Specifications

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Cisco IGX 8400 Series Provisioning Guide, Release 9.3.3 and Later Releases
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Chapter 3 Cisco IGX 8400 Series Nodes
IGX Node Configuration
Figure 3-2 Clock Source in Node
Refer to Figure 3-2. One trunk parameter has the ability to pass a clock. A trunk passes a clock if the
clock information transmitted from one end arrives as the identical clock at the other end. Many trunks
pass clock. Trunks that do not normally pass clock include:
• Satellite trunks
• Trunks that pass through a DACS (Digital Access Cross-connect Switch)
• Subrate trunks
A long-distance line that passes through another provider’s network may or may not pass clock. The
default ability for an IGX trunk is to pass clock. The following applies to clocks:
• Defining a trunk as a clock source is incompatible with defining it as passing clock.
• In an IGX/BPX network, a clock source functions as a source for the entire network.
• A trunk should be defined as a clock source only if a DACS-type device connects to the trunk.
For more information on IGX service modules, refer to the “Service Modules” section on page 2-14.
IGX Node Configuration
IGX nodes must be set up before you begin building the network. When adding a node to a pre-existing
network, perform basic node configuration tasks before joining the new node and the existing network.
Caution Different nodes in a network may be using different releases of card firmware, switch software or
Cisco IOS software. When integrating a new node into a network, or when upgrading firmware, switch
software or Cisco IOS software, refer to the Compatibility Matrix at
http://www.cisco.com/kobayashi/sw-center/sw-wan.shtml. Incompatibilities between firmware, switch
software, and the Cisco IOS software can cause operational problems.
Subnetwork A
alpha
gamma
beta
T1
Subnetwork B
delta
digamma
epsilon
T1
Primary
clock
source A
Primary
clock
source B
T1
If the packet lines in the T1 span between nodes alpha and delta are defined to pass
clock synchronization, then node delta could attempt to synchronize with primary clock
source A as well as with primary clock source B, because the distance in hops (instead of
miles or kilometers) is the same: one.
If the packet lines in the T1 span from node alpha to node delta are defined not to pass
clock synchronization, then a plesiochronous network would result.
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