Juniper® JNCIA Exam Cram Notes : Function Of Routers And Switches

1. Networking Fundamentals

1.2 Function of routers and switches

Router is a layer 3 device which works on network layer of OSI model which connects two different networks and it identifies network devices based on their IP addresses.

The Routers are the devices used for connecting local network to the other local network/s. They are generally located at the gateway where two or more than two networks connect.

Switch is a layer 2 device which works on data link layer of OSI model, it communicates by using frames and it identifies network devices on the basis of MAC addresses or physical addresses.

System Switching Board (SSB) and Forwarding Engine Board (FEB) are the two different router models used for the control board functionality.

An aggregate route is the second form of a locally configured route within the JUNOS software.

System Switching Board (SSB) and Forwarding Engine Board (FEB) are the two different router models used for the control board functionality.

An aggregate route is the second form of a locally configured route within the JUNOS software.

Each router model uses a different name for the control board functionality. The possible names include:

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.

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.

Each Routing and Control Board (RCB) consists of the following internal components:

CPU-Runs Junos OS to maintain the routing tables and routing protocols and handles these exception packets and performs the appropriate action.

EEPROM- Stores the serial number of the Routing Engine.

DRAM-Provides storage for the routing and forwarding tables and for other Routing Engine processes.













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