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Asynchronous Serial Traffic Over UDP
Supported Standards, MIBs, and RFCs
Asynchronous Serial Traffic Over UDP
This document includes the following sections:
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Supported Standards, MIBs, and RFCs
Feature Overview
The Asynchronous Serial Traffic Over User Datagram Protocol (UDP) feature provides the ability to encapsulate asynchronous data into UDP packets, and then unreliably transmit this data without needing to establish a connection with a receiving device.
You load the data you want to transmit through an asynchronous port, and then transmit it, optionally, as a multicast or a broadcast. The receiving device(s) can then receive the data whenever it wants. If the receiver ends reception, the transmission is unaffected.
This process is referred to as UDP Telnet (UDPTN), although it does not—and cannot—use the Telnet protocol. UDPTN is similar to Telnet in that both are used to transmit data, but UDPTN is unique in that it does not require that a connection be established with a receiving device.
Benefits
The Asynchronous Serial Traffic Over UDP feature provides a low bandwidth, low maintenance method to unreliably deliver data. This delivery is similar to a radio broadcast: It does not require that you establish a connection to a destination; rather, it transmits the data to whomever wants to receive it. The receivers are free to begin or end their reception without interrupting the transmission.
This feature is particularly useful for broadcast, multicast, and unstable point-to-point connections.
Asynchronous Serial Traffic Over UDP is a low-bandwidth solution for delivering streaming information for which lost packets are not critical. Such applications include stock quotes, newswires, console monitoring, and multi-user chat features.
Restrictions
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Related Documents
For information on IP multicasting, see the "Configuring IP Multicast Routing" chapter of the Network Protocols Configuration Guide, Part 1.
Supported Platforms
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Supported Standards, MIBs, and RFCs
MIBs
No new or modified MIBs are supported by this feature.
For descriptions of supported MIBs and how to use MIBs, see the Cisco MIB web site on CCO at http://www.cisco.com/public/sw-center/netmgmt/cmtk/mibs.shtml.
RFCs
No new or modified RFCs are supported by this feature.
Standards
No new or modified Standards are supported by this feature.
Prerequisites
Multicast UDPTN
You must configure multicast for the entire network that will receive and/or propagate the multicasts.
Broadcast UDPTN
You must configure broadcast flooding on the routers between network segments.
Configuration Tasks
See the following sections for configuration tasks for the Asynchronous Serial Traffic Over UDP feature.
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Configuring a Line for UDPTN
Enter the following configuration on the line that will be used to transmit and/or receive.
Enabling UDPTN
There are two methods of enabling UDPTN. You can either manually enable UDPTN when you want to begin transmission and/or reception, or you can cofigure the router to automatically enable UDPTN when a connection is made to the line.
Manually Enabling UDPTN
Enter the following EXEC command when you want to begin UDPTN transmission and/or reception.
Automatically Enabling UDPTN
Enter the following configuration to automatically enable UDPTN when a connection is made to the line.
Verifying UDPTN Traffic
Step 1
Step 2
Step 3
The following debug output shows a UDPTN session being successfully established and then disconnected.
Router# debug udptnRouter# udptn 172.16.1.1Trying 172.16.1.1 ... Open*Mar 1 00:10:15.191:udptn0:adding multicast group.*Mar 1 00:10:15.195:udptn0:open to 172.16.1.1:57 Loopback0jjaassdd*Mar 1 00:10:18.083:udptn0:output packet w 1 bytes*Mar 1 00:10:18.087:udptn0:Input packet w 1 bytesRouter# disconnectClosing connection to 172.16.1.1 [confirm] yRouter#*Mar 1 00:11:03.139:udptn0:removing multicast group.Step 4
Router# show ip socketProto Remote Port Local Port In Out Stat TTY OutputIF17 --listen-- 172.21.14.90 67 0 0 89 017 0.0.0.0 520 172.21.14.90 520 0 0 1 017 1.1.1.2 57 1.1.1.1 57 0 0 48 017 224.1.1.1 57 1.2.2.2 57 0 0 48 0 Loopback0Configuration Examples
This section provides the following configuration examples:
Point-to-Point UDPTN
These configurations are for two routers in mobile, unstable environments that wish to establish a bidirectional asynchronous tunnel. Because there is no way to ensure that both routers will be up and running when one of the routers wants to establish a tunnel, they can not use connection-dependent protocols like Telnet or LAT. They instead use the following UDPTN configurations.
Notice that each router is configured to transmit to and receive from the other's IP address. Because both routers will be transmitting and receiving, they do not use the /transmit or /receive keywords with the udptn command.
Router A
interface ethernet 0ip address 10.54.46.1 255.255.255.192!line 5no session-timeouttransport output udptndispatch-timeout 10000dispatch-character 13modem inautocommand udptn 10.54.46.2Router B
interface ethernet 0ip address 10.54.46.2 255.255.255.192!line 10no session-timeouttransport output udptndispatch-timeout 10000dispatch-character 13modem inautocommand udptn 10.54.46.1Multicast UDPTN
These configurations are for multicast UDPTN. The router that is multicasting does not require a multicast configuration—it simply transmits to the multicast IP address.
Router that is Multicasting
ip multicast-routinginterface ethernet 0ip address 10.1.1.1 255.255.255.0ip pim dense-mode!line 5no session-timeouttransport output udptndispatch-timeout 10000dispatch-character 13modem inautocommand udptn 172.1.1.1 /transmitReceiving Routers
ip multicast-routinginterface ethernet 0ip address 10.99.98.97 255.255.255.192ip pim dense-mode!line 0 16transport output udptn telnet lat rloginautocommand udptn 172.1.1.1 /receiveBroadcast UDPTN
These configurations are for broadcast UDPTN. This is the simplest method to transmit to multiple receivers. The broadcasting router transmits to the broadcast IP address, and any router that wants to receive the transmission simply connects to the broadcast IP address by using the udptn command.
Router that is Broadcasting
interface ethernet 0ip address 10.1.1.1 255.255.255.0!line 5no session-timeouttransport output udptndispatch-timeout 10000dispatch-character 13modem inautocommand udptn 255.255.255.255 /transmitReceiving Routers
interface ethernet 0ip address 10.99.98.97 255.255.255.192!line 0 16transport output udptn telnet lat rloginautocommand udptn 255.255.255.255 /receiveCommand Reference
This section documents new or modified commands. All other commands used with this feature are documented in the Cisco IOS Release 12.0 command reference publications.
transport output
To determine the protocols that can be used for outgoing connections from a line, use the transport output line configuration command.
transport output {all | lat | mop | nasi | none | pad | rlogin | telnet | udptn | v120}
Syntax Description
Default
Telnet
Command Mode
Line configuration
Command History
10.0
This command was introduced.
10.2
Keywords all, lat, pad, and rlogin added.
11.1
Keywords mop, nasi, and v120 added.
12.0(5)T
Keyword udptn added.
Usage Guidelines
You can specify one protocol, multiple protocols, all protocols, or no protocols. To specify multiple protocols, enter the keyword for each protocol, separated by a space.
Any settings made with the transport output command override settings made with the transport preferred command.
Example
The following example enables UDPTN on the line:
transport output udptnRelated Commands
udptn
To transmit or receive asynchronous serial traffic by using UDPTN, use the udptn EXEC command.
udptn ip-address [port] [/transmit] [/receive]
Syntax Description
Defaults
Disabled
The default UDP port is 57.
Command Modes
EXEC
Command History
Usage Guidelines
Before you can transmit or receive asynchronous serial traffic, you must enable the transport output command on the line that will be transmitting or receiving.
To end the UDPTN session, use the disconnect EXEC command.
CautionBecause of its ability to send raw UDP datagrams that might conflict with other protocols, UDPTN has an implicit access list that only allows UDPTN connections to UDP port 57 or UDP ports greater than 1024.
You can configure an access list to permit more or fewer ports, but Cisco suggests that you not modify this restriction if you do not fully understand the resulting security implications.
UDPTN connections will generate AAA accounting records if the aaa accounting connection command is enabled. The start of the session will be recorded, and the number of packets and bytes received and transmitted will be recorded at the end of the session.
Examples
The following example enables the router to transmit UDP packets to IP address 175.49.49.49:
udptn 175.49.49.49 /transmitRelated Commands
Debug Commands
This section documents new debug commands. All other commands used with this feature are documented in the Cisco IOS Release 12.0 command reference publications.
debug udptn
To display debug messages for UDPTN events, use the debug udptn privileged EXEC command. Use the no form of this command to disable debugging output.
[no] debug udptn
Defaults
Disabled
Command History
Examples
Router# debug udptnRouter# udptn 172.16.1.1Trying 172.16.1.1 ... Open*Mar 1 00:10:15.191:udptn0:adding multicast group.*Mar 1 00:10:15.195:udptn0:open to 172.16.1.1:57 Loopback0jjaassdd*Mar 1 00:10:18.083:udptn0:output packet w 1 bytes*Mar 1 00:10:18.087:udptn0:Input packet w 1 bytesRouter# disconnectClosing connection to 172.16.1.1 [confirm] yRouter#*Mar 1 00:11:03.139:udptn0:removing multicast group.Related Commands
Defines the protocol that can be used for outgoing connections from a line.
Enables transmission and/or reception of UDP packets.
