PPP and Metro Ethernet

Point-to-Point (PPP) is a point to point encapsulation protocol across dedicated or circuit switching across WAN network, along with protocol such as HDLC SDLC, and ISDN. Below would be a basic configuration for PPP in Cisco configuration terminal.

  1. Config
    1. Interface
      1. Encapsulation ppp/hdlc
      2. Ppp authentication chap
      3. #Ppp authentication pap
      4. #Ppp pap sent-username r1 password pass1
    2. Hostname r1
    3. Username r2 password mypass
  2. Show ppp all
  3. Config multilink
    1. Interface multilink 1
      1. Encapsulation ppp
      2. Ppp multilink
      3. Ip addresss 11111 11111
      4. Ppp multilink group 1
    2. Interface serial0/0/0
      1. Encapsulation ppp
      2. Ppp multilink
      3. No ip address
      4. Ppp multilink group 1
    3. Show ip route
    4. Show ip eigrp interface
    5. Show ip int br
    6. Show interface multilink1
      1. Interface state, mutilink open
    7. Show ppp multillink
      1. Member linnk number
      2. Interfaces
      3. Inactive member
    8. Keepalive feature helps a router notice when a link is no longer functioning.
    9. Debug ppp authentification


Metro Ethernet

  1. PoP Point of presnese – service provicer locally proximate office.
  2. Carrier ethernet – ethernet WAN service provider by a carrier also called metro ether.
  3. IEEE Ethernet Standard useful for metro ethernet access




100 Base-LX10

100 Mbps

10 km

1000 Base-LX

1 Gbps

5 km

1000 Base-LX10

1 Gbps

10 km

1000 base-ZX

1 Gbps

100 km


10 Gbps

10 km


10 Gbps



MEF Service Name

MEF Short Name

Topology Terms


Ethernet Line Service

E-Line / Virtual Private Wire Service (VPWS)


Two customer premise equipment (CPE) devices can exchange. Ethernet frames, similar in concept to a leased line.

Ethernet LAN Service

E-LAN / Virtual Private LAN Service (VPLS)

Full mesh

Acts like a LAN, in that all devices can send frames to all other devices. (N(N-1)/2)

Ethernet Tree Service


Hub-and-spoke: partial mesh: point-to-multipoint

A central site can communicate to a defined set of remote sites, but the remote sites cannot communicate directly.

  1. Route redistribution – taking routes from one routing protocol process and injecting them into another.
    1. MPLS does this between PE router using variation of Multiprotocol BGP (MPBGP)
    2. EIGRP in MPLS
      1. A CE router does become neighbors with the PE router on the othe end of the access link.
      2. A CE router does not become neighbors with toher CE routers.
      3. The MPLS network will advertise the customer’s routes between the various PE routers, so that the CE routers can learn all customer routes through their PE-CE routing protocol neighbor relationship.
    3. OSPF
      1. The MPLS Pes form a backbone area by the name of a super backbone..
      2. Each PE-CE link can be any area, a non-backbone area or the backnone area.

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