3troubleshootingjunos

Reproduction

Typical Platform FRUs

All JUNOS platforms consist of a chassis and one or more FRUs. The slide shows the

primary F Us associat with the T640.

Not

for

Reproduction

Platform Architecture and Com onents

The slide highlights the topic we discuss next.

Not

for

Reproduction

Architectural Philosophy

Architecturally, all JUNOS platforms share a common design that separates the

router’s control plane and forwarding plane. JUNOS platforms consist of the following

two major components:

•

outing Engine: The RE is the brains of the platform; it is responsible for

pe fo ming routing updates and system management. The RE runs

va ious protocol and management software processes that live inside a

p otected memory environment. The RE is a general-purpose computer

platform based on an Intel microprocessor. It connects to the PFE

through an internal 100 Mbps connection identified as fxp1 on most

Not

platforms. Some larger JUNOS platforms (such as the M320) use a

Gigabit Ethernet link, referred to as bcm0, between the RE and a Fast

forEthernet switch, which in turn has dedicated 100 Mbps links to each

FPC.

•

Packet Forwarding Engine: The PFE is responsible for forwarding transit

packets through the router using an ASIC-based switching path. Because

this architecture separates control operations—such as routing updates

and system management—from packet forwarding, the router can deliver

superior performance and highly reliable Internet operation.

The PFE receives the forwarding table from the RE. In the maj r

y f cases, the PFE’s

forwarding table and the RE’s forwarding table synchronize over

he 100 Mbps fxp1

Not

for

Reproduction

T Series Architecture

The T Series archit cture cl anly s parates control operations from packet forwarding

operations. This design liminat s processing and traffic bottlenecks, permitting the

router to achieve high performance. The router’s host subsystem—running JUNOS

for

Softwa e to handle routing protocols, traffic engineering, policy, monitoring, and

configu ation management—performs the control operation. The router’s PFEs—

consisting of ASICs—perform the forwarding operations.

The use dist ibuted memory and crossbar switching in the forwarding plane

c ntributes to a functional redundancy in the T series. Part of the distributed packet

rwarding architecture includes positioning of a PFE on each FPC, which adds to the

Not

resiliency of the T Series devices.

Note that M120 and M320 routers deploy the T Series distributed memory

p g ammableReproductionASICs—each of which is dedicated to a specific task. The PFE

contains

Logical Platform Vi

w of M Series

We design the M S

ri s architecture with scale and stability in mind, including the

modular and fault-prot

ct d design of JUNOS Software. M Series architecture offers a

clean separation of routing and packet forwarding functions, resulting in stable,

for

p edictable, and reliable systems. The Intel-based RE is responsible for running

JUNOS Software, for performing routing updates, and for system management. The

PFE is the logical entity responsible for packet forwarding. It physically consists of

a c py of the forwarding table that matches the forwarding table copy in the RE.

Similar to the T Series, the M Series device architecture includes FPCs, which could

Not

h use Physical Interface Cards (PICs). The M Series devices (with the exception of the

M120 and M320) use a shared memory architecture.

independentReproductionfrom each other.

MX Series Archit

cture

Similar to core rout

rs, MX Series devices are packet based and deploy distributed

memory archit cture. The architecture includes RE redundancy, the control plane, the

SCB, and the DPCs. The control plane of th platform’s chassis consists of Gigabit

Ethe net links between the SCBs or REs and each DPC. Each SCB has a connection to

eve y DPC in the chassis, which in turn means that each RE has a redundant

connection to each DPC. The switch fabric failover and the RE failover are

The host subsystem consists of an RE functioning together with an SCB. The router

can have one or two host subsystems. If it has two host subsystems installed, one

Not

functions as the master and the other functions as the backup. If the master host

forsubsystem (or either of its components) fails, the backup can take over as the master.

Reproduction

SRX Series Archit

cture

SRX Series devices

ploy Dynamic Services Architecture that includes the

management and control n c ssary to incorporate individual blades into a powerful

collective solution. ather than housing disparate cards, the Dynamic Services

for

Architectu e adds each blade into a growing pool of resources. The SRX Series device

can utilize these esources as necessary for optimal processing of traffic.

At the hea t the Dynamic Services Architecture is the switch fabric and SCB. The

SCB t ansf

ms the chassis from a simple blade enclosure into a highly effective

mesh netw

rk. The purpose of the SCB is to allow all blades in the chassis to send

tra ic at extremely high bandwidth.

Not