346 Chapter 10: ISDN and Dial-on-Demand Routing
Example 10-5 Completed SanFrancisco Configuration (Continued)
username GothamCity password Bruce
!
isdn switch-type basic-ni1
!
access-list 101 permit tcp any host 172.16.3.1 eq 80 access-list 101 permit tcp any host 172.16.4.1 eq 21
!
dialer-list 2 protocol ip list 101
!
interface bri 0
ip address 172.16.2.2 255.255.255.0 encapsulation ppp
ppp authentication chap isdn spid1 555555111101 isdn spid2 555555222202 dialer idle-timeout 300 dialer fast-idle 120
dialer map ip 172.16.2.1 broadcast name LosAngeles 14045551234
dialer map ip 172.16.2.3 broadcast speed 56 name GothamCity 19999999999 dialer-group 2
!
router igrp 6 network 172.16.0.0
Example 10-6 LosAngeles Configuration: Receive Only
username SanFrancisco password Clark
!
interface bri 0 encapsulation ppp
ppp authentication chap isdn switch-type basic-ni1
!
router igrp 6 network 172.16.0.0
IOS expects you to define the type of ISDN switch to which the router is connected. You can do so with the isdn switch-type command, either as a global command or with an interface subcommand. When you have multiple ISDN lines, you can use the global command to cover all interfaces.
ISDN Configuration and Dial-on-Demand Routing 347
Table 10-11 lists the types of switches.
Table 10-11 ISDN Switch Types
Type of Switch |
Where It Is Typically Found |
|
|
basic-net3 |
Australia, Europe, UK |
|
|
vn3 |
France |
|
|
ntt |
Japan |
|
|
basic-5ess |
North America |
|
|
basic-dms100 |
North America |
|
|
basic-ni1 |
North America |
|
|
You might need to configure the Service Profile Identifier (SPID) for one or both B channels, depending on the switch’s expectations. When the telco switch has configured SPIDs, it might not allow the BRI line to work unless the router announces the correct SPID values to the switch. SPIDs, when used, provide a basic authentication feature. If your service provider tells you it uses SPIDs, you should configure them, or signaling will not work.
Example 10-5 shows the commands used to configure the SPIDs. The isdn spid1 and isdn spid2 commands define the SPIDs for the first and second B channels, respectively.
To actually configure the ISDN BRI details, you simply configure the switch type, and SPIDs, if needed. The hard part typically is configuring the DDR commands. Table 10-12 summarizes the commands needed to configure ISDN BRI, beyond what is needed for Legacy DDR configuration.
Table 10-12 Summary of the New Configuration Needed for ISDN BRI Beyond Legacy DDR Configuration
Command |
Description |
Configuration Mode |
|
|
|
isdn spid1 spid |
Configures SPIDs as necessary. |
Physical interface |
isdn spid2 spid |
|
|
|
|
|
isdn switch-type type |
Configures the ISDN switch type. |
Global or physical interface |
|
|
|
Summary of Legacy DDR Configuration
You have finally made it through enough details to see a completed working configuration for Legacy DDR using the ISDN BRI interfaces. Before moving on to the other topics in this chapter, a brief review might help. Table 10-13 summarizes the commands needed to configure Legacy DDR, with some explanation of each function.
348 Chapter 10: ISDN and Dial-on-Demand Routing
Table 10-13 Summary Legacy DDR Configuration Commands
Command |
Description |
|
|
ip route |
Global command that configures static routes |
|
that route traffic out an ISDN interface. |
|
|
username name password secret |
Global command that configures CHAP |
|
usernames and passwords. |
|
|
access-list |
Global command that creates ACLs if you |
|
need to define a subset of traffic as |
|
“interesting.” |
|
|
dialer-list number protocol ip [list acl-number] |
Global command that creates a dialer list |
|
that either makes all IP traffic interesting or |
|
references the ACL to make a subset |
|
interesting. |
|
|
interface bri int-number |
Global command that selects ISDN BRI to |
|
use for DDR. |
|
|
encapsulation ppp |
Interface subcommands that configure PPP |
|
and enable CHAP. |
ppp authentication chap |
|
|
|
isdn spid1 value |
Interface subcommands that set ISDN SPID |
|
values if needed. |
isdn spid2 value |
|
|
|
dialer idle-timeout time |
Interface subcommands that set idle timeout |
|
values. |
dialer fast-idle time |
|
|
|
dialer-group number |
Interface subcommand that references the |
|
dialer list to define what is interesting. |
|
|
dialer string number |
Interface subcommands that define dial |
|
numbers for one site or many. |
dialer map ip next-hop-ip number |
|
|
|
ISDN and DDR show and debug Commands
To examine the status of ISDN, you can use ISDN show and debug commands. Example 10-7 also includes some sample output that matches the completed example shown in this chapter.
Example 10-7 SanFrancisco DDR Commands
!
! This next command occurred before the physical interface even came up.
!
SanFrancisco# show interfaces bri 0:1
BRI0:1 is down, line protocol is down
Hardware is BRI
350 Chapter 10: ISDN and Dial-on-Demand Routing
Example 10-7 SanFrancisco DDR Commands (Continued)
-------------------------------------------------------------------------------
History Table MaxLength = 320 entries
History Retain Timer = 15 Minutes
-------------------------------------------------------------------------------
Call |
Calling |
Called |
Duration |
Remote |
Time until |
Recorded Charges |
Type |
Number |
Number |
Seconds |
Name |
Disconnect |
Units/Currency |
-------------------------------------------------------------------------------
Out 14045551234 Active(847) LosAngeles 11 u
-------------------------------------------------------------------------------
!
!This next command shows an active “Layer 3” call, meaning that the Q.931
!signaling has created a call.
!
SanFrancisco# show isdn status
The current ISDN Switchtype = ntt
ISDN BRI0 interface
Layer 1 Status:
ACTIVE
Layer 2 Status:
TEI = 64, State = MULTIPLE_FRAME_ESTABLISHED
Layer 3 Status:
1 Active Layer 3 Call(s) Activated dsl 0 CCBs = 1
CCB:callid=8003, callref=0, sapi=0, ces=1, B-chan=1
Number of active calls = 1
Number of available B channels = 1
Total Allocated ISDN CCBs = 1
!
!The debug was turned on while the call was down, and then the call was made,
!so the debug output would show the Q.931 signaling to set up the call.
!
SanFrancisco# debug isdn q931
ISDN q931 protocol debugging is on
TX -> SETUP pd = 8 callref = 0x04
Bearer Capability i = 0x8890
Channel ID i = 0x83
Called Party Number i = 0x80, ’14045551234’
SanFrancisco#no debug all
All possible debugging has been turned off
!
!This next debug command was also done before the call was established so that
!when the call was set up, the output would show some useful information. In
!this case, the “interesting” traffic that causes the call is shown.
!
SanFrancisco# debug dialer events
Dialer event debugging is on
Dialing cause: BRI0: ip (s=172.16.1.1, d=172.16.3.1)
352 Chapter 10: ISDN and Dial-on-Demand Routing
With PRI, you have only a few things to configure as well. Other than the same familiar DDR and interface configuration, you mainly need to configure the following:
■Configure the type of ISDN switch to which this router is connected.
■Configure the T1 or E1 encoding and framing options (controller configuration mode).
■Configure the T1 or E1 channel range for the DS0 channels used on this PRI (controller configuration mode).
■Configure any interface settings (for example, PPP encapsulation and IP address) on the interface representing the D channel.
The configuration itself does not require a lot of extra effort as compared with ISDN BRI.
The only truly new things are the T1 or E1 controller and the new way to identify the D channel on the PRI interface.
Configuring a T1 or E1 Controller
When you add a physical interface to a Cisco router, the router recognizes a new serial interface with a new unique number. With PRIs, IOS calls the interface a serial interface. For instance, a PRI interface might simply be known as “interface serial 1/0.”
Along with the interface, any channelized T1 or E1 interface in a router, including a PRI, also has a separate configuration mode associated with each physical interface. Controller configuration mode allows you to configure physical layer parameters—the encoding, framing, and T1 or E1 channels that are in use. By separating these Layer 1 configuration details from the serial interface, the configuration on the serial interface looks like it would on any other dial interface, and with the PRI-specific configuration sitting under the controller.
The things you configure under the controller can typically be learned simply by looking at the paperwork from where you ordered the PRI. Your service provider will tell you what encoding and framing to configure on the router. Also, in almost every case, you will use all 24 DS0 channels in the PRI—23 B channels and the D channel.
To configure these options, you must first enter controller configuration mode. Example 10-8 shows the basics.
Example 10-8 PRI Controller Configuration Example
SanFrancisco(config)#controller t1 1/0
SanFrancisco(config-controller)#framing esf
SanFrancisco(config-controller)#linecode b8zs
SanFrancisco(config-controller)#pri-group timeslots 1-24
ISDN Configuration and Dial-on-Demand Routing 353
In this example, the PRI interface is installed as interface serial 1/0. To configure the PRI’s Layer 1 details, you use the controller t1 1/0 command to enter controller configuration mode for that interface. The rest of the commands are somewhat self-explanatory. You should note that the 24 channels in the PRI are numbered 1 through 24, with the last one being the D channel.
Full PRI Configuration
The only other thing you need to configure for PRI is the switch type, plus all the other things you need to configure DDR—an IP address, PPP, dialer groups, and so on. Example 10-9 shows a completed configuration on SanFrancisco, with the BRI replaced with a PRI.
Example 10-9 PRI Controller Configuration Example: Completed Configuration on SanFrancisco
Controller t1 1/0 framing esf linecode b8zs
pri-group timeslots 1-24
!
ip route 172.16.3.0 255.255.255.0 172.16.2.1 ip route 172.16.4.0 255.255.255.0 172.16.2.3
!
username LosAngeles password Clark username GothamCity password Bruce
!
isdn switch-type basic-ni1
!
access-list 101 permit tcp any host 172.16.3.1 eq 80 access-list 101 permit tcp any host 172.16.4.1 eq 21
!
dialer-list 2 protocol ip list 101
!
interface serial 1/0:23
ip address 172.16.2.2 255.255.255.0 encapsulation ppp
ppp authentication chap dialer idle-timeout 300 dialer fast-idle 120
dialer map ip 172.16.2.1 broadcast name LosAngeles 14045551234
dialer map ip 172.16.2.3 broadcast speed 56 name GothamCity 19999999999 dialer-group 2
!
router igrp 6 network 172.16.0.0
354 Chapter 10: ISDN and Dial-on-Demand Routing
There are a couple of very important things to notice about this example. First, the highlighted commands are those added specifically for PRI. The rest are exactly like the ones in the complete configuration for DDR using BRI in Example 10-4. Also note that no SPIDs are listed under the interface, because PRIs do not use SPIDs.
The most unusual part of the configuration introduces the concept of actually identifying the D channel in the interface command. Notice the command interface serial 1/0:23. The :x notation, where x identifies one of the channels inside the PRI, tells the IOS which of the 24 channels you want to configure. The DDR interface subcommands should be configured on the D channel, which is channel 23 according to the command! The interface command numbers the channels from 0 through 23, with the D channel as the last channel, so the :23 at the end correctly tells IOS that you are configuring details for the 24th channel—the D channel. (You do not need to configure anything on the B channels specifically for PRI, but you will see specific B channels listed in the output of show and debug commands.)
So, to actually configure the ISDN PRI details, you simply configure the ISDN switch type, ignore SPIDs completely, and configure the details needed under the controller. Table 10-14 summarizes the commands needed to configure ISDN PRI beyond what is needed for Legacy DDR configuration.
Table 10-14 Summary of the New Configuration Needed for ISDN PRI Beyond Legacy DDR Configuration
Command |
Description |
Configuration Mode |
|
|
|
isdn switch-type type |
Configures the ISDN switch |
Global or physical |
|
type. |
interface |
|
|
|
linecode ami | b8zs | hdb3 |
Configures encoding for the |
Controller configuration |
|
T1/E1 circuit. |
|
|
|
|
framing sf | esf | crc4 |
Configures framing for the |
Controller configuration |
|
T1/E1 circuit. |
|
|
|
|
pri-group timeslots |
Configures the DS0 |
Controller configuration |
starting_channel - ending_channel |
channels used on this PRI. |
|
|
|
|
DDR Configuration with Dialer Profiles
The configuration for Legacy DDR requires a route to point packets out a particular physical interface. As soon as the packets are routed out the interface, DDR logic can decide if the packet is interesting. If it is interesting, DDR logic causes the dial to occur.
With Legacy DDR, there is no way to support a single set of remote sites through configuration using multiple different BRIs or PRIs in a single router. When you have multiple BRIs or PRIs, Legacy DDR allows you to dial only one set of sites using one interface and another set of sites with the other, as shown in Figure 10-8.
358 Chapter 10: ISDN and Dial-on-Demand Routing
Example 10-10 SanFrancisco Configuration Migrated to Use Dialer Profiles and Two BRIs (Continued)
!
interface bri1 encapsulation ppp
ppp authentication chap isdn spid1 555555333301 isdn spid2 555555444402 dialer pool-member 3
!
router igrp 6 network 172.16.0.0
The following paragraphs take you through the configuration from top to bottom. First, the ip route commands are unchanged: They still refer to next-hop IP addresses in subnet 172.16.1.0/24. However, now the dialer interface, with address and mask of 172.16.1.2/24, is the implied outgoing interface.
Next, you see several items that are unchanged in both syntax and how they are used. The CHAP usernames and password come next, followed by the global isdn switch-type command. These work just as they always have. Likewise, the access-list commands define the interesting logic—with the same old parameters—and the dialer-list 2 command refers to those ACLs to define what is interesting and what is not.
The interface dialer 0 command comes next. It creates the virtual dialer interface. If you compare this example with Example 10-4, the Legacy DDR configuration, you will note that all the commands formerly found under BRI0 have been copied under the dialer interface, with the exception of SPIDs and switch-type commands.
The static routes now forward the packets out the dialer interface because now the dialer interface’s IP address is the same subnet as the destination IP address in the static route commands. However, the dialer interface itself cannot place a call, so the router notices the dialer pool 3 command under interface dialer 0. This tells the router to look for any ISDN interface in dialer pool 3 to actually place the call.
The two BRI interfaces come next. Each has its respective SPIDs configured. Also, each is placed in the same pool with the dialer pool-member 3 command. So both interfaces are available to the dialer interface for use to dial remote sites.
With DDR dialer profiles, you can configure many advanced features. For instance, Figure 10-10 shows the usage of multiple dialer interfaces along with some physical interfaces that are part of more than one pool.