802.1D Spanning Tree Compliant switch

1
802.1D Spanning Tree Compliant switch

• Gireesh Shrimali, Jeslin Puthenparambil
• EE384Y Course Project

2
Outline

• Features
• System Architecture
• Hardware Architecture
• Software
• Architecture
• Software-Hardware interaction
• Test topologies

3
Features

• 8x8 layer 2 switch
• External SRAM (statically allocated) for packet
  storage
• Performs address learning - Max 4 addresses per
  port
• Implements 802.1D spanning tree protocol running
  from an external server

4
System Architecture

48 port commercial switch
NetFPGA Server
Spanning Tree Server
0
7
NetFPGA 8x8 Switch hardware

Packet Gen
Spanning Tree Client (s)
Hardware part of the project
Software part of the project
5
Hardware Architecture
SRAM
SRAM
Ethernet Controller
CFPGA
UFPGA
6
Hardware UFPGA Block Diagram
Memory Interface
CFPGA Interface
Address Table
Address Learning
Ingress Data
FIFO Status
Control Engine
Addr
to/from Memory
to/from CFPGA
Egress Data
Egress Data
7
Hardware - Statistics

• Hardware Usage on EP20K400EBC652-1
• 50 for logic elements
• 52 for pins
• Speed 27MHz
• Huge MUX (50 data inputs) on read data

8
Software Architecture - Server
Server - functions as the spanning tree protocol
running with the NetFPGA switch Hardware

• 802.1D Spanning Tree Algorithm
• Startup sending BPDUs on the Configured ports
• Process Receive BPDUs
• Process timer expiries
• Sever hardware interface
• Controls the complete NetFPGA board
• Send register access commands as control packets
• Process command responses as control packets
• Send/Receive BPDUs with reserved MAC address
• Always use port 7 for communication with the
  hardware
• Encapsulate the packets with VLAN-id of the port
  7

ST-Server
Spanning Tree algorithm
BPDUs
Server H/W interface
Encapsulated Packets to/from hardware
9
Software Architecture - Client
Client - functions like an independent switch or
router running spanning tree protocol
ST-Client

• 802.1D Spanning Tree Algorithm
• Startup sending BPDUs on the Configured ports
• Process Receive BPDUs
• Process timer expiries
• Client hardware interface
• Send/Receive BPDUs using standard Spanning Tree
  broadcast MAC address
• Encapsulate the packets with appropriate VLAN-ids

Spanning Tree algorithm
BPDUs
Client H/W interface
Encapsulated Packets to/from hardware
10
Software Hardware Interaction

• Server sending a BPDU to the client on port 0

48 port commercial switch
NetFPGA Server
0
7
NetFPGA 8x8 Switch hardware
DAAA-7B-C8-BB-00-00, SAAA-7B-C8-BB-00-0F,
VID15,SAP,BPDU

DAAA-7B-C8-BB-00-00, SAAA-7B-C8-BB-00-0F,
SAP,BPDU
DA01-80-C2-00-00-00, SAAA-7B-C8-BB-00-0F,
SAP,BPDU
DA01-80-C2-00-00-00, SAAA-7B-C8-BB-00-0F,
VID08,SAP,BPDU
11
Software Hardware Interaction

• Client sending a BPDU to the Server on port 0

48 port commercial switch
NetFPGA Server
0
7
NetFPGA 8x8 Switch hardware
DA01-80-C2-00-00-00, SAAA-7B-C8-BB-00-10,
VID08,SAP,BPDU

DA01-80-C2-00-00-00, SAAA-7B-C8-BB-00-10,
SAP,BPDU
DAAA-7B-C8-BB-00-08, SAAA-7B-C8-BB-00-00,
SAP,BPDU
DAAA-7B-C8-BB-00-08, SAAA-7B-C8-BB-00-00,
VID15,SAP,BPDU
12
Test Topologies
Simple Topology
Topology with loop
Client
Client
Server
Server
client
client