Cisco Systems Router 1800 Series User Manual

 
B-5
Cisco 1800 Series Integrated Services Routers (Fixed) Software Configuration Guide
OL-6426-02
Appendix B      Concepts
  TACACS+
TACACS+
Cisco 1800 fixed-configuration routers support the Terminal Access Controller Access Control 
System
 Plus (TACACS+) protocol through Telnet. TACACS+ is a Cisco proprietary authentication 
protocol that provides remote access authentication and related network security services, such as event 
logging. User passwords are administered in a central database rather...

 
B-6
Cisco 1800 Series Integrated Services Routers (Fixed) Software Configuration Guide
OL-6426-02
Appendix B      Concepts
  Dial Backup
PVC
A PVC is a connection between remote hosts and routers. A PVC is established for each ATM end node 
with which the router communicates. The characteristics of the PVC that are established when it is 
created are set by the ATM adaptation layer (AAL) and the encapsulation type. An AAL defines the 
conversion of user information into cells. An AAL segments...

 
B-7
Cisco 1800 Series Integrated Services Routers (Fixed) Software Configuration Guide
OL-6426-02
Appendix B      Concepts
  NAT
line is up, the backup interface is placed in standby mode. In standby mode, the backup interface is 
effectively shut down until it is enabled. Any route associated with the backup interface does not appear 
in the routing table.
Because the backup interface command is dependent on the router’s identifying that an interface is 
physically down, it is commonly used to back up...

 
B-8
Cisco 1800 Series Integrated Services Routers (Fixed) Software Configuration Guide
OL-6426-02
Appendix B      Concepts
  Easy IP (Phase 1)
Translations can be static or dynamic. A static address translation establishes a one-to-one mapping 
between the inside network and the outside domain. Dynamic address translations are defined by 
describing the local addresses to be translated and the pool of addresses from which to allocate outside 
addresses. Allocation occurs in numeric order, and multiple...

 
B-9
Cisco 1800 Series Integrated Services Routers (Fixed) Software Configuration Guide
OL-6426-02
Appendix B      Concepts
  QoS
QoS
This section describes Quality of Service (QoS) parameters, including the following:
 IP Precedence
 PPP Fragmentation and Interleaving
 CBWFQ
 RSVP
 Low Latency Queuing
QoS refers to the capability of a network to provide better service to selected network traffic over various 
technologies, including ATM, Ethernet and IEEE 802.1 networks, and IP-routed networks...

 
B-10
Cisco 1800 Series Integrated Services Routers (Fixed) Software Configuration Guide
OL-6426-02
Appendix B      Concepts
  QoS
In general, multilink PPP with interleaving is used in conjunction with CBWFQ and RSVP or IP 
Precedence to ensure voice packet delivery. Use multilink PPP with interleaving and CBWFQ to define 
how data is managed; use Resource Reservation Protocol (RSVP) or IP Precedence to give priority to 
voice packets.
CBWFQ
In general, class-based weighted fair queuing (CBWFQ) is used...

 
B-11
Cisco 1800 Series Integrated Services Routers (Fixed) Software Configuration Guide
OL-6426-02
Appendix B      Concepts
  Access Lists
Access Lists
With basic standard and static extended access lists, you can approximate session filtering by using the 
established keyword with the permit command. The established keyword filters TCP packets based on 
whether the ACK or RST bits are set. (Set ACK or RST bits indicate that the packet is not the first in the 
session and the packet therefore belongs...

 
B-12
Cisco 1800 Series Integrated Services Routers (Fixed) Software Configuration Guide
OL-6426-02
Appendix B      Concepts
  Access Lists 

 
C-1
Cisco 1800 Series Integrated Services Routers (Fixed) Software Configuration Guide
OL-6426-02
APPENDIXC
ROM Monitor
The ROM monitor firmware runs when the router is powered up or reset. The firmware helps to initialize 
the processor hardware and boot the operating system software. You can use the ROM monitor to 
perform certain configuration tasks, such as recovering a lost password or downloading software over 
the console port. If there is no Cisco
 IOS software image loaded on the router, the...

 
C-2
Cisco 1800 Series Integrated Services Routers (Fixed) Software Configuration Guide
OL-6426-02
Appendix C      ROM Monitor
  ROM Monitor Commands
TimesaverBreak (system interrupt) is always enabled for 60 seconds after the router reboots, regardless of whether 
it is set to on or off in the configuration register. During this 60-second window, you can break to the 
ROM monitor prompt by pressing the Break key. 
ROM Monitor Commands
Enter ? or help at the ROM monitor prompt to display a list of...