3Com Router User Manual

45
CONFIGURING A STANDBY CENTER
This chapter covers the following topics:
■Standby Center Overview
■Configuring the Standby Center 
■Displaying and Debugging the Standby Center
■Standby Center Configuration Examples
Standby Center 
OverviewTo enhance a networks reliability, 3Com routers provide perfect standby functions 
through the use of standby centers
■Interfaces that have standby are called main interfaces. Every physical interface 
or sub-interface on a router can serve as a main interface. A logic...

648CHAPTER 45: CONFIGURING A STANDBY CENTER
main interface is a physical interface or sub-interface, use the following 
commands in system view to enter the view of the interface.
Ta b l e 695   Enter the View of the Main Interface
If the main interface is a virtual circuit, it should be treated differently depending 
on the type of the virtual circuit. First, specify its logic channel number in the view 
of the physical interface to which it is subordinate, then enter the corresponding 
logic channel...

Configuring the Standby Center 649
Setting the Delay Time 
for Switchover between 
Main and Standby 
InterfaceWhen the state of the main interface changes from up to down, the system 
doesnt switch to a standby interface immediately, but waits for a preset time 
delay instead. The system switches to the standby interface only if the state of the 
main interface remains down after the delay times out. If the main interface 
recovers within the delay time, the system will not switch to the standby...

650CHAPTER 45: CONFIGURING A STANDBY CENTER
priority; after the logic channel changes to up, its required to switch from the 
standby interface with the second highest priority to this logic channel.
Perform the following commands in the view of the logic channel.
Ta b l e 701   Set the State-judging Conditions When the Main Interface is a Logic Channel
By default, time is set to 0 and seconds is set to 1 second. 
Configuring Standby 
Load SharingConduct the following configuration under the interface...

Standby Center Configuration Examples651
Multiple Standby 
InterfacesTake both interfaces Serial 1 and Serial 2 as the standby interface of interface 
Serial 0, and use interface Serial 1 as a preference.
1Enter the view of Serial 0.
[Router] interface serial 0
2Set interfaces Serial 1 and Serial 2 as the standby interfaces, their priorities being 
30 and 20, respectively.
[Router-Serial0] standby interface serial 1 30
[Router-Serial0] standby interface serial 2 20
Logical Channel Standby 
InterfaceIn...

652CHAPTER 45: CONFIGURING A STANDBY CENTER
5Enter the view of logic channel 5 and set logic channel 3 and interface Serial 1 as 
its standby interfaces, their priorities being 50 and 20 respectively.
[Router-Serial1]logic-channel 5
[Router-logic-channel5]standby logic-channel 3 50
[Router-logic-channel5]standby interface serial 2 20 

46
CONFIGURING VRRP
This chapter covers the following topics:
■VRRP Overview
■Configuring VRRP
■Displaying and Debugging VRRP
■VRRP Configuration Examples
■Troubleshooting VRRP
VRRP OverviewVirtual Router Redundancy Protocol (VRRP) is a fault-tolerant protocol. In general, 
a default route (the next hop is 10.100.10.1) is configured for a network host so 
that packets sent by the host with destination addresses not in the local network 
segment go through the default route to Router 1 to implement...

654CHAPTER 46: CONFIGURING VRRP
Figure 208   Virtual router diagram
This virtual router has its own IP address: 10.100.10.1 (it can be the same as the 
interface address of a router within the standby group). The routers within the 
standby group have their own IP addresses (10.100.10.2 for the master routers 
and 10.100.10.3 for the backup routers). The host within the LAN only knows the 
IP address of this virtual router but not the specific IP addresses of the master 
router and the backup router....

Configuring VRRP655
Ta b l e 704   Add Virtual IP Address
The standby group numbers ranges from 1 to 255. The virtual IP address should be 
the address of the network segment where the interface resides. It can be an 
unused IP address in the network segment, or the routers own IP address. When 
the virtual IP address is the router’s own IP address, this router is called an IP 
address owner. When the first IP address is added to a standby group, the system 
establishes this standby group. Whenever this...

656CHAPTER 46: CONFIGURING VRRP
Configuring Preemption 
Mode and Delay of 
Standby Group RoutersOnce a router in the standby group becomes the master router, so long as it still 
functions properly, other routers, even configured with higher priority later, cannot 
become the master router unless they are configured with preemption mode. The 
router in preemption mode becomes the master router if it finds its own priority is 
higher than that of the present master router. Accordingly, the former master...