Traffic Flow In An Smlt Environment - Nortel 8300 User Manual

42 VLANs, Spanning Tree, and Static Link Aggregation
Traffic flow in an SMLT environment
Traffic flow in an SMLT environment follows these rules:
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Traffic flow example
In an SMLT environment, the two aggregation switches share the same
forwarding database by exchanging forwarding entries using the IST. In
the following figure,
(page
(B and C). Note that the entry for 00:E0:7B:B3:04:00 is shown on node
C as being learned on MLT-1, but because SMLT REMOTE is true, this
entry was actually learned from node B. On B, that same entry is shown
as being directly learned through MLT-1 because SMLT REMOTE is false.
Figure 12 "Network topology for traffic flow example" (page 43)
network topology.
When a packet arrives at node C destined for 00:E0:7B:B3:04:00, if the
SMLT REMOTE status is true, the switch tries to send the packet out MLT-1
first, rather than through the interswitch trunk. Traffic rarely traverses the
interswitch trunk unless there is a failure. If this same packet arrives at B, it
is forwarded to MLT-1 on the local ports.
Configuration — VLANs, Spanning Tree, and Static Link Aggregation using Device Manager
Copyright © 2005-2007, Nortel Networks
.
If a packet is received from an interswitch trunk port, it is not forwarded
to any active SMLT groups, which is key in preventing network loops.
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 out the local port (the packet cannot
be sent to the interswitch trunk for forwarding unless there is no local
connection). Unknown and Broadcast packets are flooded out all ports
that are members of this VLAN.
For loadsharing purposes in an SMLT scenario, the Ethernet Routing
Switch 8300 obeys the trunk distribution algorithm. See Nortel Ethernet
Routing Switch 8300 Planning and Engineering—Network Design
Guidelines (NN46200-200) for more details about the algorithms.
Figure 11 "show vlan info fdb-entry 10 sample output"
43), the forwarding databases are shown for a pair of IST nodes
Nortel Ethernet Routing Switch 8300
NN46200-510 03.01 Standard
4.0 27 August 2007
shows the