10-10
Cisco ONS 15454 SDH Reference Manual, R5.0
April 2008
Chapter10 Circuits and Tunnels
10.4 DCC Tunnels
The XC-VXL-10G and XC-VXL-2.5G card support both low-order and high-order c ircuits (E-1, E-3,
DS-3, STM-1, STM-4, STM-16, and STM-64 signal rates). They manage up to 192 bid irectional STM-1
cross-connects, 192 bidirectional E-3 or DS-3 cross-connects, or 1008 bidirectional E- 1 cross-connects.
The XC10G, XC-VXL-10G, and XC-VXL-2.5G cards work with the TCC2/TCC2P card to maintain
connections and set up cross-connects within the node. You can create circuits using CTC.
Note Chapter 2, “Common Control Cards,” contains detailed specifications of the XC10G, XC-VXL-10G, and
XC-VXL-2.5G cards.
10.4 DCC Tunnels
SDH provides four DCCs for network element operation, administration, maintenance, and
provisioning: one on the SDH regenerator section layer (SDCC) and three on the SDH multiplex section
layer, also called the line DCC (LDCC). A section DCC (SDCC) and line DCC (LDCC) each provide
192 Kbps of bandwidth per channel. The aggregate bandwidth of the three LDCCs is 576 Kbps. When
multiple DCC channels exist between two neighboring nodes, the ONS 15454 SDH balances traffic over
the existing DCC channels. You can tunnel third-party SDH equipment across ONS 1545 4 SDH
networks using one of two tunneling methods, a traditional DCC tunnel or an IP-encapsulated tunnel.

10.4.1 Traditional DCC Tunnels

In traditional DCC tunnels, the ONS 15454 SDH uses regenerator SDCC for inter-ONS-15454-SDH
data communications. It does not use the multiplex section DCCs; therefore, the multiplex SDCCs are
available to tunnel DCCs from third-party equipment across ONS 15454 SDH networks. If D4 through
D12 are used as data DCCs, they cannot be used for DCC tunneling.
A traditional DCC tunnel endpoint is defined by slot, port, a nd DCC, where DCC can be either the
regenerator SDCC, Tunnel 1, Tunnel 2, or Tunnel 3. You can link a regenerator SDCC to a multiplex
SDCC (Tunnel 1, Tunnel 2, or Tunnel 3) and a multiplex SDCC to a regenerator SDCC. You can also
link multiplex SDCCs to multiplex SDCCs and link regenerator SDCCs to regenerator SDCCs. To create
a DCC tunnel, you connect the tunnel end points from one O NS 15454 SDH STM-N port to another.
Cisco recommends a maximum of 84 DCC tunnel connections for an ONS 15454SDH. Table 10-4
shows the DCC tunnels that you can create.
Figure 10-3 shows a DCC tunnel example. Third-party equipment is connected to STM-1 cards at
Node 1/Slot 3/Port 1 and Node 3/Slot 3/Port 1. Each ONS 15454 SDH node is connected by STM-16
trunk (span) cards. In the example, three tunnel connections are created, one at Node 1 (STM-1 to
STM-16), one at Node 2 (STM-16 to STM-16), and one at Node 3 (STM-16 to STM-1).
Table10-4 DCC Tunnels
DCC SDH Layer SDH Bytes STM-1 (All Ports) STM-4, STM-16, STM-64
SDCC Regenerator Section D1 to D3 Yes Yes
Tunnel 1 Multiplex Section D4 to D6 No Yes
Tunnel 2 Multiplex Section D7 to D9 No Yes
Tunnel 3 Multiplex Section D10 to D12 No Yes