Volume 1 - Chapter 3: Fundamentals of WANs and IP Routing Flashcards
What are the two types of data-link protocols used for leased lines?
Point-to-Point (PPP) and High-Level Data Link Control (HDLC)
Describe the characteristics of a leased line service.
1) A physical layer service
2) Operates at a predetermined speed
3) Uses full-duplex logic
A leased line conceptually acts as if you had a ____________ link between two routers.
Full duplex ethernet link
A T1 is an example of a?
Leased line
T1 lines operate at what speed?
1.544 Mbps
A line whose data cannot be copied by other telco customers is referred to as a ______
Private line
What layer do leased lines function at?
Layer 1
The flag field in a HDLC frame is equivalent to what field in an Ethernet frame?
The preamble; used to synchronize devices so they realize a new frame is arriving
Describe what happens to an Ethernet frame when it passes across a HDLC WAN.
The packet is removed from its Ethernet frame and is encapsulated into an HDLC frame, then passed across the WAN. Then the packet is removed from the HDLC frame and re-encapsulated into an Ethernet frame.
Which traditional leased line technology is newer and supports additional features?
PPP
A WAN link that utilizes Ethernet to build a topology between only two routers is referred to as a ______.
Ethernet Point-to-Point link
A E-Line service is an example of a?
Ethernet Point-to-Point link
Describe what happens to an Ethernet frame when it passes across an Ethernet WAN.
The packet is removed from its Ethernet frame and is encapsulated into a different Ethernet frame, then passed across the WAN. Then the packet is removed from the HDLC frame and re-encapsulated into a new Ethernet frame as it is passed onto the WAN.
The term “path selection” is often used to describe the ________.
Routing process
Describe the 4 step process in routing when a router receives a frame destined for another subnet.
Step 1) Check FCS and discard corrupt frames
Step 2) Discard the old Ethernet header and trailer
Step 3) Make a forwarding decision based on the available routes for the destination
Step 4) Encapsulate the IP packet in a new Ethernet header and trailer, then forward the frame