Bit Indexed Explicit Replication (BIER) is a novel IP multicast (IPMC) forwarding paradigm proposed by the IETF. It offers a transport layer for other IPMC traffic, keeps core routers unaware of IPMC groups, and utilizes a routing underlay, e.g., an IP network, for its forwarding decisions. With BIER, core networks do not require dynamic signaling and support a large number of IPMC groups with large churn rates. The contribution of this work is threefold. First, we propose a novel fast reroute (FRR) mechanism for BIER (BIER-FRR) so that IPMC traffic can be rerouted as soon as the routing underlay is able to carry traffic again after a failure. In particular, BIER-FRR enables BIER to profit from FRR mechanisms in the routing underlay. Second, we describe a prototype for BIER and BIER-FRR within an IP network with IP fast reroute (IP-FRR). It is based on the programmable data plane technology P4. Third, we propose a controller hierarchy with local controllers for local tasks, in particular to enable IP-FRR and BIER-FRR. The prototype demonstrates that BIER-FRR reduces the protection time for BIER traffic to the protection time for unicast traffic in the routing underlay.

位索引显式复制（BIER）是IETF提出的一种新颖的IP多播（IPMC）转发范例。它为其他IPMC流量提供了一个传输层，使核心路由器不知道IPMC组，并利用路由底层（例如IP网络）进行转发决策。使用BIER，核心网络不需要动态信令，并支持大量流失率很高的IPMC组。这项工作的贡献是三方面的。首先，我们提出了一种针对BIER的新颖的快速重路由（FRR）机制（BIER-FRR），以便一旦路由底层在故障后能够再次承载流量，就可以重新路由IPMC流量。尤其是，BIER-FRR使BIER能够从路由参考中的FRR机制中获利。其次，我们描述具有IP快速重路由（IP-FRR）的IP网络中BIER和BIER-FRR的原型。它基于可编程数据平面技术P4。第三，我们提出了一个带有用于本地任务的本地控制器的控制器层次结构，特别是为了启用IP-FRR和BIER-FRR。该原型演示了BIER-FRR将BIER流量的保护时间减少到路由底层中单播流量的保护时间。