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Cisco ONS 15454 DWDM Reference Manual, R8.5
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Chapter 15 Management Network Connectivity
15.3 DCN Case Studies
15.3 DCN Case Studies
The ONS 15454 network is managed over the IP DCN and the optical service channels (OSCs), DCCs,
and generic communications channels (GCCs). ONS 15454s perform many of the same functions as
Layer 3 routers because they manage traffic between the DCN network management system (NMS) and
the dense wavelength division multiplexing (DWDM) optical networks.
This section provides case studies that show different ways an ONS 15454 network can be implemented
within the DCN. The case studies are based on actual field installations. They include the network
problem, the network topology created to solve it, IP addressing examples, and strengths and weaknesses
of the solution. Routing principles followed throughout the case studies include:
• If the ONS 15454 is connected to a DCN router, the default gateway points to the router.
• If the default gateway must advertise to the OSC/DCC/GCC network, a static route is added for the
default gateway.
• If the network element (NE) is not connected to a DCN router, the default gateway is set to 0.0.0.0.
15.3.1 SOCKS Proxy Settings
SOCKS proxy (described in the “15.2.7 Scenario 7: Provisioning the ONS 15454 Proxy Server” section
on page 15-12) enables the ONS 15454 to serve as a proxy for connections between CTC clients and
ONS 15454 nodes connected by OSCs, GCCs, or DCCs. Although SOCKS proxy can make DCN
implementations easier, it should not be used when any of the following conditions exist:
• Network management is based on SNMP and SNMP traps. The ONS 15454 can proxy SNMP traps,
but if a redundant DCN connection is required, trap duplication on the network management
platform will occur.
• Telnet and debug session are required. These are not possible over SOCKS proxy.
• Direct IP connectivity to every node is required.
If these conditions are not present and no requirement to have direct IP connectivity to every node exists
(that is, management is performed using CTC and/or Cisco Transport Manager [CTM]), Cisco
recommends that you use the SOCKS proxy only option for all nodes that connect to a DCN router.
15.3.2 OSPF
Activating OSPF (described in the “15.2.6 Scenario 6: Using OSPF” section on page 15-10) on the
ONS 15454 LAN interface is another option that can be used to create resilient DCN connections.
However, this option can only be enabled if every element in the network, from the NEs to the NOC,
runs OSPF. This is not always possible, for example, the DCN connections might be on a public network
out of the control of the organization using the ONS 15454 network. If you are considering enabling
OSPF on the LAN, the following limitations must be considered:
• If OSPF is enabled on the LAN, the internal OSC/DCC/GCC OSPF area cannot be 0.0.0.0.
• The ONS 15454 can act as an OSPF area border gateway and support OSPF virtual links. However,
virtual links cannot pass over the OSC/DCC/GCC network.
If all elements in the DCN network are not running OSPF, enabling OSPF on the LAN is very difficult
without creating isolated areas and/or segmentation of OSPF area 0. However, if the DCN network is a
full OSPF network, enabling OSPF on the LAN might be employed for resilient DCN networks.
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