PLNOG 13: Marek Janik: Rings in Ethernet Networks

HUAWEI TECHNOLOGIES CO., LTD.
www.huawei.com/enterprise
Pierścienie w sieciach Ethernet
Marek Janik
marek.janik@huawei.com

Agenda
Po co właściwie są protokoły pierścieniowe
RRPP/SEP – protokoły własne Huawei
G.8032/ERPS – ITU
Założenia
Porównanie ERPSv1 i ERPSv2
Topologie
Konfiguracje praktyczne

Drawbacks of STP – The convergence time is too long!
STP (spanning-tree protocol) is built for the redundant links and loop avoidance network. When topology changes, STP takes about 30-50 seconds to converge.
RSTP (Rapid STP) improves the speed of convergence for bridged network from 30-50 seconds to about 4 seconds, by immediately transitioning root and designated ports to the forwarding state.
Ring Protocols only spends 50-200 ms converging but it uses a ring topology instead of tree topology.
Potrzeby wynikające z ograniczeń STP
STP
RSTP
Ring Proto
Topology Type
Any Topology
Any Topology
Ring Topology
Convergence Time
30-50 seconds
6 seconds
50-250ms*

Company
Cisco
3 COM
Foundry
HP
Extreme
Huawei
Huawei
Protocol
REP
RRPP
MRP/ MRPII
RRPP
EAPS EAPSv2
RRPP
SEP
Name
Resilient Ethernet Protocol
Rapid Ring Protection Protocol
Metro Ring Protocol
Ethernet Automatic Protection Switching
Smart Ethernet Protection
Ring Topologies
Single ring/ More complex rings
Single ring/
Two or more rings
Single ring/
Overlapping rings
Single ring/
Two or more rings
Single rings/More complex rings
Single ring/
Two or more rings
Single ring/More Complex rings/Multi Rings
Convergence Time
50-250ms
< 200ms
50ms
< 200ms
Faster than RSTP
50-60ms
50-60ms
Porównanie protokołów „pierścieniowych”

Principle of RRPP---Disadvantage
RRPP meets the requirement for fast protection but encounters the following problems due to limitations of its basic mechanism:
Sub-rings must be directly connected to the major ring and a major ring can have only one level of sub-rings.
RRPP cannot be used with STP, RSTP, or MSTP properly.
The revertive switching function cannot be disabled.
The logical topology cannot be displayed, which makes network maintenance difficult.
The configuration is complex especially when there are multiple rings on the network.

Single Ring
Only one ring exists on the network. At this time, you need to define only an RRPP domain and an RRPP ring. In this networking, the change of the topology can be detected rapidly and the convergence time is short.

Intersectant Ring
There are two or more than two rings on the network. There are two common nodes between rings. Only an RRPP domain needs to be defined. One ring is specified as the major ring, and the other rings are sub-rings.

Tangent Ring
There are two or more than two rings on the network. There is one common node between rings. Each ring must belong to a different RRPP domain. This topology can be adopted when the network is of a large scale and the area-based management is required.

Principle of SEP---Feature
SEP is designed to implement failover within 50 ms on ring networks and provide the following functions:
Support more complex ring networks.
Work with STP, RSTP, or MSTP.
Prevent traffic from being switched back after link recovery, which improves network stability.
Support logical topology display to improve network maintainability.
Simplify configuration on multi-ring networks.
Support flexible selection of the blocked point to better implements traffic load balancing.

Open ring: It is a chain topology. An open ring is also called a segment, and each segment has a unique ID.
Closed ring: It can be considered as a special open ring where two edge ports are located on the same node.
A SEP basic topology must have a blocked point at any time.
Principle of SEP---Basic Topology
Open ring
Closed Ring

Closed rings and open rings can form a complex topology.
The basic topologies can transmit topology change notifications to each other, and no complex configurations are required.
Principle of SEP---Complex Topology

Konfiguracja SEP – Single-Ring krok 1
<HUAWEI> system-view
[HUAWEI] sysname LSW1
[LSW1] sep segment 1
[LSW1-sep-segment1] control-vlan 10
[LSW1-sep-segment1] protected-instance all
[LSW1-sep-segment1] quit

LSW1] interface gigabitethernet 0/0/1
[LSW1-GigabitEthernet0/0/1] port link-type hybrid
[LSW1-GigabitEthernet0/0/1] stp disable
[LSW1-GigabitEthernet0/0/1] sep segment 1 edge primary
[LSW1-GigabitEthernet0/0/1] quit
[LSW1] interface gigabitethernet 0/0/3
[LSW1-GigabitEthernet0/0/3] sep segment 1 edge secondary
[LSW2-GigabitEthernet0/0/1] sep segment 1
[LSW2-GigabitEthernet0/0/1] quit[
[LSW3-GigabitEthernet0/0/1] quit[

[LSW1-sep-segment1] block port optimal
#Set the priority of GE0/0/2 on LSW3.
[LSW3-GigabitEthernet0/0/2] sep segment 1 priority 128

Ring Network Protocol
Advantage
Disadvantage
STP/RSTP/MSTP
•Apply to all Layer 2 networks.
•Are standard IEEE protocols that allow Huawei devices to communicate with non-Huawei devices.
Provides a low convergence speed on a large network, which cannot meet the carrier-class reliability requirement.
RRPP
Features fast convergence, meeting the carrier-class reliability requirement.
•Supports only level-1 subrings on ring networks.
•Is a Huawei proprietary protocol that does not support interoperability between Huawei and non-Huawei devices.
SEP
•Applies to all Layer 2 networks.
•Features fast convergence, meeting the carrier- class reliability requirement.
•Displays the topology of an entire ring, facilitating fault location and device maintenance.
Is a Huawei proprietary protocol that does not support interoperability between Huawei and non-Huawei devices.
ERPS
Features fast convergence, meeting the carrier-class reliability requirement.
Supports single-ring and multi-ring networking.
Introduction to ERPS
On a ring network, devices supporting ERPS can communicate with each other regardless of their manufacturers.
ERPS is a protocol defined by the ITU-T to prevent loops at Layer 2. Because it is defined in Recommendation ITU-T G.8032/Y.1344, it is also called G.8032. ERPS defines R-APS PDUs and the protection switching mechanism.
ERPS blocks a specified port to prevent loops at the Ethernet link layer.
ERPS has two versions: ERPSv1 released in June 2008 and ERPSv2 released in August 2010.
Comparison Among Ring Network Protocols Supported by Huawei Devices

17
G.8032 Objectives and Principles
Use of standard 802 MAC and OAM frames around the ring. Uses standard 802.1Q (and amended Q bridges), but with xSTP disabled.
Ring nodes supports standard FDB MAC learning, forwarding, flush behaviour and port blocking/unblocking mechanisms.
Prevents loops within the ring by blocking one of the links (either a pre- determined link or a failed link).
Monitoring of the ETH layer for discovery and identification of Signal Failure (SF) conditions.
Protection and recovery switching within 50 ms for typical rings.
Total communication for the protection mechanism should consume a very small percentage of total available bandwidth.

HUAWEI TECHNOLOGIES CO., LTD.
Huawei Confidential
18
G.8032 Terms and Concepts
Ring Protection Link (RPL) – Link designated by mechanism that is blocked during Idle state to prevent loop on Bridged ring
RPL Owner – Node connected to RPL that blocks traffic on RPL during Idle state and unblocks during Protected state
Link Monitoring – Links of ring are monitored using standard ETH CC OAM messages (CFM)
Signal Fail (SF) – Signal Fail is declared when ETH trail signal fail condition is detected
No Request (NR) – No Request is declared when there are no outstanding conditions (e.g., SF, etc.) on the node
Ring APS (R-APS) Messages – Protocol messages defined in Y.1731 and G.8032
Automatic Protection Switching (APS) Channel - Ring-wide VLAN used exclusively for transmission of OAM messages including R-APS messages

Basic ERPS Concepts
Control VLAN: A control VLAN is only used to transmit R-APS PDUs. Each ERPS ring must have a control VLAN. After a port is added to an ERPS ring that has a control VLAN, the port is automatically added to the control VLAN. ERPS rings must use different control VLANs.
Data VLAN: A data VLAN is used to transmit data packets.
Protected instance: On an ERPS-enabled Layer 2 device, VLANs that transmit R-APS PDUs and data packets must be mapped to a protected instance so that ERPS forwards or blocks these VLAN packets. Otherwise, VLAN packets may cause broadcast storms on the ring network, making the network unavailable.
Example
As shown in the figure, four switches form an ERPS ring and are nodes on the ring.
The port marked in red is the RPL owner port. When ERPS works normally, the RPL owner port is in Discarding state, preventing loops on the ERPS ring.

Physical topology has all nodes connected in a ring
ERP guarantees lack of loop by blocking the RPL (link between 6 & 1 in figure)
Logical topology has all nodes connected without a loop.
Each link is monitored by its two adjacent nodes using ETH CC OAM messages
Signal Failure as defined in Y.1731, is trigger to ring protection
Loss of Continuity
Server layer failure (e.g. Phy Link Down)
RPL Owner
RPL
ETH-CC
ETH-CC
ETH-CC
ETH-CC
ETH-CC
ETH-CC
ETH-CC
ETH-CC
ETH-CC
ETH-CC
ETH-CC
ETH-CC
Physical topology
Logical topology
1
2
6
4
3
5
RPL
1
2
6
4
3
5
Ring Idle State

Protection Switching  Link Failure
A.Link/node failure is detected by the nodes adjacent to the failure.
B.The nodes adjacent to the failure, block the failed link and report this failure to the ring using R-APS (SF) message
C.R-APS (SF) message triggers
RPL Owner unblocks the RPL
All nodes perform FDB flushing
D.Ring is in protection state
E.All nodes remain connected in the logical topology.
Physical topology
Logical topology
1
2
6
4
3
5
RPL
1
2
6
4
3
5
RPL
1
2
6
4
3
5
1
2
6
4
3
5
RPL Owner
RPL
R-APS(SF)
R-APS(SF)
R-APS(SF)
R-APS(SF)

Protection Switching  Failure Recovery
A.When the failed link recovers, the traffic is kept blocked on the nodes adjacent to the recovered link
B.The nodes adjacent to the recovered link transmit R-APS(NR) message indicating they have no local request present
C.When the RPL Owner receives R- APS(NR) message it Starts WTR timer
D.Once WTR timer expires, RPL Owner blocks RPL and transmits R-APS (NR, RB) message
E.Nodes receiving the message – perform a FDB Flush and unblock their previously blocked ports
F.Ring is now returned to Idle state
RPL Owner
RPL
R-APS(NR)
R-APS(NR)
R-APS(NR)
R-APS(NR)
R-APS(NR, RB)
R-APS(NR, RB)
Physical topology
Logical topology
1
2
6
4
3
5
RPL
1
2
6
4
3
5
1
2
6
4
3
5
RPL
1
2
6
4
3
5

Porównanie ERPSv1 i ERPSv2
Function
ERPSv1
ERPSv2
Ring type
Supports single rings only.
Supports single rings and multi-rings. A multi-ring topology comprises major rings and sub-rings.
Port role configuration
Supports the ring protection link (RPL) owner port and ordinary ports.
Supports the RPL owner port, RPL neighbor port, and ordinary ports.
Topology change notification
Not supported.
Supported.
R-APS PDU transmission modes on sub-rings
Not supported.
Supported.
Revertive and non- revertive switching
Supports revertive switching by default and does not support non- revertive switching or switching mode configuration.
Supported.
Manual port blocking
Not supported.
Supports forced switch (FS) and manual switch (MS).

Interconnected rings with a VC or NVC
Page 24
VC: RAPS PDUs in sub-rings are transmitted to the major ring through interconnected nodes. The RPL owner port of the sub-ring blocks both RAPS PDUs and data traffic.
NVC: RAPS PDUs in sub-rings are terminated on the interconnected nodes. The RPL owner port blocks data traffic but not RAPS PDUs in each sub-ring.

Topologie ERPS – Single-Ring, Multi- Instance

Topologie ERPS – Multi-Ring and Ladder LSW4LSW1LSW3Blocked portLSW2LSW6LSW5Ring 2Ring 1LSW5LSW5VLAN/VPLSNPERing 3

Konfiguracja ERPS – Single Ring
# Configure SwitchA.
The configurations of SwitchB, SwitchC, SwitchD, and SwitchE are similar to the configuration of SwitchA
<Switch> system-view
[Switch] sysname SwitchA
[SwitchA] vlan batch 100 to 200
[SwitchA] interface gigabitethernet 1/0/1
[SwitchA-GigabitEthernet1/0/1] port link-type trunk
[SwitchA-GigabitEthernet1/0/1] port trunk allow-pass vlan 100 to 200
[SwitchA-GigabitEthernet1/0/1] quit
[SwitchA-GigabitEthernet1/0/2] port trunk allow-pass vlan 100 to 200
[SwitchA] erps ring 1
[SwitchA-erps-ring1] control-vlan 10
[SwitchA-erps-ring1] protected-instance 1
[SwitchA-erps-ring1] quit
[SwitchA] stp region-configuration
[SwitchA-mst-region] instance 1 vlan 10 100 to 200
[SwitchA-mst-region] active region-configuration
[SwitchA-mst-region] quit

Konfiguracja ERPS – Single Ring
[SwitchA-GigabitEthernet1/0/1] stp disable
[SwitchA-GigabitEthernet1/0/1] erps ring 1
# The configurations of SwitchB, SwitchD, and SwitchE are similar to the configuration of SwitchA,
# Configure SwitchC.
[SwitchC] interface gigabitethernet 1/0/1
[SwitchC-GigabitEthernet1/0/1] stp disable
[SwitchC-GigabitEthernet1/0/1] erps ring 1
[SwitchC-GigabitEthernet1/0/1] quit
[SwitchC-GigabitEthernet1/0/2] erps ring 1 rpl owner

[SwitchC] display erps ring 1 verbose
Ring ID : 1
Description : Ring 1
Control Vlan : 10
Protected Instance : 1
WTR Timer Setting (min) : 6 Running (s) : 0
Guard Timer Setting (csec) : 100 Running (csec) : 0
Holdoff Timer Setting (deciseconds) : 0 Running (deciseconds) : 0
Ring State : Idle
RAPS_MEL : 7
Time since last topology change : 0 days 0h:33m:4s
--------------------------------------------------------------------------------
Port Port Role Port Status Signal Status
--------------------------------------------------------------------------------
GE1/0/1 Common Forwarding Non-failed
GE1/0/2 RPL Owner Discarding Non-failed

Konfiguracja ERPS – Multi-Ring krok 1
[HUAWEI] sysname SwitchA
[HUAWEI] sysname SwitchD
[SwitchD] interface gigabitethernet 0/0/1
[SwitchD-GigabitEthernet0/0/1] port link-type trunk
[SwitchD-GigabitEthernet0/0/1] quit

[HUAWEI] sysname SwitchB
[SwitchB] interface gigabitethernet 0/0/1
[SwitchB-GigabitEthernet0/0/1] port link-type trunk
[SwitchB-GigabitEthernet0/0/1] quit
[HUAWEI] sysname SwitchC
[SwitchC-GigabitEthernet0/0/1] port link-type trunk

[SwitchB] erps ring 1
[SwitchB-erps-ring1] control-vlan 10
[SwitchB-erps-ring1] protected-instance 1
[SwitchB-erps-ring1] quit
[SwitchB] stp region-configuration
[SwitchB-mst-region] instance 1 vlan 10 100 to 200
[SwitchB-mst-region] active region-configuration
[SwitchB-mst-region] quit

[SwitchD] erps ring 1
[SwitchD-erps-ring1] control-vlan 10
[SwitchD-erps-ring1] protected-instance 1
[SwitchD-erps-ring1] quit
[SwitchD] stp region-configuration
[SwitchD-mst-region] instance 1 vlan 10 100 to 200
[SwitchD-mst-region] active region-configuration
[SwitchD-mst-region] quit
[SwitchC] erps ring 2
[SwitchC-erps-ring2] control-vlan 20
[SwitchC-erps-ring2] protected-instance 2
[SwitchC-erps-ring2] quit
[SwitchC] stp region-configuration
[SwitchC-mst-region] instance 2 vlan 20 300 to 400
[SwitchC-mst-region] active region-configuration
[SwitchC-mst-region] quit

[SwitchA-erps-ring1] version v2
[SwitchA-erps-ring2] version v2
[SwitchA-erps-ring2] sub-ring
[SwitchB-erps-ring1] version v2
[SwitchC-erps-ring2] version v2
[SwitchC-erps-ring2] sub-ring
[SwitchD-erps-ring1] version v2
[SwitchD-erps-ring2] version v2
[SwitchD-erps-ring2] sub-ring

[SwitchA-GigabitEthernet0/0/3] quit#
[SwitchB-GigabitEthernet0/0/1] stp disable
[SwitchB-GigabitEthernet0/0/1] erps ring 1 rpl owner
[SwitchB-GigabitEthernet0/0/2] erps ring 1

[SwitchC-GigabitEthernet0/0/1] erps ring 2 rpl owner
[SwitchC-GigabitEthernet0/0/2] quit#
[SwitchD-GigabitEthernet0/0/1] stp disable
[SwitchD-GigabitEthernet0/0/1] erps ring 1

[SwitchA-erps-ring2] tc-notify erps ring 1
[SwitchD-erps-ring2] tc-notify erps ring 1

Konfiguracja ERPS – Multi-Instance krok 1
[HUAWEI] sysname SwitchA
[HUAWEI] sysname SwitchB
[HUAWEI] sysname SwitchC
[HUAWEI] sysname SwitchD

[SwitchA-GigabitEthernet0/0/1] erps ring 2 rpl owner
[SwitchB-GigabitEthernet0/0/2] erps ring 1 rpl owner

PLNOG 13: Marek Janik: Rings in Ethernet Networks

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