Figure 136: Inter-As Option-B - Alcatel-Lucent 7750 SR Manual

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This form of inter-AS VPRNs does not require instances of the VPRN to be created on the ASBR,

as in option-A, as a result there is less management overhead. This is also the most common form

of Inter-AS VPRNs used between different service providers as all routes advertised between

autonomous systems can be controlled by route policies on the ASBRs.

The third option, referred to as Option-C

AS boundaries but also expands the trust model between ASNs. As a result this model is typically

used within a single company that may have multiple ASNs for various reasons.

This model differs from Option-B, in that in Option-B all direct knowledge of the remote AS is

contained and limited to the ASBR. As a result, in option-B the ASBR performs all necessary

mapping functions and the PE routers do not need perform any additional functions then in a non-

Inter-AS VPRN.

7750 SR OS Services Guide

L=Vx VPRN Label

L=Px BGP Next Hop

Figure 136: Inter-AS Option-B

Virtual Private Routed Network Services

137), allows for a higher scale of VPRNs across