H3C S9500 Series User manual

Operation Manual – RPR
H3C S9500 Series Routing Switches Table of Contents
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Table of Contents
Chapter 1 RPR Configuration....................................................................................................... 1-1
1.1 Introduction to RPR ...........................................................................................................1-1
1.1.1 Overview .................................................................................................................1-1
1.1.2 Ring Structure of RPR.............................................................................................1-1
1.1.3 Data Operations on RPR ........................................................................................1-2
1.1.4 Topology Discovery.................................................................................................1-4
1.1.5 Fault Response Methods........................................................................................1-5
1.1.6 RPR Timers.............................................................................................................1-7
1.1.7 RPR Ports ...............................................................................................................1-8
1.1.8 Protocols and Standards.........................................................................................1-9
1.2 Configuring RPR................................................................................................................1-9
1.3 Configuring Protection Mode...........................................................................................1-10
1.4 Configuring Protection Reversion Mode..........................................................................1-10
1.5 Configuring Ringlet Selection Table ................................................................................1-11
1.5.1 Adding a static ringlet selection entry ...................................................................1-12
1.5.2 Configuring default ringlet selection......................................................................1-12
1.6 Configuring Rate Limiting ................................................................................................1-12
1.7 Configuring Station Weight..............................................................................................1-13
1.8 Configuring Timers ..........................................................................................................1-14
1.9 Configuring RPR POS Interface......................................................................................1-15
1.10 Configuring Port Type....................................................................................................1-16
1.11 Configuring Station Name..............................................................................................1-16
1.12 Configuring Protection Requests...................................................................................1-16
1.13 Configuring RPR VLAN Tunnel .....................................................................................1-17
1.14 Testing Connectivity Between Stations .........................................................................1-17
1.15 Displaying and Maintaining RPR...................................................................................1-18
1.16 RPR Configuration Examples........................................................................................1-19
1.16.1 RPR Protection Mode/Static Ringlet Selection Configuration Examples............ 1-19
1.16.2 RPR VLAN Tunnel Configuration Examples.......................................................1-21

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Chapter 1 RPR Configuration
When configuring RPR, go to these sections for information you are interested in:
zIntroduction to RPR
zConfiguring RPR
zDisplaying and Maintaining RPR
zRPR Configuration Examples
1.1 Introduction to RPR
This section covers these topics:
zIntroduction to RPR
zRing Structure of RPR
zData Operations on RPR
zTopology Discovery
zFault Response Methods
zRPR Timers
zRPR Ports
zProtocols and Standards
1.1.1 Overview
Resilient packet ring (RPR) is a new MAC layer protocol designed for transferring mass
data services over MANs. It can operate on synchronous optical network/synchronous
digital hierarchy (SONET/SDH), dense wavelength division multiplexing (DWDM) and
Ethernet to provide flexible and efficient networking schemes for broadband IP MANs
carriers. The RPR technology delivers these benefits:
zPhysical layer diversity
zHigh bandwidth utilization
zMulticast and broadcast support
zAutomatic topology discovery
zQuick protection mechanism
zTraffic level guarantee based on bandwidth reservation and rate limiting
zBandwidth sharing fairness among stations on the ring
1.1.2 Ring Structure of RPR
RPR is made up of dual unidirectional counter-rotating ringlets identified as Ringlet 0
and Ringlet 1, as shown in Figure 1-1:

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Station
West
EastWest
East
West
East East West
East
West
Ringlet 0
Ringlet 1
Span
Figure 1-1 Ring structure of RPR
Ringlet 0, also called outer ring, is for clockwise or west data traffic. Ringlet 1, also
called inner ring, is for counterclockwise or east data traffic.
On Ringlet 0, stations send data frames out of east interfaces and receive data frames
from west interfaces; on Ringlet 1, stations send data frames out of west interfaces and
receive data frames from east interfaces. A group of consecutive stations associated
with the same attribute form a domain.
Any two adjacent stations are connected by a pair of unidirectional logical channels
called links transmitting in opposite directions. These two links form a span. Aspan on
which data frames are not allowed to pass is called an edge. If a ring contains at least
one detected edge, it is called open ring. If it does not contain any detected edges, it is
called closed ring.
1.1.3 Data Operations on RPR
Stations on an RPR handle data frames by performing the following operations:
zInsertion, to place a frame on a ringlet.
zCopy, to deliver an inbound frame from the ring to the upper layer. The copying of
a frame does not imply its removal from the ring.
zTransit, to pass a frame to the next station.
zStripping, to remove a frame from a ringlet.
By performing these operations, stations implement unicast transmission, broadcast
transmission, and multicast transmission.

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I. Unicast transmission
Transit
Strip
Strip
Transit
Copy from
ringlet 1
Copy from
ringlet 0
Insert to
ringlet 0
Insert to
ringlet 1
Transit
Strip
Figure 1-2 Unicast transmission on an RPR ring
Figure 1-2 shows how a unicast data frame is transmitted on an RPR ringlet:
1) Source station inserts the unicast frame into the data stream on Ringlet 0 or
Ringlet 1.
2) Transit stations transit the frame.
3) The frame is copied and stripped when it reaches the destination station or when
its time to live (TTL) expires.
Different from traditional ring technologies where unicast frames are removed from the
ring at the source station, RPR adopts destination stripping to remove unicast frames
from the ring at the destination station. This increases bandwidth utilization and spatial
bandwidth reuse efficiency.
II. Broadcast transmission
Copy from
ringlet 0
Copy from
ringlet 0
Copy from
ringlet 0
Copy from
ringlet 0
Strip
Strip
Insert to
ringlet 0
Figure 1-3 Broadcast/flooded transmission on an RPR ring
Figure 1-3 shows how a frame is flooded or broadcasted on an RPR ringlet:
1) Source station inserts the frame into the data stream on Ringlet 0 or Ringlet 1.

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2) Transit and destination stations copy and transit the frame if the TTL of the frame
has not expired.
3) The frame is stripped when it returns to the source station or whenits TTL expires.
III. Multicast transmission
Figure 1-4 Multicast transmission on an RPR ring
Figure 1-4 shows how a multicast frame is transmitted on an RPR ringlet:
zSource station inserts the frame into the data stream on Ringlet 0 or Ringlet 1.
zTransit stations transit the frame.
zDestination station transits and copies the frame.
zThe frame is stripped when it returns to the source station or whenits TTL expires.
1.1.4 Topology Discovery
RPR performs automatic topology discovery to collect such information as the number
of stations, ring state, order of the stations on the ring to build a topology database. This
database does not change after the ring topology becomes stable.
I. Topology database
Each RPR station maintains a topology database that describes the topology of the
entire RPR ring. Based on this database, the station creates its ringlet selection table.
A topology database contains three categories of information:
zRinglet topology information, such as the number of stations, ring state, and
available bandwidth.
zLocal station topology information, such as the MAC address, protection mode,
protection state, station name, topology checksum of the local station and the
neighbor stations.
zTopology information of other stations, such as the MAC address, validity state,
reachability, protection mode, station ID, station name, and reserved bandwidth.

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II. Topology discovery process
RPR uses three types of control frames for topology discovery: attribute discovery
(ATD), topology protection (TP), and topology checksum (TC).
zTP frames convey configuration and status information of stations. The stations on
an RPR ring broadcast TP frames to advertise their configuration and status
information and update their own topology databases after receiving TP frames
from other stations. Finally, all the stations reach an agreement on the topology of
the ring.
zTC frames convey topology checksum information. They are sent between
adjacent stations to check whether the topology databases on them are
synchronized, thus identifying stability of the RPR ring topology.
zATD frames convey attributes of the local station such as the MAC address and
station name. These attributes will be included in the topology database.
All these control frames are sent at regular intervals, which are user configurable. For
TP and TC frames, two types of intervals, fast sending interval and slow sending
interval, are used.
When a station on the ring starts initializing or detects a topology change, it sends TP
frames to propagate topology information throughout the network. When doing that, it
sends the first nine TP frames at fast intervals and subsequent TP frames at slow
intervals.
After the RPR ring topology converges, the station starts to send TC frames. When
doing that, it sends first five TC frames at fast intervals and then subsequent TC frames
at slow intervals.
Only one type of interval is available for sending ATD frames, regardless of topology
change.
1.1.5 Fault Response Methods
RPR delivers strong self-recovery capability. Its protection mechanism provides event
detection, quick self-recovery, and fast service recovery when faults occur to the
fiber-optic or stations. The network can thus detect faults quickly and react
appropriately to restore services in 50 ms.
RPR is available with two fault response methods: passthrough and protection.
I. Passthrough
The passthrough approach mainly applies to handle station faults. When a station
detects an internal fault, it can enter the passthrough mode where it behaves similar to
a repeater and does not handle any services on the ring. Frames arriving at this station
are forwarded directly as if it was transparent, and the station is invisible on the ring.
See Figure 1-5.

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Station failure
Pass-through
Figure 1-5 Passthrough mode
II. Protection
If a station is unable to forward traffic as the result of power failure or fiber cut for
example, it should enter protection mode.
1) Protection mode
RPR provides two protection modes: wrapping and steering.
zWrapping
In wrapping mode, after a span or station fails, protected traffic is directed at the point of
failure to the opposing ringlet. The two ringlets thus form a closed single ring around the
point of the failure.
As shown in Figure 1-6, after the span between station Aand station B fails on Ringlet 0,
traffic that should originally travel from station B to A along Ringlet 0 is directed to
Ringlet 1 to reach station B.
Figure 1-6 Wrapping mode
As the wrapping mode allows quick switchover, data frame loss can be minimized. This,
however, wastes bandwidth.
zSteering mode
Unlike in wrapping mode, in steering mode, the two stations at the two sides of the point
of failure updates their topology databases first; and then sends TP frames at fast

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intervals to the other stations on the ring. After a new topology database is stabilized,
the source station directs protected frames to the ringlet that retains connectivity to their
destinations.
As shown in Figure 1-7, traffic that should have traveled from station A to station B
along Ringlet 0 is steered to Ringlet 1 for transmission.
Steered path
Station A
Station B
Figure 1-7 Steering mode
The steering mode can avoid the bandwidth waste with wrapping mode, but as it
requires topology reconvergence, it can cause frame loss and service interruption.
2) Protection switching
RPR protection switching uses the following protection hierarchy listed in the order of
decreasing severity:
zForced switch (FS)
zSignal fail (SF), related to current physical status.
zSignal degrade (SD), related to current physical status.
zManual switch (MS)
zWait to restore (WTR)
zIdle
Protection switching occurs only when requested by a station on the ring. The hierarchy
of protection requests is the same as this protection switching hierarchy. Among
protection requests, FS and MS requests are sent manually, whereas SF, SD, and
WTR requests are sent automatically.
The MS request sent by a station will not be processed if a higher priority protection
request is present on the RPR ring.
If an FS request is present on the current ring, the SF or SD request automatically sent
as the result of a link failure will be processed only after the FS request is cleared.
1.1.6 RPR Timers
RPR is available with the following user-configurable timers:

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zTP fast timer: defines the fast interval at which TP frames are sent. A TP fast timer
starts when a station starts initializing or detects a topology change. After sending
nine TP frames at fast intervals, the station begins to send TP frames at slow
intervals.
zTP slow timer: defines the slow interval at which TP frames are sent. This timer is
active when the ring topology is stable.
zTC fast timer: defines the fast interval at which TC frames aresent. A TC fast timer
starts on a station when the ring topology becomes converged. After sending five
TC frames at fast intervals, the station begins to send TC frames at slow intervals.
zTC slow timer: defines the slow interval at which TC frames are sent. TC frames
are sent in slow intervals when the ring topology is stable.
zATD timer: defines the interval at which ATD frames are sent.
zWTR timer: When a protection switching event occurs on a station due to link
failure, the station enters automatic protection state; after the link recovers, the
station enters the idle protection state. The WTR timer defines the delay that a
station transits to the idle protection state after entering the automatic protection
state.
zHold-off timer: defines the delay for the physical layer (PHY) to report a protection
request after detecting a link failure.
zKeepalive timer: A single choke fairness frame (SCFF) is transmitted point to point
every fairness algorithm period. When a station fails to receive a SCFF, a
keepalive timer starts. If no SCFF frame is received after the timer expires, the
station sends an SF protection request.
zTopology stability timer: When a station detects a topology change on the ring, it
starts the topology stability timer and begins to collect topology information to
update its topology database. After the timer expires, the station checks the
validity of received topology information. If the information is valid, the station
enters topology valid state; if not, the station re-starts the timer.
1.1.7 RPR Ports
An RPR station comprises one RPR logical interface and two physical ports. The two
physical ports are used to transmit data to or receive data from the ring and the logical
port is provided for you to make configuration.
Logical port is available for RPR stations: XGE (10GE).
Three types of physical ports are available for RPR stations: XGE, 2.5 Gbps POS, and
10 Gbps POS.
The RPR logical ports are available depend on the physical RPR ports on your station,
as shown in the following table:

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Table 1-1 RPR physical and logical port dependencies
RPR physical port RPR logical port
XGE XGE
2.5 Gbps POS XGE
10 Gbps POS XGE
Note:
zMany commands available on an Ethernet port can be used on an RPR logical port.
These commands involve these configurations: broadcast suppression, port
description, link type, VLAN assignment, default VLAN ID assignment (for a hybrid
or trunk port), flow control, priority configuration, and the loopback command. For
how to configure them, refer to Ethernet Port Configuration.
zRPR logical ports support STP, QoS, and ACL.
1.1.8 Protocols and Standards
The RPR implementation follows the following document:
IEEE802.17: Resilient packet ring (RPR) access method and physical layer
specifications
1.2 Configuring RPR
Complete these tasks to configure RPR:
Task Remarks
Configuring Protection Mode Optional
Configuring Protection Reversion Mode Optional
Configuring Ringlet Selection Table Optional
Configuring Rate Limiting Optional
Configuring Station Weight Optional
Configuring Timers Optional
Configuring RPR POS Interface Optional
Configuring Port Type Optional
Configuring Station Name Optional
Configuring Protection Requests Optional