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New Member

Is cmd "multilink virtual-template 1" is optional while creating multilink?

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2 REPLIES
Cisco Employee

Re: Is cmd "multilink virtual-template 1" is optional while crea

Hi Balajee,

The use of this command depends on how you are configuring the multilink feature on your router.

If you are configuring a PPP Multilink endpoint, e.g. a CPE router, then this command is not necessary at all. In fact, the typical configuration of a CPE is similar to the following example:

interface Serial0/0/0

  encapsulation ppp

  ppp multilink group 1

  no shutdown

!

interface Serial0/0/1

  encapsulation ppp

  ppp multilink group 1

  no shutdown

!

interface Multilink1

  ip address ...

  ! add another relevant configuration - CHAP, NAT, etc...

Here, because you have directly grouped all relevant interfaces into a predefined Multilink bundle, there is no need for dynamic Virtual-Template interfaces at all.

The multilink virtual-template command is used when configuring an access concentrator that terminates several multilink bundles and where static configuration would be tedious, if not impossible to do beforehand. The configuration of such access concentrator would then look as:

multilink virtual-template 1

!

interface Loopback0

  ip address 192.0.2.1 255.255.255.255

!

interface Virtual-Template 1

  ip unnumbered Loopback0

  encapsulation ppp

  ! add another relevant configuration - CHAP, NAT, etc...

!

interface Serial0/0/0

  encapsulation ppp

  ppp multilink

  no shutdown

!

interface Serial0/0/1

  encapsulation ppp

  ppp multilink

  no shutdown

!

interface Serial0/1/0

  encapsulation ppp

  ppp multilink

  no shutdown

! etc.

Note the different way of configuring the multilink on this access concentrator - because it is not known beforehand which interfaces are connected to the same peer, the interfaces are not immediately put into predefined multilink groups. The ID of the peer will be determined dynamically as new PPP sessions come up (this ID verification can be performed based on authenticated name, endpoint discriminator or their combination; see multilink bundle-name for details) and only after this determination, the access concentrator knows which sessions shall be grouped together and adds them under a Virtual-Access interface cloned from the Virtual-Template.

Best regards,

Peter

New Member

Re: Is cmd "multilink virtual-template 1" is optional while crea

Thanks Peter for your clear explanation.

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