Topic 3 Hospital Network Hardware Part 1 Routers Flashcards
What is a router and its function?
A router is a computer that specialize in sending packets over the data network
- Connects multiple networks
> Interfaces on different IP networks
> Receives packet on one interface and determines which interface to forward it towards its destination
What is the basic purpose of a router?
- To deliver packets across different networks
- To select the best path for a packet to travel and forward packets to their destinations
What are the components of a router?
- CPU - execute operating system instructions
- RAM - contains the running copy of config. file. Stores routing table. RAM contents lost when power is off
- ROM - Holds diagnostic software used when router is powered up. Stores the router’s bootstrap program (Content not lost)
- NVRAM - Stores startup config.. Includes IP address (routing protocol, hostname of router)
- Flash memory - Contains the operating system
- Interfaces - Ethernet, Serial interfaces, management interfaces
What are the 2 major groups of router interfaces?
- LAN interfaces (eg. Ethernet, Fast Ethernet)
- WAN interfaces (Types: Serial, Frame Relay, etc.)
What are LAN interfaces?
- To connect router to LAN network
- Has a 2 layer MAC address
- Consist of an RJ-45 jack which supports UTP cables
What are WAN interfaces?
- To connect routers to external networks that interconnect LANs
- Depend on the WAN technology, use different layer 2 encapsulation method
- Uses a layer 3 IP address
What are 2 management ports on a router?
- Console port - Connect a terminal for initial config. of the router
- Auxiliary (AUX) port - Similar to console port and can attach a modem
What is a router interface?
A physical connector that enables a router to send or receive packets.
Every interface on the router belongs to a different network. True or False?
True
Every interface on the router has an IP address and subnet mask of a different network number. True or False?
True
What layers of the OSI model does the router operate in?
- Layer 1 - Physical layer
- Layer 2 - Data link layer
- Layer 3 - Network layer
Explain how router operate at the 3 layers. (From PC1 to PC2)
- Router 1 receives a stream of encoded bits from PC
- Bits are decoded and passed to layer 2
- Router de-encapsulates the frame.
- Remaining packet passed up to layer 3
- Routing decisions made at this layer by examining destination IP address.
- Packet is then re-encapsulated & sent out outbound interface to R2
- R2 and R3 in the path from source to destination repeat this same process of decapsulation, searching the routing table, and then re-encapsulation and pass the frame to PC2.
How does a router route using the routing table?
When it receive a packet, it will match packet’s destination IP address with a network address in the router’s routing table. The routing table (in the RAM) will include the interface to be used in forwarding the packet.
Where is routing table stored in?
It is a data file stored in RAM
What does a routing table contain?
- Directly connected networks - Occurs when a device is connected to one of the router interfaces
- Remotely connected networks - network that is not directly connected to a particular router
