Avaya 555-245-600 manual Convergence times, Ospf RIP

Convergence times

Convergence times

Convergence is the time that it takes from the instant a failure occurs in the network until a new path through the network is discovered, and all routers or switches are aware of the new path. Convergence times vary, based on the complexity and size of a network. Table 62: Sample convergence times (single link failure) on page 343 lists some sample convergence times that are based on a single link failing in a relatively simple network. They reflect update and/or hello timers expiring. Dialup “convergence” times reflect the time that it takes to dial, connect, and authenticate a connection. These times do not take into account LAG, fast spanning tree, or multipath routing, which speed up convergence. This table shows the importance of carefully planning for fail-over in a network. For example, both OSPF and EIGRP (Layer 3) protocols converge faster than spanning tree (Layer 2). When designing a highly available data network, it is more advantageous to use Layer 3 protocols, especially link-state (OSPF) or hybrid (EIGRP) protocols, than Layer 2 (spanning tree).

Table 62: Sample convergence times (single link failure)

Protocol	Approximate convergence
	time (seconds)
EIGRP (Cisco)	2
OSPF	6 to 46
RIP	210
Spanning tree (Layer 2)	50+
ISDN dialup (connect +	2
authentication)
56-k dialup (connect +	60
authentication)

Issue 6 January 2008 343