Dell PowerConnect Brocade 300 Fabric OS Administrator's Guide v7.1.0 - Page 111

Routing Traffic, Routing overview, In

Page 111 highlights

Routing Traffic Chapter 4 In this chapter •Routing overview 111 •Inter-switch links 114 •Gateway links 117 •Routing policies 118 •Route selection 122 •Frame order delivery 123 •Lossless Dynamic Load Sharing on ports 125 •Enabling forward error correction (FEC 128 •Frame Redirection 130 Routing overview Data moves through a fabric from switch to switch and from storage to server along one or more paths that make up a route. Routing policies determine the path for each frame of data. Before the fabric can begin routing traffic, it must discover the route a packet should take to reach the intended destination. Route tables are lists that indicate the next hop to which packets are directed to reach a destination. Route tables include network addresses, the next address in the data path, and a cost to reach the destination network. There are two kinds of routing protocols on intranet networks, distance vector and link state. • Distance vector is based on hop count. This is the number of switches that a frame passes through to get from the source switch to the destination switch. • Link state is based on a metric value based on a cost. The cost could be based on bandwidth, line speed, or round-trip time. With the link-state protocol, switches that discover a route identify the networks to which they are attached, receiving an initial route table from the principal switch. After an initial message is sent out, the switch only notifies the others when changes occur. It is recommended that no more than seven hops occur between any two switches. This limit is not required or enforced by Fabric Shortest Path First (FSPF). Its purpose is to ensure that a frame is not delivered to a destination after Resource Allocation TimeOut Value (R_A_TOV) has expired. Fabric OS v7.1.0 supports unicast Class 2 and 3 traffic, multicast, and broadcast traffic. Broadcast and multicast are supported in Class 3 only. Fabric OS Administrator's Guide 111 53-1002745-02

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Fabric OS Administrator’s Guide
111
53-1002745-02
Chapter
4
Routing Traffic
In this chapter
Routing overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 111
Inter-switch links . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 114
Gateway links. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
117
Routing policies . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 118
Route selection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 122
Frame order delivery . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 123
Lossless Dynamic Load Sharing on ports . . . . . . . . . . . . . . . . . . . . . . . . . . 125
Enabling forward error correction (FEC). . . . . . . . . . . . . . . . . . . . . . . . . . . . 128
Frame Redirection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 130
Routing overview
Data moves through a fabric from switch to switch and from storage to server along one or more
paths that make up a
route
. Routing policies determine the path for each frame of data.
Before the fabric can begin routing traffic, it must discover the route a packet should take to reach
the intended destination. Route tables are lists that indicate the next hop to which packets are
directed to reach a destination. Route tables include network addresses, the next address in the
data path, and a cost to reach the destination network. There are two kinds of routing protocols on
intranet networks, distance vector and link state.
Distance vector is based on hop count. This is the number of switches that a frame passes
through to get from the source switch to the destination switch.
Link state is based on a metric value based on a cost. The cost could be based on bandwidth,
line speed, or round-trip time.
With the link-state protocol, switches that discover a route identify the networks to which they are
attached, receiving an initial route table from the principal switch. After an initial message is sent
out, the switch only notifies the others when changes occur.
It is recommended that no more than seven hops occur between any two switches. This limit is not
required or enforced by Fabric Shortest Path First (FSPF). Its purpose is to ensure that a frame is
not delivered to a destination after Resource Allocation TimeOut Value (R_A_TOV) has expired.
Fabric OS v7.1.0 supports unicast Class 2 and 3 traffic, multicast, and broadcast traffic. Broadcast
and multicast are supported in Class 3 only.