Robin HJ & R. Hughes-Jones Manchester Sep 1999

Gigabit Ethernet in PtolemyStatus Sep 99 :

• Stars that exist :– GigEChip Translate between GigEPacket and “int”– GigE4Sw 4 port GigEPacket shared memory switch with Mac

address learning– GigEIntFace Translate between Amessages and GigEPackets– AmsGen Translate between Amessages and “int”

• Objects that are used inside the Stars :– GigEPacket Define various packet types data, pause ...– GigEStatistics Provide throughput and rate stats– GigELink Implement 100Mbit & Gigabit Ethernet link– GigERouter Packet router

Robin HJ & R. Hughes-Jones Manchester Sep 1999

The Gigabit Ethernet Link Object

Simple Test of the GigELink Object

PoissonGigEChip GigEChip

int GigEPacket int

Scope

GigELink Object Internals :

Used in the Stars :– GigEIntFace– GigE4Sw– GigEChip

GigEPacket

Local bus Data &Control

GigELink

Send

Packet Queue

Recv. Packet Queue

GigELinkGigEPacket

EthernetLink

Robin HJ & R. Hughes-Jones Manchester Sep 1999

0.0E+00

1.0E+05

2.0E+05

3.0E+05

4.0E+05

5.0E+05

3000 5000 7000 9000 11000 13000 15000

Poisson period ns

Sta

r-S

tar

Lat

en

cy n

s

0

20

40

60

80

100

Se

nd

Q s

ize

pac

ke

ts

Latency 1024 Latency 512 Q size 1024 Q size 512

Gigabit Ethernet

Poisson generator

All buses at 8 ns / byte

Packet times:

1024 bytes 8.29s

512 bytes 4.19 s

Qs = packets to be sent

Send bus 8 ns / byte

Receive bus 13 ns / byte

Ethernet recv. link with

hi water mark of 5 packets

see pause / data packets

recv. Q of 5

Effect of packet size on Qs and Latency

0.0E+00

2.0E+04

4.0E+04

6.0E+04

8.0E+04

1.0E+05

1.2E+05

2000 4000 6000 8000 10000 12000 14000 16000 18000

Poisson period nsS

tar-

Sta

r L

ate

ncy

ns

0

5

10

15

20

25

30

Se

nd

Q s

ize

pac

kets

Latency 1024 Latency 512 Q-size1024 Q-size512

Robin HJ & R. Hughes-Jones Manchester Sep 1999

Ethernet SwitchesInternals :

Size:

4 ports

Type:

Multi Port memory

Amsg

Gig4Sw

Gig4Sw

Amsg

A E

A E

Gig4Sw

A E

A E

A E

A E

A E A E

Test of MAC addresses Learning :

RoutingFunction

Data &Control

Data &Control

GigEPacket GigEPacket

GigEPacket

GigELink

GigELink

Send

Packet Queue

Recv. Packet Queue

GigEPacket

GigELink

Send

Packet Queue

Recv. Packet Queue

GigELink

GigERouter

Robin HJ & R. Hughes-Jones Manchester Sep 1999

The Amessage - Ethernet Interface

Internals :

Amessages stored

on sending,

deleted when recv.

Timeout needed

A E

Packetiser

Data &Control

Data &Control

Amessage GigEPacket

Amessage

GigELink

Recv. Message

Queue

GigEPacket

GigELink

Send

Packet Queue

Recv. Packet Queue

GigELink

AmessageBuilder

Send Amessage Store