HP 5500 Ei 5500 Si Switch Series Configuration Guide

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VRRP preemption delay timer 
To avoid frequent state changes among members in a VRRP group and provide the backups enough time 
to collect information (such as routing information), each backup waits for a period of time (the 
preemption delay time) after it receives an advertisement with the priority lower than the local priority, 
then sends VRRP advertisements to start a new ma ster election in the VRRP group and becomes the 
master. 
Packet format 
The master multicasts VRRP packets...

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•  Version —Version number of the protocol, 2 for VRRPv2 and 3 for VRRPv3.  
•   Ty p e —Type of the VRRPv2 or VRRPv3 packet. Only one VRRP packet type is present, that is, VRRP 
advertisement, which is represented by 1. 
•   Virtual Rtr ID (VRID) —ID of the vir tual router, that is, ID of the VRRP group. It ranges from 1 to 255. 
•   Priority —Priority of the router in the VRRP group, in the range of 0 to 255. A greater value 
represents a higher priority.  
•   Count IP Addrs/Count IPv6 Addrs...

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Tracking a specified interface 
The interface tracking function expands the backup functionality of VRRP. It provides backup not only 
when the interface to which a VRRP group is assigned fails but also when other interfaces (such as uplink 
interfaces) on the router become unavailable.  
If the uplink interface of a router in a VRRP group fails, usually the VRRP group cannot be aware of the 
uplink interface failure. If the router is the master of the VRRP group, hosts on the LAN are not able to...

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Load sharing 
More than one VRRP group can be created on an interface  o f  a  r o u t e r  t o  a l l o w  t h e  r o u t e r  t o  b e  t h e  m a s t e r  
of one VRRP group but a backup of another at the same time. 
In load sharing mode, multiple routers provide services  simultaneously. This mode requires two or more 
VRRP groups, each of which comprises a master and one or more backups. The masters of the VRRP 
groups are assumed by different routers, as shown in  Figure 35. 
Figure 35  VRRP...

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one virtual MAC address. In this way, each router in this VRRP group can respond to ARP requests (in an 
IPv4 network) or ND requests (in an IPv6 network) from corresponding hosts, so that different hosts can 
send packets to different routers, and each router in the VRRP group can forward packets. In load 
balancing mode, you need to create only one VRRP  group to balance load among multiple routers, 
instead of allowing one router to bear  the load but other routers to stay idle. 
VRRP load...

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Figure 37 Answering ARP requests 
 
 
3. Different hosts send packets to  different routers according to the requested virtual MAC addresses. 
For example, as shown in  Figure 38, Host A regards th
 e virtual MAC address of Router A as the 
gateway MAC address, so it sends packets to Rout er A for forwarding; Host B regards the virtual 
MAC address of Router B as the gateway MAC address, so it sends packets to Router B for 
forwarding.  
Figure 38  Sending packets to different routers for...

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Virtual forwarder 
Creating a virtual forwarder 
Virtual MAC addresses help different hosts transmit packets to different routers in a VRRP group. To 
enable the routers in the VRRP group to forward the packets, be sure to create virtual forwarders (VFs) on 
the routers. Each VF associates with a virtual MAC address in the VRRP group and forwards packets 
destined to this virtual MAC address. 
The following describes how VFs are created on the routers in a VRRP group:  
1.  The master assigns...

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Figure 39 VF information 
 
 
Figure 39 illustrates the VF information on each router in the VRRP group and how the routers back up 
one another. The master, Router A, as signs virtual MAC addresses 000f-e2ff-001 1, 000f-e2ff-0012, and 
000f-e2ff-0013 to itself, Router B, and Router C, respectively. The VFs corresponding to these three virtual 
MAC addresses, VF 1, VF 2, and VF 3, are created on each of the three routers, and the VFs 
corresponding to the same virtual MAC address on di fferent...

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•  Timeout Timer —The duration that the new AVF takes over the VF owner. Before this timer times out, 
all the routers in the VRRP group keep the failed AVF, and the new AVF forwards the packets 
destined for the virtual MAC address corresponding to  the failed AVF. When this timer times out, all 
the routers in the VRRP group remove the failed AVF, and the new AVF stops forwarding the packets 
destined for the virtual MAC address corresponding to the failed AVF. 
VF tracking 
The AVF forwards...

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Complete these tasks to configure VRRP for IPv4:  
Task Remarks 
Configuring a VRRP operation mode Optional 
Specifying the type of MAC addresses mapped to 
virtual IP addresses Optional 
When VRRP is operating in load balancing mode, 
this configuration is not effective.  
Creating a VRRP group and configuring virtual IP 
address 
Required 
Configuring router priority, preemptive mode and 
tracking function Optional 
Configuring VF tracking Optional 
The VF tracking function is effective only when...