Creating Dcc Tunnels; Table 6-3 Vt1.5-Mapped Sts Use In Figure - Cisco ONS 15327 User Documentation

Creating DCC Tunnels

Table 6-3 VT1.5-Mapped STS Use in Figure 6-6
Node VT Tunnel (BLSR)
1 4
2 0
3 2
4 2
5 0
6 0
When planning VT1.5 circuits, weigh the benefits of using tunnels with the need to maximize STS
capacity. For example, a VT1.5 tunnel between Node 1 and Node 4 passing (transparently) through
Nodes 2 and Node 3 is advantageous if a full STS is used for Node 1 – Node 4 VT1.5 traffic (that is, the
number of VT1.5 circuits between these nodes is close to 28). A VT tunnel is required if:
•
•
However, if the Node 1 – Node 4 tunnel will carry few VT1.5 circuits, creating a regular VT1.5 circuit
between Nodes 1, 2, 3, and 4 might maximize STS capacity.
When you create a VT1.5 circuit, CTC determines whether a tunnel already exists between source and
drop nodes. If a tunnel exists, CTC checks the tunnel capacity. If the capacity is sufficient, CTC routes
the circuit on the existing tunnel. If a tunnel does not exist, or if an existing tunnel does not have
sufficient capacity, CTC displays a dialog box asking whether you want to create a tunnel. Before you
create the tunnel, review the existing tunnel availability, keeping in mind future bandwidth needs. In
some cases, you may want to manually route a circuit rather than create a new tunnel.
6.9 Creating DCC Tunnels
SONET provides four data communications channels (DCCs) for network element operations,
administration, maintenance, and provisioning: one on the SONET Section layer and three on the
SONET Line layer. The ONS 15327 uses the Section DCC (SDCC) for ONS 15327 management and
provisioning. You can use the Line DCCs (LDCCs) and the SDCC (when the SDCC is not used for ONS
15327 DCC terminations) to tunnel third-party SONET equipment across ONS 15327 networks. To
create a DCC tunnel, you connect the tunnel end points from one ONS 15327 optical port to another.
DCC traffic is forwarded transparently across the ONS 15327 network.
A DCC tunnel is a series of connection points that map third-party equipment SDCCs to ONS 15327
LDCCs. DCC tunnel end-points are defined by Slot, Port, and DCC type, where DCC can be either the
SDCC, Tunnel 1, Tunnel 2, or Tunnel 3 (LDCCs). You can link an SDCC to an LDCC (Tunnel 1, Tunnel
2, or Tunnel 3), and an LDCC to an SDCC. You can also link LDCCs to LDCCs and link SDCCs to
SDCCs.
The ONS 15327 OC-3 card supports tunnels on all four ports. Each ONS 15327 and 15454 can support
up to 32 DCC tunnels. The maximum number of optical ports available on an ONS 15327 is 16 (four-port
OC3 cards installed in all high-speed slots). Each port can support four different DCC tunnels (one
section and three line). This allows 64 (4 x 16) tunnel terminations. Because each tunnel must have two
terminations, the ONS 15327 can support a maximum of 32 DCC tunnel connections.
Cisco ONS 15327 User Documentation, R3.3
6-20
VT Tunnel (UPSR, 1+1) No VT Tunnel (BLSR)
6 4
0 4
3 4
3 2
0 0
0 0
Node 2 or Node 3 are ONS 15454s with XC cards, or
All VT1.5-mappable STSs at Node 2 and Node 3 are in use.
Chapter 6
No VT Tunnel (UPSR) No VT Tunnel (1+1)
6 6
4 8
5 7
5 3
4 0
4 0
Circuits and Tunnels
June 2002