This post follows-up my previous article Granular BGP advertise-external for MPLS L3VPNs with the intention to tweak and illustrate the BGP add-path feature implementation in Junos OS for IPv4 unicast and IPv6 labeled-unicast (6PE) routes. BGP add-paths provide a more comprehensive path diversity approach than diverse paths or advertise-external and in my view, multiple applications can be based on Junos OS BGP add-path tactical deployment in default instance tables.
This article is a follow-up for 6PE and 6VPE over IPv4 BGP-LU - Part I and focuses on providing final instrumentation, tricks and checks to set up the complete 6PE Junosphere topology on top of IPv4 BGP-LU.
After covering the MPLS Inter-AS Option C connection scheme, this post shows how to leverage and use the address-translation feature present in the rib-group data structures to create inet6.3 routes on top of it. I will also review the route advertisement and forwarding path in a sample end-to-end connectivity case to verify that labels are correctly allocated and aligned at each hop.
Please feel free to have a look at used Junos OS resources and play around with the Junosphere topology. Feedback is more than welcome!
[RFC3107] exposed the paradigm to carry label mapping information in BGP, the so-called BGP labeled unicast or BGP-LU. In my previous Using IPv6 Labeled Unicast BGP for 6PE post, I reviewed the concept basics and more specifically, described how this mechanism is applied to IPv6 address families and used in the 6PE model to distribute routing information, more concretely labeled IPv6 unicast routes.
With this post, another major building block in Junos OS for the 6VPE and the 6PE model is analyzed: the MPLS ipv6-tunneling knob.
This configuration option addresses the second major premise mentioned in the [RFC4798] 6PE model: Allowing IPv6 resolution over MPLS LSPs, even when signalled by an IPv4-based control-plane. This resource is in fact not only needed in this model, but also in the [RFC4659] 6VPE model, because inet6-vpn unicast routes also need adequate routing resolution.
The IPv6 resolution over IP4 signalled MPLS LSPs paradigm, covered via ipv6-tunneling knob in this article (there are some other alternatives to achieve this as well, watch out for a next post here!)
Thus, with this post, the 6PE basics are reviewed and therefore, I also include a Junosphere topology as attachment and challenge interested readers to put all these concepts in practice, and hopefully post flaws and provide feedback!
The 6PE model is based on IPv6 labeled unicast BGP (BGP-LU) as routing information and distribution vehicle among different systems. Although configuring IPv6 BGP-LU is simple with Junos OS, there are some relevant details to analyze.
The 6PE model has become a very popular mechanism to enable IPv6 services on top of an MPLS network. This article intends to provide an overview of this technology, as prelude for other related posts that will analyze different 6PE scenarios and their Junos OS implementation.