High Availability
Okapi > Features > High Availability

 

VRRP

 

The Virtual Router Redundancy Protocol (VRRP) allows a group of routers to act as one virtual router and eliminating the single point of failure present in the static default routed environment. VRRP, as specified by RFC 2338 and RFC 3678, is designed to provide router failover services in the event of an interface failure. In a VRRP setup, one router is elected as the virtual router master, with the other routers acting as backups in case the virtual router master fails.

On the Okapi system, VRRP can be run on a standard Ethernet interface.

 

 

 

Salient Features

  • Redundancy : multiple routers can be used as the default gateway router, which minimizes the possibility of a single point of failure in a network
  • Load Distribution : traffic to and from LAN clients can be balanced on  multiple routers, thereby sharing the traffic load
  • Preemption : preempt a virtual router backup that has taken over for a failing virtual router master with a higher priority virtual router backup that has become available
  • Authentication : communicates using password authentication to protect against VRRP-spoofing software
  • Advertisement Protocol : addressing scheme minimizes the number of routers that must service the multicasts and allows test equipment to accurately identify VRRP packets on a segment
  • VRRP Synchronization Groups : syncs interfaces in a group such that if one of the interfaces from the router goes down, then all of the other interfaces in the group will move to the backup interface group
 
 

Link Failover

 

Link failover is used to make changes in the route configuration on discovering that one of the ISP links is down. It is similar to a routing protocol in the sense that both dynamically insert new routes into the routing table.However, Okapi's Link Failover feature does not assume the existence of a peer router running the same protocol. It is useful in an SME environment, where we use two network connections to connect to two different ISPs. Okapi monitors both the links by periodically sending ICMP packets over the two links to well known hosts(like www.google.com or www.okapirouter.net). When the links appear to be down(ICMP packets are not replied), we insert new routes into the table.