Task 3.1 Hub and Spoke - Need understanding

Hi Experts,

We are using the PPP virutal template for Layer 2 to Layer 3 mapping. I don't know how ppp correctly identifying the DLCI.

Since for 128.1.125.0/24 we mapping both DLCI in to Virtual template. Then how PPP correctly identified the DLCI. Initially i thought it will send a duplicate packets. but after debug its not.

RSRack1R5#ping 128.1.125.1 size 1000 repeat 3

Type escape sequence to abort.
Sending 3, 1000-byte ICMP Echos to 128.1.125.1, timeout is 2 seconds:
!!

Serial0/0/0.1(o): dlci 501(0x7C51), NLPID 0x3CF(IP), datagramsize 1006
Serial0/0/0.1(o): dlci 501(0x7C51), NLPID 0x3CF(IP), datagramsize 1006!
Serial0/0/0.1(o): dlci 501(0x7C51), NLPID 0x3CF(IP), datagramsize 1006

RSRack1R5#ping 128.1.125.2 size 1000 repeat 3

Serial0/0/0.1(o): dlci 502(0x7C61), NLPID 0x3CF(IP), datagramsize 1006
Serial0/0/0.1(o): dlci 502(0x7C61), NLPID 0x3CF(IP), datagramsize 1006!
Serial0/0/0.1(o): dlci 502(0x7C61), NLPID 0x3CF(IP), datagramsize 1006

Thanks,

Jayaram

Comments

  • Hi Experts,

    We are using the PPP virutal template for Layer 2 to Layer 3 mapping. I don't know how ppp correctly identifying the DLCI.

    Since for 128.1.125.0/24 we mapping both DLCI in to Virtual template. Then how PPP correctly identified the DLCI. Initially i thought it will send a duplicate packets. but after debug its not.

    Hi Jayaram,

    PPPoFR doesn't duplicate the packets, it just provides the capability to configure PPP over FR cloud. Basically, we configure frame-relay in the physical interface & map the DLCI with the interface address. We usually create a virtual-template interface & bind the DLCI with ppp option into the virtual interface. Since you don't configure an IP address on the physical interface, you won't have multiple sources of packets in this scenario.

    Hope this helps!

     

  • Thanks Hari For your response.

    Just trill down the show commands and identified that each peer is binded to seperated virtual access interface.

     

    Virtual-Access1 is up, line protocol is up
      Internet address is 128.1.125.5/24
      Broadcast address is 255.255.255.255
      Address determined by configuration file
      Peer address is 128.1.125.1

    RSRack1R5#sh ip int Virtual-Access 2
    Virtual-Access2 is up, line protocol is up
      Internet address is 128.1.125.5/24
      Broadcast address is 255.255.255.255
      Address determined by configuration file
      Peer address is 128.1.125.2

    Thanks,

    Jayaram

  • Yep, the virtual-template serves as a template in which the virtual-access interfaces are spawned from.

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