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This chapter describes how to configure the Point-to-Point Protocol (PPP) and Multilink PPP features that can be configured on any interface. This chapter also describes address pooling for point-to-point links, which is available on all asynchronous serial, synchronous serial, and ISDN interfaces.
See the "Configuring Asynchronous PPP and SLIP" chapter for information about PPP features and requirements that apply only to asynchronous lines and interfaces.
For a complete description of the PPP commands in this chapter, refer to the "Media-Independent PPP and Multilink PPP Commands" chapter of the Dial Solutions Command Reference. To locate documentation of other commands that appear in this chapter, use the command reference master index or search online.
By enabling PPP encapsulation on physical interfaces, PPP can also be in effect on calls placed by the dialer interfaces that use the physical interfaces.
The current implementation of PPP supports option 3, authentication using CHAP or PAP, option 4, Link Quality Monitoring, and option 5, Magic Number configuration options. The software always sends option 5 and negotiates for options 3 and 4 if so configured. All other options are rejected.
Magic Number support is available on all serial interfaces. PPP always attempts to negotiate for Magic Numbers, which are used to detect looped-back lines. Depending on how the down-when-looped command is configured, the router might shut down a link if it detects a loop.
To configure PPP on a serial interface (including ISDN), perform the following task in interface configuration mode:
You can also complete the tasks in the following sections; these tasks are optional but offer a variety of uses and enhancements for PPP on your systems and networks:
See the "PPP Configuration Examples" and the "MLP Interleaving and Queuing for Real-Time Traffic Examples" sections at the end of this chapter.
You can enable PPP on serial lines to encapsulate IP and other network protocol datagrams. To do so, perform the following task in interface configuration mode:
| Task | Command |
|---|---|
Enable PPP encapsulation. |
PPP echo requests are used as keepalives to minimize disruptions to the end users of your network. The no keepalive command can be used to disable echo requests.
Access control using Challenge Handshake Authentication Protocol (CHAP) or Password Authentication Protocol (PAP) is available on all serial interfaces that use PPP encapsulation. The authentication feature reduces the risk of security violations on your router or access server. You can configure either CHAP or PAP for the interface.
When CHAP is enabled on an interface and a remote device attempts to connect to it, the local router or access server sends a CHAP packet to the remote device. The CHAP packet requests or "challenges" the remote device to respond. The challenge packet consists of an ID, a random number, and the host name of the local router.
The required response consists of two parts:
When the local router or access server receives the response, it verifies the secret by performing the same encryption operation as indicated in the response and looking up the required host name or username. The secret passwords must be identical on the remote device and the local router.
By transmitting this response, the secret is never transmitted in clear text, preventing other devices from stealing it and gaining illegal access to the system. Without the proper response, the remote device cannot connect to the local router.
CHAP transactions occur only at the time a link is established. The local router or access server does not request a password during the rest of the call. (The local device can, however, respond to such requests from other devices during a call.)
When PAP is enabled, the remote router attempting to connect to the local router or access server is required to send an authentication request. If the username and password specified in the authentication request are accepted, the Cisco IOS software sends an authentication acknowledgment.
After you have enabled CHAP or PAP, the local router or access server requires authentication from remote devices. If the remote device does not support the enabled protocol, no traffic will be passed to that device.
To use CHAP or PAP, you must perform the following tasks:
Step 1 Enable PPP encapsulation.
Step 2 Enable CHAP or PAP on the interface.
Step 3 For CHAP, configure host name authentication and the secret or password for each remote system with which authentication is required.
To enable PPP encapsulation, perform the following task in interface configuration mode:
| Task | Command |
|---|---|
Enable PPP on an interface. |
To enable CHAP or PAP authentication on an interface configured for PPP encapsulation, perform the following task in interface configuration mode:
| Task | Command |
|---|---|
Define the authentication methods supported and the order in which they are used. | ppp authentication {chap | chap pap | pap chap | pap} [if-needed] [list-name | default] [callin] |
The ppp authentication chap optional keyword if-needed can be used only with TACACS or extended TACACS.
With authentication, authorization, and accounting (AAA) configured on the router and list names defined for AAA, the optional keyword list-name can be used with AAA/TACACS+.
 | Caution If you use a list-name that has not been configured with the aaa authentication ppp command, you disable PPP on the line. |
Add a username entry for each remote system from which the local router or access server requires authentication.
To specify the password to be used in CHAP or PAP caller identification, perform the following task in global configuration mode:
| Task | Command |
|---|---|
Configure identification. |
Make sure this password does not include spaces or underscores.
To configure Terminal Access Controller Access Control System (TACACS) on a specific interface as an alternative to global host authentication, perform the following task in interface configuration mode:
| Task | Command |
|---|---|
Configure TACACS. | ppp use-tacacs [single-line] |
Use the ppp use-tacacs command with TACACS and Extended TACACS. Use the aaa authentication ppp command with AAA/TACACS+.
For an example of CHAP, see the section "CHAP with an Encrypted Password Examples" at the end of this chapter. CHAP is specified in RFC 1994, "PPP Challenge Handshake Authentication Protocol (CHAP)."
Link Quality Monitoring (LQM) is available on all serial interfaces running PPP. LQM will monitor the link quality, and if the quality drops below a configured percentage, the router shuts down the link. The percentages are calculated for both the incoming and outgoing directions. The outgoing quality is calculated by comparing the total number of packets and bytes sent with the total number of packets and bytes received by the destination node. The incoming quality is calculated by comparing the total number of packets and bytes received with the total number of packets and bytes sent by the destination peer.
When LQM is enabled, Link Quality Reports (LQRs) are sent, in place of keepalives, every keepalive period. All incoming keepalives are responded to properly. If LQM is not configured, keepalives are sent every keepalive period and all incoming LQRs are responded to with an LQR.
To enable LQM on the interface, perform the following task in interface configuration mode:
| Task | Command |
|---|---|
Enable LQM on the interface. | ppp quality percentage |
The percentage argument specifies the link quality threshold. That percentage must be maintained, or the link is deemed to be of poor quality and taken down.
You can configure point-to-point software compression on serial interfaces that use PPP encapsulation. Compression reduces the size of a PPP frame via lossless data compression. PPP encapsulations support both predictor and Stacker compression algorithms.
If the majority of your traffic is already compressed files, do not use compression.
Most routers support software compression only, but in the Cisco 7000 series hardware compression and distributed compression are also available, depending on the interface processor and compression service adapter hardware installed in the router.
To configure compression, complete the tasks in one of the following sections:
Software compression is available in all router platforms. Software compression is performed by the router's main processor.
Compression is performed in software and might significantly affect system performance. Cisco recommends that you disable compression if the router CPU load exceeds 65 percent. To display the CPU load, use the show process cpu EXEC command.
To configure compression over PPP, perform the following tasks in interface configuration mode:
| Task | Command |
|---|---|
Step 1 Enable encapsulation of a single protocol on the serial line. | |
Step 2 Enable compression. |
When you configure Stacker compression on Cisco 7000 series routers with RSP7000, on Cisco 7200 series routers, and on Cisco 7500 series routers, there are three methods of compression: hardware compression, distributed compression, and software compression.
To configure hardware or distributed compression over PPP, perform the following tasks in interface configuration mode:
| Task | Command |
|---|---|
Step 1 Enable encapsulation of a single protocol on the serial line. | encapsulation ppp |
Step 2 Enable compression. | compress stac [distributed | software] (Cisco 7000 series with RSP7000 and Cisco 7500 series) or compress stac [csa slot | software] (Cisco 7200 series) |
Specifying the compress stac command with no options causes the router to use the fastest available compression method:
Using hardware compression in the CSA frees the router's main processor for other tasks. You can also configure the router to use the VIP2 to perform compression by using the distributed option, or to use the router's main processor by using the software option. If the VIP2 is not available, compression is performed in the router's main processor.
When compression is performed in software installed in the router's main processor, it might significantly affect system performance. We recommend that you disable compression in the router's main processor if the router CPU load exceeds 40 percent. To display the CPU load, use the show process cpu EXEC command.
Specifying the compress stac command with no options causes the router to use the fastest available compression method.
Point-to-point interfaces must be able to provide a remote node with its IP address through the IP Control Protocol (IPCP) address negotiation process. The IP address can be obtained from a variety of sources. The address can be configured through the command line, entered with an EXEC-level command or provided by TACACS+, DHCP, or from a locally administered pool.
IP address pooling uses a pool of IP addresses from which an incoming interface can provide an IP address to a remote node through the IP Control Protocol (IPCP) address negotiation process. IP address pooling also enhances configuration flexibility by allowing multiple types of pooling to be active simultaneously.
See the "Configuring Asynchronous PPP and SLIP" chapter for additional information about address pooling on asynchronous interfaces and about SLIP.
A peer IP address can be allocated to an interface through several methods:
The following precedence rules of peer IP address support determine which address is used. Precedence is listed from most likely to least likely:
1. AAA/TACACS+ provided address or addresses from the pool named by AAA/TACACS+
2. An address from a local IP address pool or DHCP (typically not allocated unless no other address exists)
3. Dialer map lookup address (not done unless no other address exists)
4. Address from an EXEC-level PPP or SLIP command or from a chat script
5. Configured address from the peer default ip address command or address from the protocol translate command
6. Peer provided address from IPCP negotiation (not accepted unless no other address exists)
Address pooling is available on all asynchronous serial, synchronous serial, ISDN BRI, and ISDN PRI interfaces running the Point-to-Point Protocol (PPP).
The IP address pooling feature now allows configuration of a global default address pooling mechanism, per-interface configuration of the address pooling mechanism, and per-interface configuration of a specific address or pool name.
You can define the type of IP address pooling mechanism used on router interfaces in one or both of the following ways:
The global default mechanism applies to all point-to-point interfaces that support PPP encapsulation and that have not otherwise been configured for IP address pooling. You can define the global default mechanism to be either DHCP or local address pooling.
To configure the global default mechanism for IP address pooling, perform the tasks in one of following sections:
After you have defined a global default mechanism, you can disable it on a specific interface by configuring the interface for some other pooling mechanism. You can define a local pool other than the default pool for the interface or you can configure the interface with a specific IP address to be used for dial-in peers.
The Dynamic Host Configuration Protocol (DHCP) specifies the following components:
To enable DHCP as the global default mechanism, complete the following tasks in global configuration mode:
| Task | Command |
|---|---|
Step 1 Specify DHCP client-proxy as the global default mechanism. | |
Step 2 (Optional) Specify the IP address of a DHCP server for the proxy client to use. | ip dhcp-server [ip-address | name] |
In Step 2, you can provide as few as one or as many as ten DHCP servers for the proxy-client (the Cisco router or access server) to use. DHCP servers provide temporary IP addresses.
To specify that the global default mechanism to use is local pooling, complete the following tasks in global configuration mode:
| Task | Command |
|---|---|
Step 1 Specify local pooling as the global default mechanism. | |
Step 2 Create one or more local IP address pools. | ip local pool {default | poolname} low-ip-address [high-ip-address] |
If no other pool is defined, the local pool called default is used.
After you have defined a global default mechanism for assigning IP addresses to dial-in peers, you can then configure the few interfaces for which it is important to have a nondefault configuration. You can do any of the following;
To define a nondefault address pool for use on an interface, perform the following tasks beginning in global configuration mode:
| Task | Command |
|---|---|
Create one or more local IP address pools. | |
Specify the interface and enter interface configuration mode. | interface type number |
Specify the pool for the interface to use. | peer default ip address pool poolname |
To define DHCP as the IP address mechanism for an interface, complete the following tasks beginning in global configuration mode:
| Task | Command |
|---|---|
Specify the interface and enter interface configuration mode. | interface type number |
Specify DHCP as the IP address mechanism on this interface. |
To define a specific IP address to be assigned to all dial-in peers on an interface, complete the following tasks beginning in global configuration mode:
| Task | Command |
|---|---|
Specify the interface and enter interface configuration mode. | interface type number |
Specify the IP address to assign. | peer default ip address ip-address |
Although LAPB protocol overhead consumes some bandwidth, this can be offset by the use of PPP compression over the reliable link. PPP compression is separately configurable and is not required for use of a reliable link.
PPP reliable link is available only on synchronous serial interfaces, including ISDN BRI and ISDN PRI interfaces. PPP reliable link cannot be used over V.120.
To configure PPP reliable link on a specified interface, complete the following task in interface configuration mode:
| Task | Command |
|---|---|
Enable PPP reliable link. |
Having reliable link enabled does not guarantee that all connections through the specified interface will in fact use reliable link. It only guarantees that the router will attempt to negotiate reliable link on this interface.
PPP reliable link does not work with Multilink PPP.
PPP reliable link is not available on asynchronous serial interfaces, including ISDN BRI and ISDN PRI interfaces. PPP reliable link cannot be used over V.120.
You can troubleshoot PPP reliable link by using the debug lapb command and the debug ppp negotiations, debug ppp errors, and debug ppp packets commands. You can determine whether LAPB has been established on a connection by using the show interface command.
To disable this default behavior or to reenable it once it has been disabled, complete the following tasks in interface configuration mode:
| Task | Command |
|---|---|
Disable creation of neighbor routes. | |
Reenable creation of neighbor routes. | peer neighbor-route |
For situations in which a routed network needs connectivity to a remote bridged Ethernet network, a serial or ISDN interface can be configured to function as a PPP half-bridge. The line to the remote bridge functions as a virtual Ethernet interface, and the router's serial or ISDN interface functions as a node on the same Ethernet subnetwork as the remote network.
Figure 90 shows a router with a serial interface configured as a PPP half-bridge. The interface functions as a node on the Ethernet subnetwork with the bridge. Note that the serial interface has an IP address on the same Ethernet subnetwork as the bridge.
To configure a serial interface to function as a half-bridge, compete the following tasks beginning in global configuration mode:
| Task | Command |
|---|---|
Step 1 Specify the interface (and enter interface configuration mode). | interface serial number |
Step 2 Enable PPP half-bridging for one or more routed protocols: AppleTalk, IP, or IPX. | |
Step 3 Provide a protocol address on the same subnetwork as the remote network. | ip address n.n.n.n appletalk address network.node ipx network network |
For more information about AppleTalk addressing see the "Configuring AppleTalk" chapter; for more information about IPX addresses and encapsulations, see the "Configuring Novell IPX" chapter. Both chapters are in the Network Protocols Configuration Guide, Part 2.
The Multilink Point-to-Point Protocol (PPP) feature provides load balancing functionality over multiple WAN links, while providing multivendor interoperability, packet fragmentation and proper sequencing, and load calculation on both inbound and outbound traffic. Cisco's implementation of Multilink PPP supports the fragmentation and packet sequencing specifications in RFC 1717.
Multilink PPP allows packets to be fragmented and the fragments to be sent at the same time over multiple point-to-point links to the same remote address. The multiple links come up in response to a dialer load threshold that you define. The load can be calculated on inbound traffic, outbound traffic, or on either, as needed for the traffic between the specific sites. MLP provides bandwidth on demand and reduces transmission latency across WAN links.
Multilink PPP is designed to work over single or multiple interfaces of the following types that are configured to support both dial-on-demand rotary groups and PPP encapsulation:
To configure an asynchronous interface to support DDR and PPP encapsulation, complete the following tasks beginning in global configuration mode:
| Task | Command |
|---|---|
Step 1 Specify an asynchronous interface. | interface async number |
Step 2 Specify no IP address for the interface. | no ip address |
Step 3 Enable PPP encapsulation. | encapsulation ppp |
Step 4 Enable DDR on the interface. | |
Step 5 Include the interface in a specific dialer rotary group. | dialer rotary-group number |
Repeat this step for additional asynchronous interfaces, as needed.
At some point, adding more asynchronous interfaces does not improve performance, With the default MTU size, Multilink PPP should support three asynchronous interfaces using V.34 modems. However, packets might be dropped occasionally if the MTU is small or large bursts of short frames occur.
To configure a dialer interface to support PPP encapsulation and Multilink PPP, complete the following tasks beginning in global configuration mode:
| Task | Command |
|---|---|
Step 1 Define a dialer rotary group. | interface dialer number |
Step 2 Specify no IP address for the interface. | no ip address |
Step 3 Enable PPP encapsulation. | encapsulation ppp |
Step 4 Enable DDR on the interface. | dialer in-band |
Step 5 Configure bandwidth on demand by specifying the maximum load before the dialer places another call to a destination. | dialer load-threshold load [inbound | outbound | either] |
Step 6 Enable Multilink PPP. |
To enable Multilink PPP on a single Integrated Services Digital Network (ISDN) BRI interface, you are not required to define a dialer rotary group separately because ISDN interfaces are dialer rotary groups by default.
To enable PPP on an ISDN BRI interface, perform the following tasks beginning in global configuration mode:
| Task | Command |
|---|---|
Step 1 Specify an interface. | interface bri number |
Step 2 Provide an appropriate protocol address for the interface. | ip address ip-address mask |
Step 3 Enable PPP encapsulation. | encapsulation ppp |
Step 4 (Optional) Specify a dialer idle timeout. | dialer idle-timeout seconds |
Step 5 Specify the dialer load threshold for bringing up additional WAN links. | |
Step 6 Configure the ISDN interface to call the remote site. | dialer map protocol next-hop-address [name hostname] [spc] [speed 56 | 64] [broadcast] [dial-string[:isdn-subaddress]] |
Step 7 Control access to this interface by adding it to a dialer access group. | dialer-group group-number |
Step 8 (Optional) Enable PPP authentication. | |
Step 9 Enable Multilink PPP on the dialer rotary group |
The load threshold number is required. For an example of configuring Multilink PPP on a single ISDN BRI interface, see the ""Multilink PPP on One ISDN Interface Example"" section later in this chapter.
When Multilink PPP is configured and you want a multilink bundle to be connected indefinitely, use the dialer idle-timeout command to set a very high idle timer. (The dialer-load threshold 1 command no longer keeps a multilink bundle of n links connected indefinitely and the dialer-load threshold 2 command no longer keeps a multilink bundle of two links connected indefinitely.)
To enable Multilink PPP on multiple ISDN BRI interfaces, you set up a dialer rotary interface and configure it for Multilink PPP and then you configure the BRIs separately and add them each to the same rotary group.
| Task | Command |
|---|---|
Step 1 Specify the dialer rotary interface. | interface dialer number |
Step 2 Specify the protocol address for the dialer rotary interface. | ip address address mask |
Step 3 Enable PPP encapsulation. | encapsulation ppp |
Step 4 Specify in-band dialing. | |
Step 5 (Optional) Specify the dialer idle timeout period, using the same timeout period as the individual BRI interfaces. | dialer idle-timeout seconds |
Step 6 Map the next-hop protocol address and name to the dial string needed to reach it. | dialer map protocol next-hop-address [name hostname] [spc] [speed 56 | 64] [broadcast] [dial-string[:isdn-subaddress]] |
Step 7 Specify the dialer load threshold, using the same threshold as the individual BRI interfaces. | |
Step 8 Control access to this interface by adding it to a dialer access group. | dialer-group group-number |
Step 9 (Optional) Enable PPP Challenge Handshake Authentication Protocol (CHAP) authentication. | |
Step 10 Enable Multilink PPP. |
If you do not use PPP authentication procedures (Step 10), your telephone service must pass caller ID information.
| Task | Command |
|---|---|
Step 1 Specify one of the BRI interfaces. | interface bri number |
Step 2 Specify that it does not have an individual protocol address. | no ip address |
Step 3 Enable PPP encapsulation. | encapsulation ppp |
Step 4 Set the dialer idle timeout period, using the same timeout for each of the BRI interfaces you configure. | dialer idle-timeout seconds |
Step 5 Add the interface to the rotary group. | dialer rotary-group group-number |
Step 6 Specify the dialer load threshold for bringing up additional WAN links. |
Repeat Steps 1 through 6 for each BRI you want to belong to the same dialer rotary group.
For an example of configuring Multilink PPP on multiple ISDN BRI interfaces, see the "Multiple ISDN Interfaces Configured for Multilink PPP Example" section later in this chapter.
When Multilink PPP is configured and you want a multilink bundle to be connected indefinitely, use the dialer idle-timeout command to set a very high idle timer. (The dialer load-threshold 1 command no longer keeps a multilink bundle of n links connected indefinitely and the dialer load-threshold 2 command no longer keeps a multilink bundle of two links connected indefinitely.)
Interleaving on Multilink PPP allows large packets to be multilink encapsulated and fragmented into a small enough size to satisfy the delay requirements of real-time traffic; small real-time packets are not multilink encapsulated and are transmitted between fragments of the large packets. The interleaving feature also provides a special transmit queue for the smaller, delay-sensitive packets, enabling them to be transmitted earlier than other flows.
Weighted fair-queuing is now supported on all interfaces that support Multilink PPP, including Multilink PPP virtual access interfaces and virtual interface templates. Weighted fair-queuing is enabled by default.
Fair-queuing on Multilink PPP overcomes a prior restriction. Previously, fair-queuing was not allowed on virtual access interfaces and virtual interface templates. Interleaving provides the delay bounds for delay-sensitive voice packets on a slow link that is used for other best-effort traffic.
Interleaving applies only to interfaces that can configure a multilink bundle interface. These include virtual-templates, dialer interfaces, and ISDN BRI or PRI interfaces.
Multilink and fair queuing are not supported when a multilink bundle is off-loaded to a different system using Multichassis Multilink PPP. Thus, interleaving is not supported in Multichassis Multilink PPP (MMP) networking designs.
Multilink PPP support for interleaving can be configured on virtual-templates, dialer interfaces, and ISDN BRI or PRI interfaces. To configure interleaving, complete the following tasks:
Step 1 Configure the dialer interface, BRI interface, PRI interface, or virtual template, as defined in the relevant chapters of this manual.
Step 2 Configure Multilink PPP and interleaving on the interface or template.
To configure Multilink PPP and interleaving on a configured and operational interface or virtual interface template, perform the following tasks in interface configuration mode:
| Task | Command |
|---|---|
Step 1 Enable Multilink PPP. | ppp multilink |
Step 2 Enable real-time packet interleaving. | ppp multilink interleave |
Step 3 Optionally, configure a maximum fragment delay. | ppp multilink fragment-delay milliseconds |
Step 4 Reserve a special queue for real-time packet flows to specified destination UDP ports, allowing real-time traffic to have higher priority than other flows. | ip rtp reserve lowest-UDP-port range-of-ports [maximum-bandwidth] |
Step 5 For virtual templates only, apply the virtual template to the multilink bundle.1 | multilink virtual-template 1 |
| 1This step is not used for ISDN or dialer interfaces. |
Interleaving statistics can be displayed by using the show interfaces command, specifying the particular interface on which interleaving is enabled. Interleaving data is displayed only if there are interleaves. For example, the following line shows interleaves:
Output queue: 315/64/164974/31191 (size/threshold/drops/interleaves)
To monitor and maintain virtual interfaces, you can perform any of the following tasks:
| Task | Command |
|---|---|
Display MLP and MMP bundle information. | show ppp multilink |
The examples provided in this section show various PPP configurations as follows:
The following configuration examples enable CHAP on serial interface 0 of three devices.
hostname yyy interface serial 0 encapsulation ppp ppp authentication chap username xxx password secretxy username zzz password secretzy
hostname xxx interface serial 0 encapsulation ppp ppp authentication chap
username yyy password secretxy username zzz password secretxz
hostname zzz interface serial 0 encapsulation ppp ppp authentication chap username xxx password secretxz username yyy password secretzy
When you look at the configuration file, the passwords will be encrypted and the display will look similar to the following:
hostname xxx interface serial 0 encapsulation ppp ppp authentication chap username yyy password 7 121F0A18 username zzz password 7 1329A055
The following example enables PPP reliable link and Stac compression on BRI 0:
interface BRI0 description Enables stac compression on BRI 0 ip address 172.1.1.1 255.255.255.0 encapsulation ppp dialer map ip 172.1.1.2 name baseball 14195386368 compress stac ppp authentication chap dialer-group 1 ppp reliable-link
The following example shows output of the show interface command when PPP reliable link is enabled. The LAPB output lines indicate that PPP reliable link is provided over LAPB.
Router# show interface serial 0
Serial0 is up, line protocol is up
Hardware is HD64570
Description: connects to enkidu s 0
Internet address is 172.21.10.10/8
MTU 1500 bytes, BW 1544 Kbit, DLY 20000 usec, rely 255/255, load 1/255
Encapsulation PPP, loopback not set
LCP Open
Open: IPCP, CDP
LAPB DTE, state CONNECT, modulo 8, k 7, N1 12048, N2 20
T1 3000, T2 0, interface outage (partial T3) 0, T4 0, PPP over LAPB
VS 1, VR 1, tx NR 1, Remote VR 1, Retransmissions 0
Queues: U/S frames 0, I frames 0, unack. 0, reTx 0
IFRAMEs 1017/1017 RNRs 0/0 REJs 0/0 SABM/Es 1/1 FRMRs 0/0 DISCs 0/0
Last input 00:00:18, output 00:00:08, output hang never
Last clearing of "show interface" counters never
Input queue: 0/75/0 (size/max/drops); Total output drops: 0
Queueing strategy: weighted fair
Output queue: 0/64/0 (size/threshold/drops)
Conversations 0/1 (active/max active)
Reserved Conversations 0/0 (allocated/max allocated)
5 minute input rate 3000 bits/sec, 4 packets/sec
5 minute output rate 3000 bits/sec, 7 packets/sec
1365 packets input, 107665 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
2064 packets output, 109207 bytes, 0 underruns
0 output errors, 0 collisions, 4 interface resets
0 output buffer failures, 0 output buffers swapped out
4 carrier transitions
DCD=up DSR=up DTR=up RTS=up CTS=up
The following examples configure Multilink PPP. The first example configures it on one BRI interface, and the second configures multiple BRIs to belong to the same dialer rotary group, which is then configured for Multilink PPP.
The following example enables Multilink PPP on the BRI interface 0. Because an ISDN interface is a rotary group by default, when one BRI is configured, no dialer rotary group configuration is required.
interface bri 0 description connected to ntt 81012345678902 ip address 171.1.1.7 255.255.255.0 encapsulation ppp dialer idle-timeout 30 dialer load-threshold 40 either dialer map ip 171.1.1.8 name atlanta 81012345678901 dialer-group 1 ppp authentication pap ppp multilink
The following example configures multiple ISDN BRIs to belong to the same dialer rotary group for Multilink PPP. The dialer rotary-group command is used to assign each of the ISDN BRIs to that dialer rotary group.
interface BRI0 no ip address encapsulation ppp dialer idle-timeout 500 dialer rotary-group 0 dialer load-threshold 30 either ! interface BRI1 no ip address encapsulation ppp dialer idle-timeout 500 dialer rotary-group 0 dialer load-threshold 30 either ! interface BRI2 no ip address encapsulation ppp dialer idle-timeout 500 dialer rotary-group 0 dialer load-threshold 30 either ! interface Dialer0 ip address 99.0.0.2 255.0.0.0 encapsulation ppp dialer in-band dialer idle-timeout 500 dialer map ip 99.0.0.1 name atlanta broadcast 81012345678901 dialer load-threshold 30 either dialer-group 1 ppp authentication chap ppp multilink
interface virtual-template 1 ip unnumbered ethernet 0 ppp multilink ppp multilink interleave ppp multilink fragment-delay 20 ip rtp interleave 32768 20 1000 multilink virtual-template 1
interface BRI 0 description connected into a rotary group encapsulation ppp dialer rotary-group 1 ! interface BRI 1 no ip address encapsulation ppp dialer rotary-group 1 ! interface BRI 2 encapsulation ppp dialer rotary-group 1 ! interface BRI 3 no ip address encapsulation ppp dialer rotary-group 1 ! interface BRI 4 encapsulation ppp dialer rotary-group 1 ! interface Dialer 0 description Dialer group controlling the BRIs ip address 8.1.1.1 255.255.255.0 encapsulation ppp dialer map ip 8.1.1.2 name angus 14802616900 dialer-group 1 ppp authentication chap ! Enables Multilink PPP interleaving on the dialer interface and reserves ! a special queue. ppp multilink ppp multilink interleave ip rtp reserve 32768 20 1000 ! Keeps fragments of large packets small enough to ensure delay of 20 ms or less. ppp multilink fragment-delay 20 dialer-list 1 protocol ip permit
Posted: Wed Aug 30 22:30:48 PDT 2000
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