The central design principle of the Juniper Networks platform centers on a separation of the control and forwarding planes within the router.
System Control Board (SCB)
The System Control Board is found in the M40 platform. Each chassis contains no more than one SCB.
Switching and Forwarding Module (SFM)
The Switching and Forwarding Module is found in the M40e and M160 platforms. Each M40e router can contain 2 SFMs, with only one operational at a time. The M160 router contains four SFMs working in parallel.
Memory Mezzanine Board (MMB)
The Memory Mezzanine Board is found in the T320 and T640 platforms and is located on the FPC itself.
The physical media in your network connects to the Physical Interface Card (PIC) in your router. Up to four individual PICs are contained on an FPC. A media-specific ASIC is located on each PIC.
Device Control Daemon (dcd)
The router’s interfaces are configured and maintained by the Device Control Daemon. This process controls both the physical and logical properties of the interfaces.
Management Daemon (mgd)
The Management Daemon process controls all user access to the router. For example, the user’s CLI is a client of mgd.
Chassis Daemon (chassisd)
The Chassis Daemon process controls the properties of the router itself, including the interaction of the passive midplane, the FPCs, and the control boards.
Packet Forwarding Engine Daemon (pfed)
The Packet Forwarding Engine Daemon process controls the communication between the Packet Forwarding Engine and the Routing Engine. For example, one of its functions is retrieving the interface input/output statistics from the Packet Forwarding Engine.
jroute
The jroute package contains the software that operates on the Routing Engine. This controls the Unicast routing protocols, the multicast routing protocols, and the Multiprotocol Label Switching (MPLS) signaling protocols. The package also contains the software for some daemons, such as mgd.
jpfe
The jpfe package contains the Embedded OS software that controls the components of
the Packet Forwarding Engine.
jcrypto
The jcrypto package contains software that controls various security functions, such as IP Security (IPSec) and Secure Shell (SSH). This package is available only in U.S. and Canadian versions of the software.
jbundle
The jbundle package is a single file that contains all of the other packages we discussed previously.
Routing Engine Overview
- Control of the system
- Troubleshooting tools like telnet, ping, or traceroute
- Logical location to store the JUNOS software
- Operates all routing protocols and makes all routing table decisions, building a master routing table with the best path to each destination selected
The router then places these best paths into the forwarding table on the Routing Engine and copies that same data into the forwarding table on the Packet Forwarding Engine. The forwarding table on the Packet Forwarding Engine allows the router to actually forward user data packets.
Physical Composition
Routing Engine 2 ( Distribution )
http://www.juniper.net/ru/ru/products-services/routing/m-series/
333MHz processor
768MB RAM.
File storage is handled by an 80MB internal flash drive and a 6.4GB traditional hard drive. When you use the Routing Engine 2 on an M40 router, it contains an LS 120 disk for external file storage; all other models use a removable PCMCIA flash card for this purpose.
Routing Engine 3 ( Core )
http://www.juniper.net/ru/ru/products-services/routing/t-tx-series/
600MHz processor
2GB of RAM.
File storage is handled by a 128MB internal flash drive and a 30GB traditional hard drive. The Routing Engine 3 uses a removable PCMCIA flash card for external file storage.
The RAM memory in the Routing Engine stores routing tables, forwarding tables, link-state databases, and operational memory space for the JUNOS software. The internal flash drive stores the JUNOS software and configuration files for the router. The hard drive is used to store a backup copy of the JUNOS software, log files, traceoptions output (debug), and user files.
The RAM memory in the Routing Engine stores routing tables, forwarding tables, link-state databases, and operational memory space for the JUNOS software. The internal flash drive stores the JUNOS software and configuration files for the router. The hard drive is used to store a backup copy of the JUNOS software, log files, traceoptions output (debug), and user files.
Packet Forwarding Engine Overview
The Packet Forwarding Engine is the central location for data packet forwarding through the router. The router’s throughput speed and capacity are controlled by the specially designed hardware, which sets a Juniper Networks router apart from its competitors.
Simply put, the Packet Forwarding Engine provides industry-leading performance in the forwarding of data packets across any interface in the router. Achieving this type of throughput requires dividing the forwarding plane of the router into multiple segments controlled by application specific integrated circuits (ASICs) . The interaction of these ASICs provides the forwarding path within a Juniper Networks router.
Each circuit board is controlled by software that is fairly non-intelligent when compared to the JUNOS software on the Routing Engine.
The main portions of the Packet Forwarding Engine are the Physical Interface Card, the Flexible PIC Concentrator, and a switching control board. Each component contains an ASIC custom designed by Juniper Networks engineers and manufactured by IBM. Each ASIC performs a specific function in the forwarding path of packets.
Switching Control Board
PowerPC CPU
64MB of RAM
8MB or 16MB SSRAM -- contains the forwarding table for the router
The Internet Processor ASIC
- located on the control board
- accesses the forwarding table for route lookups
- packet storage memory management
Each router model uses a different name for the control board functionality:
Forwarding Engine Board (FEB)
The Forwarding Engine Board is found in both the M5 and M10 platforms and integrates the circuit board with the FPC. Each router contains no more than one FEB, which is specific to either the M5 or the M10 chassis.
System Switching Board (SSB)
The System Switching Board is found in the M20 platform. Each platform is configured to hold dual SSBs, but only one board is operational at any one time.
The System Switching Board is found in the M20 platform. Each platform is configured to hold dual SSBs, but only one board is operational at any one time.
System Control Board (SCB)
The System Control Board is found in the M40 platform. Each chassis contains no more than one SCB.
Switching and Forwarding Module (SFM)
The Switching and Forwarding Module is found in the M40e and M160 platforms. Each M40e router can contain 2 SFMs, with only one operational at a time. The M160 router contains four SFMs working in parallel.
Memory Mezzanine Board (MMB)
The Memory Mezzanine Board is found in the T320 and T640 platforms and is located on the FPC itself.
Flexible PIC Concentrator
Connects to both the switching control board and the router’s interfaces within the Packet Forwarding Engine. A PowerPC CPU controls the FPC board, and it uses 64MB of RAM to operate the Embedded OS software. The PowerPC CPU doesn’t participate in data packet forwarding, however. This is the function of a Juniper Networks ASIC, which is located on the FPC and interacts with the data packets as they enter and exit the router interfaces.
Physical Interface Card
The physical media in your network connects to the Physical Interface Card (PIC) in your router. Up to four individual PICs are contained on an FPC. A media-specific ASIC is located on each PIC.
Routing Engine Components
Software Architecture
The JUNOS software is based on the FreeBSD Unix operating system. The open source software is modified and hardened by Juniper Networks engineers to operate in the router’s specialized environment. The result of this transformation is the kernel , the heart of the JUNOS software.
Routing Protocol Daemon (rpd)
The router’s protocols are controlled by the Routing Protocol Daemon. Its functionality includes all protocol messages, routing table updates, and implementation of routing policies.
The router’s protocols are controlled by the Routing Protocol Daemon. Its functionality includes all protocol messages, routing table updates, and implementation of routing policies.
Device Control Daemon (dcd)
The router’s interfaces are configured and maintained by the Device Control Daemon. This process controls both the physical and logical properties of the interfaces.
Management Daemon (mgd)
The Management Daemon process controls all user access to the router. For example, the user’s CLI is a client of mgd.
Chassis Daemon (chassisd)
The Chassis Daemon process controls the properties of the router itself, including the interaction of the passive midplane, the FPCs, and the control boards.
Packet Forwarding Engine Daemon (pfed)
The Packet Forwarding Engine Daemon process controls the communication between the Packet Forwarding Engine and the Routing Engine. For example, one of its functions is retrieving the interface input/output statistics from the Packet Forwarding Engine.
Software Components
jkernel
The jkernel package contains the basic components of the JUNOS software operating system.
jbase
The jbase package contains additions to the JUNOS software since the last revision of
the jkernel package.
The jbase package contains additions to the JUNOS software since the last revision of
the jkernel package.
jroute
The jroute package contains the software that operates on the Routing Engine. This controls the Unicast routing protocols, the multicast routing protocols, and the Multiprotocol Label Switching (MPLS) signaling protocols. The package also contains the software for some daemons, such as mgd.
jpfe
The jpfe package contains the Embedded OS software that controls the components of
the Packet Forwarding Engine.
jdocs
The jdocs package contains the complete JUNOS software documentation set.
The jdocs package contains the complete JUNOS software documentation set.
jcrypto
The jcrypto package contains software that controls various security functions, such as IP Security (IPSec) and Secure Shell (SSH). This package is available only in U.S. and Canadian versions of the software.
jbundle
The jbundle package is a single file that contains all of the other packages we discussed previously.
Upgrade Software
user@Merlot> show version brief
Hostname: Merlot
Model: m5
JUNOS Base OS boot [5.2R2.3]
JUNOS Base OS Software Suite [5.2R2.3]
JUNOS Kernel Software Suite [5.2R2.3]
JUNOS Packet Forwarding Engine Support [5.2R2.3]
JUNOS Routing Software Suite [5.2R2.3]
JUNOS Online Documentation [5.2R2.3]
JUNOS Crypto Software Suite [5.2R2.3]
Boot Sequence
1. Removable Media
2. Solid-State Flash Drive
3. Hard Drive
4. Halt Boot Process
Merlot (ttyp0)
login: user
Password:
--- JUNOS 5.3R1.2 built 2002-04-30 01:40:52 UTC
---
--- NOTICE: System is running on alternate media device (/dev/ad1s1a).
---
user@Merlot>
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