Avaya 8600 Configuration Manual page 28

Link aggregation fundamentals
Other SMLT aggregation switch connections
The example shown in
includes end stations which connect to each of the switches. In this example, a, b1, b2, c1, c2,
and d are clients and printers, while e and f are servers and routers.
User access switches B and C can use any method to determine which link of the MultiLink
trunk connections to use to forward a packet, as long as the same link is used for a Source
Address and Destination Address (SA/ DA) pair. This is true regardless of whether B or C
knows the DA. SMLT aggregation switches always send traffic directly to a user access switch,
and only use the interswitch trunk for traffic that they cannot forward in another, more direct
way.
SMLT environment traffic flow rules
Traffic flow in an SMLT environment adheres to the following rules:
• If a packet is received from an interswitch trunk port, it is not forwarded to any active SMLT
groups. This is key in preventing network loops.
Note:
If you want to decommission an SMLT switch, disable the ports first to prevent loops
in the network.
• When a packet is received, a look-up is performed on the forwarding database. If an entry
exists, and if the entry was learned locally from the split MultiLink trunk or through the
interswitch trunk as a remote split MultiLink trunk, it is forwarded to the local port (the
packet must not be sent to the interswitch trunk for forwarding unless there is no local
connection). Unknown and Broadcast packets flood out all ports that are members of this
VLAN.
• For load sharing purposes in an SMLT configuration, the Avaya Ethernet Routing Switch
8800/8600 obeys the MLT traffic distribution algorithm.
SMLT traffic flow examples
The following traffic flow examples are based on
operations
Example 1: Traffic flow from a to b1 or b2
Assuming a and b1/ b2 are communicating through Layer 2, traffic flows from A to switch E
and is forwarded over its direct link to B. Traffic coming from b1 or b2 to a is sent by B on one
of its MultiLink trunk ports.
B can send traffic from b1 to a on the link to switch E, and traffic from b2 to a on the link to F.
In the case of traffic from b1, switch E forwards the traffic directly to switch A, while traffic from
b2, which arrived at F, is forwarded across the interswitch trunk to E and then to A.
28 Configuration — Link Aggregation, MLT, and SMLT
Figure 5: SMLT aggregation switches and operations
on page 27.
Comments? infodev@avaya.com
Figure 5: SMLT aggregation switches and
on page 27
January 2012