So, here are two definitions we all need to know, as defined by Cisco documentation:
Stateless (Regular) Failover
When a failover occurs, all active connections are dropped. Clients need to reestablish connections when the new active unit takes over.
When Stateful Failover is enabled, the active unit continually passes per-connection state information to the standby unit. After a failover occurs, the same connection information is available at the new active unit. Supported end-user applications are not required to reconnect to keep the same communication session.
Here is what the config looked like at the end on the primary unit, using version 8.0(4). (<--- Yes, Im going to do an upgrade soon on these). Gig0/2 for is the stateful link. Gig0/3 is the stateless link.
failover lan unit primary
failover lan interface failover GigabitEthernet0/3
failover replication http
failover link state GigabitEthernet0/2
failover interface ip failover 172.20.20.1 255.255.255.252 standby 172.20.20.2
failover interface ip state 172.20.30.1 255.255.255.252 standby 172.20.30.2
no monitor-interface management
So, what communications are moved over the 'stateless failover' link and the 'stateful failover' link? Good question. Here is what Cisco says for both:
The two units in a failover pair constantly communicate over a failover link to determine the operating status of each unit. The following information is communicated over the failover link: the unit state (active or standby), hello messages (keep-alives), network link status, MAC address exchange, and configuration replication and synchronization
NAT translation table, TCP connection states, UDP connection states, the ARP table, the Layer 2 bridge table (when running in transparent firewall mode), the HTTP connection states (if HTTP replication is enabled), the ISAKMP and IPSec SA table, GTP PDP connection database, and the SIP signalling sessions.
Indeed very helpfulReplyDelete
Question: can both (failover AND state) pass through same physical link? I have just one port to spare for failover purposes. I have SINGLE context.ReplyDelete
Yes, both pass through a single link.Delete
Thanks a lot....this helpsReplyDelete