- Configuring LAN Interfaces
- Configuring Serial Interfaces
- Circuit Emulation over IP
- Lossless Compression R1 ATM Cell Switching and External BITS Clocking Source
- Minimal Disruptive Restart of VIP Cards
- Rate Based Satellite Control Protocol
- Configuring Virtual Interfaces
- Implementing Tunnels
- Tunnel Route Selection
- IP Tunnel MIBs
- IF-MIBs
- CISCO-IP-IF-MIB Support for IP Helper Addresses
- Managing Dial Shelves
- Router-Shelf Redundancy for the Cisco AS5800
- Route-Switch-Controller Handover Redundancy on the Cisco AS5850
- Route Processor Redundancy Plus
- Finding Feature Information
- Prerequisites for Circuit Emulation over IP
- Restrictions for Circuit Emulation over IP
- Information About Circuit Emulation over IP
- How to Configure Circuit Emulation over IP
Circuit Emulation over IP
Circuit Emulation over IP (CEoIP) provides a virtual circuit through an IP network--similar to a leased line--to integrate solutions that require a time-sensitive, bit-transparent transport into IP networks. Data, with proprietary framing or without, arrives at its destination unchanged; the transport is transparent to the destination.
- Finding Feature Information
- Prerequisites for Circuit Emulation over IP
- Restrictions for Circuit Emulation over IP
- Information About Circuit Emulation over IP
- How to Configure Circuit Emulation over IP
- Configuration Examples for CEoIP
- Additional References
- Command Reference
- Feature Information for Circuit Emulation over IP
Finding Feature Information
Your software release may not support all the features documented in this module. For the latest feature information and caveats, see the release notes for your platform and software release. To find information about the features documented in this module, and to see a list of the releases in which each feature is supported, see the Feature Information Table at the end of this document.
Use Cisco Feature Navigator to find information about platform support and Cisco software image support. To access Cisco Feature Navigator, go to www.cisco.com/go/cfn. An account on Cisco.com is not required.
Prerequisites for Circuit Emulation over IP
- The CEoIP feature requires a CEoIP network module (NM) on each end of the connection, either the NM-CEM-4TE1 NM or the NM-CEM-4SER NM. You do not need to use the same type of CEoIP NM on both ends of the connection.
- The CEoIP feature requires 300 KB of flash memory and 1 MB of DRAM in addition to your Cisco IOS software requirements.
Restrictions for Circuit Emulation over IP
- NM-CEM-4TE1 supports only B8ZS (T1) and HDB3 (E1) line codes.
- E1 lines do not support 56 kbps connections.
- CEoIP software cannot run payload compression for more than 3.088 Mbps) per network module.
- If you configure four T1, E1, or serial cables (over 1.544 M) at the same time in Cisco 2600XM series routers, you cannot turn on the data-protection and payload compression features. Also, in framed mode (channelized), you can use up to 60 channels without the data protection and payload compression features on Cisco 2600XM series routers. However, you can turn on the data protection and payload compression feature in one T1/E1.
- There is a limitation on the data protection and payload compression features on Cisco 3660 routers. If you configure four T1, E1, or serial cables on Cisco 3660 routers, you can turn on data protection for up to two T1/E1s. In framed mode, you can use 88 channels.
Information About Circuit Emulation over IP
- Circuit Emulation over IP
- Benefits of CEM over IP
- Adaptive Clocking for CEoIP
- Clock Switchover
- Payload Compression for CEoIP
- Data Protection (Sample Repetition)
- Dejitter
- Idle Pattern
- Payload Size
- Signaling for CEoIP
- Control Lead Configurations
Circuit Emulation over IP
Circuit emulation is an end-to-end service that allows Layer 1 data to be transported transparently through an IP network. Applications that require circuit emulation need the network to provide a constant rate bit stream.
Configuration Circuit Emulation (CEM) can be configured in unidirectional mode using the emulation-mode option. Once configured, traffic will flow only in that direction through the CEM channel. When one direction of CEM traffic is detected on that channel, the CEM channel is considered to be active and a new status of the CEM channel is created to reflect the uni-directional channel.
CEoIP may use adaptive clocking as a means of synchronizing the clock frequencies at the two endpoints. Channel associated signaling (CAS) transport is provided as an optional feature to allow channelized voice applications. Payload compression is provided as an optional feature to improve bandwidth efficiency and data protection is provided to reduce the probability of data loss.
CEoIP software supports the following network modules:
- The NM-CEM-4SER, a network module with four serial ports. To configure CEoIP software for the NM-CEM-4SER, you must configure the options of the ports. Options include dejitter buffer, payload compression, and payload size.
- The NM-CEM-4TE1, a network module with four ports that you can configure as T1 or E1 (where all four ports support the same interface type). To configure CEoIP software for the NM-CEM-TE1, you must define the card type and then configure the options of the port.
Benefits of CEM over IP
CEoIP provides a simple migration path to IP-only networks. Examples of solutions that CEoIP integrates with IP include the following:
- Legacy data services
- Legacy video applications
- Satellite data streams
- Radar data streams
- Telemetry for automated industrial environments (for example, power distribution)
- Crypto tunneling for multilevel security
Adaptive Clocking for CEoIP
The adaptive clocking option of CEoIP allows the egress clock to vary by expanding or contracting the clock period from the nominal clock. After you have implemented the clocking feature, the adaptive clocking circuits continuously adjust the selected clock based on the data buffer level. You can implement adaptive clocking on each port independently.
Clock Switchover
The clock switchover option allows you to switch the clock source over to the internal clock. The switchover ensures continuity of the CEM channel when disruption in receiving the clock from the customer premises equipment (CPE) occurs. To specify the input lead state change that triggers the clock switching over from line to internal or from internal to line, use this option in Data Circuit Terminating Equipment (DCE) split mode.
Payload Compression for CEoIP
The payload compression option minimizes the amount of bandwidth that traffic consumes. It compresses the transmission of any repetitive data pattern (for example, idle code, HDLC flags, and so on) to increase the efficiency of the solution across the network.
With CEoIP software, you can adjust the size (in bytes) of the payload for the IP packet to configure efficiency as opposed to packetization. Larger payloads provide more efficiency but increase the delay. With smaller packets the overhead of the header increases. Payload compression is disabled by default.
Data Protection (Sample Repetition)
The data protection option, also known as sample repetition, reduces the probability of errors due to packet loss by sending each sample twice, in two different IP packets. Data protection consumes more bandwidth than standard transmission, but you can minimize the amount of traffic with payload compression. This feature is disabled by default.
Dejitter
The dejitter buffer size determines the ability of the emulated circuit to tolerate network jitter. The dejitter buffer in CEoIP software is configurable up to 500 milliseconds; the maximum amount of network jitter that CEoIP can tolerate is ±250 milliseconds.
Idle Pattern
The idle pattern option specifies the idle pattern to transmit when the circuit goes down. You can specify a maximum of 64 bits with two 32-bit patterns for the NM-CEM-4SER and 8-bit patterns for the NM-CEM-4TE1.
Payload Size
Payload size is the number of bytes put into each IP packet. This parameter impacts packetization delay and efficiency. Configure a high payload size to increase packetization delay and efficiency. A smaller payload size reduces packetization delay and efficiency.
Signaling for CEoIP
CEoIP software supports the transport of channel associated signaling (CAS) bits in channelized T1/E1 mode. This option extracts incremental signaling information and sends that information in separate packets.
Control Lead Configurations
CEoIP software supports the monitoring and transport of serial interface control leads.
How to Configure Circuit Emulation over IP
- Configuring the NM-CEM-4TE1 Card Type
- Configuring the T1 E1 Line
- Creating CEM Channels on the T1 E1 Line
- Configuring the Connection Using the xconnect Command
- Configuring the CEM Channel
Configuring the NM-CEM-4TE1 Card Type
Perform this task to configure the card type for an NM-CEM-4TE1.
This task does not apply to the NM-CEM-4SER.
DETAILED STEPS
What to Do Next
Go to the Configuring the T1 E1 Line to continue configuring CEoIP on an NM-CEM-4TE1.
Configuring the T1 E1 Line
Perform this task to configure the T1 or E1 line, starting in global configuration mode.
This task does not apply to the NM-CEM-4SER.
- framing {esf | sf | unframed}
- framing {crc4 | no-crc4 | unframed}
DETAILED STEPS
Command or Action | Purpose | |||
---|---|---|---|---|
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Example: Router(config)# controller t1 1/0 |
Enters controller configuration mode.
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Example: Router(config-controller)# framing esf Example: Router(config-controller)# framing crc4 |
(Optional) Configures the framing format for a T1 or E1 port to synchronize the port and the attached device. T1 port framing options:
E1 port framing options:
T1 or E1 port framing options:
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Example: Router(config-controller)# clock source adaptive 6 |
Configures the clock source for a T1 or E1 port.
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Example: Router(config-controller)# cablelength long -15db |
(Optional) Specifies the line build-out characteristics of the internal CSU on a T1 port.
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Example: Router(config-controller)# crc-threshold 512 |
(Optional) Configures the number of cyclical redundancy check (CRC) errors in one second that results in the second being declared as a Severely Errored Second (SES).
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Example: Router(config-controller)# description T1 line to 3rd floor PBX |
(Optional) Specifies a text description of the port. |
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Example: Router(config-controller)# loopback network |
(Optional) Creates a loopback from a T1 or E1 port.
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What to Do Next
Go to the Creating CEM Channels on the T1 E1 Line to continue configuring CEoIP on an NM-CEM-4TE1
Creating CEM Channels on the T1 E1 Line
Perform this task to create CEM channels on the T1 or E1 line, starting in controller configuration mode.
This task does not apply to the NM-CEM-4SER.
DETAILED STEPS
Command or Action | Purpose | |
---|---|---|
|
Example: Router(config-controller)# cem-group 6 timeslots 1-4,9,10 speed 64 |
Creates a circuit emulation channel from one or more timeslots of a T1 or E1 line of an NM-CEM-4TE1.
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Example: Router(config-controller)# exit Example: Router(config)# |
Exits controller configuration mode and returns to global configuration mode. |
What to Do Next
Go to the Configuring the Connection Using the xconnect Command to continue configuring CEoIP on an NM-CEM-4TE1
Configuring the Connection Using the xconnect Command
Perform this task to create a connection using the xconnect command, starting in global configuration mode. This task applies to configuring CEoIP on both the NM-CEM-4TE1 and the NM-CEM-4SER.
Note |
To properly configure the CEoIP feature, two CEoIP network modules must use the same UDP port number to communicate. |
DETAILED STEPS
Command or Action | Purpose | |||
---|---|---|---|---|
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Example: Router(config)# cem 3/1/0 |
Enters CEM configuration mode to configure CEM channels.
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Example: Router(config-cem)# xconnect 10.2.0.1 0 encapsulation udp |
Creates one end of a connection between two CEM network modules and enters xconnect configuration mode.
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Example: Router(config-cem-xconnect)# local ip-address 10.2.0.2 |
Configures the IP address of an interface--regular or loopback--on the source router.
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Example: Router(config-cem-xconnect)# local udp port 15901 |
Specifies the User Datagram Protocol (UDP) port number of the local CEM channel.
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Example: Router(config-cem-xconnect)# remote udp port 15902 |
Specifies the UDP port number of the remote CEM channel.
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Example: Router(config-cem-xconnect)# exit Example: Router(config-cem)# |
Exits xconnect configuration mode and returns to CEM configuration mode.
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What to Do Next
This task must be repeated on the other CEM network module and each end of the CEM connection must be configured identically to allow traffic to pass between the network modules. When both network modules have been configured, continue to the Configuring the CEM Channel.
Configuring the CEM Channel
Perform this task to configure the CEM T1/E1 or serial channel, starting in CEM configuration mode.
DETAILED STEPS
Command or Action | Purpose | |||||
---|---|---|---|---|---|---|
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Example: Router(config-cem)# clock rate 38400 |
(Optional) For serial channels only. Specifies the nominal bit rate of a serial CEM channel.
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Example: Router(config-cem)# clock mode split |
(Optional) For serial channels only. Specifies the clock mode of a serial CEM channel.
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Example: Router(config-cem)# clock source loop |
(Optional) Configures the clock source for a serial CEM channel.
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Example: Router(config-cem)# payload-size 512 |
(Optional) Specifies the number of bytes encapsulated into a single IP packet.
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Example: Router(config-cem)# dejitter-buffer 80 |
(Optional) Specifies the size of the dejitter buffer used to compensate for the network filter.
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Example: Router(config-cem)# control-lead sampling-rate 10 |
(Optional) Specifies the sampling rate of input control leads on a serial CEM channel.
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Example: Router(config-cem)# control-lead state active rts follow remote cts |
(Optional) Specifies the state of each output control lead on a serial CEM channel.
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Example: Router(config-cem)# data-strobe dtr on |
(Optional) Specifies that an input control lead is to be monitored and data is packetized and sent only when the specified control lead is in the specified state.
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Example: idle-pattern length pattern1 [pattern2] Example: Cisco NM-CEM-4TE1: Example: idle-pattern pattern1 Example: Cisco NM-CEM-4SER: Example: Router(config-cem)# idle-pattern 53 0x12345678 0x87654321 Example: Cisco NM-CEM-4TE1: Example: Router(config-cem)# idle-pattern 0x66 |
(Optional) Defines the idle data pattern to send to the attached CPE when packets are lost or the de-jitter buffer experiences an under-run condition. For serial CEM channels:
For T1 or E1 CEM channels:
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Example: Router(config-cem)# signaling |
(Optional) Enables the transport of Channel Associated Signaling (CAS) bits.
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Example: Router(config-cem)# payload-compression |
(Optional) Enables payload compression on a CEM channel.
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Example: Router(config-cem)# data-protection |
(Optional) Enables data protection by transmitting each data bit twice, once in each of two consecutive data packets.
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Example: Router(config-cem)# ip dscp 36 |
(Optional) Configures the IP Differentiated Service Code Point (DSCP) for packets originating from this CEM channel.
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Example: Router(config-cem)# ip tos 11 |
(Optional) Configures the IP type of service (ToS) bits for the CEM channel.
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Example: Router(config-cem)# ip precedence 7 |
(Optional) Configures the IP precedence bits for the CEM channel.
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Example: Router(config-cem)# loopback network |
(Optional) Creates a loopback from a CEM serial channel.
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Example: Router(config-cem)# exit |
Exits CEM configuration mode and returns to global configuration mode.
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What to Do Next
Proceed to the Configuration Examples for CEoIP.
Configuration Examples for CEoIP
Configuring a T1 CEM Network Module Example
The following example shows a basic configuration of a T1 network module to configure the CEoIP feature.
card type t1 0 controller t1 4/0 cem-group 6 timeslots 1-4,9,10 speed 64 framing esf linecode b8zs clock source adaptive 6 cablelength long -15db crc-threshold 512 description T1 line to 3rd floor PBX loopback network no shutdown exit cem 2/1/6 xconnect 10.2.0.1 0 encapsulation udp local ip-address 10.2.0.9 local udp port 15901 remote udp port 15901 payload-size 512 dejitter-buffer 80 signaling exit
Additional References
For additional information related to the CEoIP feature, refer to the following references:
Related Documents
Related Topic |
Document Title |
---|---|
CEoIP NMs |
Release Notes for Cisco NM-CEM-4TE1 and NM-CEM-4SER Network Module Software |
Standards
Standards |
Title |
---|---|
GR-1089 |
Electromagnetic Compatibility and Electrical Safety - Generic Criteria for Network Telecommunications Equipment |
GR-63 |
Network Equipment-Building System (NEBS) Requirements: Physical Protection |
TIA/EIA-IS-968 |
Technical Requirements for Connection of Terminal Equipment to the Telephone Network |
MIBs
MIBs |
MIBs Link |
---|---|
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To locate and download MIBs for selected platforms, Cisco IOS releases, and feature sets, use Cisco MIB Locator found at the following URL: |
RFCs
RFCs |
Title |
||
---|---|---|---|
RFC 1406 |
Definitions of Managed Objects for the DS1 and E1 Interface Types |
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RFC 2495 |
Definitions of Managed Objects for the DS1, E1, DS2 and E2 Interface Types
|
Technical Assistance
Description |
Link |
---|---|
Technical Assistance Center (TAC) home page, containing 30,000 pages of searchable technical content, including links to products, technologies, solutions, technical tips, and tools. Registered Cisco.com users can log in from this page to access even more content. |
Command Reference
The following commands are introduced or modified in the feature or features documented in this module. For information about these commands, see the Cisco IOS Interface and Hardware Component Command Reference at http://www.cisco.com/en/US/docs/ios/interface/command/reference/ir_book.html. For information about all Cisco IOS commands, go to the Command Lookup Tool at http://tools.cisco.com/Support/CLILookup or to the Cisco IOS Master Commands List .
- cem
- cem-group
- clear cem
- clock mode
- clock source (CEM)
- clock-switchover
- control-lead sampling-rate
- control-lead state
- crc-threshold
- data-protection
- data-strobe
- default (CEM)
- dejitter-buffer
- emulation-mode
- framing (CEM)
- idle-pattern
- ip dscp
- local ip address
- local udp port
- loopback (CEM)
- payload-compression
- payload-size
- remote udp port
- show cem
- signaling
- xconnect (CEM)
Feature Information for Circuit Emulation over IP
The following table provides release information about the feature or features described in this module. This table lists only the software release that introduced support for a given feature in a given software release train. Unless noted otherwise, subsequent releases of that software release train also support that feature.
Use Cisco Feature Navigator to find information about platform support and Cisco software image support. To access Cisco Feature Navigator, go to www.cisco.com/go/cfn. An account on Cisco.com is not required.
Release |
Modification |
---|---|
12.3(7)T |
This feature was introduced. |
12.2(33)SRD |
Included information on clock switchover and unidirectional emulation mode. |
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Any Internet Protocol (IP) addresses and phone numbers used in this document are not intended to be actual addresses and phone numbers. Any examples, command display output, network topology diagrams, and other figures included in the document are shown for illustrative purposes only. Any use of actual IP addresses or phone numbers in illustrative content is unintentional and coincidental.