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Cisco ONS 15310-MA SDH Reference Manual, Release 9.1 and Release 9.2
78-19417-01
Chapter 7 Circuits and Tunnels
Subnetwork Connection Protection Circuits

7.5.1 Traditional DCC Tunnels

In traditional DCC tunnels, you can use the three available channels of the MS-DCC and/or the single
channel of the RS-DCC, when not used for ONS 15310-MA SDH DCC terminations, to tunnel
third-party SDH equipment across ONS networks. A DCC tunnel endpoint is defined by slot, port, and
DCC channel. You can connect any of the four available channels to any other available channel. To
create a DCC tunnel, you connect the tunnel endpoints from one ONS 15310-MA SDH optical port to
another.
Table 7-4 shows the DCC tunnels that you can create.
When you create DCC tunnels, keep the following guidelines in mind:
• An optical port used for a DCC termination cannot be used as a DCC tunnel endpoint, and an optical
port that is used as a DCC tunnel endpoint cannot be used as a DCC termination.
• All DCC tunnel connections are bidirectional.

7.5.2 IP-Encapsulated Tunnels

An IP-encapsulated tunnel puts an RS-DCC in an IP packet at a source node and dynamically routes the
packet to a destination node. To compare traditional DCC tunnels with IP-encapsulated tunnels, a
traditional DCC tunnel is configured as one dedicated path across a network and does not provide a
failure recovery mechanism if the path is down. An IP-encapsulated tunnel is a virtual path, which adds
protection when traffic travels between different networks.
IP-encapsulated tunneling has the potential to flood the DCC network with traffic, which causes CTC
performance to degrade. The data originating from an IP tunnel can be throttled to a user-specified rate,
which is a percentage of the total RS-DCC bandwidth.
Each ONS 15310-MA SDH supports one IP-encapsulated tunnel. You can convert a traditional DCC
tunnel to an IP-encapsulated tunnel or an IP-encapsulated tunnel to a traditional DCC tunnel. Only
tunnels in the Discovered status can be converted.
Caution Converting from one tunnel type to the other is service-affecting.
7.6 Subnetwork Connection Protection Circuits
From the Subnetwork Connection Protection Selectors subtab in the Edit Circuits window, you can
perform the following:
• View the Subnetwork Connection Protection(SNCP) circuit’s working and protection paths.
Tab le 7- 4 DC C Tu nn el s
DCC SDH Layer SDH Bytes STM1, STM4
DCC1 Section D1 to D3 Yes
DCC2 Line D4 to D6 Yes
DCC3 Line D7 to D9 Yes
DCC4 Line D10 to D12 Yes