Tunneling Protocols ========================== This section covers tunneling protocols that encapsulate network traffic to enable secure or specialized communication across untrusted or incompatible networks. These protocols are widely used in VPNs, broadband services, and network interoperability solutions. .. toctree:: :maxdepth: 1 :hidden: :includehidden: L2TP PPPoE PPP IP_in_IP .. list-table:: :widths: 20 60 20 :header-rows: 1 * - Protocol / Tech - Description - Use Case * - L2TP (Layer 2 Tunneling Protocol) - Tunneling protocol often combined with IPsec for encryption. *Encapsulates PPP frames for VPNs.* - Secure remote VPN access. * - PPPoE (Point-to-Point Protocol over Ethernet) - Encapsulates PPP frames within Ethernet frames, enabling ISPs to manage individual subscriber sessions over a shared Ethernet infrastructure. PPPoE supports authentication protocols (PAP, CHAP), IP address assignment, and session management. *Widely used for broadband Internet access via DSL lines.* - DSL broadband subscriber management * - PPP (Point-to-Point Protocol) - A data link protocol that encapsulates network layer packets for transmission over serial links. Supports authentication, compression, and encryption. *Common for dial-up and VPN links.* - Dial-up and VPN connections * - IP-in-IP (IP Encapsulation within IP) - Encapsulates one IP packet inside another IP packet. *Used for simple IP tunneling across different network segments.* - Site-to-site tunneling, mobile IP, IPv6 transition mechanisms .. tab-set:: .. tab-item:: L2TP (Layer 2 Tunneling Protocol) **RFC:** RFC 2661 **Main Features:** - Tunnels PPP frames across IP networks - No built-in encryption (typically paired with IPsec) - Often used in legacy VPN setups **Use Cases:** - L2TP/IPsec VPN for remote users - Legacy Windows VPN infrastructure **Alternative Protocols:** - PPTP (deprecated) - OpenVPN, WireGuard .. panels:: :container: container pb-4 :column: col-lg-12 p-2 **Let us learn more about L2TP:** * :ref:`Learnings in this section ` * :ref:`Terminology ` * :ref:`Version Info ` * :ref:`L2TP Version&RFC Details ` * :ref:`L2TP Basic Setup on Ubuntu using IPv4 ` * :ref:`L2TP Basic Setup on Ubuntu using IPv6 ` * :ref:`L2TP Protocol Packet Details ` * :ref:`L2TP Usecases ` * :ref:`L2TP Basic Features ` * :ref:`L2TP Feature : Tunneling ` * :ref:`L2TP Feature : Session Multiplexing ` * :ref:`L2TP Feature : Control and Data Separation ` * :ref:`L2TP Feature : Protocol Independence ` * :ref:`L2TP Feature : UDP-Based Transport ` * :ref:`L2TP Feature : No Native Encryption ` * :ref:`L2TP Feature : AVP-Based Control Messages ` * :ref:`L2TP Feature : Reliability for Control Messages ` * :ref:`L2TP Feature : Tunnel and Session IDs ` * :ref:`L2TP Feature : Extensibility (L2TPv3) ` * :ref:`Reference links ` .. button-link:: ./L2TP.html :color: primary :shadow: :expand: Jump to "L2TP" .. tab-set:: .. tab-item:: PPPoE (Point-to-Point Protocol over Ethernet) **RFC:** RFC 2516 **Main Features:** - Encapsulates PPP frames within Ethernet frames - Supports authentication protocols like PAP and CHAP - Enables per-user session identification and accounting - Operates on standard Ethernet (Layer 2) - Provides dynamic IP address assignment - Used by ISPs for subscriber session management **Use Cases:** - DSL broadband subscriber authentication and management - Session-based IP address leasing by ISPs - Accounting and usage-based billing for residential internet - Point-to-point virtual connections over Ethernet infrastructure **Alternative Protocols:** - IPoE (IP over Ethernet) – A simpler alternative without PPP overhead - L2TP – For tunneling PPP over IP networks in broadband aggregation - 802.1X + RADIUS – Secure enterprise authentication at Layer 2 - DHCP + VLANs – For IP provisioning with logical segmentation .. panels:: :container: container pb-4 :column: col-lg-12 p-2 :card: What You Will Learn in This Section **Let us learn more about PPPoE:** * :ref:`Learnings in this section ` * :ref:`Terminology ` * :ref:`Version Info ` * :ref:`PPPoE Version&RFC Details ` * :ref:`PPPoE Basic Setup on Ubuntu using IPv4 ` * :ref:`PPPoE Basic Setup on Ubuntu using IPv6 ` * :ref:`PPPoE Protocol Packet Details ` * :ref:`PPPoE Usecases ` * :ref:`PPPoE Basic Features ` * :ref:`PPPoE Feature : Encapsulation ` * :ref:`PPPoE Feature : Authentication ` * :ref:`PPPoE Feature : Session Establishment ` * :ref:`PPPoE Feature : Dynamic IP Assignment ` * :ref:`PPPoE Feature : Bandwidth Management ` * :ref:`PPPoE Feature : Error Detection ` * :ref:`PPPoE Feature : Support for IPv4&IPv6 ` * :ref:`PPPoE Feature : Accounting ` * :ref:`PPPoE Feature : Compatiblity ` * :ref:`PPPoE Feature : Scablity ` * :ref:`Reference links ` .. button-link:: ./PPPoE.html :color: primary :shadow: :expand: Jump to "PPPoE" .. tab-set:: .. tab-item:: PPP (Point-to-Point Protocol) **RFC:** RFC 1661 **Main Features:** - Encapsulates Layer 3 protocols over point-to-point links - Supports authentication (PAP, CHAP) - Includes error detection and framing - Optional compression and encryption - Multi-protocol support (e.g., IP, IPX, AppleTalk) - Link negotiation and teardown mechanisms **Use Cases:** - Dial-up modem internet access - Point-to-point leased lines (ISDN, serial links) - Tunneling PPP over IP networks (e.g., PPP over L2TP) - Remote user VPN and secure access **Alternative Protocols:** - HDLC – Simpler point-to-point encapsulation - SLIP – Outdated protocol replaced by PPP - L2TP – Encapsulates PPP for tunneling - Ethernet – For LAN and broadband access .. panels:: :container: container pb-4 :column: col-lg-12 p-2 :card: What You Will Learn in This Section **Let us learn more about PPP:** * :ref:`Learnings in this section ` * :ref:`Terminology ` * :ref:`Version Info ` * :ref:`PPP Version&IEEE Details ` * :ref:`PPP Basic Setup on Ubuntu using IPv4 ` * :ref:`PPP Basic Setup on Ubuntu using IPv6 ` * :ref:`PPP Protocol Packet Details ` * :ref:`PPP Usecases ` * :ref:`PPP Basic Features ` * :ref:`Reference links ` .. button-link:: ./PPP.html :color: primary :shadow: :expand: Jump to "PPP" .. tab-set:: .. tab-item:: IP-in-IP (IP Encapsulation within IP) **RFC:** RFC 2003 **Main Features:** - Encapsulates a complete IP packet within another IP packet - Outer IP header is used for routing over intermediary networks - Supports both IPv4-in-IPv4 and IPv6-in-IPv6 encapsulation - Minimal overhead and no encryption - Used as a basic tunneling mechanism in many systems **Use Cases:** - Site-to-site tunneling across intermediate IP networks - Transport of private IP traffic over a public IP backbone - Supporting Mobile IP (mobile node to home agent) - IPv6 transition technologies (6in4, ISATAP) **Alternative Protocols:** - GRE – More flexible tunneling with protocol field and checksum - L2TP – Tunneling of PPP across IP - IPsec – Adds encryption and authentication to tunneling - VXLAN – Overlay network tunneling for data centers .. panels:: :container: container pb-4 :column: col-lg-12 p-2 :card: What You Will Learn in This Section **Let us learn more about IP-in-IP:** * :ref:`Learnings in this section ` * :ref:`Terminology ` * :ref:`Version Info ` * :ref:`IP-in-IP Version&IEEE Details ` * :ref:`IP-in-IP Basic Setup on Ubuntu using IPv4 ` * :ref:`IP-in-IP Basic Setup on Ubuntu using IPv6 ` * :ref:`IP-in-IP Protocol Packet Details ` * :ref:`IP-in-IP Usecases ` * :ref:`IP-in-IP Basic Features ` * :ref:`Reference links ` .. button-link:: ./IP_in_IP.html :color: primary :shadow: :expand: Jump to "IP-in-IP"