Configuring EtherChannels

This chapter describes how come configure EtherChannels on Layer 2 and Layer 3 harbor on the aramuseum.org ME 3800X and ME 3600X switch. EtherChannel provides fault-tolerant high-speed links between switches, routers, and servers. You can use the to rise the bandwidth between the wiring closets and the data center, and you can deploy it all over in the network wherein bottlenecks are likely to occur. EtherChannel provides automatic recovery because that the loss of a attach by redistributing the load across the continuing to be links. If a attach fails, EtherChannel redirects traffic native the failed link to the remaining links in the channel there is no intervention.


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NoteAlthough EtherChannels are not supported on harbor configured with organization instances, you deserve to configure a company instance on one EtherChannel port channel.

For finish syntax and usage details for the regulates used in this chapter, view the command referral for this release.

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•Understanding EtherChannels

•Configuring EtherChannels

•Displaying EtherChannel, PAgP, and LACP Status

Understanding EtherChannels

•EtherChannel Overview

•Port-Channel Interfaces

•Port Aggregation Protocol

•Link Aggregation regulate Protocol

•EtherChannel ~ above Mode

•Load Balancing and also Forwarding Methods

EtherChannel Overview

An EtherChannel is composed of individual ports bundled right into a single logical connect as presented in Figure 36-1.

Figure 36-1Typical EtherChannel Configuration


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The EtherChannel provides full-duplex bandwidth of as much as 800 Mbps between your switch and also another move or hold for fast EtherChannel ~ above a switch with 24 rapid Ethernet ports. For Gigabit EtherChannel, you deserve to configure up to 8 Gbps (8 port of 1 Gbps), depending on the number of supported Gigabit Ethernet interfaces.

Each EtherChannel deserve to consist of as much as eight compatibly configured Ethernet ports. Every ports in every EtherChannel must be configured together either Layer 2 or Layer 3 ports. The variety of EtherChannels is restricted to 48. For much more information, check out the "EtherChannel construction Guidelines" section. The EtherChannel class 3 ports are consisted of of routed ports. Routed ports are physical ports configured to it is in in layer 3 setting by using the no switchport interface configuration command. For much more information, watch the Chapter 10 "Configuring Interfaces."

You have the right to configure one EtherChannel in one of these modes: harbor Aggregation Protocol (PAgP), attach Aggregation manage Protocol (LACP), or on mode. Configure both ends of the EtherChannel in the same mode:

•When friend configure one end of one EtherChannel in one of two people PAgP or LACP mode, the system negotiates through the other finish of the channel to determine which ports should come to be active. Incompatible ports are suspended.

•When girlfriend configure one EtherChannel in the on mode, no negotiations take place. The switch forces all compatible ports to become active in the EtherChannel. The other finish of the channel (on the other switch) must additionally be configured in the on mode; otherwise, packet loss can occur.

The local port is put into an independent state and continues to lug data website traffic as would any other single link. The harbor configuration does not change, however the harbor does not participate in the EtherChannel.

If a link within an EtherChannel fails, website traffic previously brought over that failed link alters to the remaining links within the EtherChannel. A catch is sent for a failure, identifying the switch, the EtherChannel, and the failure link. Inbound broadcast and also multicast packets ~ above one link in an EtherChannel are blocked from return on any kind of other link of the EtherChannel.

Port-Channel Interfaces

When you create an EtherChannel, a port-channel logical interface is involved:

•With layer 2 ports, use the channel-group user interface configuration command to dynamically create the port-channel logical interface.

You additionally can usage the interface port-channel port-channel-number an international configuration command to manually produce the port-channel reasonable interface, but then you need to use the channel-group channel-group-number command to bind the logical user interface to a physical port. The channel-group-number deserve to be the same as the port-channel-number, or you have the right to use a brand-new number. If you use a brand-new number, the channel-group command dynamically creates a brand-new port channel.

•With great 3 ports, you should manually create the logical user interface by using the interface port-channel worldwide configuration command complied with by the no switchport interface configuration command. Then you manually entrust an user interface to the EtherChannel by utilizing the channel-group interface configuration command.

For both great 2 and also Layer 3 ports, the channel-group command binds the physical port and also the logical interface together as shown in Figure 36-2.

Each EtherChannel has actually a port-channel logical user interface numbered from 1 come 48. This port-channel interface number corresponds to the one mentioned with the channel-group user interface configuration command.

Figure 36-2Relationship of physics Ports, Logical harbor Channels, and Channel Groups


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After girlfriend configure one EtherChannel, construction changes applied to the port-channel interface use to all the physical ports assigned come the port-channel interface. Construction changes applied to the physics port influence only the port to which you use the configuration. To adjust the parameters of every ports in one EtherChannel, use the configuration commands to the port-channel interface.

Port Aggregation Protocol

The harbor Aggregation Protocol (PAgP) is a aramuseum.org-proprietary protocol that have the right to be run just on aramuseum.org switches and on those switches license is granted by merchants to assistance PAgP. PAgP facilitates the automatic development of EtherChannels by trading PAgP packets between Ethernet ports.

By utilizing PAgP, the switch learns the identity of partners qualified of supporting PAgP and the ability of each port. It climate dynamically groups likewise configured ports into a solitary logical attach (channel or accumulation port). Similarly configured ports room grouped based on hardware, administrative, and port parameter constraints. For example, PAgP teams the ports with the exact same speed, duplex mode, aboriginal VLAN, VLAN range, and trunking status and also type. After group the links into an EtherChannel, PAgP to add the team to the covering tree as a solitary switch port.

PAgP modes

Table 36-1 mirrors the user-configurable EtherChannel PAgP settings for the channel-group user interface configuration command on an port.


auto

Places a port into a passive negotiating state in i m sorry the port responds come PAgP packets it receives yet does not start PAgP packet negotiation. This setup minimizes the infection of PAgP packets.

desirable

Places a port into an active negotiating state in i beg your pardon the harbor starts negotiation with other ports by sending out PAgP packets.


Switch port exchange PAgP packets only with companion ports configured in the auto or desirable modes. Harbor configured in the on setting do no exchange PAgP packets.

Both the auto and also desirable modes enable ports come negotiate with partner ports to kind an EtherChannel based upon criteria such together port speed and, for Layer 2 EtherChannels, trunking state and VLAN numbers.

Ports can form an EtherChannel as soon as they space in various PAgP modes as lengthy as the settings are compatible. Because that example:

•A harbor in the desirable mode can type an EtherChannel with an additional port the is in the desirable or auto mode.

•A port in the auto mode can form an EtherChannel with another port the is in the desirable mode.

A harbor in the auto setting cannot type an EtherChannel with another port the is additionally in the auto mode because neither port starts PAgP negotiation.

If your switch is associated to a companion that is PAgP-capable, you can configure the switch harbor for nonsilent procedure by making use of the non-silent keyword. If you carry out not specify non-silent through the auto or desirable mode, silent setting is assumed.

Use the silent mode when the switch is connected to a device that is no PAgP-capable and seldom, if ever, sends packets. An example of a silent partner is a file server or a packet analyzer the is no generating traffic. In this case, to run PAgP top top a physical port associated to a silent partner stays clear of that switch harbor from ever coming to be operational. However, the silent setting allows PAgP to operate, to connect the port to a channel group, and to usage the harbor for transmission.

PAgP communication with Other features

aramuseum.org exploration Protocol (CDP) sends and also receives packets over the physical ports in the EtherChannel.

Trunk ports send and also receive PAgP protocol data devices (PDUs) top top the lowest numbered VLAN.

In layer 2 EtherChannels, the an initial port in the channel the comes up gives its MAC deal with to the EtherChannel. If this harbor is eliminated from the bundle, among the staying ports in the bundle provides its MAC attend to to the EtherChannel.

PAgP sends and also receives PAgP PDUs just from port that room up and also have PAgP permitted for the auto or desirable mode.

Link Aggregation control Protocol

The LACP is characterized in IEEE 802.3ad typical and permits aramuseum.org switches to manage Ethernet channels in between switches the conform to the standard. LACP facilitates the automatic creation of EtherChannels by exchanging LACP packets between Ethernet ports.

By making use of LACP, the switch learns the identification of partners capable of supporting LACP and the ability of every port. It then dynamically groups similarly configured ports right into a solitary logical connect (channel or aggregate port). An in similar way configured ports are grouped based upon hardware, administrative, and port parameter constraints. Because that example, LACP groups the ports with the very same speed, duplex mode, native VLAN, VLAN range, and trunking status and also type. After group the links right into an EtherChannel, LACP to add the group to the spanning tree together a solitary switch port.

LACP Modes

Table 36-2 reflects the user-configurable EtherChannel LACP modes for the channel-group interface configuration command ~ above a port.


active

Places a port right into an energetic negotiating state in i beg your pardon the port starts negotiation with various other ports by sending LACP packets.

passive

Places a port right into a passive negotiating state in which the port responds come LACP packets that it receives, yet does not start LACP packet negotiation. This setup minimizes the transmission of LACP packets.


Both the active and passive LACP modes allow ports come negotiate with partner ports come an EtherChannel based on criteria such together port rate and, for Layer 2 EtherChannels, trunking state and VLAN numbers.

Ports can kind an EtherChannel when they are in various LACP modes as lengthy as the settings are compatible. For example:

•A harbor in the active mode can type an EtherChannel with another port that is in the active or passive mode.

•A port in the passive mode cannot form an EtherChannel with an additional port that is also in the passive mode due to the fact that neither port starts LACP negotiation.

LACP interaction with Other attributes

The CDP sends and receives packets over the physics ports in the EtherChannel. Trunk ports send and also receive LACP PDUs on the lowest numbered VLAN.

In layer 2 EtherChannels, the an initial port in the channel the comes up provides its MAC deal with to the EtherChannel. If this port is gotten rid of from the bundle, among the remaining ports in the bundle offers its MAC address to the EtherChannel.

LACP sends and receives LACP PDUs just from harbor that are up and also have LACP allowed for the active or passive mode.

EtherChannel ~ above Mode

EtherChannel ~ above mode can be provided to manually configure one EtherChannel. The top top mode pressures a harbor to join an EtherChannel there is no negotiations. It deserve to be valuable if the remote maker does not support PAgP or LACP. With the ~ above mode, a usable EtherChannel exists only when both ends of the link are configured in the ~ above mode.

Ports that are configured in the on setting in the very same channel group must have actually compatible port characteristics, such together speed and duplex. Ports that room not compatible are suspended, also though they are configured in the ~ above mode.


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CautionYou need to use treatment when utilizing the top top mode. This is a manual configuration, and ports on both end of the EtherChannel must have the very same configuration. If the group is misconfigured, packet ns or spanning-tree loops deserve to occur.

Load Balancing and also Forwarding Methods

EtherChannel balances the web traffic load across the links in a channel by reducing component of the binary pattern developed from the addresses in the structure to a numerical value that selects among the links in the channel. EtherChannel pack balancing can use MAC addresses or IP addresses, resource or destination addresses, or both resource and location addresses. The selected mode uses to every EtherChannels configured top top the switch. Friend configure the load balancing and also forwarding method by utilizing the port-channel load-balance global configuration command.

With source-MAC resolve forwarding, once packets are forwarded to an EtherChannel, they space distributed across the ports in the channel based upon the source-MAC address of the just arrive packet. Therefore, to provide load balancing, packets from different hosts use different ports in the channel, yet packets from the same host use the same port in the channel.

With destination-MAC address forwarding, as soon as packets space forwarded come an EtherChannel, they space distributed throughout the harbor in the channel based on the destination-host MAC attend to of the just arrived packet. Therefore, packets come the same destination are forwarded end the same port, and packets to a different destination are sent on a various port in the channel.

The move supports pack distribution based upon the destination host MAC attend to supports for only 4 ports per EtherChannel. When you configure EtherChannel destination-MAC resolve load balancing, the web traffic is balanced only amongst four port in the channel group.If you configure an ext than four ports in an EtherChannel with destination host MAC attend to load distribution, only 4 of the ports receive distributed traffic. This limitation walk not apply to the other load circulation methods.

With source-and-destination MAC attend to forwarding, once packets room forwarded to an EtherChannel, they room distributed across the port in the channel based on both the source and location MAC addresses. This forwarding method, a mix source-MAC and also destination-MAC deal with forwarding techniques of fill distribution, deserve to be provided if the is no clear even if it is source-MAC or destination-MAC address forwarding is much better suited on a particular switch. V source-and-destination MAC-address forwarding, packets sent out from host A to hold B, organize A to hold C, and host C to hold B can all use different ports in the channel.

With source-IP-address-based forwarding, when packets room forwarded to an EtherChannel, they space distributed across the harbor in the EtherChannel based on the source-IP address of the just arrive packet. Therefore, to provide load-balancing, packets from various IP addresses use various ports in the channel, yet packets indigenous the very same IP resolve use the very same port in the channel.

With destination-IP-address-based forwarding, when packets space forwarded to an EtherChannel, they are distributed throughout the harbor in the EtherChannel based upon the destination-IP resolve of the just arrive packet. Therefore, to carry out load-balancing, packets native the same IP source address sent to various IP location addresses might be sent on different ports in the channel. But packets sent from different resource IP addresses to the same location IP deal with are constantly sent top top the very same port in the channel.

With source-and-destination IP address-based forwarding, as soon as packets are forwarded to an EtherChannel, they room distributed throughout the harbor in the EtherChannel based upon both the source and location IP addresses of the just arrived packet. This forwarding method, a combination of source-IP and destination-IP address-based forwarding, can be supplied if it is not clear whether source-IP or destination-IP address-based forwarding is far better suited top top a certain switch. In this method, packets sent out from the IP deal with A come IP deal with B, native IP resolve A to IP resolve C, and from IP resolve C come IP deal with B could all use various ports in the channel.

Different load-balancing methods have different advantages, and also the an option of a details load-balancing technique should be based on the place of the switch in the network and also the kind of website traffic that requirements to it is in load-distributed. In Figure 36-3, an EtherChannel of four workstations communicates through a router. Due to the fact that the router is a single-MAC-address device, source-based forwarding on the move EtherChannel ensures that the switch provides all obtainable bandwidth come the router. The router is configured because that destination-based forwarding due to the fact that the big number the workstations ensures that the traffic is evenly dispersed from the router EtherChannel.

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Use the alternative that gives the greatest selection in her configuration. For example, if the web traffic on a channel is going only to a single MAC address, making use of the destination-MAC resolve always choose the same connect in the channel. Using source addresses or IP addresses might an outcome in better load balancing.