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3.0  PPP OPERATIONAL BACKGROUND

PPP is a protocol used for multi-plexed transport over a point-to-point

link.  PPP operates on all full duplex media, and is a symmetric peer-to-peer
protocol, which can be broken into three main components: 1. A standard
method to encapsulate datagrams over serial links; 2. A Link Control Protocol
(LCP) to establish, configure, and test the data-link connection; 3. A family of
Network Control Protocols (NCPs) to establish and configure different net-
work layer protocols.

In order to establish communications over a point-to-point link, each end

of the PPP link must first announce its capabilities and agree on the param-
eters of the link’s operation. This exchange is facilitated through LCP
Configure-Request packets.  

Once the link has been established and optional facilities have been

negotiated, PPP will attempt to establish a network protocol.  PPP will use
Network Control Protocol (NCP) to choose and configure one or more net-
work layer protocols.  Once each of the network layer protocols have been
configured, datagrams from the established network layer protocol can be
sent over the link.  The link will remain configured for these communications
until explicit LCP or NCP packets close the link down, or until some external
event occurs.

The PPP Bridging Control Protocol (BCP), defined in RFC 1638,

configures and enables/disables the bridge protocol on both ends of
the point-to-point link.  BCP uses the same packet exchange mecha-
nism as the Link Control Protocol (LCP). BCP is a Network Control
Protocol of PPP, bridge packets may not be exchanged until PPP has
reached the network layer protocol phase.

3.1  APPLICATION

In situations where a routed network requires connectivity to a

remote Ethernet network, the interface on a router can be configured
as a PPP IP Half Bridge.  The serial line to the remote bridge functions
as a Virtual Ethernet interface, effectively extending the routers serial
port connection to the remote network. The bridge device sends bridge
packets (BPDU's) to the router's serial interface. The router will receive
the layer three address information and will forward these packets
based on its IP address.   

Figure 1 shows a typical Cisco router with a serial interface configured

as a PPP Half Bridge. The router serial interface uses a remote device that
supports PPP bridging to function as a node on the remote Ethernet net-
work. The serial interface on the Cisco will have an IP address on the
same Ethernet subnet as the bridge.

For example, the customer site is assigned the addresses

192.168.1.0/24 through 192.168.1.1/24. The address 192.168.1.1/24 is
also the default gateway for the remote network. The above settings

2.0  GENERAL INFORMATION

Thank you for your purchase of this Patton Electronics product.

This product has been thoroughly inspected and tested and is warranted
for One Year parts and labor.  If any questions arise during installation or
use of the unit, contact Patton Electronics Technical Services at (301)
975-1007.

2.1  FEATURES

•  Terminates T1/FT1 Circuits over a 4-Wire RJ-48C interface
•  10Base-T Ethernet bridge
•  PPP (Point to Point Protocol, RFC 1661) with Bridge Control

Protocol (RFC 1638)

•  Unstructured Rates at 1.544 Mbps
•  D4 or ESF Framing Modes
•  Supports AMI or B8ZS/B7ZS Line Coding
•  Configuration via Software Control Port or Internal DIP Switches 
•  Six Easy-to-Read LED Indicators Monitor Data & Diagnostics
•  Internal or Receive Recover Clocking
•  Also Operates as a High-Speed Point-to-Point Modem
•  Made in USA

2.2  GENERAL PRODUCT DESCRIPTION

The 

NetLink-T1™

Model 2720/I is a

single port T1/FT1 CSU/DSU

with Ethernet Bridging that provides  high-speed LAN-to-WAN connectiv-
ity. Plugging directly into the 10Base-T port of  a hub or LAN switch, the
NetLink-T1™ provides T1 or FT1 access at connection data rates of
1.544 Mbps, nx64, and nx56 (n=1 to 24 channels).  The Netlink-T1™ is
an excellent choice for internet access as well as LAN-to-LAN services.

The Netlink-T1™ provides digital access to a local WAN service

provider or directly between two facilities over a dedicated 4-Wire  cir-
cuit.  WAN bandwidth, framing and coding options are programmed via
externally accessible DIP switches or via a VT-100 type terminal using
the rear-mounted EIA-232 Control Port. Netlink-T1™ supports D4/ESF
framing options and AMI/B8ZS/B7ZS line coding.  Netlink-T1™ also sup-
ports a full range of system and diagnostic features that make system
setup easy.  The Ethernet Bridge in this unit requires no configuration at
all.

The NetLink-T1™ provides T1 terminations over a modular RJ-48C

jack and comply with jitter tolerance capabilities as specified in ANSI
T1.403 and AT&T TR62411. External power options include 120VAC and
universal interface 100-240VAC. 48VDC and rack card versions are also
available.

Summary of Contents for 2720/I Series

Page 1: ...2720 I T1 Fractional T1 CSU DSU with Ethernet Bridging SALES OFFICE 301 975 1000 TECHNICAL SUPPORT 301 975 1007 http www patton com Part 07M2720I UM Doc 08618U2 001 Rev C Revised 10 05 07 An ISO 9001...

Page 2: ...Application 3 2 Configuration 4 0 Installation 31 4 1 Connecting the 10Base T Ethernet Port to PC DTE 4 2 Connecting the 10Base T Ethernet Port to a Hub 4 3 T1 FT1 Interface Connection 4 4 DC Power C...

Page 3: ...ed or implied and the installation or use of this product shall be deemed an acceptance of these terms In the event that you detect intermittent or continuous product malfunction due to nearby high po...

Page 4: ...This protection may be particularly important in rural areas 1 4 FCC PART 68 COMPLIANCE STATEMENT The Model 2720 Series has been tested and registered in compli ance with the specifications in Part 6...

Page 5: ...ed from Patton Electronics Technical Support at tel 301 975 1007 email support patton com www http www patton com NOTE Packages received without an RMA number will not be accepted Patton Electronics t...

Page 6: ...high speed LAN to WAN connectiv ity Plugging directly into the 10Base T port of a hub or LAN switch the NetLink T1 provides T1 or FT1 access at connection data rates of 1 544 Mbps nx64 and nx56 n 1 t...

Page 7: ...il some external event occurs The PPP Bridging Control Protocol BCP defined in RFC 1638 configures and enables disables the bridge protocol on both ends of the point to point link BCP uses the same pa...

Page 8: ...o transport non routable protocols Figure 2 illustrates transparent bridging between two routers over a serial interface s0 Bridging will occur between the two Ethernet Interfaces on Router A e0 and e...

Page 9: ...nes density To meet this requirement each time slot can be reduced to 56 kbps and the Least Significant Bit LSB of each time slot set to one Bipolar 8 Zero Patton 2720 Bridge Ethernet LAN PEC Device w...

Page 10: ...el timeslots Switch S2 5 DS0 Channel Rate Use Switch S2 5 to set the DS0 rate SW2 5 Setting Off 56 kbps On 64 kbps 9 S2 SUMMARY TABLE Position Function Factory Default Selected Option S2 1 Data Rate O...

Page 11: ...ck is derived from an internal oscillator NOTE 1 When using the Model 2720 as a high speed short range modem one unit of the link must be configured in Internal Clock mode and the opposite end unit mu...

Page 12: ...the transmit clock originating in the 2720 When S1 2 is set for transmit clock it may be necessary to invert the transmit clock to allow for delays due to long cables S1 3 Tx Clock Invert On Transmit...

Page 13: ...e stereo plug into the rear of the unit The small recessed jack on the left side of the unit is the control port jack NOTE If your terminal uses a DB 25 connector please use a DB 9 to DB 25 Adapter to...

Page 14: ...wise clock slips and framing errors and bit errors may occur Internal This is commonly used in campus applications where the unit is not connected to the public telephone network directly In this mode...

Page 15: ...ear in the middle of the screen 5 Type in the password and press Enter The factory default password for the unit is password is case sensitive patton NOTE If the entry is incorrect the password screen...

Page 16: ...HINTS 1 To make a selection key the highlighted letter that corre sponds to a menu selection 2 To execute the selection type Enter CR 3 To toggle between options on a highlighted selection Press space...

Page 17: ...o customize the Model 2720 for your location You can change the default header names to give each unit a unique name and password Also you can reset the unit to its default settings without the manual...

Page 18: ...known as Superframe format According to TR 62411 The Superframe format consists of 12 frames of 193 bits each for a total of 2316 bits Each 193 bit frame consists of 192 bits preceded by one framing b...

Page 19: ...gnals are transmitted as a sequence of ones and zeros Ones are sent as pulses and zeros are sent as spaces i e no pulse Every other pulse is inverted from the previous pulse in polarity so that the si...

Page 20: ...ons 64kbps 56kbps 64kbps Also known as Clear Channel this takes full advantage of the available bandwidth in a DS0 channel Implementing it usually requires B8ZS line coding In certain cases special eq...

Page 21: ...I performance Only the service provider or special test equip ment can send these requests When AT T TR54016 is selected ANSI PRMs are still transmitted by the unit but only PRMs sent by the carrier w...

Page 22: ...ver the data stream This is the only remote loopback that the unit can initiate This is useful for campus applica tions when you need to put a remote unit in loopback The remote unit responds to the V...

Page 23: ...at the Bandwidth Selected will display 1 544k and the Total Channels will display n a When the DS0 Channel Rate is 56kbps the Bandwidth Selected will be a multiple of 56k not of 64k When using the DIP...

Page 24: ...well as the communica tion link between them Data from the local DTE is sent across the entire communication circuit and looped back to the local DTE The Model 2720 Initiating a RL can be in one of t...

Page 25: ...ing c spacebar TxTr The Model 2720 is sending a Terminate Loopback mes sage to the remote unit If the remote unit does not respond the local unit will return to the Idle state Tx1s If the remote Model...

Page 26: ...tern Off The Model 2720 is in local loopback Test Pattern Idle default Options Idle or Sending To send a pattern press the c key and press spacebar to send the test pattern The OK message indicates th...

Page 27: ...ed framing formats or severe errors in the data stream This error may indicate a noisy line or cable condition This error may indicate a noisy line or cable connection if the frames appear to be set c...

Page 28: ...m ber of seconds which have elapsed in the current interval respectively The Valid Interval Count saturates at the count of 96 96 15min 24 hours while the Current Interval Time rolls over after 900 co...

Page 29: ...e PRM is coming from a Carrier whereas the address 38h indicates the PRM is coming from a Customer When the ESF Data Link is set to AT T TR54016 the unit recognizes Carrier originated PRMs which have...

Page 30: ...p to 40 letters long Two lines provide 80 letters for your use That s a lot of flexibility Password The Password facility provides security by allowing only those who know the correct password to conf...

Page 31: ...e will transmit with respect to the Transmit clock sent out from the 2720 Please review the information provided with your DTE equipment for more information on its operation In most cases when there...

Page 32: ...as shown in the dia gram below Figure 4 10BaseT Port 10Base T DTE RJ 45 Pin No RJ 45 Pin No 1 TD 1 TD 2 TD 2 TD 3 RD 3 RD 6 RD 6 RD 4 2 Connecting the 10Base T Ethernet Port to a Hub The 10Base T int...

Page 33: ...ase T Ethernet Port to a Hub Figure 6 Model 2720 twisted pair line interface 1 RX Data TIP 2 RX Data RING 3 no connection 4 TX Data TIP 5 TX Data RING 6 no connection 7 no connection 8 no connection 1...

Page 34: ...Solid green indicates that the 10BaseT Ethernet interface has detect ed a valid SQE heartbeat signifying a valid 10BaseT connection Status Blinks yellow from one to eleven times to indicate system sta...

Page 35: ...test patterns When sending a test pattern the LED will remain lit if the unit does not receive the identical pattern When it receives the cor rect pattern the LED will turn off If error insertion is...

Page 36: ...perform a LL test follow these steps 1 Activate LL This may be done in one of two ways a Enter Local Loop from the System Diagnostics Statistics menu and toggle the Spacebar until LL appears next to...

Page 37: ...loop that the unit uses to loop up the remote unit NOTE The NetLink T1 will respond to both loops regard less of the state of the RDL Type To perform an RDL test follow these steps 1 Activate RDL Thi...

Page 38: ...l central office loops 5 3 BIT ERROR RATE V 52 DIAGNOSTICS The NetLink T1 offers three V 52 Bit Error Rate BER test pat terns These test patterns may be invoked along with the LAL and RDL tests to eva...

Page 39: ...Statistics menu and toggle the Spacebar until the desired test pattern appears b Enter Test Pattern and toggle the Spacebar to send the selected pattern c One of two result codes will appear to the ri...

Page 40: ...Clock Options Internal or network clock Diagnostics Responds to CO initiated D4 loopup and loopdown codes ESF line loop and payload loop FDL messages Universal Loopback De activate mes sage V 54 Remot...

Page 41: ...Protocol PPP RFC 1661 with Bridging Control RFC 1638 MAC Address Table Size 4096 entries MAC Address Aging MAC addresses deleted after 8 min utes of inactivity Frame Buffer 512 Frames Frame Latency 1...

Page 42: ...MENT PARTS AND ACCESSORIES Patton Model Description 10 09F 6 Foot Control Port Cable 2 5mm to DB9F 07M2720 I User Manual 2720 C UI T1 N x 64 CSU DSU M 34 female UI 2720 B UI T1 N x 64 CSU DSU DB25 fem...

Page 43: ...ata RING TRS Jack RS 232 Control Port Pin Signal Direction Tip Tx Data From Model 2720 Ring Rx Data To Model 2720 Sleeve Ground RS 232 Control Port Signals at DB 25 Connector Pin Signal Signal Directi...

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Page 48: ...Copyright 2001 2007 Patton Electronics Company All Rights Reserved...

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