9. Point-to-Point Protocol (PPP)
• Purpose:
– Transport layer-3 packets across a
Data Link layer point-to-point link
• Can be used over asynchronous
serial (dial-up) or synchronous
serial (ISDN) media
– Uses Link Control Protocol (LCP)
• Builds & maintains data-link
connections
21. Frame Relay
• Background
– High-performance WAN
encapsulation method
– OSI Physical & data Link layer
– Originally designed for use across
ISDN
• Supported Protocols
– IP, DECnet, AppleTalk, Xerox
Network Service (XNS), Novell IPX,
Banyan Vines, Transparent Bridging,
& ISO
24. Frame Relay
• Purpose
– Provide a communications
interface between DTE & DCE
equipment
– Connection-oriented Data Link
layer communication
• Via virtual circuits
• Provides a complete path from the
source to destination before sending
the first frame
26. Frame Relay Encapsulation
• Specified on serial interfaces
• Encapsulation types:
– Cisco (default encapsulation type)
– IETF (used between Cisco & non-
Cisco devices)
RouterA(config)#int s0
RouterA(config-if)#encapsulation frame-
relay ?
ietf Use RFC1490 encapsulation
<cr>
27. Data Link Connection Identifiers
(DLCIs)
• Frame Relay PVCs are identified by DLCIs
• IP end devices are mapped to DLCIs
– Mapped dynamically or mapped by IARP
• Global Significance:
– Advertised to all remote sites as the same PVC
• Local Significance:
– DLCIs do not need to be unique
• Configuration
RouterA(config-if)#frame-relay interface-dlci ?
<16-1007> Define a DLCI as part of the current
subinterface
RouterA(config-if)#frame-relay interface-dlci 16
31. Sub-interfaces
• Definition
– Multiple virtual circuits on a single
serial interface
– Enables the assignment of different
network-layer characteristics to each
sub-interface
• IP routing on one sub-interface
• IPX routing on another
– Mitigates difficulties associated with:
• Partial meshed Frame Relay networks
• Split Horizon protocols
33. Creating Sub-interfaces
Configuration:
#1: Set the encapsulation on the serial interface
#2: Define the subinterface
RouterA(config)#int s0
RouterA(config)#encapsulation frame-relay
RouterA(config)#int s0.?
<0-4294967295> Serial interface number
RouterA(config)#int s0.16 ?
multipoint Treat as a multipoint link
point-to-point Treat as a point-to-point link
34. Mapping Frame Relay
Necessary to IP end devices to
communicate
– Addresses must be mapped to
the DLCIs
– Methods:
• Frame Relay map command
• Inverse-arp function
35. Using the map command
RouterA(config)#int s0
RouterA(config-if)#encap frame
RouterA(config-if)#int s0.16 point-to-point
RouterA(config-if)#no inverse-arp
RouterA(config-if)#ip address 172.16.30.1 255.255.255.0
RouterA(config-if)#frame-relay map ip 172.16.30.17 16
ietf broadcast
RouterA(config-if)#frame-relay map ip 172.16.30.18 17
broadcast
RouterA(config-if)#frame-relay map ip 172.16.30.19 18
36. Using the inverse arp
command
RouterA(config)#int s0.16 point-to-point
RouterA(config-if)#encap frame-relay ietf
RouterA(config-if)#ip address 172.16.30.1
255.255.255.0
38. Committed Information
Rate (CIR)
• Definition: Provision allowing
customers to purchase amounts of
bandwidth lower than what they
might need
– Cost savings
– Good for bursty traffic
– Not good for constant amounts of
data transmission
39. Monitoring Frame Relay
RouterA>sho frame ?
ip show frame relay IP statistics
lmi show frame relay lmi statistics
map Frame-Relay map table
pvc show frame relay pvc statistics
route show frame relay route
traffic Frame-Relay protocol statistics
RouterA#sho int s0
RouterB#show frame map
Router#debug frame-relay lmi
42. Introduction to VPN’s
• VPNs are used daily to give
remote users and disjointed
networks connectivity over a
public medium like the Internet
instead of using more
expensive permanent means.
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43. Types of VPN’s
• REMOTE ACCESS VPNS
Remote access VPNs allow remote users like telecommuters to securely
access the corporate network wherever and whenever they need to.
• SITE-TO-SITE VPNS
Site-to-site VPNs, or, intranet VPNs, allow a company to connect its remote
sites to the corporate backbone securely over a public medium like the
Internet instead of requiring more expensive WAN connections like
Frame Relay.
• EXTRANET VPNS
Extranet VPNs allow an organization’s suppliers, partners, and customers to
be connected to the corporate network in a limited way for business-to-
business (B2B) communications.
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44. Written Labs and Review
Questions
– Open your books and go through all the
written labs and the review questions.
– Review the answers in class.
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