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  • Table of Contents
  • Layer 2 Technologies
    • Ethernet Switching
      • L2 Switch Operations
      • Spanning Tree
        • 802.1d – STP
        • 802.1w – RSTP
        • 802.1s – MSTP
      • VTP 101
      • Private VLANs
      • VLANs
      • EtherChannel 101
    • Layer 2 WAN Protocols
      • HDLC
        • HDLC 101
      • PPP
        • PPP 101
        • PPP Authentication - PAP
        • PPP Authentication – CHAP
        • PPP Authentication – EAP
        • PPP Multilink
        • PPPoFR – PPP over Frame Relay
        • PPPoE – PPP over Ethernet
      • Frame Relay
        • Frame Relay 101
        • Frame Relay 102
        • Frame Relay Encapsulations – IETF vs Cisco
        • Multilink Frame Relay
        • Frame Relay Switching
        • Routing over Frame Relay
      • Bridging
        • Bridging on a router
        • MTU 101
    • Wireless
      • Wireless Principles
      • Wireless Implementations
      • Wireless Roaming
      • Wireless Authentication
        • WPA2 PSK
        • WPA2 802.1X
  • IPv4
    • IPv4 Addressing
      • Backup Interfaces
      • FHRP 101
      • DHCP 101
      • DNS 101
      • ARP 101
      • IPv4 101
      • Tunnel Interfaces
        • GRE Tunnels
      • BFD – Bidirectional Forwarding Detection
    • IPv4 Routing
      • How the routing table is built
        • How CEF works
        • Routing Order of Operations
        • NSF – Non Stop Forwarding
      • RIP
        • RIP 101
      • EIGRP
        • EIGRP 101
        • EIGRP Metric
        • More EIGRP Features
      • OSPF
        • OSPF 101
        • OSPF Areas
        • OSPF LSAs
        • OSPF Mechanics
      • IS-IS
        • IS-IS 101
        • IS-IS Mechanics – CLNP
      • BGP
        • BGP 101
        • BGP Attributes
        • More BGP
      • Route Redistribution
      • Policy based Routing
      • PfR 101 – Perfromance Routing
      • ODR
  • IPv6
    • IPv6-101
    • IPv6 Routing
    • Interconnecting IPv6 and IPv4
  • MPLS
    • MPLS 101
    • MPLS L3 VPN
  • Multicast
    • Multicast 101
    • PIM 101
    • IGMP 101
    • Inter Domain Multicast
    • IPv6 Multicast
    • Multicast features on switches
  • Security
    • NAT 101
    • NAT for Overlapping Networks
    • ACLs 101
    • ACLs 102
    • Cisco IOS Firewall
    • Zone Based Firewall
    • AAA 101
    • Controlling CLI Access
    • Control Plane
    • Switch Security
      • Switchport Traffic Control
      • Switchport Port Security
      • DHCP Snooping and DAI
      • 802.1x
      • Switch ACLs
    • IPSec VPN 101
      • IKE / ISAKMP 101
      • IPSEC Crypto Maps 101
      • IPSEC VTI 101
      • DMVPN 101
    • EAP 101
  • Network Services
    • NTP 101
    • HTTP 101
    • File Transfer 101 – TFTP & FTP
    • WCCP 101
  • QoS
    • QoS 101
    • Classification and Marking
    • Congestion Management
      • Legacy Congestion Management
      • SPD – Selective Packet Discard
      • CBWFQ
      • IP RTP Priority
    • Congestion Avoidance – WRED
    • Policing and Shaping
      • CAR 101
    • Compression and LFI
      • Header and Payload Compression
      • LFI for MultiLink PPP
    • Frame Relay QoS
      • Per VC Frame Relay QoS
    • RSVP 101
    • Switching QoS
  • Network Optimization
    • NetFlow 101 – TNF – Traditional NetFlow
    • NetFlow 102 – FNF – Flexible NetFlow
    • IP SLA 101
    • IP Accounting 101
    • Logging 101
    • SNMP and RMON 101
    • Cisco CLI Tips and Tricks
    • AutoInstall
    • Enhanced Object Tracking
    • Troubleshooting 101
    • SPAN, RSPAN, ERSPAN
  • Network Architecture
    • Hierarchical Network Architecture
    • SD Access
    • SD WAN
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  • PPP Mulitlink
  • PPP Multilink over Frame Relay

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  1. Layer 2 Technologies
  2. Layer 2 WAN Protocols
  3. PPP

PPP Multilink

PPP Mulitlink

One feature that PPP can offer is the posibility to bundle multiple physical links into one logical link, much like an EtherChannel interface available on the Ethernet Switches. Considering two routers connected back-to-back over more than one serial links. Each serial interface can be configured for PPP encapsulation and assigned to a Multilink Group:

R(config-if)# encapsulation ppp
R(config-if)# ppp multilink group GROUP

Then, you can use the virtual Multilink interface to assign an IP Address:

R(config)# interface Multilink GROUP
R(config-if)# ppp multilink
R(config-if)# ip address IP-ADDR NETMASK

By default the peer neighbor-route feature is eanbled, and we will see /32 routes in the routing table.

The link will be operational as long as one link is active. This behaviour can be changed using the command:

R1(config-if)#ppp multilink links minimum MIN [mandatory]

MIN specifies the minimum number of links needed to be up before the multilink interface goes up. When the mandatory keyowrd is used, if the number of active links goes below the number of minimum links, the multilink interface goes down. If mandatory is not used, the minimum links value is checked only when the interface first comes up. If the number of active links drops below minimum while the interface is up, the multilink will still remain up as long as one link is operational.

You can check the status of the multilink using:

R1#sh ppp multilink
Multilink1, bundle name is R2
Endpoint discriminator is R2
Bundle up for 00:14:20, total bandwidth 3088, load 1/255
Receive buffer limit 24000 bytes, frag timeout 1000 ms
0/0 fragments/bytes in reassembly list
30 lost fragments, 53 reordered
16/918 discarded fragments/bytes, 0 lost received
0x89 received sequence, 0x2E sent sequence
Member links: 2 active, 0 inactive (max not set, min not set)
Se1/2, since 00:14:20
Se1/0, since 00:12:54
No inactive multilink interfaces

PPP Multilink over Frame Relay

PPP Multilink over Frame Relay is configured similarly. The steps to enable it are: 1. Configure the Serial interfaces for Frame Relay encapsulation

R(config)# interface INTERFACE
R(config-if)# encapsulation frame-relay

2. Configure the Serial interfaces for PPP:

R(config-if)# frame-relay interface-dlci DLCI ppp VIRTUAL-TEMPLATE-INTERFACE

3. Configure the Virtual Template to be part of the Multilink Group

R(config)# interface VIRTUAL-TEMPLATE-INTERFACE
R(config-if)# ppp multilink
R(config-if)# ppp multilink group GROUP

4. Configure the Multilink interface

R(config)# interface MULTILINK-INTERFACE
R(config-if)# ppp multilink
R(config-if)# ppp multilink group GROUP
R(config-if)# ip address...
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Last updated 3 years ago

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