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This chapter describes how to prepare asynchronous interfaces to allow connections such as analog modem calls to enter an access server. These tasks are presented in the following main sections:
See the section "Asynchronous Interfaces" in the chapter "Interfaces, Controllers, and Lines Used for Dial Access Overview" for more information about Cisco asynchronous serial interfaces.
For a complete description of the modem support commands 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.
Modems attach to asynchronous lines, which in turn attach to asynchronous interfaces. Depending on the type of access server you have, these components appear outside or inside the physical chassis. Figure 14 shows the logical relationship between modems, asynchronous lines, asynchronous interfaces, and group asynchronous interfaces. All these components work together to deliver packets as follows:
 |
Note The number of interfaces and modems varies among access server product models. |
Deciding which asynchronous features to use, to some degree, depends on your hardware configuration. All Cisco access servers must have their asynchronous interfaces and lines configured for network protocol support. Commands entered in asynchronous interface mode configure protocol-specific parameters for asynchronous interfaces, whereas commands entered in line configuration mode configure the physical and logical aspects for the same port.
Modems inside high-end access servers need localized modem country code. This code is projected from the Cisco IOS software to the onboard modems using the modem country {mica | microcom_hdms} country command. The following are high-end access servers: Cisco AS5800, Cisco AccessPath, Cisco AS5300, and the Cisco AS5200.
Modems externally attached to low-end access servers need to receive initialization strings from the modem autoconfigure discovery command. For troubleshooting tips, see the section "Attaching External Modems" in the chapter "Configuring Modems and Chat Scripts." The following are low-end access servers: Cisco AS2511-RJ, Cisco AS2509-RJ, Cisco 2509, Cisco 2511, and the Cisco 2512.
Figure 15 shows a Cisco AS2511-RJ access server. Figure 16 shows a Cisco AS5300 access server. Notice that modems are either inside or outside the chassis, depending on the product model.
Asynchronous line configuration commands configure ports for the following options:
To enter line configuration mode, first connect to the console port of the access server and enter privileged EXEC mode. Then enter global configuration mode and finally enter line configuration mode for the asynchronous lines that you want to configure.
Interfaces enable the Cisco IOS software to use routing functions. Specifically, you configure asynchronous interfaces to support PPP connections. Asynchronous interfaces are configured on access servers for the following functions:
To configure multiple asynchronous interfaces at the same time (with the same parameters), you can assign each asynchronous interface to a group and then configure the group. Configurations throughout this guide configure group asynchronous interfaces, rather than each interface separately.
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Note If you want to configure different attributes on different asynchronous interfaces, do not assign them to the group or assign different interfaces to different groups. After assigning asynchronous interfaces to a group, you cannot configure these interfaces separately. For example, on a Cisco AS5300 access server in a T1 configuration, you could assign asynchronous interfaces 1 to 48 as part of one group (such as group-async1) and asynchronous interfaces 49 to 96 as part of another group (group-async2). You can also use the member command to perform a similar grouping function. |
The TTY line numbering scheme used by your access server or router is specific to your product and its hardware configuration. Refer to the product-specific documentation that came with your product for line numbering scheme information.
For example, the Cisco AS5200 access server has TTY lines that map directly to integrated modems, as shown in Table 4. Depending on the shelf, slot, and port physical architecture of the access server, the modem and TTY line number schemes will change.
As shown in Table 4, TTY lines 1 through 24 directly connect to modems 1/0 through 1/23, which are installed in the first chassis slot in this example. The TTY lines 25 through 48 directly connect to modems 2/0 through 2/23, which are installed in the second slot.
| TTY Line | Slot/Modem Number | TTY Line | Slot/Modem Number |
|---|---|---|---|
1 | 1/0 | 25 | 2/0 |
2 | 1/1 | 26 | 2/1 |
3 | 1/2 | 27 | 2/2 |
4 | 1/3 | 28 | 2/3 |
5 | 1/4 | 29 | 2/4 |
6 | 1/5 | 30 | 2/5 |
7 | 1/6 | 31 | 2/6 |
8 | 1/7 | 32 | 2/7 |
9 | 1/8 | 33 | 2/8 |
10 | 1/9 | 34 | 2/9 |
11 | 1/10 | 35 | 2/10 |
12 | 1/11 | 36 | 2/11 |
13 | 1/12 | 37 | 2/12 |
14 | 1/13 | 38 | 2/13 |
15 | 1/14 | 39 | 2/14 |
16 | 1/15 | 40 | 2/15 |
17 | 1/16 | 41 | 2/16 |
18 | 1/17 | 42 | 2/17 |
19 | 1/18 | 43 | 2/18 |
20 | 1/19 | 44 | 2/19 |
21 | 1/20 | 45 | 2/20 |
22 | 1/21 | 46 | 2/21 |
23 | 1/22 | 47 | 2/22 |
24 | 1/23 | 48 | 2/23 |
To configure an asynchronous interface, perform the tasks in the following sections. The first task is required; the second task is optional.
To configure a group asynchronous interface, use the following commands beginning in global configuration mode:
| Command | Purpose | |
|---|---|---|
Step 1 | interface async number | Brings up a single asynchronous interface. |
Step2 | description description | Provides a description for the interface. |
Step3 | ip address address mask | Specifies an IP address. |
Step4 | encapsulation ppp | Enables PPP to run on the asynchronous interfaces in the group. |
Step5 | async default routing | Enables the router to pass routing updates to other routers over the AUX port configured as an asynchronous interface. |
Step6 | async mode dedicated | Places a line into dedicated asynchronous mode using Serial Line Internet Protocol (SLIP) or PPP encapsulation. |
Step7 | dialer in-band | Specifies that dial-on-demand routing (DDR) is to be supported. |
Step8 | dialer map protocol next-hop-address | Configures a serial interface to call one or multiple sites or to receive calls from multiple sites. |
Step9 | dialer-group | Controls access by configuring an interface to belong to a specific dialing group. |
Step10 | ppp authentication chap pap list-name | Enables Challenge Handshake Authentication Protocol (CHAP) and Password Authentication Protocol (PAP) authentication on the interface. Replace the list-name variable with a specified authentication list name.1 |
Step11 | exit | Return to global configuration mode. |
See the sections "Configuring an Asynchronous Interface" and "Asynchronous Interface As the Only Network Interface" later in this chapter for examples of how to configure an asynchronous interface.
Create a group asynchronous interface to project a set of core protocol characteristics to a range of asynchronous interfaces. Configuring the asynchronous interfaces as a group saves you time. Analog modem calls cannot enter the access server without this configuration.
To configure a group asynchronous interface, use the following commands beginning in global configuration mode:
| Command | Purpose | |
|---|---|---|
Step1 | interface group-async number | Brings up a single group asynchronous interface. |
Step2 | ip unnumbered loopback number | Configures the asynchronous interfaces as unnumbered, and assigns the IP address of the loopback interface to them, to conserve IP addresses.1 |
Step3 | encapsulation ppp | Enables PPP to run on the asynchronous interfaces in the group. |
Step4 | async mode interactive | Configures interactive mode on the asynchronous interface. |
Step5 | ppp authentication chap pap list-name | Enables CHAP and PAP authentication on the interface. Replace the list-name variable with a specified authentication list name.2 |
Step6 | peer default ip address pool poolname | Assigns dial-in clients IP addresses from an address pool.3 |
Step7 | no cdp enable | Disables the Cisco Discovery Protocol (CDP) on the interface. |
Step8 | group-range low-end-of-range high-end-of-range | Specifies the range of asynchronous interfaces to include in the group, which is usually equal to the number of modems you have in the access server. |
Step9 | exit | Returns to global configuration mode. |
See the section "Creating a Group Asynchronous Interface" later in this chapter for an example of how to configure a group interface.
To verify the group interface configuration and check if one of the asynchronous interfaces is up, use the show interface async command:
NAS# show interface async 1
Async1 is up, line protocol is up
modem(slot/port)=1/0, csm_state(0x00000204)=CSM_IC4_CONNECTED, bchan_num=18
modem_status(0x0002): VDEV_STATUS_ACTIVE_CALL.
Hardware is Async Serial
Interface is unnumbered. Using address of FastEthernet0 (10.1.1.10)
MTU 1500 bytes, BW 115 Kbit, DLY 100000 usec, rely 255/255, load 1/255
Encapsulation PPP, loopback not set, keepalive not set
DTR is pulsed for 5 seconds on reset
LCP Open
Open: IPCP
Last input 00:00:00, output 00:00:00, output hang never
Last clearing of "show interface" counters never
Queueing strategy: fifo
Output queue 0/5, 0 drops; input queue 1/5, 0 drops
5 minute input rate 37000 bits/sec, 87 packets/sec
5 minute output rate 0 bits/sec, 0 packets/sec
31063 packets input, 1459806 bytes, 0 no buffer
Received 0 broadcasts, 0 runts, 0 giants, 0 throttles
0 input errors, 0 CRC, 0 frame, 0 overrun, 0 ignored, 0 abort
33 packets output, 1998 bytes, 0 underruns
0 output errors, 0 collisions, 0 interface resets
0 output buffer failures, 0 output buffers swapped out
0 carrier transitions
If you are having trouble, enter one of the following debug commands and then send a call into the access server. Interpret the output and make configuration changes accordingly.
nas-1# undebug all All possible debugging has been turned off nas-1# debug ppp negotiation PPP protocol negotiation debugging is on nas-1# debug ppp authentication PPP authentication debugging is on nas-1# debug modem Modem control/process activation debugging is on nas-1# debug ip peer IP peer address activity debugging is on nas-1# show debug General OS: Modem control/process activation debugging is on Generic IP: IP peer address activity debugging is on PPP: PPP authentication debugging is on PPP protocol negotiation debugging is on nas-1# *Mar 1 21:34:56.958: TTY4: DSR came up *Mar 1 21:34:56.962: tty4: Modem: IDLE->READY *Mar 1 21:34:56.970: TTY4: EXEC creation *Mar 1 21:34:56.978: TTY4: set timer type 10, 30 seconds *Mar 1 21:34:59.722: TTY4: Autoselect(2) sample 7E *Mar 1 21:34:59.726: TTY4: Autoselect(2) sample 7EFF *Mar 1 21:34:59.730: TTY4: Autoselect(2) sample 7EFF7D *Mar 1 21:34:59.730: TTY4: Autoselect(2) sample 7EFF7D23 *Mar 1 21:34:59.734: TTY4 Autoselect cmd: ppp negotiate *Mar 1 21:34:59.746: TTY4: EXEC creation *Mar 1 21:34:59.746: TTY4: create timer type 1, 600 seconds *Mar 1 21:34:59.786: ip_get_pool: As4: using pool default *Mar 1 21:34:59.790: ip_get_pool: As4: returning address = 172.20.1.101 *Mar 1 21:34:59.794: TTY4: destroy timer type 1 (OK) *Mar 1 21:34:59.794: TTY4: destroy timer type 0 *Mar 1 21:35:01.798: %LINK-3-UPDOWN: Interface Async4, changed state to up *Mar 1 21:35:01.834: As4 PPP: Treating connection as a dedicated line *Mar 1 21:35:01.838: As4 PPP: Phase is ESTABLISHING, Active Open *Mar 1 21:35:01.842: As4 LCP: O CONFREQ [Closed] id 1 len 25 *Mar 1 21:35:01.846: As4 LCP: ACCM 0x000A0000 (0x0206000A0000) *Mar 1 21:35:01.850: As4 LCP: AuthProto CHAP (0x0305C22305) *Mar 1 21:35:01.854: As4 LCP: MagicNumber 0x64E923A8 (0x050664E923A8) *Mar 1 21:35:01.854: As4 LCP: PFC (0x0702) *Mar 1 21:35:01.858: As4 LCP: ACFC (0x0802) *Mar 1 21:35:02.718: As4 LCP: I CONFREQ [REQsent] id 3 len 23 *Mar 1 21:35:02.722: As4 LCP: ACCM 0x000A0000 (0x0206000A0000) *Mar 1 21:35:02.726: As4 LCP: MagicNumber 0x00472467 (0x050600472467) *Mar 1 21:35:02.726: As4 LCP: PFC (0x0702) *Mar 1 21:35:02.730: As4 LCP: ACFC (0x0802) *Mar 1 21:35:02.730: As4 LCP: Callback 6 (0x0D0306) *Mar 1 21:35:02.738: As4 LCP: O CONFREJ [REQsent] id 3 len 7 *Mar 1 21:35:02.738: As4 LCP: Callback 6 (0x0D0306) *Mar 1 21:35:02.850: As4 LCP: I CONFREQ [REQsent] id 4 len 20 *Mar 1 21:35:02.854: As4 LCP: ACCM 0x000A0000 (0x0206000A0000) *Mar 1 21:35:02.854: As4 LCP: MagicNumber 0x00472467 (0x050600472467) *Mar 1 21:35:02.858: As4 LCP: PFC (0x0702) *Mar 1 21:35:02.858: As4 LCP: ACFC (0x0802) *Mar 1 21:35:02.862: As4 LCP: O CONFACK [REQsent] id 4 len 20 *Mar 1 21:35:02.866: As4 LCP: ACCM 0x000A0000 (0x0206000A0000) *Mar 1 21:35:02.870: As4 LCP: MagicNumber 0x00472467 (0x050600472467) *Mar 1 21:35:02.870: As4 LCP: PFC (0x0702) *Mar 1 21:35:02.874: As4 LCP: ACFC (0x0802) *Mar 1 21:35:03.842: As4 LCP: TIMEout: State ACKsent *Mar 1 21:35:03.842: As4 LCP: O CONFREQ [ACKsent] id 2 len 25 *Mar 1 21:35:03.846: As4 LCP: ACCM 0x000A0000 (0x0206000A0000) *Mar 1 21:35:03.850: As4 LCP: AuthProto CHAP (0x0305C22305) *Mar 1 21:35:03.854: As4 LCP: MagicNumber 0x64E923A8 (0x050664E923A8) *Mar 1 21:35:03.854: As4 LCP: PFC (0x0702) *Mar 1 21:35:03.858: As4 LCP: ACFC (0x0802) *Mar 1 21:35:03.962: As4 LCP: I CONFACK [ACKsent] id 2 len 25 *Mar 1 21:35:03.966: As4 LCP: ACCM 0x000A0000 (0x0206000A0000) *Mar 1 21:35:03.966: As4 LCP: AuthProto CHAP (0x0305C22305) *Mar 1 21:35:03.970: As4 LCP: MagicNumber 0x64E923A8 (0x050664E923A8) *Mar 1 21:35:03.974: As4 LCP: PFC (0x0702) *Mar 1 21:35:03.974: As4 LCP: ACFC (0x0802) *Mar 1 21:35:03.978: As4 LCP: State is Open *Mar 1 21:35:03.978: As4 PPP: Phase is AUTHENTICATING, by this end *Mar 1 21:35:03.982: As4 CHAP: O CHALLENGE id 1 len 26 from "nas-1" *Mar 1 21:35:04.162: As4 CHAP: I RESPONSE id 1 len 26 from "krist" *Mar 1 21:35:04.170: As4 AUTH: Started process 0 pid 47 *Mar 1 21:35:04.182: As4 CHAP: O SUCCESS id 1 len 4 *Mar 1 21:35:04.186: As4 PPP: Phase is UP *Mar 1 21:35:04.190: As4 IPCP: O CONFREQ [Not negotiated] id 1 len 10 *Mar 1 21:35:04.194: As4 IPCP: Address 172.20.1.2 (0x0306AC140102) *Mar 1 21:35:04.202: As4 CDPCP: O CONFREQ [Closed] id 1 len 4 *Mar 1 21:35:04.282: As4 IPCP: I CONFREQ [REQsent] id 1 len 40 *Mar 1 21:35:04.282: As4 IPCP: CompressType VJ 15 slots CompressSlotID (0x02 06002D0F01) *Mar 1 21:35:04.286: As4 IPCP: Address 0.0.0.0 (0x030600000000) *Mar 1 21:35:04.290: As4 IPCP: PrimaryDNS 0.0.0.0 (0x810600000000) *Mar 1 21:35:04.294: As4 IPCP: PrimaryWINS 0.0.0.0 (0x820600000000) *Mar 1 21:35:04.298: As4 IPCP: SecondaryDNS 0.0.0.0 (0x830600000000) *Mar 1 21:35:04.302: As4 IPCP: SecondaryWINS 0.0.0.0 (0x840600000000) *Mar 1 21:35:04.306: As4 IPCP: O CONFREJ [REQsent] id 1 len 10 *Mar 1 21:35:04.310: As4 IPCP: CompressType VJ 15 slots CompressSlotID (0x02 06002D0F01) *Mar 1 21:35:04.314: As4 CCP: I CONFREQ [Not negotiated] id 1 len 15 *Mar 1 21:35:04.318: As4 CCP: MS-PPC supported bits 0x00000001 (0x1206000000 01) *Mar 1 21:35:04.318: As4 CCP: Stacker history 1 check mode EXTENDED (0x11050 00104) *Mar 1 21:35:04.322: As4 LCP: O PROTREJ [Open] id 3 len 21 protocol CCP *Mar 1 21:35:04.326: As4 LCP: (0x80FD0101000F12060000000111050001) *Mar 1 21:35:04.330: As4 LCP: (0x04) *Mar 1 21:35:04.334: As4 IPCP: I CONFACK [REQsent] id 1 len 10 *Mar 1 21:35:04.338: As4 IPCP: Address 172.20.1.2 (0x0306AC140102) *Mar 1 21:35:04.342: As4 LCP: I PROTREJ [Open] id 5 len 10 protocol CDPCP (0x82 0701010004) *Mar 1 21:35:04.342: As4 CDPCP: State is Closed *Mar 1 21:35:05.186: %LINEPROTO-5-UPDOWN: Line protocol on Interface Async4, ch anged state to up *Mar 1 21:35:05.190: As4 PPP: Unsupported or un-negotiated protocol. Link cdp *Mar 1 21:35:05.190: As4 PPP: Trying to negotiate NCP for Link cdp *Mar 1 21:35:05.194: As4 CDPCP: State is Closed *Mar 1 21:35:05.198: As4 CDPCP: TIMEout: State Closed *Mar 1 21:35:05.202: As4 CDPCP: State is Listen *Mar 1 21:35:06.202: As4 IPCP: TIMEout: State ACKrcvd *Mar 1 21:35:06.206: As4 IPCP: O CONFREQ [ACKrcvd] id 2 len 10 *Mar 1 21:35:06.206: As4 IPCP: Address 172.20.1.2 (0x0306AC140102) *Mar 1 21:35:06.314: As4 IPCP: I CONFACK [REQsent] id 2 len 10 *Mar 1 21:35:06.318: As4 IPCP: Address 172.20.1.2 (0x0306AC140102) *Mar 1 21:35:07.274: As4 IPCP: I CONFREQ [ACKrcvd] id 2 len 34 *Mar 1 21:35:07.278: As4 IPCP: Address 0.0.0.0 (0x030600000000) *Mar 1 21:35:07.282: As4 IPCP: PrimaryDNS 0.0.0.0 (0x810600000000) *Mar 1 21:35:07.286: As4 IPCP: PrimaryWINS 0.0.0.0 (0x820600000000) *Mar 1 21:35:07.286: As4 IPCP: SecondaryDNS 0.0.0.0 (0x830600000000) *Mar 1 21:35:07.290: As4 IPCP: SecondaryWINS 0.0.0.0 (0x840600000000) *Mar 1 21:35:07.294: As4 IPCP: O CONFNAK [ACKrcvd] id 2 len 34 *Mar 1 21:35:07.298: As4 IPCP: Address 172.20.1.101 (0x0306AC140165) *Mar 1 21:35:07.302: As4 IPCP: PrimaryDNS 172.20.5.100 (0x8106AC140564) *Mar 1 21:35:07.306: As4 IPCP: PrimaryWINS 172.20.5.101 (0x8206AC140565) *Mar 1 21:35:07.310: As4 IPCP: SecondaryDNS 172.20.6.100 (0x8306AC140664) *Mar 1 21:35:07.314: As4 IPCP: SecondaryWINS 172.20.6.101 (0x8406AC140665) *Mar 1 21:35:07.426: As4 IPCP: I CONFREQ [ACKrcvd] id 3 len 34 *Mar 1 21:35:07.430: As4 IPCP: Address 172.20.1.101 (0x0306AC140165) *Mar 1 21:35:07.434: As4 IPCP: PrimaryDNS 172.20.5.100 (0x8106AC140564) *Mar 1 21:35:07.438: As4 IPCP: PrimaryWINS 172.20.5.101 (0x8206AC140565) *Mar 1 21:35:07.442: As4 IPCP: SecondaryDNS 172.20.6.100 (0x8306AC140664) *Mar 1 21:35:07.446: As4 IPCP: SecondaryWINS 172.20.6.101 (0x8406AC140665) *Mar 1 21:35:07.446: ip_get_pool: As4: validate address = 172.20.1.101 *Mar 1 21:35:07.450: ip_get_pool: As4: using pool default *Mar 1 21:35:07.450: ip_get_pool: As4: returning address = 172.20.1.101 *Mar 1 21:35:07.454: set_ip_peer_addr: As4: address = 172.20.1.101 (3) is redun dant *Mar 1 21:35:07.458: As4 IPCP: O CONFACK [ACKrcvd] id 3 len 34 *Mar 1 21:35:07.462: As4 IPCP: Address 172.20.1.101 (0x0306AC140165) *Mar 1 21:35:07.466: As4 IPCP: PrimaryDNS 172.20.5.100 (0x8106AC140564) *Mar 1 21:35:07.470: As4 IPCP: PrimaryWINS 172.20.5.101 (0x8206AC140565) *Mar 1 21:35:07.474: As4 IPCP: SecondaryDNS 172.20.6.100 (0x8306AC140664) *Mar 1 21:35:07.474: As4 IPCP: SecondaryWINS 172.20.6.101 (0x8406AC140665) *Mar 1 21:35:07.478: As4 IPCP: State is Open *Mar 1 21:35:07.490: As4 IPCP: Install route to 172.20.1.101 *Mar 1 21:35:25.038: As4 PPP: Unsupported or un-negotiated protocol. Link cdp *Mar 1 21:36:12.614: TTY0: timer type 1 expired *Mar 1 21:36:12.614: TTY0: Exec timer (continued) *Mar 1 21:36:25.038: As4 PPP: Unsupported or un-negotiated protocol. Link cdp *Mar 1 21:37:25.038: As4 PPP: Unsupported or un-negotiated protocol. Link cdp *Mar 1 21:38:25.038: As4 PPP: Unsupported or un-negotiated protocol. Link cdp *Mar 1 21:39:25.038: As4 PPP: Unsupported or un-negotiated protocol. Link cdp *Mar 1 21:40:25.038: As4 PPP: Unsupported or un-negotiated protocol. Link cdp *Mar 1 21:41:25.038: As4 PPP: Unsupported or un-negotiated protocol. Link cdp *Mar 1 21:42:25.038: As4 PPP: Unsupported or un-negotiated protocol. Link cdp *Mar 1 21:43:25.038: As4 PPP: Unsupported or un-negotiated protocol. Link cdp
This section provides the following asynchronous interface configuration examples:
The following is an example of one asynchronous interface configuration on a Cisco AS2511-RJ access server that is used in an asynchronous backup DDR scenario:
interface async 1 description ASYNC LINE 5293731 TO HIGHWAY encapsulation ppp async default routing async mode dedicated dialer in-band dialer map ip 192.168.10.2 name Router2 broadcast dialer-group 1 ppp authentication chap
The following configuration shows interface and line configuration. The interface is configured with access lists, passive header compression, and a default address. The line is configured for TACACS authentication.
interface async 1 ip access-group 1 in ip access-group 1 out ip tcp header-compression passive async default ip address 172.31.176.201 line 1 login tacacs location 457-5xxx exec-timeout 20 0 password XXXXXXXX session-timeout 20 stopbits 1
The following example configures a Cisco AS5800 access server, which is used as a high-density dial-in solution:
configure terminal line 1/2/00 1/9/71 session-timeout 30 exec-timeout 30 0 absolute-timeout 240 autoselect during-login autoselect ppp modem InOut transport preferred none transport input all
The following example configures one asynchronous line on a Cisco AS2511-RJ access server that is used in an asynchronous backup DDR scenario:
configure terminal line 1 modem InOut speed 115200 transport input all flowcontrol hardware
The following example shows how to assign an IP address to an asynchronous interface and place the line in dedicated network mode. Setting the stop bit to 1 is a performance enhancement.
line 20 location Department PC Lab stopbits 1 speed 19200 ! interface async 20 async default ip address 182.32.7.51 async mode dedicated
The following example shows how to allow most terminal users access to anything on the local network, but restrict access to certain servers designated as asynchronous servers:
! access list for normal connections access-list 1 permit 131.108.0.0 0.0.255.255 ! access-list 2 permit 131.108.42.55 access-list 2 permit 131.108.111.1 access-list 2 permit 131.108.55.99 ! line 1 speed 19200 flow hardware modem inout interface async 1 async mode interactive async dynamic address ip access-group 1 out ip access-group 2 in
interface group-async 0
group-range 2 7
The following example shows how you need to configure asynchronous interfaces 1, 2, and 3 separately if you do not have a group interface configured:
interface Async1 ip unnumbered Ethernet0 encapsulation ppp async default ip address 172.30.1.1 async mode interactive async dynamic routing ! interface Async2 ip unnumbered Ethernet0 encapsulation ppp async default ip address 172.30.1.2 async mode interactive async dynamic routing ! interface Async3 ip unnumbered Ethernet0 ! encapsulation ppp async default ip address 172.30.1.3 async mode interactive async dynamic routing
The following example configures the same interfaces, but from a single group asynchronous interface:
! interface Group-Async 0 ip unnumbered Ethernet0 encapsulation ppp async mode interactive async dynamic routing group-range 1 3 member 1 async default ip address 172.30.1.1 member 2 async default ip address 172.30.1.2 member 3 async default ip address 172.30.1.3
To configure a group asynchronous interface, specify the group async number (an arbitrary number) and the group range (beginning and ending asynchronous interface number). The following example shows the process of creating and configuring a group asynchronous interface for asynchronous interfaces 1through96 on a Cisco AS5300 access server, which is loaded with ninety-six 56K MICA technologies modems:
interface group-async 1 ip unnumbered ethernet 0 encapsulation ppp async mode interactive ppp authentication chap pap peer default ip address pool default group-range 1 96
The following example configures a Cisco AS5800 access server that is used as a high-density dial-in solution:
interface group-async 0 ip unnumbered FastEthernet0/2/0 encapsulation ppp async mode interactive peer default ip address pool default no cdp enable ppp authentication chap hold-queue 10 in group-range 1/2/00 1/9/71
The following sections provide examples of the use of Dynamic Host Configuration Protocol (DHCP) and local pooling mechanisms:
ip address-pool dhcp-proxy-client
The following global configuration example shows how to specify which DHCP servers are used on your network. You can specify up to four servers using IP addresses or names. If you do not specify servers, the default is to use the IP limited broadcast address of 255.255.255.255 for transactions with any and all discovered DHCP servers.
ip dhcp-server jones smith wesson
The following interface configuration example illustrates how to disable DHCP proxy-client functionality on asynchronous interface 1:
async interface interface 1 no peer default ip address
! this command tells the access server to use a local pool ip address-pool local ! this command defines the ip address pool.
! The address pool is named group1 and comprised of addresses ! 10.1.2.1through 10.1.2.5 inclusive ip local-pool group1 10.1.2.1 10.1.2.5
The following example shows how to configure the access server so that it will use the default address pool on all interfaces except interface 7, on which it will use an address pool called lass:
ip address-pool local ip local-pool lass 172.30.0.1 async interface interface 7 peer default ip address lass
The following example configures IP and SLIP on asynchronous interface 6. The IP address for the interface is assigned to Ethernet 0, interactive mode has been enabled, and the IP address of the client PC running SLIP has been specified.
IP and the appropriate IP routing protocols have already been enabled on the access server or router.
interface async 6 ip unnumbered ethernet 0 encapsulation slip async mode interactive async default ip address 172.18.1.128
The following example configures asynchronous interface 4 on the router so that users can access AppleTalk zones by dialing in to the router via PPP to this interface. Users accessing the network can run AppleTalk and IP natively on a remote Macintosh, access any available AppleTalk zones from Chooser, use networked peripherals, and share files with other Macintosh users. Routing is not supported on the asynchronous interface 6.
interface async 6 encapsulation ppp appletalk virtual-net 12345 saivite appletalk client-mode
The following example configures IP and PPP on asynchronous interface 6. The IP address for the interface is assigned to Ethernet 0, interactive mode has been enabled, and the IP address of the client PC running PPP has been specified.
IP and the appropriate IP routing protocols have already been enabled on the access server or router.
interface async 6 ip unnumbered ethernet 0 encapsulation ppp async mode interactive peer default ip address 172.18.1.128
The following example shows how to configure IPX to run over PPP on an asynchronous interface. The asynchronous interface is associated with a loopback interface configured to run IPX. This example enables a nonrouting IPX client to connect to the router.
ipx routing 0000.0c07.b509 interface loopback0 no ip address ipx network 544 ipx sap-interval 2000 interface ethernet0 ip address 172.21.14.64 ipx network AC150E00 ipx encapsulation SAP interface async 3 ip unnumbered ethernet0 encapsulation ppp async mode interactive async default ip address 172.18.1.128 ipx ppp-client loopback0 ipx sap-interval 0
In this example, IPX client connections are permitted to asynchronous interface 3, which is associated with loopback interface 0. Loopback interface 0 is configured to run IPX. Routing updates have been filtered on asynchronous interface 3. Routing updates take up much of the bandwidth, and asynchronous interfaces have low bandwidth.
The following example shows how to configure IPX to run over PPP on an asynchronous interface. A dedicated IPX network number has been specified for each interface, which can require a substantial number of network numbers for a large number of interfaces. This example permits an IPX client with routing enabled to connect with the router.
ipx routing 0000.0c07.b509 interface async 6 ip unnumbered ethernet0 encapsulation ppp async mode interactive ipx network AC150E00 ipx sap-interval 0
In this example, IPX client connections are permitted to asynchronous interface 6, which has a unique IPX network number. Routing updates have been filtered on asynchronous interface 6. Routing updates take up much of the bandwidth, and asynchronous interfaces have low bandwidth.
The following example shows how to enable IPX and PPP on vty lines. First, enable PPP to run on virtual terminal lines, then associate the virtual terminal line with a loopback interface configured to run IPX:
ipx routing 0000.0c07.b509 interface loopback0 no ip address ipx network 544 vty-async ipx ppp-client loopback0
This example enables a nonrouting IPX client to connect to the router by permitting IPX client connections to vty lines, which have been associated with loopback interface 0. Loopback interface 0 is configured with an IPX network number that is used by the virtual terminal lines.
The following example shows a simple configuration that allows routing and dynamic addressing. With this configuration, if the user specifies /routing in the EXEC slip or ppp command, routing protocols will be sent and received.
interface async 6 async dynamic routing async dynamic address
The following example configures async interface 7 with a default IP address, allowing header compression if it is specified in the slip or ppp connection command entered by the user or if the connecting system sends compressed packets.
interface async 7 ip address 172.31.79.1 async default ip address 172.31.79.2 ip tcp header-compression passive
The following example shows how to configure your router for routing using unnumbered interfaces. The source (local) address is shared between Ethernet 0 and async 6 (172.18.1.1). The default remote address is 172.18.1.2.
interface ethernet 0 ip address 172.18.1.1 255.255.255.0 ! interface async 6 ip unnumbered ethernet 0 async dynamic routing ! default address is on the local subnet async dynamic address async default ip address 172.18.1.2 ip tcp header-compression passive
The following example shows how the IP unnumbered configuration works. Although the user assigned an address, the system response shows the interface as unnumbered, and the address entered by the user will be used only in response to BOOTP requests.
router> slip /compressed 10.11.11.254 Password: Entering async mode. Interface IP address is unnumbered, MTU is 1500 bytes. Header compression is On.
The following example shows how one of the asynchronous lines can be used as the only network interface. The router is used primarily as a terminal server, but is at a remote location and dials in to the central site for its only network connection.
ip default-gateway 10.11.12.2 interface ethernet 0 shutdown interface async 1 async dynamic routing ip tcp header-compression on async default ip address 10.11.16.12 async mode dedicated ip address 10.11.12.32 255.255.255.0
The following example shows how a router is set up as a dedicated dial-in router. Interfaces are configured as IP unnumbered to conserve network resources, primarily IP addresses.
ip routing interface ether 0 ip address 10.129.128.2 255.255.255.0!interface async 1 ip unnumbered ethernet 0 async dynamic routing ! The addresses assigned with SLIP or PPP EXEC commands are not used except ! to reply to BOOTP requests.
! Normally, the routers dialing in will have their own address and not use BOOTP at all. async default ip address 10.11.11.254! interface async 2 ip unnumbered ethernet 0 async default ip address 10.11.12.16ip tcp header-compression passive async mode dedicated ! ! Run RIP on the asynchronous lines, because few implementations of SLIP
! understand IGRP. Run IGRP on the Rthernet (and in the local network). ! router igrp 110 network 10.11.12.0 ! Send routes from the asynchronous lines on the production network. redistribute RIP ! Don't send IGRP updates on the async interfaces. passive-interface async 1 ! router RIP network 10.11.12.0 redistribute igrp passive-interface ethernet 0 ! Consider filtering everything except a default route from the routing ! updates sent on the (slow) asynchronous lines. distribute-list 1 out ip unnumbered async 2 async dynamic routing
In the following example, only the Interior Gateway Routing Protocol (IGRP) TCP/IP routing protocol is running; it is assumed that the systems that are dialing in to use routing will either support IGRP or have some other method (for example, a static default route) of determining that the router is the best place to send most of its packets:
router igrp 111 network 10.11.12.0 interface ethernet 0 ip address 10.11.12.92 255.255.255.0 ! interface async 1 async default ip address 10.11.12.96 async dynamic routing ip tcp header-compression passive ip unnumbered ethernet 0 line 1 modem ri-is-cd
Posted: Tue Jul 18 13:12:16 PDT 2000
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