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This document includes the following sections:
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.
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 broadcasting and multicasting.
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.
For information on IP multicasting, see the "Configuring IP Multicast Routing" chapter of the Network Protocols Configuration Guide, Part 1.
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.
No new or modified RFCs are supported by this feature.
No new or modified Standards are supported by this feature.
You must configure multicast for the entire network that will receive and/or propagate the multicasts.
You must configure broadcast flooding on the routers between network segments.
See the following sections for configuration tasks for the Asynchronous Serial Traffic Over UDP feature.
Enter the following configuration on all routers that will receive the multicast. The router that is transmitting the multicast does not need to be configured for multicast. This task is not required for point-to-point or broadcast configurations.
| Step | Command | Purpose | ||
|---|---|---|---|---|
| terrapin(config)#ip multicast-routing | Enables multicast routing on the router. | ||
| terrapin(config)#interface ethernet 0 | Enters interface configuration mode on the Ethernet 0 interface. | ||
| terrapin(config-if)#ip address ip-address mask | Specifies the IP address and mask for Ethernet 0. | ||
| terrapin(config-if)#ip pim dense-mode | Enables dense mode Protocol-Independent Multicast (PIM). |
Enter the following configuration on the line that will be used to transmit and/or receive.
| Step | Command | Purpose | ||
|---|---|---|---|---|
| terrapin(config)#line line-number | Enters line configuration mode. | ||
| terrapin(config-line)# | Enables the line to transport UDP packets. | ||
| terrapin(config-line)#dispatch-timeout 1000 | Transmits packets every 1000 milliseconds. | ||
| terrapin(config-line)#dispatch-character 13 | Transmits packets after every new line. | ||
| terrapin(config-line)#no session-timeout | Disables timeout connection closing. |
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.
Enter the following EXEC command when you want to begin UDPTN transmission and/or reception.
| Command | Purpose |
|---|---|
terrapin#udptn ip-address [port] [/transmit] [/receive] | Enables UDPTN to the specified IP address (optionally, using the specified port). Use the /transmit or /receive keywords if the router will only be transmitting or receiving UDPTN. |
Enter the following configuration to automatically enable UDPTN when a connection is made to the line.
| Command | Purpose |
|---|---|
terrapin(config)#line line-number | Enters line configuration mode. |
terrapin(config-line)# | Enables UDPTN automatically when a connection is made to the line (optionally, using the specified port). Use the /transmit or /receive keywords if the router will only be transmitting or receiving UDPTN. |
Step 1 Enable UDPTN debugging by using the debug udptn EXEC command.
Step 2 Enable UDPTN by using the udptn ip-address EXEC command.
Step 3 Observe the debug output.
The following debug output shows a UDPTN session being successfully established and then disconnected.
terrapin#debug udptn terrapin#udptn 172.16.1.1 Trying 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 bytes terrapin#disconnect Closing connection to 172.16.1.1 [confirm] y terrapin# *Mar 1 00:11:03.139:udptn0:removing multicast group.
Step 4 While the udptn command is enabled, enter the show ip socket command to verify that the socket being used for UDPTN opened correctly.
terrapin#show ip socket Proto Remote Port Local Port In Out Stat TTY OutputIF 17 --listen-- 172.21.14.90 67 0 0 89 0 17 0.0.0.0 520 172.21.14.90 520 0 0 1 0 17 1.1.1.2 57 1.1.1.1 57 0 0 48 0 17 224.1.1.1 57 1.2.2.2 57 0 0 48 0 Loopback0
This section provides the following configuration examples:
These configurations are for two routers in mobile, unstable environments that wish to establish a 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.
interface ethernet 0 ip address 10.54.46.1 255.255.255.192 ! line 5 no session-timeout transport output udptn dispatch-timeout 10000 dispatch-character 13 modem in autocommand udptn 10.54.46.2
interface ethernet 0 ip address 10.54.46.2 255.255.255.192 ! line 10 no session-timeout transport output udptn dispatch-timeout 10000 dispatch-character 13 modem in autocommand udptn 10.54.46.1
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.
interface ethernet 0 ip address 10.1.1.1 255.255.255.0 ip pim dense-mode ! line 5 no session-timeout transport output udptn dispatch-timeout 10000 dispatch-character 13 modem in autocommand udptn 172.1.1.1 /transmit
ip multicast-routing interface ethernet 0 ip address 10.99.98.97 255.255.255.192 ip pim dense-mode ! line 0 16 transport output udptn telnet lat rlogin udptn 172.1.1.1 /receive
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.
interface ethernet 0 ip address 10.1.1.1 255.255.255.0 ip pim dense-mode ! line 5 no session-timeout transport output udptn dispatch-timeout 10000 dispatch-character 13 modem in autocommand udptn 255.255.255.255 /transmit
interface ethernet 0 ip address 10.99.98.97 255.255.255.192 ip pim dense-mode ! line 0 16 transport output udptn telnet lat rlogin udptn 255.255.255.255 /receive
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 publication.
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}
all | Selects all protocols. |
lat | Selects the digital LAT protocol, which is the protocol used most often to connect routers to digital hosts. |
mop | Selects Maintenance Operation Protocol (MOP). |
nasi | Select NetWare Access Server Interface (NASI) as the output transport protocol. |
none | Prevents any protocol selection on the line. The system normally assumes that any unrecognized command is a host name. If the protocol is set to none, the system no longer makes that assumption. No connection will be attempted if the command is not recognized. |
pad | Selects X.3 PAD, used most often to connect routers to X.25 hosts. |
rlogin | Selects the UNIX rlogin protocol for TCP connections. The rlogin setting is a special case of a Telnet connection. If an rlogin attempt to a particular host has failed, the failure will be tracked, and subsequent connection attempts will use a Telnet connection instead. |
telnet | Selects the TCP/IP Telnet protocol. It allows a user at one site to establish a TCP connection to a login server at another site. |
udptn | Selects UDPTN connections. |
v120 | Select the V.120 protocol for outgoing asynchronous over ISDN connections. |
Telnet
Line configuration
| Release | Modification |
|---|---|
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. |
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.
The following example enables UDPTN on the line:
transport output udptn
| Command | Description |
transport input | Defines which protocols is used to connect to the line. |
transport preferred | Specifies the protocol that is used if the user does not specify a protocol when initiating a connection. |
terminal transport preferred | Specifies the protocol to use for the current session when a command does not specify a protocol. |
To transmit or receive asynchronous serial traffic by using UDPTN, use the udptn EXEC command.
udptn ip-address [port] [/transmit] [/receive]
ip-address | IP address |
port | (Optional) UDP port that is to be used to transmit or receive. |
/transmit | (Optional) Transmits asynchronous data as UDP packets, but silently discards any packets that are received from the network. |
/receive | (Optional) Receives UDP packets from the network and sends them to the asynchronous line, but silently discards any other traffic received from the network. |
Disabled
The default UDP port is 57.
EXEC
| Release | Modification |
|---|---|
12.0(5)T | This command was introduced. |
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.
 | Caution
Because 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.
The following example enables the router terrapin to transmit UDP packets to IP address 175.49.49.49:
udptn 175.49.49.49 /transmit
| Command | Description |
transport output | Defines the protocol that can be used for outgoing connections from a line. |
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 udptnDisabled
| Release | Modification |
|---|---|
12.0(5)T | This command was introduced. |
terrapin#debug udptn terrapin#udptn 172.16.1.1 Trying 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 bytes terrapin#disconnect Closing connection to 172.16.1.1 [confirm] y terrapin# *Mar 1 00:11:03.139:udptn0:removing multicast group.
| Command | Description |
udptn | Enables transmission and/or reception of UDP packets. |
transport output | Defines the protocol that can be used for outgoing connections from a line. |
Posted: Mon Nov 15 14:22:10 PST 1999
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