3Com Router User Manual

Displaying and Debugging VRRP657
Configure Standby 
Group TimerThe master router of a VRRP standby group notifies its normal operation state to 
the routers within the group by sending them VRRP packets regularly 
(adver_interval).
 If the backup routers fail to receive the VRRP packets over a 
certain period of time (master_down_interval), they reach the conclusion that the 
master routers are not functioning properly and will change their own state to 
master.
The user can adjust the master routers...

658CHAPTER 46: CONFIGURING VRRP
Ta b l e 710   Display and Debug VRRP
VRRP Configuration 
ExamplesThis section describes several different configurations of VRRP with a suggested 
procedure for each configuration
VRRP Single Standby 
GroupHost A uses the VRRP standby group which combines router A and router B as its 
default gateway to visit host B on the Internet.
A VRRP standby group consists of the following parts: standby group number1, 
virtual IP address 202.38.160.111, router A as the MASTER and...

Troubleshooting VRRP659
VRRP Monitoring 
Interface As shown in Figure 209, even when router A is still functioning, it may want router 
B to function as a gateway when the Internet interface connected with it does not 
function properly. This can be implemented by configuring the monitoring 
interface.
To facilitate explanation, the standby group number is set as 1 with configuration 
of authorization key and timer added (which are unnecessary in this application).
1Configure router A:
[Router-Ethernet0]...

660CHAPTER 46: CONFIGURING VRRP
The console frequently displays messages about configuration mistakes.
This shows that a mistaken VRRP packet has been received. One reason may be 
inconsistent configuration of another router within the standby group. Another 
reason may be the attempt of some devices to send out illegal VRRP packets. 
The first possibility can be solved through modifying the configuration. The second 
possibility is caused by the malicious attempt of some devices so non-technical...

XI
QOS
Chapter 47QoS Overview
Chapter 48Traffic Policing, Traffic Shaping and Line Rate
Chapter 49Congestion Management
Chapter 50Congestion Avoidance 

662 

47
QOS OVERVIEW
This chapter covers the following topics:
■What Is QoS?
■Three Types of QoS Services
■Benefits of QoS for the Network Service
What Is QoS?In the traditional IP network, all the packets are treated identically. Each router has 
to handle these packets a following first in first out (FIFO) policy. That is, it makes 
best effort to transmit the packets to the destination without considering the 
throughput, delay, jitter, drop rate of the packets, etc. This may be advantageous 
or...

664CHAPTER 47: QOS OVERVIEW
■Differentiated service: This is is a kind of multi-service model oriented to 
different demands. It sorts the services into classes, and provides different 
qualities of services according to the various classes without the support of 
signal. Differentiated service adopts the following technologies:
■Traffic policing: Performing the traffic policing for one or more or all flows.
■Traffic shaping: Performing the traffic shaping for one or more or all flows.
■Queue management:...

Benefits of QoS for the Network Service665
■Adjustable network service. If the user is ISP, by using QoS, the adjustable 
network services of different priority levels can be provided to various types of 
clients.
■Secure network services for specific data flows. For example, it can ensure that 
the multimedia data flows and voice flows sensitive to the delay will acquire 
the service in time. 

666CHAPTER 47: QOS OVERVIEW