Dcc Tunnels; Traditional Dcc Tunnels; Ip-Encapsulated Tunnels; Table 7-5 Dcc Tunnels - Cisco ONS 15600 Reference Manual

7.4 DCC Tunnels

7.4 DCC Tunnels
SONET provides four data communications channels (DCCs) for network element operations,
administration, maintenance, and provisioning: one on the SONET Section layer (DCC1) and three on
the SONET Line layer (DCC2, DCC3, DCC4). The ONS 15600 uses the Section DCC (SDCC) for
ONS 15600 management and provisioning. An SDCC and Line DCC (LDCC) each provide 192 Kbps of
bandwidth per channel. The aggregate bandwidth of the three LDCCs is 576 Kbps. You can tunnel
third-party SONET equipment across ONS 15600 networks using one of two tunneling methods, a
traditional DCC tunnel or an IP-encapsulated tunnel.

7.4.1 Traditional DCC Tunnels

In traditional DCC tunnels, you can use the three Line DCCs (LDCCs) and the SDCC (when not used
for ONS 15600 DCC terminations). A DCC tunnel endpoint is defined by slot, port, and DCC, where
DCC can be either the SDCC or one of the LDCCs. You can link LDCCs to LDCCs and link SDCCs to
SDCCs. You can also link an SDCC to an LDCC and an LDCC to an SDCC. To create a DCC tunnel,
connect the tunnel endpoints from one ONS 15600 optical port to another.
tunnels that you can create.
Table 7-5
DCC
DCC1
DCC2
DCC3
DCC4
When you create DCC tunnels, keep the following guidelines in mind:
•
•
•
•

7.4.2 IP-Encapsulated Tunnels

An IP-encapsulated tunnel puts an SDCC 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 of flooding the DCC network with traffic resulting in a
degradation of performance for CTC. The data originating from an IP tunnel can be throttled to a
user-specified rate, which is a percentage of the total SDCC bandwidth.
Cisco ONS 15600 Reference Manual, R8.0
7-12
DCC Tunnels
SONET Layer SONET Bytes
Section D1 to D3
Line D4 to D6
Line D7 to D9
Line D10 to D12
Each ONS 15600 can have up to 64 DCC tunnel connections.
An SDCC that is terminated cannot be used as a DCC tunnel endpoint.
An SDCC that is used as an DCC tunnel endpoint cannot be terminated.
All DCC tunnel connections are bidirectional.
Chapter 7 Circuits and Tunnels
Table 7-5 lists the DCC