Network Processors: Architecture, Applications, and Algorithms, Slides of Computer Architecture and Organization

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Network Processor and Its

Applications (1)

Outline

• Overview of the network processors

• Networking protocol stack

• IP routing

• Packet Classification

• Other applications

Typical NP Architecture

SDRAM

(Packet buffer)

SRAM

(Routing table)

multi-threaded processing elements

Co-processor

Input ports Output ports

Network Processor

Bus Bus

Network Architecture and Applications

• Introduction to networking
• IP packet structure
• Control and data planes
• Traditional applications
  • IPv4 routing, classification etc.
• New applications
  • URL-based switching,transcoding, etc.

TCP/IP Model

• ISO OSI (Open Systems Interconnection) not fully implemented
• Presentation and Session layers not present in TCP/IP

Application

Pre.

Session

Transport

Network

Data Link

Physical

Application

TCP

IP

Host-to-Net

OSI TCP/IP

TCP/IP packet

MAC IP TCP APP. DATA MAC

Source Port Destination Port

Sequence Number

Acknowledgement Number

Header Length and Options Window Size

Checksum Urgent Pointer

Options (0 or more 32-bit words)

TCP/IP packet

MAC IP TCP APP. DATA MAC

Preamble D. Add. S. Add. Leng. CRC

Application Categorization

• Control-Plane tasks

– Less time-critical

– Control and management of device operation

• Table maintenance, port states, etc.

• Data-Plane tasks

– Operations occurring real-time on “packet path”

– Core device operations

• Receive, process and transmit packets

Data Plane Tasks

• Media Access Control

• Low-level protocol implementation
  • Ethernet, SONET framing, ATM cell processing, etc.

• Data Parsing

• Parsing cell or packet headers for address or protocol information

• Classification

• Identify packet against a criteria (filtering / forwarding decision, QoS, accounting, etc.)

• Data Transformation

• Transformation of packet data between protocols

• Traffic Management

• Queuing, scheduling and policing packet data

Network Processor Applications

• Routing table lookup
  • Determine the next hop for incoming packets
• Packet Classification
  • classify packets using header fields against a set of rules
• URL-based Switching
  • Distribute HTTP requests based on URLs.
• Transcoding
  • Encryption/Decryption, intrusion detection, firewall,

access control checking, denial-of-service

Trie-based Routing Table Lookup

• Trie block keeps pointers to route entry and other trie blocks
• Destination IP address bits are examined group by group (4-bit)

rt_ptr trie_ptr

Next hop 1

0

15

Next hop 2

Next hop 3 Next hop 4

Prefix Netmask Next hop 0010 0xF 1 0001,0011 0xFF 2 1110,1110 0xFF 2 0001,0011,0000 0xFFF 3 0001,0011,1111,111 0xFFFE 4

Trie block

Example

rt_ptr trie_ptr

Next hop 1

0

15

Next hop 2

Next hop 3 Next hop 4

Prefix Netmask Next hop 0010 0xF 1 0001,0011 0xFF 2 1110,1110 0xFF 2 0001,0011,0000 0xFFF 3 0001,0011,1111,111 0xFFFE 4

Packet destination IP address =0x13fe (0001,0011,1111,1110,…)

Multi-way multi-column search

P1: 1* -> [100000,111111]

P2: 101* -> [101000,101111]

P3: 10101* -> [101010,101011]

p1) 1 0 0 0 0 0 p1 p

p2) 1 0 1 0 0 0 p2 p

p3) 1 0 1 0 1 0 p3 p

1 0 1 0 1 1 p2 p

1 0 1 1 1 1 p1 p

1 1 1 1 1 1 - p

Any region in the binary search

between two consecutive numbers

corresponds to a unique prefix

k3 k

k1 k2 k4 k5 k7 k

info info info^ info^ info^ infoinfo^ info info

3-way tree for 8 keys

Multi-column search

is used for wide address such as IPv

A C E

A D C

A M W

B M W

B N X

B N Y

W/M words

Probe 1 2 3

Packet Classification

• Routers are required to distinguish packets for
  • Flow identification
  • Fair sharing of bandwidth
  • QoS
  • Security
  • Accounting, billing
  • etc
• Packets are classified by rules
  • Src IP, Dest IP, src port #, dest port # etc
• Classification Algorithm Metrics
  • Search speed
  • Storage cost
  • Scalability
  • Updates
  • Etc.