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NE40E-M2 V800R010C10SPC500 Configuration Guide - WAN Access 01

This is NE40E-M2 V800R010C10SPC500 Configuration Guide - WAN Access
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Configuring an Interface to Support PPP

Configuring an Interface to Support PPP

Configure an interface to support PPP so that it can implement point-to-point (P2P) traffic transmission.

Usage Scenario

PPP is a link layer protocol that transmits network layer packets over P2P links. PPP defines a group of protocols, including LCP and NCP.
  • During the LCP negotiation phase, an MRU, negotiation timeout period, and PPP LCP link dead duration are negotiated.
  • During the NCP negotiation phase, network layer packet attributes and types are negotiated. For example, during the IPCP negotiation, the IP address of a DNS server will be negotiated.

To monitor link status in real time, configure link status monitoring parameters so that link faults can be identified in time. A PPP link does not require that the peer route and local route be on the same network segment. To avoid incorrect routing information, prohibit the addition of the peer host route to the local routing table of direct routes.

Pre-configuration Tasks

Before configuring an interface to support PPP, connect the interface and set physical parameters to ensure that the physical status of the interface is Up.

Configuration Procedures

The following flowchart shows how to configure an interface to support PPP.

Figure 8-1 Flowchart for configuring an interface to support PPP

Configuring PPP as the Link Layer Protocol of an Interface

Configure PPP as the link layer protocol of an interface for the interface to implement P2P traffic transmission.

Context

PPP is a data link layer protocol used to transmit network layer packets on P2P links. It is extensible and supports both synchronous and asynchronous communication. Before configuring PPP parameters of an interface, configure PPP as the link layer protocol of the interface.

Procedure

  1. Run system-view

    The system view is displayed.

  2. Run interface interface-type interface-number

    The interface view is displayed.

  3. Run link-protocol ppp

    PPP is configured as the link layer protocol of the interface.

  4. Run commit

    The configuration is committed.

(Optional) Configuring PPP Negotiation Parameters

For a PPP link to be established between two communicating devices that have PPP enabled, configure the following PPP negotiation parameters: MRU, negotiation timeout period, PPP LCP link dead duration, and DNS server IP address.

Context

A PPP link is established between two communicating devices after successful LCP negotiation and NCP negotiation. After the physical link goes Up, the two devices enter the link establishment phase, during which one device initiates LCP negotiation. After LCP negotiation succeeds, if the two devices have a network layer protocol configured, the device continues to initiate NCP negotiation on network layer packet attributes and types.

Table 8-1 Usage scenario for negotiation parameters

Negotiation Parameter

Usage Scenario

Negotiation Phase

PPP MRU

If an MTU is configured on an interface of a PPP link, enable the PPP MRU negotiation function so that interfaces on both ends of the PPP link have the same MTU, which ensures proper data transmission. If the interfaces have different MTUs, the smaller MTU will be selected as the PPP link MTU after the negotiation.

LCP negotiation phase

Negotiation timeout period

During LCP negotiation, the local device sends an LCP negotiation packet to the remote device. If the local device does not receive a reply packet from the remote device within the specified negotiation timeout period, the local device resends an LCP negotiation packet.

LCP link dead duration

During LCP negotiation, if the local device fails to receive a reply packet from the remote device after retransmitting LCP negotiation packets for a specified number of times, the LCP negotiation enters the Dead state, and the devices stop performing LCP negotiation. In this situation, configure an LCP link dead duration. After the duration elapses, the local device will re-initiate LCP negotiation.

DNS server IP address

During IPCP negotiation, the local device can either provide a DNS server IP address for the remote device or accept the DNS server IP address assigned by the remote device. A DNS server is responsible for resolving domain names.
  • When a device is connected to a remote device over a PPP link, for example, a PC dials up to the device, configure the device to assign a DNS server IP address to the PC.
  • When a device is connected to a carrier's access server over a PPP link, configure the device to accept the DNS server IP address assigned by the access server.

NCP negotiation phase

OSICP and MPLSCP

When the default OSICP and MPLSCP configurations differ on devices that are to communicate, enables or disables negotiation to ensure consistent configurations on both devices.

NCP negotiation phase

NOTE:

The configuration of Negotiation timeout period is supported only on the Admin-VS.

Procedure

  • Configure PPP MRU negotiation.
    1. Run system-view

      The system view is displayed.

    2. Run interface interface-type interface-number

      The interface view is displayed.

    3. Run ppp mru-negotiate { ipv4 | ipv6 }

      MRU negotiation is enabled at the link control layer.

      If an IPv6 MTU is configured on the interface, enable PPP IPv6 MRU negotiation for the device. After PPP MRU negotiation is enabled, to make this configuration take effect, you must run the shutdown, commit, undo shutdown, and commit commands in sequence, or run the restart and commit commands.

  • Configure a negotiation timeout period.
    1. Run system-view

      The system view is displayed.

    2. Run interface interface-type interface-number

      The interface view is displayed.

    3. Run ppp timer negotiate seconds

      A negotiation timeout period is configured.

    4. Run commit

      The configuration is committed.

  • Configure a PPP LCP link dead duration.
    1. Run system-view

      The system view is displayed.

    2. Run interface interface-type interface-number

      The interface view is displayed.

    3. Run ppp timer link-dead timer

      The PPP LCP link dead duration is configured.

    4. Run commit

      The configuration is committed.

  • Configure a DNS server IP address

    • Configure the device to assign a DNS server IP address to the remote device.
      1. Run system-view

        The system view is displayed.

      2. Run interface interface-type interface-number

        The interface view is displayed.

      3. Run ppp ipcp dns primary-dns-address [ secondary-dns-address ]

        The device is configured to assign a DNS server IP address to the remote device.

    • Configure the device to accept any DNS server IP address assigned by the remote device.
      1. Run system-view

        The system view is displayed.

      2. Run interface interface-type interface-number

        The interface view is displayed.

      3. Run ppp ipcp dns admit-any

        The device is configured to accept any DNS server address assigned by the remote device.

        NOTE:
        If the remote device forcibly assigns a DNS server address to the local device, the local device may refuse to accept the address, causing a negotiation failure between the two devices. To prevent this situation, run the ppp ipcp dns admit-any command to configure the local device to accept any DNS server IP address assigned by the remote device.

    After a DNS server address is configured, to make this configuration take effect, you must run the shutdown, commit, undo shutdown, commit, or restart, commit commands.

  • Configure the OSICP and MPLSCP
    1. Run system-view

      The system view is displayed.

    2. Run interface interface-type interface-number

      The interface view is displayed.

    3. Run ppp osicp { enable | disable }orppp mplscp { enable | disable }

      The negotiation between two devices before OSICP and MPLSCP go Up on both devices can be enabled or disabled.

      When the default OSICP and MPLSCP configurations differ on devices that are to communicate, run the ppp osicp or ppp mplscp command as follows to ensure consistent configurations on both devices:
      • If OSICP and MPLSCP are configured to go Up without negotiation on a peer device, run the ppp osicp disable or ppp mplscp disable command on a local device.

      • If OSICP and MPLSCP are configured to go Up only after negotiation on a peer device, run the ppp osicp enable or ppp mplscp enable command on a local device. Alternatively, use the default configuration on the local device.

      NOTE:

      Run the shutdown and undo shutdown command in the interface view to make the configuration take effect.

(Optional) Configuring PPP Link Status Monitoring

The PPP link status can be effectively monitored using the PPP link status monitoring function.

Context

The parameters for PPP link status monitoring are as follows:

  • Keepalive time

    • Polling interval

      The polling interval determines how often an interface sends a Keepalive message. When PPP is specified as the link layer protocol on the interface, the interface sends a Keepalive message to its peer device at the set polling interval. If the interface fails to receive a Keepalive message from the peer after five polling intervals, the interface considers the peer device to be faulty and sets the PPP link to Down. In situations with unfavorable network delay or significant congestion, you can increase the polling interval to reduce network flapping.

    • Keepalive count

      If a device does not receive a Keepalive message from its peer within a specified polling interval, the Keepalive count increases by 1. If the device still fails to receive a Keepalive message from its peer after a specified Keepalive count is reached, the device considers the link connecting to the peer device to be faulty and sets the PPP link to Down.

    The Keepalive time equals the polling interval multiplied by the Keepalive count. In situations with unfavorable network delay or significant congestion, a short Keepalive time may cause network flapping. Conversely, a long Keepalive time would lead to slow link detection. Therefore, make sure that the Keepalive time is appropriate and fits the network situations.

  • PPP magic number check

    PPP magic number check is used to trigger LCP renegotiation. On a network where two devices are connected over intermediate transmission devices, if the two devices are incorrectly connected, the transmission devices will adjust the connection relationship between the two devices. However, the two devices are not aware of this adjustment because the status of their interfaces does not alternate between Down and Up. Consequently, LCP renegotiation between the two devices is not triggered. After the PPP magic number check function is enabled, when the local device finds that the magic number carried in the Echo Reply packet from the remote device is inconsistent with the one previously learned, the local device will record an error. After error statistics on an interface reach a specific threshold, the interface sets the PPP link to Down, triggering LCP renegotiation.

Procedure

  • Configure a polling interval.
    1. Run system-view

      The system view is displayed.

    2. Run interface interface-type interface-number

      The interface view is displayed.

    3. Run timer hold seconds

      A polling interval is configured.

      NOTE:

      The polling intervals on two interconnected devices must be set to the same value (other than 0s). If both polling intervals are set to 0s, the link detection function is disabled.

    4. Run commit

      The configuration is committed.

  • Configure a Keepalive count.
    1. Run system-view

      The system view is displayed.

    2. Run interface interface-type interface-number

      The interface view is displayed.

    3. Run keepalive count count-number

      A Keepalive count is configured.

    4. Run commit

      The configuration is committed.

  • Configure the PPP magic number check function.
    1. Run system-view

      The system view is displayed.

    2. Run interface interface-type interface-number

      The interface view is displayed.

    3. Run ppp magic-number check

      The PPP magic number check function is enabled.

      • Currently, the magic number check function can only be enabled on a POS interface.
      • After configuring the PPP magic number check function, to make the configuration take effect, you must run the shutdown, commit, undo shutdown, and commit commands in sequence, or run the restart and commit commands.

(Optional) Prohibiting a Local Device from Adding the Peer Host Route to the Local Routing Table of Direct Routes

To avoid incorrect routing information in the local routing table, you can prohibit a local device from adding the peer host route to the local routing table of direct routes.

Context

Devices on both ends of a PPP link may have IP addresses at different network segments. When the two devices communicate with each other, one device automatically adds the host route of the other end to the local routing table of direct routes. If one end has an incorrect IP address configured, incorrect routing information will be advertised on the network. To prevent incorrect routing information, prohibit the local device from adding the peer host route to the local routing table of direct routes.

Procedure

  1. Run system-view

    The system view is displayed.

  2. Run interface interface-type interface-number

    The interface view is displayed.

  3. Run ppp peer hostroute-suppress

    The device is prohibited from adding the peer host route to the local routing table of direct routes.

  4. Run commit

    The configuration is committed.

(Optional) Configuring the PPP Link Dampening Function

To prevent frequent PPP link flapping from causing flapping of the link and network layers, configure the PPP link dampening function.

Context

Optical fiber flapping on a physical interface causes PPP link to alternate between Up and Down frequently. This results in unstable link or network layers. To prevent the link or network layer flapping from causing PPP link frequent alternating between Up and Down, configure the PPP link dampening function. By default, PPP link dampening is enabled.

Procedure

  1. Run system-view

    The system view is displayed.

  2. Run ppp dampening level { light | middle | heavy | manual { half-life-period half-life-period suppress-value suppress-value reuse-value reuse-value max-suppress-time max-suppress-time } }

    The PPP link dampening level is configured.

    When the PPP link dampening function is enabled, run the ppp dampening level command to configure a light, middle, or heavy dampening level based on PPP link dampening requirements, or configure suppress-value manually.

    • light: If light PPP link dampening is configured, dampening procedure will be triggered only when the PPP link flaps frequently and rapidly.
    • middle: If middle PPP link dampening is configured, intensity of PPP link dampening is between the light and heavy.
    • heavy: If heavy PPP link dampening is configured, dampening will be triggered even if link flapping is not severe. That is, the link is vulnerable to dampening.
    • manual: If PPP link dampening is configured manually, you can configure a PPP link dampening level based on sensitivity of flapping.

  3. Run commit

    The configuration is committed.

Verifying the PPP Configuration

After configuring PPP as the link layer protocol, verify the configuration.

Prerequisites

PPP has been configured as the link layer protocol.

Procedure

  • Run the display interface [ interface-type [ interface-number ] ] command to check the status of and statistics about a specific PPP-enabled interface.
  • Run the display ppp information interface interface-type interface-number command to check PPP link information about a specific interface.

Example

Run the display interface [ interface-type [ interface-number ] ] command. The command output shows that PPP is configured as the link layer protocol.
<HUAWEI> display interface pos 0/1/0
Pos0/1/0 current state : UP (ifindex: 15)
Line protocol current state : UP 
Last line protocol up time : 2010-07-13 16:47:08
Description: HUAWEI, Quidway Series, Pos0/1/0 Interface
Route Port,The Maximum Transmit Unit is 1600, Hold timer is 10(sec) 
Internet Address is 1.1.1.1/24
Link layer protocol is PPP 
LCP opened, IPCP opened, IP6CP opened, OSICP opened, MPLSCP opened
PPP negotiated peer ip address is 1.1.1.2
Current system time: 2010-07-13 17:29:44 
The Vendor PN is FTLF1322P1BTR-HW
The Vendor Name is FINISAR CORP.   
Port BW: 622M, Transceiver max BW: 622M, Transceiver Mode: SingleMode
WaveLength: 1310nm, Transmission Distance: 15km
Rx Power:  7.66dBm,  Tx Power: -11.78dBm
Physical layer is Packet Over SDH
Scramble enabled, clock master, CRC-32, loopback: none
Flag J0 "NetEngine       "
Flag J1 "NetEngine       "
Flag C2 22(0x16)
    SDH alarm:
        section layer:  none
        line    layer:  none
        path    layer:  none
    SDH error:
        section layer:  B1 284236
        line    layer:  B2 1871  REI 4445
        path    layer:  B3 719417  REI 12417181
Statistics last cleared:never
    Last 300 seconds input rate 304 bits/sec, 0 packets/sec
    Last 300 seconds output rate 320 bits/sec, 0 packets/sec
    Input: 5754803980 packets, 540947996544 bytes
    Input error: 0 shortpackets, 0 longpackets, 0 CRC, 0 lostpackets
    Output: 5676758063 packets, 533611565328 bytes
    Output error: 0 lostpackets
    Output error: 0 overrunpackets, 0 underrunpackets
Run the display ppp information interface interface-type interface-number command. The command output shows PPP link information about a specific interface.
<HUAWEI> display ppp information interface pos 0/1/0
-----------------------------------------------------------
Interface         : Pos0/1/0                                 
LCP               : opened(damping)                                   
IPCP              : -                                        
MRU               : 4470 Bytes                               
Peer MRU          : 4470 Bytes                               
Magic number      : 3527110287                               
Negotiate Timeout : 3/s                                      
Peer IP Address   : 0.0.0.0/32                               
MPLSCP            : -                                       
OSICP             : -                                        
IP6CP             : -                                        
Damping reuse time: 13/s
-----------------------------------------------------------
Last down information:
-----------------------------------------------------------
ID   Time                Reason                          
-----------------------------------------------------------
1    2011-05-24 21:24:12 Receive ConfReq packet             
2    2011-05-24 21:24:11 Receive ConfReq packet          
3    2011-05-24 21:24:09 Receive ConfReq packet          
4    2011-05-24 21:24:08 Receive ConfReq packet          
5    2011-05-24 21:23:51 Receive ConfReq packet          
6    2011-05-24 21:23:50 Receive ConfReq packet          
7    2011-05-24 21:23:48 Receive ConfReq packet          
8    2011-05-24 21:23:47 Receive ConfReq packet          
9    2011-05-24 21:23:45 Receive ConfReq packet          
10   2011-05-24 21:23:44 Receive ConfReq packet          
-----------------------------------------------------------
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Updated: 2019-01-02

Document ID: EDOC1100058399

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