Command:

x25 map

Mode:

Router(config-if)#


Syntax:

x25 map protocol address [protocol2 address2[...[protocol9
address9
]]] x121-address [option]

no x25 map protocol address x121-address


Syntax Description:

protocol

The upper layer protocol to be associated with the X.121 address specified in this map. To specify a protocol, use the protocol's keyword as listed in the table below. As many as nine protocol and address pairs can be specified in one command line.

address

Protocol address.

x121-address

X.121 address of the remote host.

option

(Optional) Additional functionality that can be specified for originated calls. Can be any of the options listed in Table.


Command Description:

To set up the LAN protocols-to-remote host mapping, use the x25 map interface configuration command. To remove an existing x25 map, use the no form of this command with the appropriate network protocol(s) and X.121 address arguments.

Routers use connections across X.25 networks to provide a transport path for higher layer protocols. To ensure that these connections are established to the correct destinations, the routers must be configured with the X.121 address of the X.25 destination for a given higher layer protocol. The x25 map command is used to do this, as well as specify other options and parameters that the router must use when connecting to the specified destination.

Two methods are available to encapsulate traffic; Cisco's traditional encapsulation method, and the IETF standard defined in RFC 1356. The IETF method allows for a single virtual circuit to be used by multiple higher layer protocols. Cisco's traditional encapsulation method is used by default. Include the method option keyword to specify an alternative encapsulation technique.

When you configure multiprotocol maps, you can specify a maximum of nine protocol and address pairs in an x25 map command. However, you can specify a protocol only once. For example, you can specify the IP protocol and an IP address, but you cannot specify another IP address. If compressedtcp and ip are both specified, the same IP address must be used.

Bridging is supported only if you are using Cisco's traditional encapsulation method. For correct operation, bridging maps must specify the broadcast option.

Since most datagram routing protocols rely on broadcasts or multicasts to send routing information to their neighbors, the broadcast keyword is needed to run such routing protocols over X.25.

Encapsulation maps might also specify that traffic between the two hosts should be compressed, thus increasing the effective bandwidth between them at the expense of memory and computation time. Because each compression virtual circuit requires memory and computation resources, compression must be used with care and monitored to maintain acceptable resource usage and overall performance.

OSPF treats a nonbroadcast, multiaccess network such as X.25 in much the same way as it treats a broadcast network by requiring the selection of a designated router. In previous releases, this required manual assignment in the OSPF configuration using the neighbor router configuration command. When the x25 map command is included in the configuration with the broadcast, and the ip ospf network command (with the broadcast keyword) is configured, there is no need to configure any neighbors manually. OSPF will now run over the X.25 network as a broadcast network. (Refer to the ip ospf network interface configuration command for more detail.)


Note   The OSPF broadcast mechanism assumes that IP class D addresses are never used for regular traffic over X.25.

You can modify the options of an x25 map command by restating the complete set of protocols and addresses specified for the map, followed by the desired options. To delete a map command, you must also specify the complete set of protocols and addresses. The options can be omitted.

Once defined, a map's protocols and addresses cannot be changed. This requirement exists because the Cisco IOS software cannot determine whether you want to add to, delete from, or modify an existing map's protocol and address specification, or simply mistyped the command. To change a map's protocol and address specification, you must delete it and create a new map.

A given protocol-address pair cannot be used in more than one map on the same interface.

Table below lists the protocols supported by X.25.

Table: Protocols Supported by X.25

Keyword Protocol

apollo

Apollo Domain

appletalk

AppleTalk

bridge

Bridging1

clns

ISO Connectionless Network Service

compressedtcp

TCP/IP header compression

decnet

DECnet

ip

IP

ipx

Novell IPX

pad

PAD links 2

qllc

System Network Architecture (SNA) encapsulation in X.253

vines

Banyan VINES

xns

XNS

1 Bridging traffic is supported only for Cisco's traditional encapsulation method, so a bridge map cannot specify other protocols. 2Packet Assembly/Disassembly (PAD) maps are used to configure session and protocol translation access, therefore, this protocol is not available for multiprotocol encapsulation. 3Qualified Logical Link Control (QLLC) is not available for multiprotocol encapsulation.

Note   The CMNS map form is obsolete; its function is replaced by the enhanced x25 route command.

Table lists the map options supported by X.25 using the x25 map command.

Table: x25 map Options

Option Description

compress

Specifies that X.25 payload compression be used for mapping the traffic to this host. Each virtual circuit established for compressed traffic uses a significant amount of memory (for a table of learned data patterns) and for computation (for compression and decompression of all data). Cisco recommends that compression be used with careful consideration to its impact on overall performance.

method {cisco | ietf | snap | multi}

Specifies the encapsulation method. The choices are as follows:

  •  

  • cisco�Cisco's traditional encapsulation method; not available if more than one protocol is to be carried. If the method option is not specified then Cisco encapsulation is used.
  • ietf�Standard RFC 1356 operation: protocol identification uses the standard encoding, which is compatible with RFC 877. Multiprotocol virtual circuits are used only if needed.
  • snap�RFC 1356 operation where IP is identified with SNAP rather than the standard IETF method. SNAP encapsulation is NOT compatible with RFC 877.
  • multi�Forces a map that specifies a single protocol to set up a multiprotocol virtual circuit when a call is originated; also forces a single-protocol PVC to use multiprotocol data identification methods for all datagrams sent and received.

     

no-incoming

Use the map only to originate calls.

no-outgoing

Do not originate calls when using the map.

idle minutes

Specifies an idle timeout for calls other than the interface default; 0 minutes disables the idle timeout.

reverse

Specifies reverse charging for outgoing calls.

accept-reverse

Causes the Cisco IOS software to accept incoming reverse-charged calls. If this option is not present, the Cisco IOS software clears reverse-charged calls unless the interface accepts all reverse-charged calls.

broadcast

Causes the Cisco IOS software to direct any broadcasts sent through this interface to the specified X.121 address. This option also simplifies the configuration of OSPF; see "Usage Guidelines" for more detail.

cug group-number

Specifies a closed user group number (from 1 to 9999) for the mapping in an outgoing call.

nvc count

Sets the maximum number of virtual circuits for this map or host. The default count is the x25 nvc setting of the interface. A maximum number of eight virtual circuits can be configured for each map. Compressed TCP may use only 1 virtual circuit.

packetsize in-size out-size

Proposes maximum input packet size (in-size) and maximum output packet size (out-size) for an outgoing call. Both values typically are the same and must be one of the following values: 16, 32, 64, 128, 256, 512, 1024, 2048, or 4096.

windowsize in-size out-size

Proposes the packet count for input window (in-size) and output window (out-size) for an outgoing call. Both values typically are the same, must be in the range 1 to 127, and must be less than the value set by the x25 modulo command.

throughput in out

Sets the requested throughput class values for input (in) and output (out) throughput across the network for an outgoing call. Values for in and out are in bits per second (bps) and range from 75 to 48000 bps.

transit-delay milliseconds

Specifies the transit delay value in milliseconds (0 to 65534) for an outgoing call, for networks that support transit delay.

nuid username password

Specifies that a network user ID (NUID) facility be sent in the outgoing call with the specified Terminal Access Controller Access Control System (TACACS) username and password (in a format defined by Cisco). This option should be used only when connecting to another Cisco router. The combined length of the username and password should not exceed 127 characters. This option only works if the router is configured as an X.25 DTE.

nudata string

Specifies the network user identification in a format determined by the network administrator (as allowed by the standards). This option is provided for connecting to non-Cisco equipment that requires an NUID facility. The string should not exceed 130 characters and must be enclosed in quotation marks ("") if there are any spaces present. This option only works if the router is configured as an X.25 DTE.

roa name

Specifies the name defined by the x25 roa command for a list of transit Recognized Operating Agencies (ROAs, formerly called Recognized Private Operating Agencies, or RPOAs) to use in outgoing Call Request packets.

passive

Specifies that the X.25 interface should send compressed outgoing TCP datagrams only if they were already compressed when they were received. This option is available only for compressed TCP maps.


Examples:

The following example maps IP address 172.20.2.5 to X.121 address 000000010300. The broadcast keyword directs any broadcasts sent through this interface to the specified X.121 address.

Router(config)#interface serial 0/0
 Router(config-if)#x25 map ip 171.20.2.5 000000010300 broadcast
 

The following example specifies an ROA name to be used for originating connections:

Router(config)#x25 roa green_list 23 35 36
Router(config)#interface serial 0/0
 Router(config-if)#x25 map ip 172.20.170.26 10 roa green_list
 

The following example specifies a network user ID (NUID) facility to send on calls originated for the address map:

Router(config)#interface serial 0/0
 Router(config-if)#x25 map ip 172.20.174.32 2 nudata "Network User ID 35"
 

Strings can be quoted, but quotation marks are not required unless embedded blanks are present.


Misconceptions:
None

Related commands:
x25 map compressedtcp

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