Ch4 Routing Concepts Flashcards
IPv6 Loopback Address
::1/128
Data Communications Equipment
DCE
Side of serial cable that sends /sets clock rate
Usually Female
Data Terminal Equipment
DTE
Side of Serial Cable that receives the clock rate
Usually Male
Network Characteristics (7)
Topology Speed Cost Availability Security Scalability Reliability
Router Memory Types
RAM; volatile; system memory runs IOS running config
ROM: non-volatile; bootstrap
NVRAM: non-volatile; startup-config files
Flash: non-volatile: IOS and other system files
Packet Forwarding Mechanisms
Process Switching
Fast Switching
Cisco Express Forwarding (CEF)
Process Switching
Matches destination address with routing table and determines exit interface; slowest because process is done for every packet incoming.
Fast Switching
Uses fast switch cache to store next-hop information; if packet has no known destination then it is process switched then later packets to same destination are fast-switched
Cisco Express Forwarding
CEF;Cisco proprietary version of fast switching using Forwarding Information Base(FIB) and adjacency table; not packet triggered but change triggered; fastest
FIB contains pre-computed reverse lookups, next hop router info, and layer 2 information
Information Needed for Router Set-Up
IP Address
Subnet Mask
Default Gateway
Configure Switch for IP Address
interface _interface_id ip address _ip_address subnet_mask no shutdown exit id default-gateway _ip_address
Procedure for Securing Router Management
enable secret _password line console 0 password login exit line vty 0 4 password _password login exit service password-encryption
Setting Banner Procedure
banner motd $ Message $ ; $= delimiting character which is any character not in message.
Configuring IPv4 Interface on Router
interface _interface_id description _240_char_max_description ip address _ip_address subnet_mask clock rate _value_ :sets on DCE side of Serial Cbl no shutdown
Configuring IPv4 Loopback Interface
interface loopback Lo _value
ip address _ip_address subnet_mask
exit
show ip interface brief
displays summary of interfaces with IP address and operational status
show ip route
displays contents of IPv4 routing table in RAM
C : direct connection
L : local connection
show running-config interface
displays configured commands on specific interface.
show interfaces
shows interface information and packet flow count for all interfaces on device
show ip interfaces
displays all IPv4 related info. for all interfaces on router
terminal length
specifies the number of lines to be displayed before -More- prompt; value of 0 means no pauses
Show Filters
section
include
exclude
begin
show history
cmd that will display last 10 lines of commands (default) within a specific level
terminal history size
cmd that modifies history command buffer size by a specific number of lines
3 Major Steps of Routing
- De-encapsulate layer 2 frame header and trailer to expose Layer 3 packet
- Examines destination IP address of packet to find best path in routing table
- Re-encapsulates Layer 3 packet into new Layer 2 frame and forwards frame out exit interface
3 Path Determinations of Routers
- Directly Connected Network
- Remote Network
- No Route Determined: packet dropped with no gateway of last resort present.
Dynamic Routing Protocols
- Routing Information Protocol (RIP): hop count metric
- Open Shortest Path First (OPSF) : based on cumulative bandwidth from source to dest.
- Enhanced Interior Gateway Routing Protocol (EIGRP)
Uses bandwidth,delay,load, and reliability to determine best path.
Equal Cost Load Balancing
using multiple paths with equal cost metrics by sending equal amounts of packets over the paths to reach the destination
Administrative Distance(AD)
the “trustworthiness” of a route; the lower the value the more “trustworthy” the site
Connected AD
0
Static AD
1
EIGRP Summary Route AD
5
External BGP AD
Border Gateway Protocol: 20
Internal EIGRP AD
90
IGRP AD
Interior Gateway Routing Protocol: 100
OSPF AD
Open Shortest Path First: 110
IS-IS AD
Intermediate System to Intermediate System: 115
RIP AD
Routing Information Protocol: 120
External EIGRP
170
Internal BGP
Border Gateway Protocol: 200
Routing Table Codes
L : Identifies address assigned to router interface C: Directly Connected Network S: Static route D: network learned from EIGRP O: network learned from OSPF
Remote Network Entry Identifiers
Route_Source Dest_Network [Admin. Distance/Metric] via Next-hop_Ip Route_Timestamp Outgoing_interface
Directly Connected Network Entry Identifiers
Route_Source Destination_Network Outgoing_Interface
Benefits of Static Routes
- Improved Security
2. Resource Efficiency
Command to set static route
ip route _ip_address subnet_mask {next_hop_ip | exit_interface}
Command to set default static route
ip route 0.0.0.0 0.0.0.0 {next_hop_ip | exit_interface}
router ? (command)
global config command used to display which IPv4 protocols a router is capable of using
