Advanced Configuration and Management Guide

Comparison of VRRP, VRRPE, and SRP

This section compares HP’s router redundancy protocols.

VRRP

VRRP is a standards-based protocol, described in RFC 2338. The HP implementation of VRRP contains the features in RFC 2338. The HP implementation also provides the following additional features:

•Track ports – An HP feature that enables you to diagnose the health of all the routing switch’s ports used by the backed-up VRID, instead of only the port connected to the client sub-net. See “Track Ports and Track Priority” on page 12-5.

•Suppression of RIP advertisements on Backup routes for the backed up interface – You can enable the routing switches to advertise only the path to the Master router for the backed up interface. Normally, a VRRP Backup router includes route information for the interface it is backing up in RIP advertisements.

HP routing switches configured for VRRP can interoperate with third-party routers using VRRP.

VRRPE

VRRPE is an HP protocol that provides the benefits of VRRP without the limitations. In fact, VRRPE combines the benefits of HP’s VRRP and SRP (see “SRP”). VRRPE is unlike VRRP and is like SRP in the following ways:

•There is no “Owner” router. You do not need to use an IP address configured on one of the routing switches as the virtual router ID (VRID), which is the address you are backing up for redundancy. The VRID is independent of the IP interfaces configured in the routing switches. As a result, the protocol does not have an “Owner” as VRRP does.

•There is no restriction on which router can be the default master router. In VRRP, the “Owner” (the routing switch on which the IP interface that is used for the VRID is configured) must be the default Master.

HP routing switches configured for VRRPE can interoperate only with other HP routing switches.

SRP

The Standby Router Protocol (SRP) is another HP router redundancy protocol that provides many of the same features as HP’s implementation of VRRP and VRRPE. However, SRP does not provide authentication, which VRRP and VRRPE do. In addition, SRP allows only one backup router.

SRP is available only on HP routing switches.

Architectural Differences

The protocols have the following architectural differences.

Management Protocol

•VRRP – VRRP routers send VRRP Hello and Hello messages to IP Multicast address 224.0.0.18.

•VRRPE – VRRPE sends messages to destination MAC address 01-00-5E-00-00-02 and destination IP address 224.0.0.2 (the standard IP multicast address for “all routers”).

•SRP – SRP sends management traffic to a user-configured unicast address.

Virtual Router IP Address (the address you are backing up)

•VRRP – The virtual router IP address is the same as an IP address or virtual interface configured on one of the routing switches, which is the “Owner” and becomes the default Master.

•VRRPE – The virtual router IP address is the gateway address you want to backup, but does not need to be an IP interface configured on one of the routing switch’s ports or a virtual interface.

•SRP – The virtual router IP address is a user-configured virtual IP address.

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