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Table Of Contents
EtherChannel Flow-Based
Limited 1:1 RedundancyInformation About EtherChannel Flow-based Limited 1:1 Redundancy
EtherChannel Flow-Based Limited 1:1 Redundancy Functionality
Traffic Flow Balancing on a Per-Port-Channel Basis
Dynamic Mapping of Flows to the Member Links of a Port-channel
How to Configure Flow-Based Load Balancing
Configuring EtherChannel Flow-Based Limited 1:1 Redundancy with Fast-Switchover
Prerequisites for Configuring EtherChannel Flow-Based Limited 1:1 Redundancy
Setting the Switchover Rate with Carrier Delay
Configuration Examples for EtherChannel Flow-based Limited1:1 Redundancy
EtherChannel 1:1 Active Standby: Example
Setting Priority for 1:1 Redundancy Using LACP: Example
EtherChannel Flow-Based
Limited 1:1 Redundancy
First Published: June 30, 2009Last Updated: June 30, 2009EtherChannel flow-based limited 1:1 redundancy provides MAC, or layer 2, traffic protection to avoid higher layer protocols from reacting to single link failures and re-converging. To use EtherChannel flow-based limited 1:1 redundancy, you configure an EtherChannel with two ports (one active and one standby). If the active link goes down, the EtherChannel stays up and the system performs fast switchover to the hot-standby link. Depending on how you have the priorities set, when the failed link becomes operational again, the EtherChannel performs another fast switchover to revert to the original active link. if all port-priorities are the same, it will not revert, but remain on the current active link.
With 1:1 redundancy configured, only one link is active at any given time so all flows are directed over the active link.
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Information About EtherChannel Flow-based Limited 1:1 Redundancy
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Information About EtherChannel Flow-based Limited 1:1 Redundancy
Before configuring EtherChannel Flow-Based Limited 1:1 Redundancy, you should be familiar with the following topics:
EtherChannel Flow-Based Limited 1:1 Redundancy Functionality
Flow-based load balancing allows you to identify different flows of traffic based on the key fields in the data packet. For example, IPv4 source and destination IP addressees can be used to identify a flow. The various data traffic flows are mapped to different member links of a specified port-channel. Once the mapping is configured, the data traffic on that flow is transmitted through the specified member link. The flow mapping is dynamic and can change if there is any change in the state of the member link to which it is assigned. The flow mappings may also change if member links are added to or removed from the EtherChannel. Multiple flows may be mapped to each member link.
EtherChannel flow-based limited 1:1 redundancy provides an EtherChannel configuration with one active link and fast switchover to a hot standby link.
To use EtherChannel flow-based limited 1:1 redundancy, you configure an LACP EtherChannel with two ports (one active and one standby). If the active link goes down, the EtherChannel stays up and the system performs fast switchover to the hot standby link. Depending on how the priorities of the links are set, when the failed link becomes operational again, the EtherChannel performs another fast switchover to revert to the original active link, or to the link with the higher priority.
For EtherChannel flow-based limited 1:1 redundancy to work correctly (especially the fast switchover capability) the feature needs to be enabled at both ends of the link.
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Traffic Flow Balancing on a Per-Port-Channel Basis
All port channels use either VLAN manual load balancing and dynamic flow-based load balancing. If VLAN load balancing is not configured explicitly, the load balancing is flow-based.
Dynamic Mapping of Flows to the Member Links of a Port-channel
Flow-to-member link mappings are managed through buckets. The various defined traffic flows are mapped to the buckets and the buckets are distributed among the member links. The flows mapped to a bucket use the member link to which this bucket is assigned. The ASR1000 forwarding processor receives mapping information and forwards it to be programmed in the QFP, including
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When a member link goes down or is removed from a port-channel, the buckets associated with that member link are re-distributed among the other active member links. When a member link comes up or is added to a port-channel, some of the buckets associated with other links are assigned to this link.
You can display the bucket-to-member link mapping through show commands. When you display information about the links configured for the 1:1 redundancy, you will see that all buckets are directed to the active link.
How to Configure Flow-Based Load Balancing
Flow-based load balancing has to be enabled globally. If nothing is configured on a port-channel, the load-balancing type configuration is enabled by default at the global level.
This section contains the following tasks:
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Configuring EtherChannel Flow-Based Limited 1:1 Redundancy with Fast-Switchover
The EtherChannel flow-based 1:1 redundancy provides an EtherChannel configuration with one active link and fast switchover to a hot standby link.
To use EtherChannel flow-based 1:1 redundancy, configure an LACP EtherChannel with two ports (one active and one standby). If the active link goes down, the EtherChannel stays up and the system performs fast switchover to the hot-standby link. Depending on the priorities assigned to each link, when the failed link becomes operational again, the EtherChannel performs another fast switchover to revert to the original active link if that link is the one with the higher priority.
You can control which link is the primary active link by setting the port priority on the links used for the redundancy. To prevent the switchover to revert, you can assign both link the same priority.
Prerequisites for Configuring EtherChannel Flow-Based Limited 1:1 Redundancy
To use EtherChannel 1:1 redundancy, especially the fast switchover capability, the feature needs to be enabled at both ends of the link.
The EtherChannel must contain exactly two links, of which only one is active. You may use bundled links. To configure a primary link and enable the EtherChannel to revert to the original link, one link must have a higher port priority than the other and the LACP max-bundle must be set to 1. This configuration results in link 1 being active and link 2 being in hot standby state.
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DETAILED STEPS
Setting the Switchover Rate with Carrier Delay
Optionally, you can control the speed of the switchover between the active and standby links by setting the carrier delay on each link. The carrier-delay command controls how long it takes for IOS to propagate the information about the links status to other modules.
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DETAILED STEPS
Troubleshooting Tips
Use these show commands to verify the configuration and to display information about the port channel.
Configuration Examples for EtherChannel Flow-based Limited1:1 Redundancy
This section contains the following examples:
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EtherChannel 1:1 Active Standby: Example
This example shows how to configure a port channel for 1:1 link redundancy for equal priority ports so there is no preference for which port is active.
Router# enableRouter# configure terminalRouter(config)# interface port-channel 2Router(config-if)# ip address 10.1.1.1 255.255.0.0Router(config-if)# negotiation autoRouter(config-if)# lacp max-bundle 1Router(config-if)# lacp fast-switchoverRouter(config)# interface Tengigabitethernet0/1/0Router(config-if)# channel-group 2 mode activeRouter(config-if)# negotiation autoRouter(config)# interface Tengigabitethernet 2/1/0Router(config-if)# channel-group 2 mode activeRouter(config-if)# negotiation autoRouter(config)# interface GigabitEthernet0/1/6Router(config-if)# negotiation autoRouter(config-if)#channel-group 19 mode activeRouter(config-if)#interface GigabitEthernet0/1/7Router(config-if)#negotiation autoRouter(config-if)#channel-group 19 mode activeRouter(config-if)# interface Port-channel19Router(config-if)# ip address 10.19.1.1 255.255.255.0Router(config-if)# no negotiation autoRouter(config-if)# lacp fast-switchoverRouter(config-if)# lacp max-bundle 1Router(config-if)# endNotice that in the show command display that the priorities are the same value.
Router# show lacp internalFlags: S - Device is requesting Slow LACPDUsF - Device is requesting Fast LACPDUsA - Device is in Active mode P - Device is in Passive modeChannel group 19LACP port Admin Oper Port PortPort Flags State Priority Key Key Number StateGi0/1/6 SA bndl 32768 0x13 0x13 0x47 0x3DGi0/1/7 FA hot-sby 32768 0x13 0x13 0x48 0x7Setting Priority for 1:1 Redundancy Using LACP: Example
This example shows how to configure an LACP EtherChannel with 1:1 redundancy. GigabitEthernet 0/1/7 is the active link, because it is configured with a lower number which gives it a higher port priority.
Router> enableRouter# configure terminalRouter(config)# interface GigabitEthernet0/1/6Router(config-if)# lacp port-priority 32767Router(config-if)# endRouter(config)#interface GigabitEthernet0/1/7Router(config-if)#lacp fast-switchoverRouter(config-if)#lacp max-bundle 1Router(config-if)#negotiation autoRouter(config-if)#channel-group 19 mode activeIn this show display, notice that the bundled link is set at a higher priority. This will ensure that the bundled link is used as the first active link in the standby configuration.
Router#show lacp internalFlags: S - Device is requesting Slow LACPDUsF - Device is requesting Fast LACPDUsA - Device is in Active mode P - Device is in Passive modeChannel group 19LACP port Admin Oper Port PortPort Flags State Priority Key Key Number StateGi0/1/6 FA hot-sby 32768 0x13 0x13 0x47 0x7Gi0/1/7 SA bndl 32767 0x13 0x13 0x48 0x3DAdditional References
The following sections provide references related to the <<Feature Name>> feature.
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