9 - Routers Flashcards
What are the different forwarding mechanisms on a router?
process switching
fast switching
cisco express forwarding
Describe process switching.
uses the routers cpu to determine the next hop and forwarding interface, typically on used for difficult packets that require encryption or nat, or destinations that have not been entered into the route cache
Describe fast switching.
does not use the routers cpu, handles significantly higher throughput than process switching
Describe CEF or cisco express forwarding?
Uses FIB or forwarding information table, the fib table contains all the ip prefixes and remains synced with the ip routing table
What command is used to determine the type of forwarding mechanism that is enabled on the interface?
sh ip interface fa0/0
What are some common features for cisco routers?
- modularity
- low port count
- most ports are typically routed ports
- aux port
- compact flash storage
What is an aui port?
15 pin port attachment unit interface
what are bri ports?
used to connect to an isdn line
What does nm stand for on a cisco router?
Network Module
What does wic stand for on a cisco router?
Wan Interface Card
How many interfaces of a router can be on a single subnet?
one
What is the meaning of interface status up and line protocol up?
both the interface and protocol are working as intended
What is the meaning of interface status up and line protocol down?
layer 2 problem exists
What is the meaning of interface status down and line protocol down?
layer 1 problem exists
What is the meaning of interface status administratively down and line protocol down?
the interface was configured with the shutdown command
What layer do encapsulation protocols operate?
data link layer
What are the two primary encapsulation methods in cisco serial interfaces?
HDLC or high level data link
PPP point to point protocol
What encapsulation method is default for all synchronous serial ports on cisco devices?
HDLC
Is cisco’s interpretation of hdlc proprietary?
yes, uses a proprietary field that indicates the payload protocol
What encapsulation method is used with multi vendor implementations?
PPP
What are the protocols used by PPP?
LCP link control protocol
NCP network control protocol
What does LCP do?
configures authentication, compression, and other options used by PPP
What does NCP do?
negotiates which lan protocols will be encapsulated
What are some examples of the authentication used in PPP?
Chap or challenge handshake authentication protocol
PAP or password authentication protocol