Hi all. As the previous discussion on this topic showed, the WG would like a more thorough taxonomy in section 2 of the HA/LS draft. Here's what I have come up with so far. Please send comments to the list.
2. Terminology "Single Gateway" is an implementation of IKE and IPsec enforcing a certain policy, as described in [RFC4301]. "Cluster" is a set of two or more gateways, implementing the same security policy, and protecting the same domain. Clusters exist to provide both high availability through redundancy, and scalability through load sharing. "Member" is one gateway in a cluster. "High Availability" is a condition of a system, not a configuration type. A system is said to have high availability if its expected down time is low. High availability can be achieved in various ways, one of which is clustering. All the clusters described in this document achieve high availability. "Fault Tolerance" is a condition related to high availability, where a system maintains service availability, even when a specified set of fault conditions occur. In clusters, we expect the system to maintain service availability, when one of the cluster members fails. "Completely Transparent Cluster" is a cluster where the occurence of a fault is never visible to the peers. "Partially Transparent Cluster" is a cluster where the occurence of a fault may be visible to the peers. "Hot Standby Cluster", or "HS Cluster" is a cluster where only one of the members is active at any one time. This member is also referred to as the the "active", whereas the others are referred to as "stand- bys". [VRRP] is one method of building such a cluster. "Load Sharing Cluster", or "LS Cluster" is a cluster where more than one of the members may be active at the same time. The term "load balancing" is also common, but it implies that the load is actually balanced between the members, and we don't want to even imply that this is a requirement. "Failover" is the event where a one member takes over some load from some other member. In a hot standby cluster, this hapens when a standby memeber becomes active due to a failure of the former active member, or because of an administrator command. In a load sharing cluster this usually happens because of a failure of one of the members, but certain load-balancing technologies may allow a particular load (an SA) to move from one member to another to even out the load, even without any failures. "Tight Cluster" is a cluster where all the members share an IP address. This could be accomplished using configured interfaces with specialized protocols or hardware, such as VRRP, or through the use of multicast addresses, but in any case, peers need only be configured with one IP address in the PAD. "Loose Cluster" is a cluster where each member has a different IP address. Peers find the correct member using some method such as DNS queries or [REDIRECT]. "Synch Channel" is a communications channel among the cluster members, used to transfer state information. The synch channel may or may not be IP based, may or may not be encrypted, and may work over short or long distances. The security and physical characteristics of this channel are out of scope for this document, but it is a requirement that its use be minimized for scalability. _______________________________________________ IPsec mailing list IPsec@ietf.org https://www.ietf.org/mailman/listinfo/ipsec
