3Com 3036, Configuration Manual

Page: 663 / 762

Troubleshooting VRRP 659
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).
1 Configure router A:
[Router-Ethernet0] vrrp vrid 1 virtual-ip 202.38.160.111
[Router-Ethernet0] vrrp vrid 1 priority 120
[Router-Ethernet0] vrrp authentication-mode simple 3Com Router
[Router-Ethernet0] vrrp vrid 1 timer-advertise 5
[Router-Ethernet0] vrrp vrid 1 track serial0 reduced 30
2 Configure router B:
[Router-Ethernet0] vrrp vrid 1 virtual-ip 202.38.160.111
[Router-Ethernet0] vrrp authentication-mode simple 3Com Router
[Router-Ethernet0] vrrp vrid 1 timer-advertise 5
Under normal conditions, router A functions as the gateway, but when the
interface Serial0 of router A is malfunctioning, its priority will be reduced by 30,
lower than that of router B so that router B will preempt to function as master for
gateway services instead.
When Serial0, the interface of router A, recovers, this router will resume its
gateway function as the master.
Multiple Standby
Groups Configuration
One 3Com router is allowed to function as the standby router for many standby
groups. See Figure 209.
Such a multi-backup configuration can implement load balancing. Some hosts
(like host A) use hot standby group 1 as their gateways, some other hosts (like
host B) use hot standby group 2 as their gateways. In this way, both data stream
balancing and mutual backup are implemented.
1 Configure router A:
[Router-Ethernet0] vrrp vrid 1 virtual-ip 202.38.160.111
[Router-Ethernet0] vrrp vrid 1 priority 120
[Router-Ethernet0] vrrp vrid 2 virtual-ip 202.38.160.112
2 Configure router B:
[Router-Ethernet0] vrrp vrid 1 virtual-ip 202.38.160.111
[Router-Ethernet0] vrrp vrid 2 virtual-ip 202.38.160.112
[Router-Ethernet0] vrrp vrid 2 priority 120
Troubleshooting VRRP
As the configuration of VRRP is not very complicated, almost all the malfunctions
can be located through checking the information of configuration and debugging.
Explanations are made of common failures trouble-shooting in the following part.