the times
defined in the timer profile)
For example, for one link using a timer profile, outgoing access may be block,
while for another WAN link using the same timer profile, access may be block
for all data traffic.
Timer profiles
consideration
Warning When blocking both outgoing and incoming access, the timer pro-
file must be the same in both the routers over the WAN link.
This is particularly important for dial-up (switched) WAN links where operating
costs are dependent on the use of the link.
If the timer profiles are not the same and only one of the routers is denying in-
coming access at some time, the other router may continually attempt to establish
the WAN link. This can lead to the following problems for the calling router:
■for dial-up WAN links, excessive operating costs for the WAN link
■error messages being logged
■the link being disabled (faulted)
1235
Link 2
PPP
Leased
Line
Link 4
X.25
Dial Up
Backup for Link 2
Link 5
X.25
Dial Up
Backup for Link 4
Link 6
X.25
Dial Up
Backup for Link 5

Reference.bok : Chapter01 7 Wed Apr 22 10:58:08 1998
7
WAN Services
LAN and WAN Services in the Router
Example use of a timer
profile
For example, a timer profile could be set up to deny both incoming and outgoing
access on a WAN link outside normal office hours of 7:30 to 17:30, and to deny
all access at weekends.
Daily Activity Limit The Intel Express 8100 Router has a Daily Activity Limit function which can be
used to control the use, and therefore the cost of operation, of dial-up WAN
Links. The alarm generates an SNMP Trap and can also be set up to close and
lock the associated WAN link when it has been in the Up (for both call directions)
state for the configured time-period within a day (midnight to midnight). That is,
the activity counter is incremented for both incoming and outgoing calls on the
links. If the link has been locked by the Daily Activity Limit, it stays locked until
it is manually reset from Intel Device View.
When a dial-up link has been locked by the Daily Activity Limit, the router does
not permit outgoing calls on the link until the link has been unlocked again from
Intel Device View. However, the link accepts incoming calls, thereby allowing a
remote connection via the link to unlock the link.
0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23
Time
Day
Sun
Mon
Tue
Wed
Thu
Fri
Sat
1290
Access allowed Mon-Fri
between 7.30 and 17.30

Reference.bok : Chapter02 8 Wed Apr 22 10:58:08 1998
8
Chapter 2
Leased Lines Links
In this chapter The WAN connect protocol used for communicating over leased line WAN con-
nections by the Intel Express 8100 Router is the Point-to-Point Protocol (PPP).
When communicating over leased line connections, PPP runs on top of the High-
level Data Link Control (HDLC) protocol.
Note PPP is also used for communications over ISDN links (PPP over
ISDN).
This chapter gives an introduction to the Point-to-Point Protocol (PPP) and de-
scribes the features of the protocol offered by the Intel Express 8100 Router.
Point-to-Point Protocol (PPP)
Introduction to PPP The Point-to-Point Protocol (PPP) was designed to enable simultaneous transfer
of network-layer protocols across a point-to-point link. Its main function is to es-
tablish a synchronous link connection between routers from any manufacturer.
PPP functions include:
■encapsulating multi-protocol datagrams
■establishing, configuring and testing the data-link connection using a Link
Control Protocol (LCP)
■establishing and configuring bridging and various network-layer communi-
cations across the link using Network Control Protocols (NCPs). This is han-
dled by the Internet Protocol Control Protocol (IPCP) for IP, and the
Internetwork Packet Exchange Control Protocol (IPXCP) for IPX and the
Bridging Control Protocol (BCP) for bridging services
■authenticating peers using the Challenge Handshake Authentication Protocol
(CHAP) and Password Authentication Protocol (PAP) to ensure that commu-
nications are between authorized devices
■encrypting and decrypting data transmitted via the link to offer data security
■compression/decompression of data to improve the throughput of data