Command Attributes
(VRRP Group Configuration Detail)
• Associated IP Table – IP interfaces asso ciated with thi s virtual rou ter grou p.
• Associated IP – IP address of the virtual router, or secon dary IP ad dresses
assigned to the current VLAN interface that are supported by this VRRP group . If
this address matches a real interface on this switch, then this interface will become
the virtual master router for this VRRP group.
• Advertisement Interval – Interval at which the master virtual router sends
advertisements communicating its state as the master. (Range: 1-255 seconds;
Default: 1 second)
- VRRP advertisements from the current master virtual router incl ude information
about its priority and current state as the master.
- VRRP advertisements are sent to the multicast address 224 .0.0.8 . Usin g a
multicast address reduces the amount of traff ic that has to be proces sed b y
network devices that are not part of the designated VRRP group.
- If the master router stops sending advertisements, backup routers will bid to
become the master router based on priority. The dead interval before attempting
to take over as the master is three times the hello in terv al plus half a se cond.
• Preempt Mode – Allows a backup router to take over a s th e ma ster v irtual rou ter
if it has a higher priority than the acting master virtual rout er (i.e., a maste r router
that is not the group’s address owner, or another backup router that has taken over
from the previous master.) (Default: Enabled)
• Preempt Delay – Time to wait before issuing a claim to becom e the ma ster.
(Range: 0-120 seconds; 0 seconds)
•
Priority
– The priority of this router in a VRRP group. (Range: 1-254; Default: 100)
- The priority for the VRRP group address owner is automatically set to 255.
- The priority for backup routers is used to determine which router will tak e over
as the acting master router if the current master fails.
• Authentication Type – Authenticatio n mode us ed to verif y VRRP pa ckets
received from other routers. (Options: None, Simple T ext)
- If simple text authentication is selected, then you must also enter an
authentication string.
- All routers in the same VRRP group must be set to the same authentication
mode, and be configured with the same authentication string.
- Plain text authentication does not provide any real securi ty. It is supp orted onl y
to prevent a misconfigured router from participating in VRRP.
• Authentication String – Key used to authenticate VRRP packets received from
other routers. (Range: 1-8 alphanumeric characters)
- When a VRRP packet is received from another router in the group, its
authentication string is compared to the string configured on this router. If the
strings match, the message is accepted. Otherwise, the p acket is di scarded .
18-4
Configuring Router Redundancy
18