- Cisco IOS Wide-Area Networking Command Reference, Release 12.2
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x25 bfe-decision
This command is no longer supported.
x25 bfe-emergency
This command is no longer supported.
x25 default
To set a default protocol that Cisco IOS software will assume applies to incoming calls with unknown or missing protocol identifier in the call user data (CUD), use the x25 default interface configuration command. To remove the default protocol specified, use the no form of this command.
x25 default protocol
no x25 default protocol
Syntax Description
Defaults
No default protocol is specified.
Command Modes
Interface configuration
X.25 profile configuration
Command History
Usage Guidelines
This command specifies the protocol assumed by the Cisco IOS software for incoming calls with unknown or missing protocol identifier in the call user data (CUD). If you do not use the x25 default interface configuration command, the software clears any incoming calls with unrecognized CUD.
Examples
The following example establishes IP as the default protocol for X.25 calls:
interface serial 0x25 default ipRelated Commands
x25 facility
To force facilities on a per-call basis for calls originated by the router (switched calls are not affected), use the x25 facility interface configuration command. To disable a facility, use the no form of this command.
x25 facility option value
no x25 facility option value
Syntax Description
option
Set of user facilities options. See Table 55 for a list of supported facilities and their values.
value
Option value. See Table 55 for a list of supported facilities and their values.
Defaults
No facility is sent.
Command Modes
Interface configuration
X.25 profile configuration
Command History
Usage Guidelines
Table 55 lists the set of x25 facility command user facilities options.
Examples
The following example specifies a transit delay value in an X.25 configuration:
interface serial 0x25 facility transit-delay 24000The following example sets an ROA name and then sends the list via the X.25 user facilities:
x25 roa green_list 23 35 36interface serial 0x25 facility roa green_listRelated Commands
x25 fail-over
To configure a secondary interface and set the number of seconds for which a primary interface must be up before the secondary interface resets, use the x25 fail-over command in the appropriate configuration mode. To prevent the secondary interface from resetting, use the no form of this command.
x25 fail-over seconds interface type number [dlci | mac-address]
no x25 fail-over seconds interface type number [dlci | mac-address]
Syntax Description
Defaults
No default behavior or values.
Command Modes
Interface configuration
X.25 profile configuration
Command History
Usage Guidelines
The x25 fail-over command can be configured on a primary X.25 interface or an X.25 profile only.
Examples
In the following example, X.25 failover is configured on a network that is also configured for Annex G. If data-link connection identifier (DLCI) 13 or DLCI 14 on serial interface 1/0 goes down, dialer interface 1 will serve as the secondary interface. After DLCI 13 or 14 comes back up and remains up for 20 seconds, dialer interface 1 will reset, sending all calls back to the primary interface.
interface serial1/0encapsulation frame-relayframe-relay interface-dlci 13x25-profile frame1exitframe-relay interface-dlci 14x25-profile frame1 dteexit!interface dialer1encapsulation x25exitx25 route ^1234 interface serial1/0 dlci 13x25 route ^1234 interface serial1/0 dlci 14x25 route ^1234 interface dialer1!x25 profile frame1x25 fail-over 20 interface dialer1exit!Related Commands
Displays information about X.25 links.
Configures an X.25 profile without specifying any hardware-specific information.
x25 hic
To set the highest incoming-only virtual circuit (VC) number, use the x25 hic interface configuration command.
x25 hic circuit-number
Syntax Description
Defaults
0
Command Modes
Interface configuration
X.25 profile configuration
Command History
Usage Guidelines
This command is applicable only if you have the X.25 switch configured for an incoming-only VC range. Incoming is from the perspective of the X.25 data terminal equipment (DTE). If you do not want any outgoing calls from your DTE, configure both ends to disable the two-way range (set the values of x25 ltc and x25 htc to 0) and configure an incoming-only range. Any incoming-only range must come before (that is, must be numerically less than) any two-way range. Any two-way range must come before any outgoing-only range.
Examples
The following example sets a valid incoming-only VC range of 1 to 5:
interface serial 0x25 lic 1x25 hic 5Related Commands
x25 hoc
To set the highest outgoing-only virtual circuit (VC) number, use the x25 hoc interface configuration command.
x25 hoc circuit-number
Syntax Description
Defaults
0
Command Modes
Interface configuration
Command History
Usage Guidelines
This command is applicable only if you have the X.25 switch configured for an outgoing-only VC range. Outgoing is from the perspective of the X.25 data terminal equipment (DTE). If you do not want any incoming calls on your DTE, disable the two-way range (set the values of x25 ltc and x25 htc to 0) and configure an outgoing-only range. Any outgoing-only range must come after (that is, be numerically greater than) any other range.
Examples
The following example sets a valid outgoing-only VC range of 2000 to 2005:
interface serial 0x25 loc 2000x25 hoc 2005Related Commands
x25 hold-queue
To set the maximum number of packets to hold until a virtual circuit (VC) is able to send, use the x25 hold-queue interface configuration command. To remove this command from the configuration file and restore the default value, use the no form of this command without an argument.
x25 hold-queue packets
no x25 hold-queue [packets]
Syntax Description
packets
Number of packets. A hold queue value of 0 allows an unlimited number of packets in the hold queue.
Defaults
10 packets
Command Modes
Interface configuration
X.25 profile configuration
Command History
Usage Guidelines
If you set the queue-size argument to 0 when using the no x25 hold-queue command, there will be no hold queue limit. While this setting will prevent drops until the router runs out of memory, it is only rarely appropriate. A VC hold queue value is determined when it is created; changing this parameter will not affect the hold queue limits of the existing virtual circuits.
Examples
The following example sets the X.25 hold queue to hold 25 packets:
interface serial 0x25 hold-queue 25Related Commands
x25 hold-vc-timer
To start the timer that prevents additional calls to a destination for a given period of time (thus preventing overruns on some X.25 switches caused by Call Request packets), use the x25 hold-vc-timer interface configuration command. To restore the default value for the timer, use the no form of this command.
x25 hold-vc-timer minutes
no x25 hold-vc-timer
Syntax Description
minutes
Number of minutes that calls to a previously failed destination will be prevented. Incoming calls are still accepted.
Defaults
0 minutes
Command Modes
Interface configuration
X.25 profile configuration
Command History
Usage Guidelines
Only Call Requests that the router originates are held down; routed X.25 Call Requests are not affected by this parameter.
Upon receiving a Clear Request for an outstanding Call Request, the X.25 support code immediately tries another Call Request if it has more traffic to send, and this action might cause overrun problems.
Examples
The following example sets this timer to 3 minutes:
interface serial 0x25 hold-vc-timer 3x25 host
To define a static host name-to-address mapping, use the x25 host global configuration command. To remove the host name, use the no form of the command.
x25 host name x121-address [cud call-user-data]
no x25 host name
Syntax Description
name
Host name.
x121-address
The X.121 address.
cud call-user-data
(Optional) Sets the Call User Data (CUD) field in the X.25 Call Request packet.
Defaults
No static host name-to-address mapping is defined.
Command Modes
Global configuration
Command History
Usage Guidelines
This command permits you to map an X.121 address to an easily recognizable name. You can later use this host name instead of the X.121 address when you issue the translate command for X.25.
Examples
The following example specifies a static address mapping:
x25 host Willard 4085551212The following example removes a static address mapping:
no x25 host WillardThe following example specifies static address mapping from the X.121 address 12345678 to the host name "ocean". It then uses the name "ocean" in the translate command in place of the X.121 address when translating from the X.25 host to the PPP host with address 10.0.0.2.
x25 host ocean 12345678translate x25 ocean ppp 10.0.0.2 routingRelated Commands
x25 htc
To set the highest two-way virtual circuit (VC) number, use the x25 htc interface configuration command.
x25 htc circuit-number
Syntax Description
Defaults
1024 for X.25 network service interfaces; 4095 for CMNS network service interfaces.
Command Modes
Interface configuration
X.25 profile configuration
Command History
Usage Guidelines
This command is applicable if the X.25 switch is configured for a two-way VC range. Any two-way VC range must come after (that is, be numerically larger than) any incoming-only range, and must come before any outgoing-only range.
Examples
The following example sets a valid two-way VC range of 5 to 25:
interface serial 0x25 ltc 5x25 htc 25Related Commands
x25 hunt-group
To create and maintain a hunt group, use the x25 hunt-group global configuration command. To delete this hunt group, use the no form of this command.
x25 hunt-group name {rotary | vc-count}
no x25 hunt-group name
Syntax Description
name
Name you assign to the particular hunt group.
rotary
Each call steps to the next interface.
vc-count
Each call is placed on the interface with most available logical channels.
Command Modes
Global configuration
Command History
Usage Guidelines
Only one load-balancing distribution method can be selected for a hunt group, although one interface can participate in one or more hunt groups.
The rotary distribution method sends every call to the next available interface regardless of line speed and the number of available VCs on that interface.
The vc-count distribution method sends calls to the interface with the largest number of available logical channels. This method ensures a good load balance when you have lines of equal speed. If the line speeds are unequal, the vc-count method will favor the line with the higher speed. In cases where interfaces have the same line speed, the call is sent to the interface that is defined earliest in the hunt group.
To distribute calls equally among interfaces regardless of line speed, configure each interface with the same number of VCs.
With the vc-count distribution method, if a hunt group does not contain an operational interface, the call will be forwared to the next route if one was specified. If a session is terminated on an interface within the hunt group, that interface now has more available VCs and it will be chosen next.
Examples
X.25 Load Balancing Using VC-Count Distribution Method Example
In the following example, the vc-count distribution method is used on a hunt group that contains two serial interfaces that have different numbers of VCs. Assuming no sessions are being terminated at this time, the first 450 calls will be sent to Serial1, and subsequent calls will alternate between Serial0 and Serial1 until the interfaces are full.
interface serial0description 56k link supporting 50 virtual circuitsx25 htc 50!interface serial1description T1 line supporting 500 virtual circuitsx25 htc 500!x25 hunt-group hg-vc vc-countinterface serial0interface serial1!Hunt Group Configuration Example
The following example shows the creation of hunt group "HG1" with serial interfaces 1 and 2 and two specific XOT target IP addresses (172.17.125.54 and 172.17.125.34). Hunt group "HG1" is configured to use rotary distribution method. The example also shows the creation of hunt group "HG2" with serial interfaces 0 and 3. Hunt group "HG2" will use vc-count distribution method.
x25 hunt-group HG1 rotaryinterface serial 1interface serial 2xot 172.17.125.54xot 172.17.125.34exitx25 hunt-group HG2 vc-countinterface serial 0interface serial 3Related Commands
Displays X.25 hunt groups, detailed interface statistics, and distribution methods.
x25 idle
To define the period of inactivity after which the router can clear a switched virtual circuit (SVC), use the x25 idle interface configuration command.
x25 idle minutes
Syntax Description
Defaults
0 (the SVC is kept open indefinitely)
Command Modes
Interface configuration
X.25 profile configuration
Command History
Usage Guidelines
Calls originated and terminated by the router are cleared; packet assembler/disassembler (PAD) and switched virtual circuits are not affected. To clear one or all virtual circuits at once, use the clear x25 privileged EXEC command.
Examples
The following example sets a 5-minute wait period before an idle circuit is cleared:
interface serial 2x25 idle 5Related Commands
x25 ip-precedence
To enable the Cisco IOS software to use the IP precedence value when it opens a new virtual circuit (VC), use the x25 ip-precedence interface configuration command. To cause the Cisco IOS software to ignore the precedence value when opening VCs, use the no form of this command.
x25 ip-precedence
no x25 ip-precedence
Syntax Description
This command has no arguments or keywords.
Defaults
The router opens one VC for all types of service.
Command Modes
Interface configuration
Command History
Usage Guidelines
This feature is useful only for Defense Data Network (DDN) or Blacker Front End (BFE) encapsulations because only these methods have an IP precedence facility defined to allow the source and destination devices to both use the VC for traffic of the given IP priority.
Verify that your host does not send nonstandard data in the IP type of service (TOS) field because it can cause multiple wasteful virtual circuits to be created.
Four VCs may be opened based on IP precedence to encapsulate routine, priority, immediate, and all higher precedences.
The x25 map nvc limit or the default x25 nvc limit still applies.
Examples
The following example allows new IP encapsulation VCs based on the IP precedence:
interface serial 3x25 ip-precedencex25 ips
To set the interface default maximum input packet size to match that of the network, use the x25 ips interface configuration command.
x25 ips bytes
Syntax Description
bytes
Byte count. It can be one of the following values: 16, 32, 64, 128, 256, 512, 1024, 2048, or 4096.
Defaults
128 bytes
Command Modes
Interface configuration
Command History
Usage Guidelines
X.25 network connections have a default maximum input packet size set by the network administrator. Larger packet sizes require less overhead processing. To send a packet larger than the X.25 packet size over an X.25 virtual circuit, the Cisco IOS software must break the packet into two or more X.25 packets with the more data bit (M-bit) set. The receiving device collects all packets with the M-bit set and reassembles the original packet.
Note
Set the x25 ips and x25 ops commands to the same value unless your network supports asymmetric input and output packet sizes.
Examples
The following example sets the default maximum packet sizes to 512:
interface serial 1x25 ips 512x25 ops 512Related Commands
x25 lic
To set the lowest incoming-only virtual circuit (VC) number, use the x25 lic interface configuration command.
x25 lic circuit-number
Syntax Description
Defaults
0
Command Modes
Interface configuration
X.25 profile configuration
Command History
Usage Guidelines
This command is applicable only if you have the X.25 switch configured for an incoming-only VC range. Incoming is from the perspective of the X.25 DTE device. If you do not want any outgoing calls on your DTE device, disable the two-way range (set the values of x25 ltc and x25 htc to 0).
The following example sets a valid incoming-only VC range of 1 to 5, and sets the lowest two-way VC number:
interface serial 0x25 lic 1x25 hic 5x25 ltc 6Related Commands
x25 linkrestart
To force X.25 Level 3 (packet level) to restart when Level 2 (Link Access Procedure, Balanced [LAPB], the link level) resets, use the x25 linkrestart interface configuration command. To disable this function, use the no form of this command.
x25 linkrestart
no x25 linkrestart
Syntax Description
This command has no arguments or keywords.
Defaults
Forcing packet-level restarts is the default and is necessary for networks that expect this behavior.
Command Modes
Interface configuration
X.25 profile configuration
Command History
Examples
The following example disables the link-level restart:
interface serial 3no x25 linkrestartx25 loc
To set the lowest outgoing-only virtual circuit (VC) number, use the x25 loc interface configuration command.
x25 loc circuit-number
Syntax Description
Defaults
0
Command Modes
Interface configuration
X.25 profile configuration
Command History
Usage Guidelines
This command is applicable only if you have the X.25 switch configured for an outgoing-only VC range. Outgoing is from the perspective of the X.25 DTE device. If you do not want any incoming calls from your DTE device, configure the values of x25 loc and x25 hoc and set the values of x25 ltc and x25 htc to 0.
Examples
The following example sets a valid outgoing-only virtual circuit range of 2000 to 2005:
interface serial 0x25 loc 2000x25 hoc 2005Related Commands
x25 ltc
To set the lowest two-way virtual circuit (VC) number, use the x25 ltc interface configuration command.
x25 ltc circuit-number
Syntax Description
Defaults
1
Command Modes
Interface configuration
X.25 profile configuration
Command History
Usage Guidelines
This command is applicable if you have the X.25 switch configured for a two-way virtual circuit range. Any two-way virtual circuit range must come after (that is, be numerically larger than) any incoming-only range, and must come before any outgoing-only range.
Examples
The following example sets a valid two-way virtual circuit range of 5 to 25:
interface serial 0x25 ltc 5x25 htc 25Related Commands
x25 map
To set up the LAN protocols-to-remote host mapping, use the x25 map interface configuration command. To retract a prior mapping, use the no form of this command with the appropriate network protocols and X.121 address argument.
x25 map protocol address [protocol2 address2 [...[protocol9 address9]]] x121-address [option]
no x25 map protocol address x121-address
Syntax Description
protocol
Protocol type, entered by keyword. Supported protocols are entered by keyword, as listed in Table 56. 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 57.
Defaults
No LAN protocol-to-remote host mapping is set up.
Command Modes
Interface configuration
X.25 profile configuration
Command History
Usage Guidelines
Because no defined protocol can dynamically determine LAN protocol-to-remote host mappings, you must enter all the information for each host with which the router may exchange X.25 encapsulation traffic.
Two methods are available to encapsulate traffic: Cisco's long-available encapsulation method and the Internet Engineering Task Force (IETF) standard method (defined in RFC 1356); the latter allows hosts to exchange several protocols over a single virtual circuit. Cisco's encapsulation method is the default (for backward compatibility) unless the interface configuration command specifies the ietf keyword.
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 the compressedtcp and ip keywords 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.
Open Shortest Path First (OSPF) Protocol 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
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 when deleting a map.
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 56 lists the protocols supported by X.25.
Table 56 Protocols Supported by X.25
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 links2
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.
2 Packet assembler/disassembler (PAD) maps are used to configure session and protocol translation access, therefore, this protocol is not available for multiprotocol encapsulation.
3 Qualified Logical Link Control (QLLC) is not available for multiprotocol encapsulation.
Note
Table 57 lists the map options supported by X.25 using the x25 map command.
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.
interface serial 0x25 map ip 171.20.2.5 000000010300 broadcastThe following example specifies an ROA name to be used for originating connections:
x25 roa green_list 23 35 36interface serial 0x25 map ip 172.20.170.26 10 roa green_listThe following example specifies an NUID facility to send on calls originated for the address map:
interface serial 0x25 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.
Related Commands
x25 map bridge
To configure an Internet-to-X.121 address mapping for bridging of packets in X.25 frames, use the x25 map bridge interface configuration command. Use the no form of this command to disable the Internet-to-X.121 address mapping.
x25 map bridge x121-address broadcast [option]
Syntax Description
Defaults
No bridging over X.25 is configured.
Command Modes
Interface configuration
Command History
Usage Guidelines
The X.25 bridging software uses the same spanning-tree algorithm as the other bridging functions, but allows packets to be encapsulated in X.25 frames and transmitted across X.25 media. This command specifies IP-to-X.121 address mapping and maintains a table of both the Ethernet and X.121 addresses.
Table 58 lists x25 map bridge options.
Examples
The following example configures transparent bridging over X.25 between two Cisco routers using a maximum of six virtual circuits:
interface serial 1x25 map bridge 000000010300 broadcast nvc 6Related Commands
Sets up the LAN protocols-to-remote host mapping.
Sets the X.121 address of a particular network interface.
x25 map cmns
The x25 map cmns command is replaced by the enhanced x25 route command. See the description of the x25 route command in this chapter for more information.
x25 map compressedtcp
To map compressed TCP traffic to an X.121 address, use the x25 map compressedtcp interface configuration command. To delete a TCP/IP header compression map for the link, use the no form of this command.
x25 map compressedtcp ip-address [protocol2 address2 [...[protocol9 address9]]]
x121-address [option]no x25 map compressedtcp address [protocol2 address2 [...[protocol9 address9]]]
x121-addressSyntax Description
ip-address
IP address.
protocol
(Optional) Protocol type, entered by keyword. Supported protocols are entered by keyword, as listed in Table 56 earlier in this chapter. As many as nine protocol and address pairs can be specified in one command line.
address
(Optional) Protocol address.
x121-address
X.121 address.
option
(Optional) The same options as those for the x25 map command; see Table 57 earlier in this chapter.
Defaults
No mapping is configured.
Command Modes
Interface configuration
Command History
Usage Guidelines
Cisco supports RFC 1144 TCP/IP header compression (THC) on serial lines using HDLC and X.25 encapsulation. THC encapsulation is only slightly different from other encapsulation traffic, but these differences are worth noting. The implementation of compressed TCP over X.25 uses one virtual circuit to pass the compressed packets. Any IP traffic (including standard TCP) is separate from TCH traffic; it is carried over separate IP encapsulation virtual circuits or identified separately in a multiprotocol virtual circuit.
Note
The nvc map option cannot be used for TCP/IP header compression, because only one virtual circuit can carry compressed TCP/IP header traffic to a given host.
Examples
The following example establishes a map for TCP/IP header compression on serial interface 4:
interface serial 4ip tcp header-compressionx25 map compressedtcp 172.20.2.5 000000010300Related Commands
x25 map pad
To configure an X.121 address mapping for packet assembler/disassembler (PAD) access over X.25, use the x25 map pad interface configuration command.
x25 map pad x121-address [option]
Syntax Description
x121-address
X.121 address of the interface.
option
(Optional) Services that can be added to this map—the same options as the x25 map command; see Table 57 earlier in this chapter.
Defaults
No specific options are used for PAD access.
Command Modes
Interface configuration
Command History
Usage Guidelines
Use a PAD map to configure optional X.25 facility use for PAD access. When used with the x25 pad-access interface configuration command, the x25 map pad command restricts incoming PAD access to those statically mapped hosts.
Examples
The following example configures an X.25 interface to restrict incoming PAD access to the single mapped host. This example requires that both incoming and outgoing PAD access use the network user identification (NUID) user authentication.
interface serial 1x25 pad-accessx25 map pad 000000010300 nuid johndoe secretRelated Commands
Sets up the LAN protocols-to-remote host mapping.
Causes the PAD software to accept PAD connections only from statically mapped X.25 hosts.
x25 modulo
To set the window modulus, use the x25 modulo interface configuration command.
x25 modulo modulus
Syntax Description
modulus
Either 8 or 128. The value of the modulo parameter must agree with that of the device on the other end of the X.25 link.
Defaults
8
Command Modes
Interface configuration
Command History
Usage Guidelines
X.25 supports flow control with a sliding window sequence count. The window counter restarts at zero upon reaching the upper limit, which is called the window modulus. Modulo 128 operation is also referred to as extended packet sequence numbering, which allows larger packet windows.
Examples
The following example sets the window modulus to 128:
interface serial 0x25 modulo 128Related Commands
x25 nvc
To specify the maximum number of virtual circuits (VCs) that a protocol can have open simultaneously to one host, use the x25 nvc interface configuration command. To increase throughput across networks, you can establish up to eight virtual circuits to a host and protocol.
x25 nvc count
Syntax Description
Defaults
1
Command Modes
Interface configuration
X.25 profile configuration
Command History
Usage Guidelines
When the windows and output queues of all existing connections to a host are full, a new virtual circuit will be opened to the designated circuit count. If a new connection cannot be opened, the data is dropped.
Note
Examples
The following example sets the default maximum number of VCs that each map can have open simultaneously to 4:
interface serial 0x25 nvc 4x25 ops
To set the interface default maximum output packet size to match that of the network, use the x25 ops interface configuration command.
x25 ops bytes
Syntax Description
Defaults
128 bytes
Command Modes
Interface configuration
X.25 profile configuration
Command History
Usage Guidelines
X.25 networks use maximum output packet sizes set by the network administrator. Larger packet sizes are better because smaller packets require more overhead processing. To send a packet larger than the X.25 packet size over an X.25 virtual circuit, the Cisco IOS software must break the packet into two or more X.25 packets with the more data bit (M-bit) set. The receiving device collects all packets with the M-bit set and reassembles the original packet.
Note
Examples
The following example sets the default maximum packet sizes to 512:
interface serial 1x25 ips 512x25 ops 512Related Commands
Sets the interface default maximum input packet size to match that of the network.
x25 pad-access
To cause the packet assembler/disassembler (PAD) software to accept PAD connections only from statically mapped X.25 hosts, use the x25 pad-access interface configuration command. To disable checking maps on PAD connections, use the no form of this command.
x25 pad-access
no x25 pad-access
Syntax Description
This command has no arguments or keywords.
Defaults
Accept PAD connections from any host.
Command Modes
Interface configuration
Command History
Usage Guidelines
By default, all PAD connection attempts are processed for session creation or protocol translation, subject to the configuration of those functions. If you use the x25 pad-access command, PAD connections are processed only for incoming calls with a source address that matches a statically mapped address configured with the x25 map pad interface configuration command. PAD connections are refused for any incoming calls with a source address that has not been statically mapped.
Examples
The following example restricts incoming PAD access on the interface to attempts from the host with the X.121 address 000000010300:
interface serial 1x25 pad-accessx25 map pad 000000010300Related Commands
x25 profile
To configure an X.25 profile without allocating any hardware specific information, use the x25 profile command in global configuration mode. To delete this profile, use the no form of this command.
x25 profile name {dce | dte | dxe}
no x25 profile name
Syntax Description
Defaults
dte
Command Modes
Global configuration
Command History
12.0(3)T
This command was introduced.
12.0(7)T
The x25 subscribe flow-control command was added to the X.25 profile configuration mode X.25 options.
Usage Guidelines
You can enable many X.25 commands in X.25 profile configuration mode. Table 59 lists the following X.25 commands in X.25 profile configuration mode, which you may use to create your X.25 profile.
Table 60 lists LAPB commands in X.25 configuration mode, which you may use to create your X.25 profile.
Examples
The following example shows the NetworkNodeA profile being set as a DCE interface, and with x25 htc, x25 idle, x25 accept-reverse, and x25 modulo commands enabled:
Router(config)# x25 profile NetworkNodeA dceRouter(config-x25)# x25 htc 128Router(config-x25)# x25 idle 5Router(config-x25)# x25 accept-reverseRouter(config-x25)# x25 modulo 128Related Commands
x25 pvc (encapsulation)
To establish an encapsulation permanent virtual circuit (PVC), use the encapsulating version of the x25 pvc interface configuration command. To delete the PVC, use the no form of this command with the appropriate channel number.
x25 pvc circuit protocol address [protocol2 address2 [...[protocol9 address9]]] x121-address
[option]no x25 pvc circuit
Syntax Description
circuit
Virtual-circuit channel number, which must be less than the virtual circuits assigned to the switched virtual circuits (SVCs).
protocol
Protocol type, entered by keyword. Supported protocols are listed in Table 61. As many as nine protocol and address pairs can be specified in one command line.
address
Protocol address of the host at the other end of the PVC.
x121-address
X.121 address.
option
(Optional) Provides additional functionality or allows X.25 parameters to be specified for the PVC. Can be any of the options listed in Table 62.
Defaults
The PVC window and maximum packet sizes default to the interface default values.
Command Modes
Interface configuration
Command History
Usage Guidelines
PVCs are not supported for ISO Connection-Mode Network Service (CMNS).
You no longer need to specify a datagram protocol-to-address mapping before you can set up a PVC; a map is implied from the PVC configuration. Configurations generated by the router will no longer specify a map for encapsulating PVCs.
When configuring a PVC to carry CLNS traffic, use the X.121 address as the subnetwork point of attachment (SNPA) to associate the PVC with a CLNS neighbor configuration. When configuring a PVC to carry transparent bridge traffic, the X.121 address is required to identify the remote host to the bridging function. Other encapsulation PVCs do not require an X.121 address.
Table 61 lists supported protocols.
Table 61 Protocols Supported by X.25 PVCs
apollo
Apollo Domain
appletalk
AppleTalk
bridge
Bridging1
clns
OSI Connectionless Network Service
compressedtcp
TCP/IP header compression
decnet
DECnet
ip
IP
ipx
Novell IPX
qllc
SNA encapsulation in X.252
vines
Banyan VINES
xns
XNS
1 Bridging traffic is supported only for Cisco's traditional encapsulation method, so a bridge PVC cannot specify other protocols.
2 QLLC is not available for multiprotocol encapsulation.
Table 62 lists supported X.25 PVC options.
Examples
The following example establishes a PVC on channel 2 to encapsulate VINES and IP with the far host:
interface serial 0x25 ltc 5x25 pvc 2 vines 60002A2D:0001 ip 172.20.170.91 11110001Related Commands
x25 pvc (switched)
To configure a switched permanent virtual circuit (PVC) for a given interface, use the switched version of the x25 pvc interface configuration command.
x25 pvc number1 interface type number pvc number2 [option]
Syntax Description
number1
PVC number that will be used on the local interface (as defined by the primary interface command).
interface
Required keyword to specify an interface.
type
Remote interface type.
number
Remote interface number.
pvc
Required keyword to specify a switched PVC.
number2
PVC number that will be used on the remote interface.
option
(Optional) Adds certain features to the mapping specified; can be either option listed in Table 63.
Defaults
The PVC window and maximum packet sizes default to the interface default values.
Command Modes
Interface configuration
Command History
Usage Guidelines
You can configure X.25 PVCs in the X.25 switching software. As a result, data terminal equipment (DTE) devices that require permanent circuits can be connected to the router acting as an X.25 switch and have a properly functioning connection. X.25 resets will be sent to indicate when the circuit comes up or goes down.
PVC circuit numbers must come before (that is, be numerically smaller than) the circuit numbers allocated to any SVC range.
Table 63 lists the switched PVC options supported by X.25.
Examples
The following example configures a PVC connected between two serial interfaces on the same router. In this type of interconnection configuration, the alternate interface must be specified along with the PVC number on that interface. To make a working PVC connection, two commands must be specified, each pointing to the other, as this example illustrates.
interface serial 0encapsulation x25x25 ltc 5x25 pvc 1 interface serial 1 pvc 1interface serial 1encapsulation x25x25 ltc 5x25 pvc 1 interface serial 0 pvc 1x25 pvc (switched PVC to SVC)
To configure a switched permanent virtual circuit (PVC) to a switched virtual circuit (SVC) for a given interface, use the switched PVC to SVC version of the x25 pvc interface configuration command.
x25 pvc number1 svc x121-address [flow-control-options] [call-control-options]
Syntax Description
number1
Logical channel ID of the PVC. Value must be lower than any range of circuit numbers defined for SVCs.
svc
Specifies a SVC type.
x121-address
Destination X.121 address for opening an outbound SVC and source X.121 address for matching an inbound SVC.
flow-control-options
(Optional) Adds certain features to the mapping specified. It can be any of the options listed in Table 64.
call-control-options
(Optional) Adds certain features to the mapping specified. It can be any of the options listed in Table 65.
Defaults
This command has no default values.
Command Modes
Interface configuration
Command History
Usage Guidelines
The PVC window and maximum packet sizes default to the interface default values. The default idle time comes from the interface on which the x25 pvc command is configured, not the interface on which the call is sent/received.
PVC circuit numbers must come before (that is, be numerically smaller than) the circuit numbers allocated to any SVC range.
On an outgoing call, the packet size facilities and window size facilities will be included. The call will be cleared if the call accepted packet specifies different values.
On an incoming call, requested values that do not match the configured values will be refused.
Table 64 lists the flow control options supported by X.25 during PVC to SVC switching.
Table 65 lists the call control options supported by X.25 during PVC to SVC switching.
Examples
The following example configures PVC to SVC switching between two serial interfaces:
x25 routinginterface serial0encapsulation x25x25 address 201700x25 ltc 128x25 idle 2interface serial2encapsulation x25 dcex25 address 101702x25 route ^20 interface serial0x25 route ^10 interface serial2interface serial0x25 pvc 5 svc 101601 packetsize 128 128 windowsize 2 2 no-incomingx25 pvc 6 svc 101602 packetsize 128 128 windowsize 2 2 no-outgoing idle 0x25 pvc 7 svc 101603 packetsize 128 128 windowsize 2 2Any call with a destination address beginning with 20 will be routed to serial interface 0. Any call with a destination address beginning with 10 will be routed to serial interface 2. (Note that incoming calls will not be routed back to the same interface from which they arrived.)
Traffic received on PVC 5 on serial interface 0 will cause a call to be placed from address 201700 to the X.121 address 101601. The routing table will then forward the call to serial interface 2. If no data is sent or received on the circuit for two minutes, the call will be cleared, as defined by the x25 idle command. All incoming calls from 101601 to 201700 will be refused, as defined by the no-incoming attribute.
The second x25 pvc command configures the circuit to allow incoming calls from 101602 to 201700 to be connected to PVC 6 on serial interface 1. Because idle is set to 0, the call will remain connected until cleared by the remote host or an X.25 restart. Because outgoing calls are not permitted for this connection, if traffic is received on PVC 6 on serial interface 0 before the call is established, the traffic will be discarded and the PVC will be reset.
The last x25 pvc command configures the circuit to accept an incoming call from 101603 to 201700 and connects the call to PVC 7 on serial interface 0. If no data is sent or received on the circuit for two minutes, the call will be cleared. If traffic is received on PVC 7 on serial interface 0 before the call is established, a call will be placed to 101503 to 201700.
x25 pvc (XOT)
To connect two permanent virtual circuits (PVCs) across a TCP/IP LAN, use the X.25-over-TCP (XOT) service form of the x25 pvc interface configuration command.
x25 pvc number1 xot address interface serial string pvc number2 [option]
Syntax Description
number1
PVC number of the connecting device.
xot
Indicates two PVCs will be connected across a TCP/IP LAN using XOT.
address
IP address of the device to which you are connecting.
interface serial
Indicates the interface is serial.
string
Serial interface specification that accepts either a number or a string in model 7000 format (number/number) to denote the serial interface.
pvc
Indicates a PVC.
number2
Remote PVC number on the target interface.
option
(Optional) Adds certain features for the connection; can be one or more of the options listed in Table 66.
Defaults
The PVC window and packet sizes default to the interface default values.
The default for the xot-keepalive-period option is 60 seconds.
The default for the xot-keepalive-tries option is 4 tries.
Command Modes
Interface configuration
Command History
Usage Guidelines
Use the PVC tunnel commands to tell the Cisco IOS software what the far end of the PVC is connected to. The incoming and outgoing packet sizes and window sizes must match the remote PVC outgoing and incoming sizes.
It is recommended that the xot-source option be used on the remote host so that a consistent IP address is used for the connection.
Table 66 lists the PVC tunnel options supported by X.25.
Each XOT connection relies on a TCP session to carry traffic. To ensure that these TCP sessions remain connected in the absence of XOT traffic, use the service tcp-keepalives-in and service tcp-keepalives-out global configuration commands. If TCP keepalives are not enabled, the XOT PVCs might encounter problems if one end of the connection is reloaded. When the reloaded host attempts to establish a new connection, the other host refuses the new connection because it has not been informed that the old session is no longer active. Recovery from this state requires the other host to be informed that its TCP session is no longer viable so that it attempts to reconnect the PVC.
Also, TCP keepalives inform a router when an XOT switched virtual circuit (SVC) session is not active, thus freeing the router's resources.
Examples
The following example enters the parameters for one side of a connection destined for a platform other than the Cisco 7000 series with RSP7000:
service tcp-keepalives-inservice tcp-keepalives-outinterface serial 0x25 pvc 1 xot 172.20.1.2 interface serial 1 pvc 2The following example enters the parameters for one side of a connection destined for the Cisco 7000 series with RSP7000:service tcp-keepalives-inservice tcp-keepalives-outinterface serial 0x25 pvc 1 xot 172.20.1.2 interface serial 1/1 pvc 2Refer to the section "X.25 and LAPB Configuration Examples" in the Cisco IOS Wide-Area Networking Configuration Guide for more complete configuration examples.
Related Commands
