Information About PRP
PRP allows a data communication network to prevent data transmission failures by providing network nodes two alternate paths for the traffic to reach its destination. Two local area networks (LANs) provide alternate paths for the traffic over independent LAN segments. However, the two LANs must share a similar topology.
Role of the Switch
A switch operating with PRP has a Gigabit Ethernet port connection to each of the two LANs. The switch sends two packets simultaneously to each LAN through the two different ports to the destination node. When the destination node receives the first packet successfully, it discards the second packet if it arrives successfully as well. Each packet sent includes an incremented sequence number that helps the destination node distinguish between duplicate packets.
Key Terms
The following terms are relevant when you configure PRP on the switch:
■PRP channel– A logical interface that aggregates PRP groups (access, trunk or routed) into a single link. The PRP channel remains up as long as both of its member ports remain up and send traffic. When both member ports are down, the channel is down. Only the up and down states of the ports can trigger different redundancy behavior or Single Attached Node (SAN) traffic routing decisions.
Each channel contains two Layer 2 or Layer 3 Gigabit Ethernet interfaces.
Within each channel group, Gigabit Ethernet interfaces (GI1/17 and Gi1/18) will always be the primary ports; and, Gigabit Ethernet interfaces, (Gi1/18) and (Gi1/20) will be the secondary port. PRP group 1 always contains the GI1/17 and Gi1/18 interfaces.
■PRP group–A group is composed of two ports, one of which represents LAN A and the other LAN B.
–PRP group 1 always contains the GI1/17 and Gi1/18 interfaces.
–PRP group 2 always contains Gi1/19 and Gi1/20 interfaces.
Guidelines and Limitations
■PRP configuration should always be done in default status mode.
■PRP traffic load cannot exceed 90% bandwidth of the Gigabit Ethernet interface channels.
■PRP does not support third-party systems.
■A PRP channel must have two active ports configured within a channel to remain active and maintain redundancy.
■Both interfaces within a channel group must have the same configuration.
■For Layer 3, you must configure the IP address on the PRP channel interface.
■Precision Time Protocol (PTP), when enabled, traverses PRP within LAN A only.
■Load-balancing is not supported.
■LLDP and CDP must be disabled on a system level.
■Primary link, GI1/17 and Gi1/18, should not be shut down.
■(Optional configuration) Precision Time Protocol (PTP) traffic only traverses PRP within LAN A only.
■The following message might appear after the switch reloads; it can be ignored (CSCuq52270):
Gi1/18 is not compatible with Gi1/17
■The Protocol status displays incorrectly for the Layer type = L3 section when you enter the show prp channel detail command. Refer to the Ports in the group section for the correct Protocol status (CSCur88178).
Port state = prp-channel is Inuse
Logical slot/port = 1/17 Port state = Inuse
Logical slot/port = 1/19 Port state = Inuse
■When a link, LAN A (Gi1/17) or LAN B (Gi1/18) goes down, both links will continue to show a link status of UP. Use the show prp channel command to confirm the status of the links.
Configuring PRP
This section includes the following topics:
■Creating a PRP Channel and Group
■(Optional) General Usage Precision Time Protocol (PTP) Enable on LAN A Channel
■Disabling the PRP Channel and Group
Creating a PRP Channel and Group
To create and enable a PRP channel and group on the switch, follow the steps in this section.
DETAILED STEPS
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1. |
configure terminal |
Enters global configuration mode. |
2. |
no spanning-tree etherchannel guard misconfig |
Prevents the PRP link from going into an err-disable state. |
3. |
interface range {GigabitEthernet1/17-18 | GigabitEthernet1/19-20} |
Assigns two Gigabit Ethernet interfaces to the PRP channel group. Note: You must apply the Gi1/17 interface before the Gi1/18 interface. So, we recommend using the interface range command. Similarly, you must apply the Gi1/19 interface before the Gi1/20 interface. Use the no interface prp-channel 1|2 command to disable PRP on the defined interfaces and shut down the interfaces. |
4. |
[no] switchport |
(Optional) For Layer 2 traffic, enter switchport. (Default). Note: For Layer 3 traffic, enter no switchport. |
5. |
switchport mode access |
(Optional) Sets a non-trunking, non-tagged single VLAN Layer 2 (access) interface. |
6. |
switchport access vlan <value> |
(Optional) Creates a VLAN for the Gi1/17-18 interfaces. Note: Only required for Layer 2 traffic. |
7. |
no ptp enable |
Disables Precision Time Protocol (PTP) on the switch. |
8. |
no keepalive |
Disables loop detection for the redundancy channel. |
9. |
prp-channel-group prp-channel group |
Enters sub-interface mode and creates a PRP channel group. prp-channel group -Value of 1 or 2. You must assign two interfaces to a channel group. The no form of this command is not supported. |
10. |
no shutdown |
Brings up the PRP channel. |
EXAMPLE 1
This example shows how to create a PRP channel on an IE 5000 switch, create a PRP channel group, and assign two ports to that group.
router# configure terminal
router(config)# no spanning-tree etherchannel guard misconfig
router(config)# interface range GigabitEthernet1/17-18
router(config-if)# no ptp enable
router(config-if)# no keepalive
router(config-if)# prp-channel-group 1
router(config-if)# no shutdown
EXAMPLE 2
This example shows how to create a PRP channel on the IE 5000 switch with a VLAN ID of 2.
router# configure terminal
router(config)# no spanning-tree etherchannel guard misconfig
router(config)# interface range GigabitEthernet1/17-18
router(config-if)# switchport
router(config-if)# switchport mode access
router(config-if)# switchport access vlan 2
router(config-if)# no ptp enable
router(config-if)# no keepalive
router(config-if)# prp-channel-group 1
router(config-if)# no shutdown
EXAMPLE 3
This example shows how to create a PRP channel on a switch configured with Layer 3.
router# configure terminal
router(config)# no spanning-tree etherchannel guard misconfig
router(config)# interface range GigabitEthernet1/17-18
router(config-if)# no switchport
router(config-if)# no ptp enable
router(config-if)# no keepalive
router(config-if)# prp-channel-group 1
router(config-if)# no shutdown
router(config)# interface prp-channel 1
router(config)# ip address 192.0.0.2 255.255.255.0
EXAMPLE 4
In this example, the configuration establishes two VLANs, 80 and 81 and the Spanning Tree Protocol is configured for each PRP channel on the VLANs, MST-PRP1 and MST-PRP2, respectively.
There are two IE 5000 switches within the topology, identified as switch 1 (SW1) and switch 2 (SW2).
The steps below show how to configure the Spanning Tree Protocol, VLANs and PRP channels and groups on SW1:
spanning-tree portfast bpduguard default
spanning-tree portfast bpdufilter default
no spanning-tree etherchannel guard misconfig
spanning-tree extend system-id
spanning-tree mst configuration
switchport access vlan 81
spanning-tree bpdufilter enable
switchport access vlan 80
spanning-tree bpdufilter enable
interface GigabitEthernet1/17
switchport access vlan 81
interface GigabitEthernet1/18
switchport access vlan 81
interface GigabitEthernet1/19
switchport access vlan 80
interface GigabitEthernet1/20
switchport access vlan 80
interface GigabitEthernet1/9
switchport access vlan 81
interface GigabitEthernet1/10
ip address 192.168.100.222 255.255.255.0
interface GigabitEthernet1/11
switchport access vlan 80
interface GigabitEthernet1/12
switchport access vlan 80
interface GigabitEthernet1/13
switchport access vlan 81
ip address 10.208.80.111 255.255.255.0
ip address 10.208.81.111 255.255.255.0
The steps below show how to configure the Spanning Tree Protocol, VLANs, and PRP channels and groups on SW2:
spanning-tree portfast bpduguard default
spanning-tree portfast bpdufilter default
no spanning-tree etherchannel guard misconfig
spanning-tree extend system-id
spanning-tree mst configuration
switchport access vlan 81
spanning-tree bpdufilter enable
switchport access vlan 80
spanning-tree bpdufilter enable
interface GigabitEthernet1/17
switchport access vlan 81
interface GigabitEthernet1/18
switchport access vlan 81
interface GigabitEthernet1/19
switchport access vlan 80
interface GigabitEthernet1/20
switchport access vlan 80
interface GigabitEthernet1/9
switchport access vlan 81
interface GigabitEthernet1/10
ip address 192.168.100.223 255.255.255.0
interface GigabitEthernet1/11
switchport access vlan 80
interface GigabitEthernet1/12
switchport access vlan 80
interface GigabitEthernet1/13
switchport access vlan 81
ip address 10.208.80.222 255.255.255.0
ip address 10.208.81.222 255.255.255.0
The steps below show how to configure the Spanning Tree Protocol and VLANs on SW3:
spanning-tree extend system-id
spanning-tree mst configuration
interface GigabitEthernet1/0/1
switchport access vlan 81
interface GigabitEthernet1/0/2
switchport access vlan 81
interface GigabitEthernet1/0/5
switchport trunk allowed vlan 20,80,81,88
interface GigabitEthernet1/0/8
switchport access vlan 80
The steps below show how to configure the Spanning Tree Protocol and VLANs on SW4:
spanning-tree extend system-id
spanning-tree mst configuration
interface gigabitethernet0/3
switchport trunk allowed vlan 20,80,81,88
interface gigabitethernet0/7
switchport access vlan 80
interface gigabitethernet0/8
switchport access vlan 80
interface GigabitEthernet1/17
switchport access vlan 81
interface GigabitEthernet1/18
switchport access vlan 81
The steps below show how to configure the Spanning Tree Protocol and VLANs on SW5:
spanning-tree extend system-id
spanning-tree mst configuration
interface gigabitethernet1/7
switchport access vlan 80
ip device tracking maximum 0
interface gigabitethernet1/8
switchport access vlan 80
ip device tracking maximum 0
interface GigabitEthernet1/17
switchport access vlan 81
ip device tracking maximum 0
interface GigabitEthernet1/18
switchport access vlan 81
ip device tracking maximum 0
(Optional) General Usage Precision Time Protocol (PTP) Enable on LAN A Channel
PTP traffic traverses PRP within LAN A only.
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1. |
configure terminal |
Enters the global configuration mode. |
2. |
interface range {gi1/17-20} |
Specifies the two Gigabit Ethernet interfaces in the PRP channel that you want to modify and enters interface mode. |
3. |
ptp enable |
Enables PTP on the interface. |
4. |
exit |
Exits interface mode |
Disabling the PRP Channel and Group
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1. |
configure terminal |
Enters the global configuration mode. |
2. |
no interface prp-channel prp-channel-number |
Disables the PRP channel. ■ prp-channel number : Value of 1 or 2. |
3. |
exit |
Exits the interface mode. |
PRP Mode LED
For IE 5000 systems with the HSR/PRP LED on the faceplate, the switch supports the following states.
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HSR/PRP mode LED |
Green (solid). |
PRP mode enabled. |
Port LEDs |
Green (solid). |
Uplink port configured for PRP channel 1 (Gi1/17,Gi1/18) and/or PRP channel 2 (Gi1/19, Gi1/20) |
Black. |
Feature disabled or No uplink port configured for PRP channel 1 (Gi1/17,Gi1/18) and/or PRP channel 2 (Gi1/19, Gi1/20) |
Black. |
Downlink ports. |