Router Installation and Configuration Manual/Configuring a Packet over Sonet Interface

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(New page: :This chapter describes how to configure the ImageStream router POS OC3/OC12 WAN interfaces and includes the following topics: :*Packet over SONET/SDH overview :*WAN Port Uses :*Underst...)
Line 4: Line 4:
:*WAN Port Uses  
:*WAN Port Uses  
:*Understanding the Network Interface Configuration File  
:*Understanding the Network Interface Configuration File  
-
:*Configuring a POS OC3 Interface
+
:*Configuring a POS OC3/OC12 Interface
-
:*Configuring a POS OC12 Interface
+
:*Configuring OC12 Ethernet Accelerated Cross-Connect Mode
:*Configuring OC12 Ethernet Accelerated Cross-Connect Mode
   
   
Line 66: Line 65:
       !  
       !  
       interface Serial0  
       interface Serial0  
-
      shutdown  
+
        shutdown  
-
      description ATM connection to branch offices encapsulation hdlc
+
        description ATM connection to branch offices encapsulation PPP
-
      ip address 192.168.10.1 255.255.255.252
+
       !  
-
       !
+
====Setting the IP Address and Netmask====
====Setting the IP Address and Netmask====
Line 76: Line 74:
       !  
       !  
       interface Serial0  
       interface Serial0  
-
      shutdown  
+
        shutdown  
-
      description ATM connection to branch offices encapsulation hdlc
+
        description POS connection to branch offices encapsulation PPP
-
       !  
+
        ip address 192.168.10.1 255.255.255.252
 +
       !
====Setting Serial Transport Encapsulation====
====Setting Serial Transport Encapsulation====
-
:The serial transport encapsulation must be set to an ATM encapsulation for an ATM interface.  No other encapsulation types may be specified.The syntax of this command is:  
+
:The serial transport encapsulation can be set to PPP or Cisco HDLC encapsulation for an ATM interface.  No other encapsulation types may be specified.The syntax of this command is:  
-
       '''encapsulation''' ''atm'':
+
       '''encapsulation''' ''ppp | hdlc'':
-
::In the default configuration below, we have changed the encapsulation to Classical IP over ATM.  This encapsulation type corresponds to "encapsulation aal5" on a Cisco router.  Alternately, you may specify an encapsulation type of aal5snap for SNAP encapsulated ATM connections.  See the ImageStream Technical Support Web site for additional ATM configuration examples.  
+
::In the default configuration below, we have changed the encapsulation to PPP.
       !  
       !  
       interface Serial0  
       interface Serial0  
-
      shutdown  
+
        shutdown  
-
      description ATM connection to branch offices  
+
        description POS connection to branch offices encapsulation PPP
-
      encapsulation atm
+
        encapsulation ppp
 +
        ip address 192.168.10.1 255.255.255.252
       !
       !
-
====Setting ATM DS3/E3 Circuit Transport====
+
====Setting POS OC-3/OC-12 Circuit Transport=====
-
:ImageStream's ATM DS3/E3 card supports either DS3 or E3 transport.  By default, the card uses DS3 transport.  The transport type can be set using the '''transport''' command. The syntax of this command is:
+
:ImageStream's POS OC-3 and OC-12 cards support either SONET or SDH as the underlying network transport for the POS traffic.  By default, the cards use SONET mode.  The mode can be set using the '''service-module''' ''{ oc3 | oc12 }'' mode command and specifying a value of either sonet or sdh.
-
       '''transport''' ''{ ds3 | e3 }'':
+
       '''service-module''' ''oc3'' ''mode'' ''sonet | sdh'':
-
::In the default configuration below, we have set the default transport type of DS3.  
+
====Setting POS OC-3/OC-12 Payload Scrambling=====
 +
:ImageStream's POS OC-3 and OC-12 cards default to scrambling enabled. To disable scrambling use the '''service-module''' ''{oc3 | oc12 }'' ''scrambling'' command specifying a value of either ''on'' or ''off''.
-
       !
+
       '''service-module''' ''oc3'' ''scrambling'' ''on | off'':
-
      interface Serial0
+
 
-
      shutdown
+
====Overriding the POS OC-3/OC-12 C2 Byte=====
-
      description ATM connection to branch offices encapsulation atm
+
:ImageStream's POS OC-3 and OC-12 cards use a SONET C2 byte value of 0x16 when scrambling is enabled and 0xCF when scrambling is disabled according to RFC 2615. To allow interoperability with routers the predate RFC 2615 use the '''service-module''' ''{oc3 | oc12 }'' ''c2-flag'' command specifying the C2 byte value. To specify a hexidecimal value use a format like 0xcf. To specify a decimal value omit the ''0x'' like 207.
-
      transport ds3
+
-
      !
+
-
====Setting ATM OC-3/OC-12 Circuit Transport=====
+
      '''service-module''' ''oc3'' ''c2-flag'' ''0x16'':
-
:ImageStream's ATM OC-3 and OC-12 cards support either SONET or SDH as the underlying network transport for the ATM traffic.  By default, the cards use SONET mode.  The  mode can be set using the '''service-module''' ''{ oc-3 | oc-12 }'' mode command and specifying a value of either sonet or sdh.
+
====Enabling or Disabling a Serial Interface====
====Enabling or Disabling a Serial Interface====
Line 118: Line 116:
       !  
       !  
       interface Serial0  
       interface Serial0  
-
      shutdown  
+
        shutdown  
-
      description ATM connection to branch offices encapsulation atm
+
        description POS connection to branch offices encapsulation PPP
-
      transport ds3
+
       !
       !
Line 130: Line 127:
       !  
       !  
       interface Serial0  
       interface Serial0  
-
      #NOC phone: 800-555-1212 - Our account #58935 description ATM connection to branch offices encapsulation atm
+
        #NOC phone: 800-555-1212 - Our account #58935
-
      transport ds3
+
        description POS connection to branch offices encapsulation PPP
       !
       !
Line 145: Line 142:
       !  
       !  
       interface Serial0  
       interface Serial0  
-
      #NOC phone: 800-555-1212 - Our account #58935 description ATM connection to branch offices bandwidth 10000000
+
        #NOC phone: 800-555-1212 - Our account #58935
-
      encapsulation atm
+
        description POS connection to branch offices
 +
        encapsulation PPP
 +
        bandwidth 10000000
       !
       !
-
 
-
===Setting ATM DS3/E3 Master Interface Parameters===
 
-
:The '''service-module''' command is used to configure the master interface for the ATM card.  In most cases, the defaults provided on the card will match the network configuration.  Check with your line provider to determine if your line settings differ from the default configuration.  The configurations in the interface configuration must match in three places: on the router, on the ATM switch, and at the remote end.  If these settings do not match, your serial interface will not function correctly.
 
-
 
-
====Configuring the DS3/E3 Line Clocking Source====
 
-
:One and only one clock source should be configured on a line.  In most cases, your line provider will provide a clock source for the ATM circuit.  The ATM DS3/E3 card can also be configured to provide a clock source. The syntax of this command is:
 
-
 
-
      '''service-module''' ''{ ds3 | e3 }'' '''clock source''' ''{ line | internal }''
 
-
 
-
:The line or internal keyword specifies the type of clocking to use on this interface.  Line (also known as "network" or "external") timing is the default value.  Using the ''internal'' keyword will enable the card's internal clock and will instruct the card to place this clock source on the line.  Configuring more than one clock source, or having no clock source, can cause a line to have synchronization problems resulting in framing errors and data loss.  Check with your line provider before enabling internal clocking to ensure that this
 
-
setting is needed.  We have specified the default value in the default configuration below:
 
-
 
-
      !
 
-
      interface Serial0
 
-
      #NOC phone: 800-555-1212 - Our account #58935 description ATM connection to branch offices bandwidth 10000000
 
-
      encapsulation atm
 
-
      service-module ds3 clock source line
 
-
      !
 
-
 
-
====Configuring DS3/E3 Cell Mode====
 
-
:By default, DS3 and E3 ATM interfaces add a special header for the Physical Layer Convergence Protocol (PLCP).  This mode can be disabled allowing the interface to operate in direct cell mapping mode (DCM) and eliminating the PLCP header.  To enable DCM, include the command:
 
-
 
-
      '''service-module''' ''{ ds3 | e3 }'' '''mode dcm''' :
 
-
 
-
:in the interface configuration.  Cisco router configurations may refer to Direct Cell Mapping as ATM Direct Cell Mapping or ADM.
 
-
 
-
====Configuring DS3 Line Buildout====
 
-
:The DS3 interface has a setting for line buildout.  The line buildout setting is used to set the signal attenuation factor due to the impedance of copper cabling.  The line buildout setting is used on when the connection between the integrated CSU/DSU and the line provider demarcation point is greater than 225 feet.  By default, the DS3 interfaces use the shortest setting (none).  To turn on line buildout, use the command:
 
-
 
-
      '''service-module ds3 lbo'''
 
-
 
-
:In E3 transport mode, the line buildout command is invalid.
 
-
 
-
====Configuring the DS3/E3 Equalizer Gain Limiter====
 
-
:The DS3/E3 interface has an equalizer gain limiter.  This setting is used to turn on the receiver gain limiter to overcome impedance of copper cabling.  The gain limiter should be turned on when the connection between the integrated CSU/DSU and the line provider demarcation point is greater than 225 feet.  By default, the DS3/E3 interfaces do not enable the gain limiter. To enable the equalizer gain limiter, add the command '''service-module { ds3 | e3 } egl''' to the interface configuration.  This command is normally used in conjunction with the line buildout command.
 
-
 
-
 
-
====Configuring DS3 Framing====
 
-
:By default, ATM DS3 interfaces use c-bit parity for framing.  This command is not valid in E3 transport mode.  To explicitly configure ESF framing, include the framing statement in the interface configuration for the serial device:
 
-
 
-
      '''service-module ds3 framing''' ''cbit'' :
 
-
 
-
:You can configure the m23 format as an alternative.  To have the interface use the m23 framing format, include the framing statement in the interface configuration, specifying the m23 option.  In the default configuration below, we have specified the default c-bit framing:
 
-
 
-
    !
 
-
    interface Serial0
 
-
      #NOC phone: 800-555-1212 - Our account #58935 description ATM connection to branch offices bandwidth 10000000
 
-
      encapsulation atm
 
-
      service-module ds3 clock source line
 
-
      service-module ds3 framing cbit
 
-
    !
 
-
 
-
====Configuring DS3/E3 Cell Scrambling====
 
-
:By default, DS3/E3 ATM interfaces enable cell scrambling.  Scrambling cells randomizes the ATM cell payload frames to avoid continuous non-variable bit patterns and improves the efficiency of ATM's cell delineation algorithms.  Normally, the default setting for this command is sufficient.
 
-
 
-
:To explicitly configure cell scrambling, include the scrambling statement in the interface configuration for the serial device:
 
-
 
-
      '''service-module { ds3 | e3 } scrambling''' ''on'' :
 
-
 
-
::You can turn off scrambling as an alternative.  To have the interface disable cell scrambling, include the scrambling statement in the interface configuration, specifying the off option.  This setting must match the remote router or your ATM master interface will not function correctly.  In the default configuration below, we have specified the default  "scrambling":
 
-
 
-
      !
 
-
      interface Serial0
 
-
      #NOC phone: 800-555-1212 - Our account #58935 description ATM connection to branch offices bandwidth 10000000
 
-
      encapsulation atm
 
-
      service-module ds3 clock source line service-module ds3 framing cbit
 
-
      service-module ds3 scrambling on
 
-
      !
 
-
 
-
===Setting ATM OC-3/OC-12 Master Interface Parameters===
 
-
:The '''service-module''' command is used to configure the master interface for the ATM card.  In most cases, the defaults provided on the card will match the network configuration.  Check with your line provider to determine if your line settings differ from the default configuration.  The configurations in the interface configuration must match in three places: on the router, on the ATM switch, and at the remote end.  If these settings do not match, your serial interface will not function correctly
 
====Configuring the OC-3/OC-12 Line Clocking Source====
====Configuring the OC-3/OC-12 Line Clocking Source====
-
:One and only one clock source should be configured on a line.  In most cases, your line provider will provide a clock source for the ATM circuit.  The ATM OC-3/OC-12 card can also be configured to provide a clock source. The syntax of this command is:  
+
:One and only one clock source should be configured on a line.  In most cases, your line provider will provide a clock source for the POS circuit.  The POS OC-3/OC-12 card can also be configured to provide a clock source for back-to-back testing. The syntax of this command is:  
       '''service-module''' ''{ oc3 | oc12 }'' '''clock source''' ''{ line | internal }''  
       '''service-module''' ''{ oc3 | oc12 }'' '''clock source''' ''{ line | internal }''  
Line 229: Line 157:
       !  
       !  
       interface Serial0  
       interface Serial0  
-
      #NOC phone: 800-555-1212 - Our account #58935 description ATM connection to branch offices bandwidth 10000000  
+
        #NOC phone: 800-555-1212 - Our account #58935  
-
      encapsulation atm
+
        description POS connection to branch offices
-
      service-module oc3 clock source line
+
        bandwidth 10000000  
 +
        encapsulation ppp
 +
        service-module oc3 clock source line
       !
       !
-
====Configuring OC-3/OC-12 Cell Scrambling====  
+
===Configuring OC12 Ethernet Accelerated Cross-Connect Mode===
-
:By default, OC-3/OC-12 ATM interfaces enable cell scrambling. Scrambling cells randomizes the ATM cell payload frames to avoid continuous non-variable bit patterns and improves the efficiency of ATM's cell delineation algorithms. Normally, the default setting for this command is sufficient.  
+
:The POS OC12 card is not capable of OC12 line rates without the Ethernet accelerated cross-connect feature. This feature requires a Gigabit Ethernet SFP placed in the bottom SFP slot of the POS OC12 card. This Gigabit Ethernet SFP port should be connected via Category 5 or better straight-through Ethernet cable to another Gigabit Ethernet port known as the ''xconnect port''. All IPv4 data transmitted on this xconnect port will be transmitted on the OC12 port using wirespeed hardware acceleration in the card. All IPv4 data received on the OC12 port will be received on the xconnect port.
-
:To explicitly configure cell scrambling, include the scrambling statement in the interface configuration for the serial device:  
+
A sample xconnect configuration:
-
      '''service-module { oc3 | oc12 } scrambling''' ''on''
+
  interface Serial0
 +
  service-module oc12 xconnect Ethernet0
 +
  encapsulation ppp
 +
  !
 +
  interface Ethernet0
 +
  ip address 5.5.5.1 255.255.255.252
 +
  !
-
:You can turn off scrambling as an alternativeTo have the interface disable cell scrambling, include the scrambling statement in the interface configuration, specifying the off optionThis setting must match the remote router or your ATM master interface will not function correctlyIn the default configuration below, we have specified the default cell scrambling:
+
<pre>
 +
18:51:44              Interface Summary                                    lab1
 +
#  Interface Description          Encaps      Bandwidth    HW  Proto  In  Out
 +
0 Ethernet0 1Gb Ethernet        1000baseTx-FD601.00 Mbit up  up    0%  0%
 +
1 Ethernet1 100Mb Ethernet      100baseTx-FD 100.00 Mbit up  up    0%  0%
 +
2 Serial0  ISis 1104-O3 Port 0  PPP          601.34 Mbit up  up    0%  0%
 +
-------------------------------------------------------------------------------
 +
d Detail | s Sleep interval | h Help | q Quit
 +
</pre>
-
      !
+
The system will automatically set the bandwidth to 600 Mbps and install an HTB shaper for the xconnect Ethernet port. Hardware status on the xconnect Ethernet port will also follow the OC12's hardware status.
-
      interface Serial0
+
-
      #NOC phone: 800-555-1212 - Our account #58935 description ATM connection to branch offices bandwidth 10000000
+
-
      encapsulation atm
+
-
      service-module oc3 clock source line service-module oc12 scrambling on
+
-
      !
+
-
 
+
-
===Configuring an ATM Subinterface===
+
-
:This section will use the example configuration from the ATM DS3 configuration section above.
+
-
 
+
-
:ATM subinterfaces provide a mechanism for supporting partially meshed ATM networks. Most protocols assume transitivity on a logical network; that is, if station A can talk to station B, and station B can talk to station C, then station A should be able to talk to station C directly. Transitivity is true on LAN's, but not on ATM networks unless A is directly connected to C.
+
-
 
+
-
:Additionally, certain protocols, such as AppleTalk and transparent bridging, cannot be supported on partially meshed networks because they require "split horizon" in which a packet received on an interface cannot be transmitted out the same interface even if the packet is received and transmitted on different virtual circuits.
+
-
 
+
-
:Configuring ATM subinterfaces ensures that a single physical interface is treated as multiple virtual interfaces. This capability allows us to overcome split horizon rules. Packets received on one virtual interface can now be forwarded out another virtual interface, even if they are configured on the same physical interface.
+
-
 
+
-
:SubInterfaces provide a way to subdivide an ATM network into a number of smaller, fully meshed (or point-to-point) subnetworks. Each subnetwork is assigned its own network number (Virtual Circuit Identifier, or VCI) and appears to the protocols as if it is reachable through a separate interface.  Note that point-to-point subinterfaces can be unnumbered for use with IP, reducing the addressing burden that might otherwise result.  
+
-
 
+
-
 
+
-
====Adding an ATM Subinterface to a Configuration====
+
-
:Each virtual interface (ATM Permanent Virtual Circuit, or PVC) is configured using a subinterface in the''' wan.conf''' file.  Although the order of the devices in the file does not matter, ImageStream by convention keeps the interfaces in order.
+
-
+
-
:ATM subinterfaces are configured in the same manner as Serial0 in our example configuration.  Add an additional '''interface''' command for each ATM serial interface, separating each section with a ! symbol.  The syntax of the '''interface''' command is:
+
-
 
+
-
      '''interface''' ''DeviceName.subinterface#''
+
-
 
+
-
:This command creates an ATM subinterface under the specified interface name. A subinterface is treated as a separate interface dedicated for an ATM PVC to a remote site. In the example below, "Serial0" indicates that the subinterface belongs to the physical Serial0 interface and "1" is the unique subinterface ID number. The subinterface ID number can be any unique value between zero and 64,000 and does not have to be in any particular order (i.e. it is not necessary to begin with 1 and sequentially progress with 2, 3, 4, etc.). To reduce confusion, ImageStream recommends sequential progression or identifying a subinterface with the same number as the VPI/VCI used on that subinterface.
+
-
 
+
-
:In the default example below, we have added a two ATM subinterfaces.
+
-
 
+
-
      !
+
-
      interface Serial0
+
-
      #NOC phone: 800-555-1212 - Our account #58935 description ATM connection to branch offices bandwidth 10000000
+
-
      encapsulation atm
+
-
      service-module ds3 clock source line
+
-
      service-module ds3 framing cbit
+
-
      service-module ds3 scrambling on
+
-
      !
+
-
      interface Serial0.1
+
-
      description Connection to NYC office encapsulation atm
+
-
      !
+
-
      interface Serial0.2
+
-
      description Connection to Dallas office encapsulation atm
+
-
      !
+
-
 
+
-
====Configuring the VPI and VCI for an ATM Subinterface====
+
-
:The configuration above is not yet complete.  Each subinterface must contain a unique identifier used to send traffic across the ATM network.  ATM networks are connection oriented. Before information is transferred from the router to the network, a logical/virtual connection is set.    When you are using ATM encapsulation on an interface, you must map each subinterface to a virtual circuit identifier (VCI) and a virtual path identifier (VPI) assigned by your ATM line provider.
+
-
 
+
-
:To configure a VCI and a VPI on a point-to-point ATM subinterface, include the '''pvc''' statement in the subinterface configuration. The syntax of the '''pvc''' command is:
+
-
 
+
-
      '''pvc'''  ''{ vpi }/{ vci }''
+
-
 
+
-
:For each subinterface, you must configure the VCI and VPI identifiers.  On many networks, your line provider will not specify a VPI.  Use a value of 0 as this is the most common VPI value.  Your line provider will assign a unique VCI to each PVC.  In the default example below, we have added '''pvc''' statements.  '''NOTE:''' These settings must match those used on the ATM network by your line provider or the ATM interface will not function correctly.
+
-
+
-
      !
+
-
      interface Serial0
+
-
      #NOC phone: 800-555-1212 - Our account #58935 description ATM connection to branch offices bandwidth 10000000
+
-
      encapsulation atm
+
-
      service-module ds3 clock source line
+
-
      service-module ds3 framing cbit
+
-
      service-module ds3 scrambling on
+
-
      !
+
-
      interface Serial0.1
+
-
      description Connection to NYC office encapsulation atm
+
-
      pvc 0/10
+
-
      !
+
-
      interface Serial0.2
+
-
      description Connection to Dallas office encapsulation atm
+
-
      pvc 1/22
+
-
    !
+
-
 
+
-
====Setting the IP Address and Netmask====
+
-
:During the subinterface setup process, you will set the IP address and netmask for the subinterface.  To change the IP address and netmask of the Serial subinterface, modify the '''ip address''' command.  The syntax of this command is:
+
-
 
+
-
      '''ip address''' ''ipaddress netmask''
+
-
 
+
-
:Set the IP address to the address to be used by the ATM subinterface of the router on your network. If you have divided your network into subnets, enter the subnet mask that identifies how your network addresses are divided between the network portion and the host portion.
+
-
 
+
-
:Using the default configuration below, we have set the Serial0.1 IP address to 25.0.0.1 with a netmask of 255.255.255.252.  We have also set Serial0.2 to use an IP address of 30.0.0.1 and a /30 subnet mask.  Often, with numbered point-to-point Serial links, the netmask will be a /30 (a subnet with 2 valid addresses).  '''NOTE:''' You will need to substitute your address and netmask for your network.
+
-
 
+
-
      !
+
-
      interface Serial0
+
-
      #NOC phone: 800-555-1212 - Our account #58935 description ATM connection to branch offices bandwidth 10000000
+
-
      encapsulation atm
+
-
      service-module ds3 clock source line
+
-
      service-module ds3 framing cbit
+
-
      service-module ds3 scrambling on
+
-
      !
+
-
      interface Serial0.1
+
-
      description Connection to NYC office encapsulation atm
+
-
      pvc 0/10
+
-
      ip address 25.0.0.1 255.255.255.252
+
-
      !
+
-
      interface Serial0.2
+
-
      description Connection to Dallas office encapsulation atm
+
-
      pvc 1/22
+
-
      ip address 30.0.0.1 255.255.255.252
+
-
      !
+
-
 
+
-
====Adding Secondary Serial Addresses====
+
-
:Although rarely necessary, depending on your network configuration, you may need to configure more than one address on a subinterface.  This task is accomplished by adding the '''secondary''' keyword to the '''ip address''' line used previously.  The''' secondary''' keyword is used for all addresses on a Serial device other than the primary address. Only one primary address can be configured on a Serial device. 
+
-
 
+
-
:'''NOTE:''' Configuring more than one primary address or leaving the '''secondary''' keyword off of a secondary address configuration will cause the last primary IP address to be used when the port is configured by SAND.
+
-
 
+
-
:Using the default configuration below, we have added two secondary IP addresses to Serial0.1.  Only a portion of the previous configuration is shown.
+
-
 
+
-
      !
+
-
      interface Serial0.1
+
-
      description Connection to NYC office encapsulation atm
+
-
      pvc 0/10
+
-
      ip address 25.0.0.1 255.255.255.252
+
-
      ip address 20.0.1.1 255.255.255.0 secondary
+
-
      !
+
'''Note: You must save the settings to the router's non-volatile flash memory!  If the router is rebooted before saving, your changes will be lost!  See Chapter 26, "Backup/Restore Menu: Managing Configurations" for more information.'''
'''Note: You must save the settings to the router's non-volatile flash memory!  If the router is rebooted before saving, your changes will be lost!  See Chapter 26, "Backup/Restore Menu: Managing Configurations" for more information.'''

Revision as of 17:56, 31 July 2009

This chapter describes how to configure the ImageStream router POS OC3/OC12 WAN interfaces and includes the following topics:
  • Packet over SONET/SDH overview
  • WAN Port Uses
  • Understanding the Network Interface Configuration File
  • Configuring a POS OC3/OC12 Interface
  • Configuring OC12 Ethernet Accelerated Cross-Connect Mode
Before configuring the WAN interface, you must make the appropriate cabling connection for your needs. Refer to the hardware installation guide for your ImageStream product for information on making the WAN connection. See the Technical Notes section on the ImageStream Web site or the Command Reference for more detailed command descriptions, examples and instructions.

Contents

Packet over SONET/SDH overview

Packet over SONET/SDH, abbreviated POS, is a communications protocol for transmitting packets in the form of the Point to Point Protocol (PPP) over SDH or SONET, which are both standard protocols for communicating digital information using lasers or light emitting diodes (LEDs) over optical fibre at high line rates. POS is defined by RFC 2615 as PPP over SONET/SDH. PPP is the Point to Point Protocol that was designed as a standard method of communicating over point-to-point links. Since SONET/SDH utilises point-to-point circuits, PPP is well suited for use over these links. Scrambling is performed during insertion of the PPP packets into the SONET/SDH frame.

WAN Port Uses

WAN ports uses has been explained in Chapter 7, Router Installation and Configuration Manual/Configuring a Synchronous Serial WAN Interface and in Chapter 31 Router Installation and Configuration Manual/Basic Networking.

Understanding the Network Interface Configuration File

The wan.conf file is explained in detail in Chapter 5, Router Installation and Configuration Manual/Configuring a LAN Interface, and in Chapter 31,Router Installation and Configuration Manual/Basic Networking.

Configuring a POS OC3 or OC12 Interface

     Configuration menu 
     1. AAA (Password) Configuration 
     2. Global configuration 
     3. Network interface configuration 
     4. Firewall and QOS configuration 
     5. Service configuration 
     6. Dynamic routing configuration 
     7. Save configuration to flash 
     0. ISis-Router main menu 
From the :Configuration menu", select menu option 2, Network interface configuration, and press Enter. This will open the ImageStream router's primary configuration file, wan.conf in the default editor. The wan.conf file is also accessible from the command line in the /usr/local/sand directory.

Default POS OC3/OC12 WAN Card Configuration

The default values of cards equipped with an POS interface are as follows:
  • SONET interface mode
  • Scrambler enabled
  • 16-bit CRC
  • Line (external) clock source for transmit
  • C2 byte 0x16
Remember that default settings are not necessarily shown in the configuration file.

Customizing the Configuration

To customize the WAN port configurations, complete the following sections. The ordering of the commands is done by convention, but a specific order is not required. Likewise, all configurations are indented to make configurations easy to read, but indentation is not required. In general, ImageStream follows this ordering convention:
  1. Comments
  2. Port description
  3. Bandwidth scaling statement
  4. POS interface settings
  5. Other optional settings
  6. IP address/netmask
  7. Secondary IP addresses/netmasks

Setting the Port Description

You can assign description to all WAN ports. Although this feature is optional, it may be particularly useful to assign names to facilitate administration. Setting a description does not change the operation or name of the port.
To assign a description to a port, enter this command in the wan.conf file in the Serial interface configuration section:
     description string 
Using the router's default configuration below, we have modified the description for Serial0:
     ! 
     interface Serial0 
       shutdown 
       description ATM connection to branch offices encapsulation PPP
     ! 

Setting the IP Address and Netmask

The ATM master interface does not contain IP addressing information. All IP addresses are contained in the subinterfaces (logical interfaces) configured on the master interface. Using the default configuration below, we have deleted the ip address line.
     ! 
     interface Serial0 
       shutdown 
       description POS connection to branch offices encapsulation PPP
       ip address 192.168.10.1 255.255.255.252
     !

Setting Serial Transport Encapsulation

The serial transport encapsulation can be set to PPP or Cisco HDLC encapsulation for an ATM interface. No other encapsulation types may be specified.The syntax of this command is:
     encapsulation ppp | hdlc:
In the default configuration below, we have changed the encapsulation to PPP.
     ! 
     interface Serial0 
       shutdown 
       description POS connection to branch offices encapsulation PPP
       encapsulation ppp
       ip address 192.168.10.1 255.255.255.252
     !

Setting POS OC-3/OC-12 Circuit Transport=

ImageStream's POS OC-3 and OC-12 cards support either SONET or SDH as the underlying network transport for the POS traffic. By default, the cards use SONET mode. The mode can be set using the service-module { oc3 | oc12 } mode command and specifying a value of either sonet or sdh.
     service-module oc3 mode sonet | sdh:

Setting POS OC-3/OC-12 Payload Scrambling=

ImageStream's POS OC-3 and OC-12 cards default to scrambling enabled. To disable scrambling use the service-module {oc3 | oc12 } scrambling command specifying a value of either on or off.
     service-module oc3 scrambling on | off:

Overriding the POS OC-3/OC-12 C2 Byte=

ImageStream's POS OC-3 and OC-12 cards use a SONET C2 byte value of 0x16 when scrambling is enabled and 0xCF when scrambling is disabled according to RFC 2615. To allow interoperability with routers the predate RFC 2615 use the service-module {oc3 | oc12 } c2-flag command specifying the C2 byte value. To specify a hexidecimal value use a format like 0xcf. To specify a decimal value omit the 0x like 207.
     service-module oc3 c2-flag 0x16:

Enabling or Disabling a Serial Interface

To disable an interface, use the shutdown interface configuration command. Unlike other command line interfaces, the wan.conf file does not require a "no" version of a command to reverse the operation. Entering "no" followed by a command will be ignored by SAND.
By default, Serial0 is disabled in the default configuration below because the shutdown command has been entered. Disabling a master interface will also disable all subinterfaces configured on the master device.
     ! 
     interface Serial0 
       shutdown 
       description POS connection to branch offices encapsulation PPP
     !
To enable Serial0 in the configuration, remove the shutdown command. Do not use "no shutdown', as this will be ignored by SAND. It is not necessary to enter "no" and a command to negate the command. Simply remove the command from the configuration file.

Adding Comments to a Serial Configuration

Comments may be added to the Serial configuration, or anywhere in the wan.conf file by inserting a line that begins with the # symbol. The contents of the line will be ignored by SAND. Comments may be used to place contact information, ticket numbers, circuit IDs or any other information into the wan.conf file. There are no limits on the number or length of comments that may be inserted.
     ! 
     interface Serial0 
       #NOC phone: 800-555-1212 - Our account #58935
       description POS connection to branch offices encapsulation PPP
     !

Scaling The Connection Speed Calculation

For some media, such as Ethernet and Token Ring, the bandwidth is fixed; for other media, such as serial lines, you can change the actual bandwidth by adjusting the hardware. For both classes of media, you can use the bandwidth configuration command to communicate the current bandwidth to the router's statistical output program and other programs. The bandwidth command sets an informational parameter only to communicate the current bandwidth to other programs.
The bandwidth command does not adjust the actual bandwidth of an interface. ATM ports automatically calculate the bandwidth value based on the type of ATM device configured and the bandwidths of the subinterfaces. The syntax of the bandwidth command is:
     bandwidth bits per second: 
In the default example below, we have added a bandwidth equal to 10 Mbps line (less overhead) to the Serial0 interface. This value is calculated automatically, so this command is optional:
     ! 
     interface Serial0 
       #NOC phone: 800-555-1212 - Our account #58935
       description POS connection to branch offices
       encapsulation PPP
       bandwidth 10000000 
     !

Configuring the OC-3/OC-12 Line Clocking Source

One and only one clock source should be configured on a line. In most cases, your line provider will provide a clock source for the POS circuit. The POS OC-3/OC-12 card can also be configured to provide a clock source for back-to-back testing. The syntax of this command is:
     service-module { oc3 | oc12 } clock source { line | internal } 
The line or internal keyword specifies the type of clocking to use on this interface. Line (also known as "network" or "external') timing is the default value. Using the internal keyword will enable the card's internal clock and will instruct the card to place this clock source on the line. Configuring more than one clock source, or having no clock source, can cause a line to have synchronization problems resulting in framing errors and data loss. Check with your line provider before enabling internal clocking to ensure that this setting is needed. We have specified the default value in the default configuration below:
     ! 
     interface Serial0 
       #NOC phone: 800-555-1212 - Our account #58935 
       description POS connection to branch offices
       bandwidth 10000000 
       encapsulation ppp 
       service-module oc3 clock source line
     !

Configuring OC12 Ethernet Accelerated Cross-Connect Mode

The POS OC12 card is not capable of OC12 line rates without the Ethernet accelerated cross-connect feature. This feature requires a Gigabit Ethernet SFP placed in the bottom SFP slot of the POS OC12 card. This Gigabit Ethernet SFP port should be connected via Category 5 or better straight-through Ethernet cable to another Gigabit Ethernet port known as the xconnect port. All IPv4 data transmitted on this xconnect port will be transmitted on the OC12 port using wirespeed hardware acceleration in the card. All IPv4 data received on the OC12 port will be received on the xconnect port.

A sample xconnect configuration:

 interface Serial0
  service-module oc12 xconnect Ethernet0
  encapsulation ppp
 !
 interface Ethernet0
  ip address 5.5.5.1 255.255.255.252
 !
18:51:44              Interface Summary                                    lab1
#  Interface Description          Encaps       Bandwidth    HW  Proto  In   Out
 0 Ethernet0 1Gb Ethernet         1000baseTx-FD601.00 Mbit  up   up     0%   0%
 1 Ethernet1 100Mb Ethernet       100baseTx-FD 100.00 Mbit  up   up     0%   0%
 2 Serial0   ISis 1104-O3 Port 0  PPP          601.34 Mbit  up   up     0%   0%
-------------------------------------------------------------------------------
d Detail | s Sleep interval | h Help | q Quit

The system will automatically set the bandwidth to 600 Mbps and install an HTB shaper for the xconnect Ethernet port. Hardware status on the xconnect Ethernet port will also follow the OC12's hardware status.

Note: You must save the settings to the router's non-volatile flash memory! If the router is rebooted before saving, your changes will be lost! See Chapter 26, "Backup/Restore Menu: Managing Configurations" for more information.

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