Digital Access Services T-1 and SONET. Topics. T-Carrier Hierarchy SONET Hierarchy Other fiber Leased Line Details Pricing and Billing Router configuration PPP configuration. Leased Line Service Rates. T1 Channelized T1: 24 × DS0 (64k bps) unchannelized T1: 1.544MP bps
Each DS0 called a time slot
8000 frames/sec * 8 bits/slot = 64 Kbps
24 * 8 + 1 = 193 bits/frame
8000 frames/sec * 193 bits/frame = 1.544 Mbps
8000 Framing bits sent per second
Physical facility: T-1 (4-wire)
Data rate: 64 kbps × 8 = 512 kbps (for this example)
The customer pays a monthly charge of physical facility (data rate independent) + data services (data rate dependent)
Source: KnowledgeLink, Inc.
= 1 SF
= 1 ESF
S: Synchronization (001011) C: error detection F: Facility Data Link control
1 0 0 0 0 0 0 0 0 0 1
Similar to T-1, used outside North America
The E-1 interface provides a 2,048 kbit/s access rate. It can support up to 32 channels (64 Kbps DS0).
“Framed E1” supports 30 voice channels
Unchannelized E1 gives you the full 2.048 Mbps.
TS0 is dedicated for synchronization, alarms, control messages, and future extensions.
TS16 is usually used for signaling. It is known as Clear Channel Signaling, an example of out of band signaling.
TS0 and TS16 can carry data as well (unchannelized E1)
TS1-TS15 and TS17-TS31 are used for carrying user data.
Cisco 2811 Router
WIC T1 CSU/DSU
Leased Line Service Charge (1Y pan)
Monthly charge = $575*2 + $1.85 ×300 (miles) × (1-25%) = $1,278
ADM = Add-Drop Multiplexer
to the ring
out of the ring
SDH: Synchronous Digital Hierarchy by ITU-T
SONET: Synchronous Optical Network by ANSI
OC: Optical Carrier
STS: Synchronous Transport Signal
STM: Synchronous Transmission Mode
Each frame: 90 col × 9 rows = 810 bytes
Payload: 86 col × 9 rows = 774 bytes
Each byte of payload can be allocated as a separate 64 Kbps customer channel
STS-1 frame can support up to 774 standard DS0 channels (digital voice or 64 Kbps data).
Transmission Rate (raw): 51.84M bps
Transmission Rate (payload): 49.54M bps
SPE (payload) = 7 VT Groups + packing bytes
One VT Group = 12 columns
Each VT Group is split into multiple VTs of the same type
Either 4 x VT1.5 or 3 x VT2 or 2 x VT3 or 1 x VT6
SONET Transmission Equipment:
SONET Network Topologies:
Metro SONET Ring
ADM: Add/Drop Multiplexer
Point-to-Point (with Automatic Protection Switching (APS))
DS1s, DS3s, Ethernet, ...
DS1s, DS3s, Ethernet, ...
Faults detected and managed using span switching within 50 msec automatically!
FIGURE 20-7 2-fiber ULSR (Unidirectional Line Switched Ring) uses one ring in normal operation. If both fibers are cut, the rings are wrapped around.
SSONET Networks (BLSR)
Ring Topology BLSR (2-fiber)
Ring Topology BLSR (4-fiber)