Overview Of Vrrpe - Foundry Networks FESX Manual

Foundry Configuration Guide for the FESX, FSX, and FWSX
Independent Operation of VRRP alongside RIP, OSPF, and BGP4
VRRP operation is independent of the RIP, OSPF, and BGP4 protocols. Their operation is unaffected when VRRP
is enabled on a RIP, OSPF, or BGP4 interface.
Dynamic VRRP Configuration
All VRRP global and interface parameters take effect immediately. You do not need to reset the system to place
VRRP configuration parameters into effect.

Overview of VRRPE

VRRPE is similar to VRRP, but differs in the following respects:
• Owners and Backups
• VRRP has an Owner and one or more Backups for each VRID. The Owner is the router on which the
VRID's IP address is also configured as a real address. All the other routers supporting the VRID are
Backups.
• VRRPE does not use Owners. All routers are Backups for a given VRID. The router with the highest
priority becomes Master. If there is a tie for highest priority, the router with the highest IP address
becomes Master. The elected Master owns the virtual IP address and answers ping and ARP requests
and so on.
• VRID's IP address
• VRRP requires that the VRID also be a real IP address configured on the VRID's interface on the Owner.
• VRRPE requires only that the VRID be in the same sub-net as an interface configured on the VRID's
interface. In fact, VRRPE does not allow you to specify a real IP address configured on the interface as
the VRID IP address.
• VRID's MAC Address
• VRRP source MAC is a virtual MAC address defined as 00-00-5E-00-01-<vrid>, where <vrid> is the
VRID. The Master owns the Virtual MAC address.
• VRRPE uses the interface's actual MAC address as the source MAC address. The MAC address is
02-E0-52-<hash-value>-<vrid>, where <hash-value> is a two-octet hashed value for the IP address and
<vrid> is the VRID.
• Hello packets
• VRRP sends Hello messages to IP Multicast address 224.0.0.18.
• VRRPE uses UDP to send Hello messages in IP multicast messages. The Hello packets use the
interface's actual MAC address and IP address as the source addresses. The destination MAC address
is 01-00-5E-00-00-02, and the destination IP address is 224.0.0.2 (the well-known IP multicast address
for "all routers"). Both the source and destination UDP port number is 8888. VRRP messages are
encapsulated in the data portion of the packet.
• Track ports and track priority
• VRRP changes the priority of the VRID to the track priority, which typically is lower than the VRID priority
and lower than the VRID's priorities configured on the Backups. For example, if the VRRP interface's
priority is 100 and a tracked interface with track priority 20 goes down, the software changes the VRRP
interface's priority to 20.
• VRRPE reduces the priority of a VRRPE interface by the amount of a tracked interface's priority if the
tracked interface's link goes down. For example, if the VRRPE interface's priority is 200 and a tracked
interface with track priority 20 goes down, the software changes the VRRPE interface's priority to 180. If
another tracked interface goes down, the software reduces the VRID's priority again, by the amount of
the tracked interface's track priority.
The most important difference is that all VRRPE routers are Backups. There is no Owner router. VRRPE
overcomes the limitations in standard VRRP by removing the Owner.
22 - 6 © Foundry Networks, Inc. December 2005