MPLS Option A & B

Created: Jan 9, 2020 19:00:14Latest reply: Jan 15, 2020 02:26:09 93 3 0 0
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Hi, in MPLS VPN option A we configure VPN instance on ASBRs & assign RT vlaue for each VPN on PE & ASBR ,

and Option B we configure only on PE not on ASBRs.,,,as Option A used for minimum number of VPN as we configure manually .....

whats the main difference advantage & difference b/w Option A & B ..

  • x
  • convention:

Featured Answers
gabo.lr
MVE Created Jan 9, 2020 21:12:32 Helpful(1) Helpful(1)

Hello LSA

Option A characteristics:
Simplified configuration: MPLS does not need to run between ASBRs and no additional configuration is required.
Low scalability: ASBRs need to manage all VPN routes and create a VPN instance for each VPN. Because IP forwarding is performed between the ASBRs, they must reserve an interface for each inter-AS VPN. Therefore, the PE devices must have high performance. If a VPN spans multiple ASs, the intermediate ASs must support the VPN service. The configuration workload is huge and intermediate ASs are affected. Option A is applicable when only a few inter-AS VPNs are deployed.

Option B characteristics:
Unlike Option A, Option B is not limited by the number of links between ASBRs. Information about VPN routes is stored on and advertised by ASBRs. If a large number of VPN routes exist, ASBRs are likely to become a bottleneck as the burden on them increases. Therefore, in the MP-EBGP solution, the ASBRs that maintain VPN routes do not perform IP forwarding on the public network.

You can find more info and examples here: https://support.huawei.com/enterprise/my/doc/EDOC1100074766/19aa8610/inter-as-vpn

Best regards
  • x
  • convention:

LSA
LSA Created Jan 10, 2020 05:01:49
Thanks gabo thats very helpgull,,,,,but what you say if we configure one Vpn-instance with multiple RT values in Option A .  
Telecommunications%20and%20Electronics%20Engineer%2C%20with%208%20years%20of%20experience%20working%20with%20Huawei%20equipment.
All Answers
gabo.lr
gabo.lr MVE Created Jan 9, 2020 21:12:32 Helpful(1) Helpful(1)

Hello LSA

Option A characteristics:
Simplified configuration: MPLS does not need to run between ASBRs and no additional configuration is required.
Low scalability: ASBRs need to manage all VPN routes and create a VPN instance for each VPN. Because IP forwarding is performed between the ASBRs, they must reserve an interface for each inter-AS VPN. Therefore, the PE devices must have high performance. If a VPN spans multiple ASs, the intermediate ASs must support the VPN service. The configuration workload is huge and intermediate ASs are affected. Option A is applicable when only a few inter-AS VPNs are deployed.

Option B characteristics:
Unlike Option A, Option B is not limited by the number of links between ASBRs. Information about VPN routes is stored on and advertised by ASBRs. If a large number of VPN routes exist, ASBRs are likely to become a bottleneck as the burden on them increases. Therefore, in the MP-EBGP solution, the ASBRs that maintain VPN routes do not perform IP forwarding on the public network.

You can find more info and examples here: https://support.huawei.com/enterprise/my/doc/EDOC1100074766/19aa8610/inter-as-vpn

Best regards
  • x
  • convention:

LSA
LSA Created Jan 10, 2020 05:01:49
Thanks gabo thats very helpgull,,,,,but what you say if we configure one Vpn-instance with multiple RT values in Option A .  
Telecommunications%20and%20Electronics%20Engineer%2C%20with%208%20years%20of%20experience%20working%20with%20Huawei%20equipment.
chenhui
chenhui Admin Created Jan 15, 2020 02:26:09 Helpful(0) Helpful(0)

Hello @LSA
the RT value is unique, you can only assign one RT value to one VPN-instance.
  • x
  • convention:

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