User Manual

Features Overview and ConfigurationRev 2.3-1.0.1
Mellanox Technologies
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(looped) by suffixing its radix specification with one of m, M, t, or T. Thus, "mesh 3T 4 5" and
"torus 3 4M 5M" both specify the same topology.
Note that although torus-2QoS can route mesh fabrics, its ability to route around failed compo-
nents is severely compromised on such fabrics. A failed fabric componentis very likely to cause a
disjoint ring; see UNICAST ROUTING in torus-2QoS(8).
xp_link sw0_GUID sw1_GUID
yp_link sw0_GUID sw1_GUID
zp_link sw0_GUID sw1_GUID
xm_link sw0_GUID sw1_GUID
ym_link sw0_GUID sw1_GUID
zm_link sw0_GUID sw1_GUID
These keywords are used to seed the torus/mesh topology. For example, "xp_link 0x2000
0x2001" specifies that a link from the switch with node GUID 0x2000 to the switch with node
GUID 0x2001 would point in the positive x direction, while "xm_link 0x2000 0x2001" specifies
that a link from the switch with node GUID 0x2000 to the switch with node GUID 0x2001 would
point in the negative x direction. All the link keywords for a given seed must specify the same
"from" switch.
In general, it is not necessary to configure both the positive and negative directions for a given
coordinate; either is suf
ficient. However, the algorithm used for topology discovery needs extra
information for torus dimensions of radix four (see TOPOLOGY DISCOVERY in torus-
2QoS(8)). For such cases both the positive and negative coordinate directions must be specified.
Based on the topology specified via the torus/mesh keyword, torus-2QoS will detect and log
when it has insuf
ficient seed configuration.
x_dateline position
y_dateline position
z_dateline position
In order for torus-2QoS to provide the guarantee that path SL values do not change under any
conditions for which it can still route the fabric, its idea of dateline position must not change rel-
ative to physical switch locations. The dateline keywords provide the means to configure such
behavior
.
The dateline for a torus dimension is always between the switch with coordinate 0 and the switch
with coordinate radix-1 for that dimension. By default, the common switch in a torus seed is
taken as the origin of the coordinate system used to describe switch location.
The position param-
eter for a dateline keyword moves the origin (and hence the dateline) the specified amount rela-
tive to the common switch in a torus seed.
next_seed
If any of the switches used to specify a seed were to fail torus-2QoS would be unable to complete
topology discovery successfully. The next_seed keyword specifies that the following link and
dateline keywords apply to a new seed specification.
For maximum resiliency, no seed specification should share a switch with any other seed specifi-
cation. Multiple seed specifications should use dateline configuration to ensure that torus-2QoS
can grant path SL values that are constant, regardless of which seed was used to initiate topology
discovery
.