Presentation from SIEPON Seminar on 20 April in Czech Republic, sponsored by IEEE-SA & CAG. Opinions presented by the speakers in this presentation are their own, and not necessarily those of their employers or of IEEE.

1. Resilience and Service
Protection in EPON
Hesham ElBakoury
Huawei Technologies
Hesham.ElBakoury@huawei.com
20 April 2012 IEEE P1904.1 Seminar, Prague, Czech Republic 1

2. EPON is a Universal Access Architecture
 All user types
– Residential
– Business
– Cellular backhaul
 All configurations
– SFU
– MDU/MTU
– FTTH
– FTTC/FTTN
 All Data Rates
– 1 Gb/s (.3ah-2004)
– 10/1 Gb/s (.3av-2009)
– 10/10 Gb/s (.3av-2009)
 One architecture simultaneously supports all user types,
all deployment configurations, and all equipment
generations on the same network!
20 April 2012 IEEE P1904.1 Seminar, Prague, Czech Republic 2

3. Motivation for Protection in EPON
 With the increasing rate of deployments of EPON systems
to support both residential and business applications,
service protection becomes of paramount importance to
maintain the QoS and high availability of these applications
 A network can offer protection by providing backup
resources to be used when the primary resource fails.
 Survivability is property of a network to be resilient to
failure
– Requires physical redundancy and protection switching
mechanisms
 Survivability is a very important aspect of modern networks
– The ever-increasing bit rate makes an unrecovered
failure a significant loss for network operators.
– No network-operator is willing to accept unprotected
networks anymore.
20 April 2012 IEEE P1904.1 Seminar, Prague, Czech Republic 3

4. EPON Failures
 The common EPON failures are:
– Fiber cut in feeder/drop fiber, which affect users connected to the
given fiber trunk/branch;
– Failure of OLT/ONU transceivers, affecting either all or selected users;
– Failure of other passive optical components, e.g. Passive Splitter
Combiner (PSC), connectors, splices etc.
– Different types of OLT/ONU failures, related with all other electronic,
electric or mechanical components of these devices, including among
the others, ASIC, connectors, power supplies etc.
User (error
Configuration) ODN, 19%
13%
OLT(card &
Transceiver)
Platform , 7%
(ITMS,IPTV,
SS/IMS,
etc.), 26%
ONU,
35%
20 April 2012 IEEE P1904.1 Seminar, Prague, Czech Republic 4

5. Failure Detection in EPON
 Fiber Plant monitoring using OTDR
– Active Monitoring
– Used for both fault detection and localization.
– Not specified by SIEPON.
 Transceiver Status Monitoring
– SIEPON provides network operators with ability to
monitor major optical transceiver parameters for both
OLT and ONU.
 Link Fault Detection
– BER Measurements.
– Failure to receive valid optical signal for more than 2ms.
– Loss of single REPORT/GATE messages within 50 msec.
20 April 2012 IEEE P1904.1 Seminar, Prague, Czech Republic 5

6. SIEPON Protection Techniques
 Two types of Optical Link Protection are
introduced by SIEPON:
– Trunk Protection
– Tree Protection
 Both OLT intra-chassis and inter-chassis (dual-
homing/parenting) protection are supported.
– Inter-chassis communications protocol is unspecified by
SIEPON.
 Both on-demand and automatic protection
switching are supported.
 Both Line and Client Protection are supported.
– Key difference depends on whether the MAC client block
uses combinatorial or sequential logic.
20 April 2012 IEEE P1904.1 Seminar, Prague, Czech Republic 6

7. Line Protection
 In Line Protection Scheme, the entire MAC Client data path is shared
between primary and backup paths. For example, queues and shaper/policer
are shared between primary and backup paths.
 Line Protection Scheme is functionally equivalent to an implementation
where a protection switch is located within an ONU ASIC containing two line
interfaces
20 April 2012 IEEE P1904.1 Seminar, Prague, Czech Republic 7

8. Client Protection
 In Client Protection Scheme, the entire MAC Client data path is fully
decoupled.
 Upon protection switchover event, the backup path starts with clean history
 Client Protection Scheme is functionally equivalent to an implementation
where a protection switch connects to two separate ONU/OLT ASICs, each
with a single line interface
20 April 2012 IEEE P1904.1 Seminar, Prague, Czech Republic 8

9. Trunk Protection
Trunk Protection
 ONU is not protected.
 The OLT and trunk fiber are duplicated.
Protection area  Backup OLT can be in hot or cold stand-by mode
 Switching time must not exceed150 msec.
ONU#1
2:N optical splitter PON IF
PON IF
OLT 1

PON IF ONU#N
OLT 2 PON IF
20 April 2012 IEEE P1904.1 Seminar, Prague, Czech Republic 9

10. Tree Protection
Tree Protection To balance traffic loads of different ONUs between
 OLT, ONU and the entire fiber plant are two OLTs, a single OLT can act as working OLT for
protected against failure. some ONUs, while simultaneously act as stand-by
 Only Hot Stand-by mode is supported. OLT for other ONUs.
 Switching time must not exceed 50 msec.
20 April 2012 IEEE P1904.1 Seminar, Prague, Czech Republic 10

11. Applications of SIEPON Protection
 Trunk Protection
– Switch over time is <= 150msec.
– Frame loss is allowed.
– Most suitable for residential deployments
where tree protection is too expensive due to
high number of fibers in the drop section.
 Tree Protection
– Switch over time is <= 50msec
– Frame loss is minimized.
– High-end business users.
– Mission Critical applications.
20 April 2012 IEEE P1904.1 Seminar, Prague, Czech Republic 11