DHCP relay for IPv6 HLD (#765)

Signed-off-by: Shlomi Bitton <shlomibi@nvidia.com>

doc/DHCPv6_Relay/DHCPv6_Relay_HLD.md

@@ -0,0 +1,155 @@
+# DHCP Relay for IPv6 HLD
+
+# High Level Design Document
+
+#### Rev 0.1
+
+# Table of Contents
+- [DHCP Relay for IPv6 HLD](#dhcp-relay-for-ipv6-hld)
+- [High Level Design Document](#high-level-design-document)
+      - [Rev 0.1](#rev-01)
+- [Table of Contents](#table-of-contents)
+- [List of Tables](#list-of-tables)
+- [List of Figures](#list-of-figures)
+- [Revision](#revision)
+- [About this Manual](#about-this-manual)
+- [Scope](#scope)
+- [Definitions/Abbreviation](#definitionsabbreviation)
+- [1 Requirements Overview](#1-requirements-overview)
+  - [1.1 Functional requirements](#11-functional-requirements)
+  - [1.2 Configuration and Management Requirements](#12-configuration-and-management-requirements)
+- [2 Modules design](#2-modules-design)
+  - [2.1 DHCP Relay for IPv6 build and runtime dependencies](#21-dhcp-relay-for-ipv6-build-and-runtime-dependencies)
+  - [2.2 DHCP Relay for IPv6 process in dhcp-relay container](#22-dhcp-relay-for-ipv6-process-in-dhcp-relay-container)
+  - [2.3 DHCP Monitor](#23-dhcp-monitor)
+- [3 CLI](#3-cli)
+- [4 Init flow](#4-init-flow)
+
+# List of Tables
+* [Table 1: Abbreviations](#definitionsabbreviation)
+
+# List of Figures
+* [DHCPv6 Diagram](#2-modules-design)
+* [DHCPv6 init flow](#4-init-flow)
+
+# Revision
+| Rev | Date     | Author          | Change Description                 |
+|:---:|:--------:|:---------------:|------------------------------------|
+| 0.1 | 03/04    | Shlomi Bitton   | Initial version                    |
+
+# About this Manual
+This document provides an overview of the implementation and integration of DHCP Relay for IPv6 feature in SONiC.
+
+# Scope
+This document describes the high level design of the DHCP Relay for IPv6 feature in SONiC.
+
+# Definitions/Abbreviation
+| Abbreviation  | Description                               |
+|---------------|-------------------------------------------|
+| DHCP          | Dynamic Host Configuration Protocol       |
+
+# 1 Requirements Overview
+
+## 1.1 Functional Requirements
+
+DHCP Relay for IPv6 feature in SONiC should meet the following high-level functional requirements:
+
+- Give the support for relaying DHCP packets from downstream networks to upstream networks using IPv6 addresses.
+- Provide the functionality as a seperate process running on dhcp-relay docker container.
+- Relaying messages to multiple unicast and multicast addresses.
+
+## 1.2 Configuration and Management Requirements
+
+- DHCPv6 trap should be enabled through the COPP manager when the DHCP relay feature is enabled and vice versa. 
+- Downstream network is the VLAN interface with the relay configuration. Global IPv6 address is required to be configured on that interface. 
+- Config DB schema should meet the following format:
+```
+{
+"VLAN": {
+  "Vlan1000": {
+    "dhcp_servers": [
+      "192.0.0.1", 
+      "192.0.0.2", 
+    ], 
+    "dhcpv6_servers": [ 
+      "21da:d3:0:2f3b::7", 
+      "21da:d3:0:2f3b::6", 
+    ], 
+    "vlanid": "1000" 
+    } 
+  }
+}
+```
+
+# 2 Modules design
+
+![DHCPv6 Diagram](/doc/DHCPv6_Relay/diagram.png)
+
+## 2.1 DHCP Relay for IPv6 build and runtime dependencies
+
+The DHCP Relay for IPv6 feature, same as the IPv4 version, will be based on the open source project 'isc-dhcp'.
+
+## 2.2 DHCP Relay for IPv6 process in dhcp-relay container
+
+A new process will run in parallel to the other process for IPv4 support.
+The new process will listen to DHCP packets for IPv6 and forward them to the relevant interface according to the configuration.
+For example, from the configuration described on the previous section, the following daemon will start:
+```
+admin@sonic:/# /usr/sbin/dhcrelay -6 -d --name-alias-map-file /tmp/port-name-alias-map.txt -l Vlan1000 -u 21da:d3:0:2f3b::7%Ethernet28 -u 21da:d3:0:2f3b::6%Ethernet28
+```
+
+## 2.3 DHCP Monitor
+
+The existing DHCP monitor will be enhanced in order to support monitoring for DHCP IPv6 as well.
+
+## 3 CLI
+
+The existing CLI will be enhanced to support configuring DHCP IPv6 along with the IPv4 support.
+
+**config vlan dhcp_relay add**
+
+Usage:
+```
+config vlan dhcp_relay add <vlan_id> <dhcp_relay_destination_ip>
+```
+Example:
+```
+admin@sonic:~$ sudo config vlan dhcp_relay add 1000 21da:d3:0:2f3b::7
+Added DHCP relay destination address 21da:d3:0:2f3b::7 to Vlan1000
+Restarting DHCP relay service...
+```
+
+**config vlan dhcp_relay delete**
+
+Usage:
+```
+config vlan dhcp_relay del <vlan-id> <dhcp_relay_destination_ip>
+```
+Example:
+```
+admin@sonic:~$ sudo config vlan dhcp_relay del 1000 21da:d3:0:2f3b::7
+Removed DHCP relay destination address 21da:d3:0:2f3b::7 from Vlan1000
+Restarting DHCP relay service...
+```
+
+**show vlan brief**
+
+Usage:
+```
+show vlan brief
+```
+Example:
+```
+admin@sonic:~$ show vlan brief
++-----------+----------------------+------------+----------------+-----------------------+-------------+
+|   VLAN ID | IP Address           | Ports      | Port Tagging   | DHCP Helper Address   | Proxy ARP   |
++===========+======================+============+================+=======================+=============+
+|      1000 | 21da:d3:0:2f3b::6/96 | Ethernet28 | untagged       | 21da:d3:0:2f3b::6     | disabled    |
+|           |                      |            |                | 21da:d3:0:2f3b::7     |             |
++-----------+----------------------+------------+----------------+-----------------------+-------------+
+```
+
+## 4 Init flow
+
+![DHCPv6 init flow](/doc/DHCPv6_Relay/init.svg)
+