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This chapter describes how to configure X.25 over ISDN. It includes the following main sections:
For a complete description of the commands mentioned in this chapter, see the Cisco IOS Dial Services Command Reference publication. To locate documentation of other commands that appear in this chapter, use the command reference master index or search online.
BRI is an ISDN interface, and it consists of two B channels (B1 and B2) and one D channel. The B channels are used to transfer data, voice, and video. The D channel controls the B channels.
ISDN uses the D channel to carry signal information. ISDN can also use the D channel in a BRI to carry X.25 packets. The D channel has a capacity of 16 kbps, and the X.25 over D channel can utilize up to 9.6 kbps.
When X.25 on ISDN is configured, a separate X.25-over-D-channel logical interface is created. You can set its parameters without disrupting the original ISDN interface configuration. The original BRI interface will continue to represent the D, B1, and B2 channels.
Because some end-user equipment uses static terminal endpoint identifiers (TEIs) to access this feature, static TEIs are supported. The dialer understands the X.25-over-D-channel calls and initiates them on a new interface.
This feature is not available on the ISDN PRI.
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Note X.25 on ISDN is also supported using the ISDN Always On/Dynamic (AO/DI) feature. AO/DI uses the Multilink PPP (MLP) protocol signalling with standard Q.922 and X.25 encapsulations, and can additionally use the Bandwidth Allocation Control Protocol (BACP) to optimize bandwidth on demand. For information about how to configure AO/DI, see the chapter "Configuring X.25 on ISDN Using AO/DI" in this publication. |
Current Cisco IOS software enables circuit-switched X.25 clients---PAD, X.25 switching, and Qualified Logical Link Control (QLLC)---to initiate calls and dynamically bring the X.25 context (which runs the X.25 protocol) up or down as needed. This capability allows packet-switched traffic over ISDN.
In earlier releases of the Cisco IOS software, X.25 circuit-switched clients were required to do an X.25 route lookup to forward a call. If the lookup resulted in a route to a dialer interface, the client would check the X.25 protocol state on the dialer interface. If the interface was not already bound to run the X.25 protocol, the software would reroute the call instead of bringing up a link and running the X.25 protocol. With this new feature, the X.25 context is dynamically created on demand and then removed when the X.25 session is cleared on the dialer interface.
For dialer profile interfaces, the X.25 context is created on the dialer interface, because X.25 protocol functions run on the dialer interface itself. Member links act like forwarding devices, because their topmost interface runs the actual encapsulated protocol. But for legacy dialer interfaces, the X.25 context is created on the member links once they come up and bind to a dialer.
There are no specific configuration tasks required to enable outbound circuit-switched X.25 support. See the "Outbound Circuit-Switched X.25" example in the section "X.25 on ISDN Configuration Examples" at the end of this chapter for an example of how to make use of this feature in your network.
You can configure X.25 on ISDN in three ways:
| Command | Purpose | |
|---|---|---|
Step 1 | interface bri number | Specifies an ISDN BRI interface. |
Step2 | isdn x25 static-tei tei-number | Specifies a static TEI, if required by the switch. |
Step3 | isdn x25 dchannel | Creates a configurable interface for X.25 traffic over the ISDN Dchannel. |
The last step is to configure the X.25-over-ISDN interface for X.25 traffic. See the chapter "Configuring LAPB and X.25" in the Cisco IOS Wide-Area Networking Configuration Guide for the commands and tasks.
The new X.25-over-ISDN interface is called interface bri number:0 in configuration displays. It must be configured as an individual X.25 interface. For information about configuring an interface for X.25 traffic, see the Cisco IOS Wide-Area Networking Configuration Guide.
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NoteThe encapsulation x25 command is neither required nor used on this new interface, but other X.25 commands can be used to configure this interface. |
If you want to remove the X.25-over-ISDN interface later, use the no isdn x25 dchannel command.
See the section "X.25 on ISDN D-Channel Configuration" at the end of this chapter for a configuration example.
This section illustrates X.25 on ISDN with the following examples:
interface bri0 isdn x25 dchannel isdn x25 static-tei 8 ! interface bri0:0 ip address 10.1.1.2 255.255.255.0 x25 address 31107000000100 x25 htc 1 x25 suppress-calling-address x25 facility windowsize 2 2 x25 facility packetsize 256 256 x25 facility throughput 9600 9600 x25 map ip 10.1.1.3 31107000000200
The following example shows how to configure dynamic X.25 on an ISDN interface. Figure 23 illustrates the configuration.
Configuration for Yen
version 12.0(5)T service timestamps debug uptime service timestamps log uptime no service password-encryption service udp-small-servers service tcp-small-servers ! hostname yen ! enable secret 5 $1$K32j$4AZW2oMDivpUeuMa/Fdcd. enable password secret ! username mark password 0 cisco username dinar password 0 cisco ip subnet-zero no ip domain-lookup ip domain-name cicso.com ip name-server 172.18.1.148 ! isdn switch-type basic-5ess x25 routing ! interface Loopback0 no ip address no ip directed-broadcast no ip mroute-cache ! interface Ethernet0 ip address 172.21.75.2 255.255.255.0 no ip directed-broadcast no ip mroute-cache media-type 10BaseT ! interface BRI1 no ip address no ip directed-broadcast no ip mroute-cache dialer pool-member 1 isdn switch-type basic-5ess no fair-queue ! interface Dialer0 ip address 2.1.1.1 255.0.0.0 no ip directed-broadcast encapsulation x25 no ip mroute-cache dialer remote-name dinar dialer idle-timeout 180 dialer string 81060 dialer caller 81060 dialer max-call 1 dialer pool 1 dialer-group 1 x25 address 11111 x25 map ip 2.1.1.2 22222 ! ip default-gateway 172.21.75.1 no ip classless ip route 0.0.0.0 0.0.0.0 172.21.75.1 no ip http server ! access-list 101 permit ip any any dialer-list 1 protocol ip list 101 ! x25 route 22222 interface Dialer0 x25 route 33333 interface Dialer0 ! line con 0 exec-timeout 0 0 transport input none line aux 0 transport input all line vty 0 4 password cisco login line vty 5 100 password cisco login ! end
Configuration for Peso Acting as X.25 Switch
version 12.0(5)T service timestamps debug uptime service timestamps log uptime no service password-encryption ! hostname peso ! enable secret 5 $1$.Q00$h3vIhbOwO1fPvA2LYx2gE. enable password cisco ! ip subnet-zero ! isdn switch-type primary-5ess x25 routing ! controller T1 0 cablelength short cablelength short 133 ! controller T1 1 framing esf clock source line primary pri-group timeslots 1-24 ! controller T1 2 cablelength short cablelength short 133 ! controller T1 3 cablelength short cablelength short 133 ! interface Ethernet0 ip address 172.21.75.3 255.255.255.0 no ip directed-broadcast ! interface Serial1:23 no ip address no ip directed-broadcast encapsulation ppp dialer pool-member 1 isdn switch-type primary-5ess isdn incoming-voice modem no fair-queue no cdp enable ppp authentication chap ! interface Dialer0 no ip address no ip directed-broadcast encapsulation x25 dce no ip mroute-cache dialer remote-name yen dialer idle-timeout 180 dialer string 61401 dialer caller 61401 dialer max-call 1 dialer pool 1 x25 address 33333 ! interface Dialer1 no ip address no ip directed-broadcast encapsulation x25 dce no ip mroute-cache dialer remote-name dinar dialer idle-timeout 180 dialer string 61403 dialer caller 61403 dialer max-call 1 dialer pool 1 x25 address 44444 ! ip default-gateway 172.21.75.1 no ip classless ip route 0.0.0.0 0.0.0.0 172.21.75.1 no ip http server ! x25 route 11111 interface Dialer0 x25 route 22222 interface Dialer1 x25 route source 11111 interface Dialer1 x25 route input-interface Dialer0 interface Dialer1 ! line con 0 transport input none line 1 48 line aux 0 line vty 0 4 password cisco login line vty 5 100 password cisco login ! end
version 12.0(5)T service timestamps debug uptime service timestamps log uptime no service password-encryption ! hostname dinar ! logging buffered 16384 debugging enable secret 5 $1$8EjF$4.S0AoMOVa5OIAYEMrrFI/ enable password cisco ! username yen password 0 cisco username 7701 username drachma password 0 cisco username AODI password 0 cisco ip subnet-zero ip rcmd rcp-enable ip rcmd rsh-enable ip rcmd remote-username atirumal ! isdn switch-type basic-5ess x25 routing ! controller T1 0/0 ! interface BRI3/1 no ip address no ip directed-broadcast no ip mroute-cache dialer pool-member 1 isdn switch-type basic-5ess no fair-queue ! interface Dialer0 ip address 2.1.1.2 255.0.0.0 no ip directed-broadcast encapsulation x25 no ip mroute-cache dialer remote-name yen dialer idle-timeout 180 dialer string 81060 dialer caller 81060 dialer max-call 1 dialer pool 1 dialer-group 1 x25 address 22222 x25 map ip 2.1.1.1 11111 ! interface Dialer1 ip address 6.1.1.10 255.0.0.0 no ip directed-broadcast no ip mroute-cache dialer in-band dialer-group 1 no fair-queue ! ip default-gateway 172.21.75.1 no ip classless ip route 0.0.0.0 0.0.0.0 172.21.75.1 no ip http server ! access-list 101 permit ip any any dialer-list 1 protocol ip list 101 ! x25 route 11111 interface Dialer0 x25 route 44444 interface Dialer0 !
Posted: Tue Jul 18 15:15:49 PDT 2000
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