From Map-and-Encap to BIER: Observations on Network Routing Scalability

Fuente: arXiv
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Auteurs principaux: Yu, Tianyuan, Wang, Lan, Zhang, Beichuan, Zhang, Lixia
Format: Preprint
Publié: 2026
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author Yu, Tianyuan
Wang, Lan
Zhang, Beichuan
Zhang, Lixia
author_facet Yu, Tianyuan
Wang, Lan
Zhang, Beichuan
Zhang, Lixia
contents The TCP/IP protocol stack uses IP addresses for two distinct roles: identifying hosts and locating their attachment points in the network topology. This dual purpose creates a fundamental tension that has led to routing and forwarding scalability challenges throughout the history of the Internet in unicast packet delivery and, more notably, in multicast delivery. This paper reviews the evolution of routing scalability solutions over the years and makes four observations. First, map-and-encap is a recurring architectural solution shared by all scalable unicast and multicast delivery methods, developed independently across different problem contexts. Second, a new solution tends to succeed when it can bring immediate local gains to early adopters without requiring coordination across administrative domains. Third, network routing and forwarding designs that depend on external factors, such as the number of distinct end sites or even application-specific deliveries, inherently preclude an upper bound on their scalability. Fourth, today's inter-domain routing protocol, BGP, lacks a topological abstraction equivalent to an egress router within a routing domain, thereby inherently preventing a map-and-encap solution for scalability. These observations offer insights into the design of future scalable routing system architectures.
format Preprint
id arxiv_https___arxiv_org_abs_2605_07071
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle From Map-and-Encap to BIER: Observations on Network Routing Scalability
Yu, Tianyuan
Wang, Lan
Zhang, Beichuan
Zhang, Lixia
Networking and Internet Architecture
The TCP/IP protocol stack uses IP addresses for two distinct roles: identifying hosts and locating their attachment points in the network topology. This dual purpose creates a fundamental tension that has led to routing and forwarding scalability challenges throughout the history of the Internet in unicast packet delivery and, more notably, in multicast delivery. This paper reviews the evolution of routing scalability solutions over the years and makes four observations. First, map-and-encap is a recurring architectural solution shared by all scalable unicast and multicast delivery methods, developed independently across different problem contexts. Second, a new solution tends to succeed when it can bring immediate local gains to early adopters without requiring coordination across administrative domains. Third, network routing and forwarding designs that depend on external factors, such as the number of distinct end sites or even application-specific deliveries, inherently preclude an upper bound on their scalability. Fourth, today's inter-domain routing protocol, BGP, lacks a topological abstraction equivalent to an egress router within a routing domain, thereby inherently preventing a map-and-encap solution for scalability. These observations offer insights into the design of future scalable routing system architectures.
title From Map-and-Encap to BIER: Observations on Network Routing Scalability
topic Networking and Internet Architecture
url https://arxiv.org/abs/2605.07071