EtherChannel provides a level of link redundancy. If one link in the bundle fails, traffic sent through that link is automatically moved to an adjacent link.
Is a port Trunking technology or port-channel architecture used primarily on Cisco switches. It allows grouping several physical Ethernet links to create one logical Ethernet link for the purpose of providing fault-tolerance and high-speed links between switches, routers and servers.
An EtherChannel can be created from between two and eight active Fast Ethernet, Gigabit Ethernet or 10-Gigabit Ethernet ports, with an additional one to eight inactive (failover) ports which become active as the other active ports fail. EtherChannel is primarily used in the backbone network, but can also be used to connect end user machines.
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CISCO – ETHERCHANNEL |
EtherChannel is a trunking technology that groups together multiple full-duplex 802.3 Ethernet interfaces to provide fault-tolerant high-speed links between switches, routers, and servers. EtherChannel is a logical aggregation of multiple Ethernet interfaces. EtherChannel forms a single higher bandwidth routing or bridging endpoint. EtherChannel is designed primarily for host-to-switch connectivity or Inter-Switch Link (ISL) switch-to-switch connectivity.
UNDERSTANDING ETHERCHANNELS:
- EtherChannels consist of individual links bundled into a single logical link.
- Provides fault tolerant high speed links between switches, routers, and servers.
- EtherChannels can consist of up to eight interfaces.
- You must manually assign an interface to an EtherChannel using the channel-group command.
- Each etherchannel has a logical port channel interface numbered from 1-6.
- The EtherChannel provides full-duplex bandwidth up to 800 Mbps (Fast EtherChannel) or 2 Gbps (Gigabit EtherChannel) between your switch and another switch or host.
- Each EtherChannel can consist of up to eight compatibly configured Ethernet interfaces. All interfaces in each EtherChannel must be the same speed, and all must be configured as Layer 2 interfaces.
- Cisco EtherChannel® technology builds upon standards-based 802.3 full-duplex Fast Ethernet to provide network managers with a reliable, high-speed solution for the campus network backbone. EtherChannel technology provides bandwidth scalability within the campus by providing up to 800 Mbps, 8 Gbps, or 80 Gbps of aggregate bandwidth for a Fast EtherChannel, Gigabit EtherChannel, or 10 Gigabit EtherChannel connection, respectively. Each of these connection speeds can vary in amounts equal to the speed of the links used (100 Mbps, 1 Gbps, or 10 Gbps). Even in the most bandwidth-demanding situations, EtherChannel technology helps aggregate traffic and keep oversubscription to a minimum, while providing effective link-resiliency mechanisms.
TWO TYPE OF ETHERCHANNEL:
Fast EtherChannel is a technology-leveraging, standards-based Fast Ethernet used in parallel to provide the additional bandwidth network backbones require today. It provides flexible, scalable bandwidth with resiliency and load sharing across links for switches, router interfaces, and servers. Supports up to eight links per channel.
Gigabit EtherChannel is high-performance Ethernet technology that provides gigabit per second transmission rates. It provides flexible, scalable bandwidth with resiliency and load sharing across links for switches, router interfaces and servers. Supports up to eight links per channel.
Note:
- All interfaces using EtherChannel must be set up with the same speeds and duplex modes.
- Specifically for the Catalyst 2950 switches, the EtherChannels are limited to six with eight ports per EtherChannel, and all must have the same speed and be configured on Layer 2 interfaces.
- While it might seem obvious, don’t forget that the interfaces must be enabled. If not, the switch thinks that there is a problem and will use another interface path unnecessarily.
Using an EtherChannel has numerous advantages, and probably the most desirable aspect is the bandwidth. Using the maximum of 8 active ports a total bandwidth of 800 Mbit/s, 8 Gbit/s or 80 Gbit/s is possible depending on port speed. This assumes there is a traffic mixture, as those speeds do not apply to a single application only. It can be used with Ethernet running on twisted pair wiring, single-mode and multimode fiber.
Because EtherChannel takes advantage of existing wiring it makes it very scalable. It can be used at all levels of the network to create higher bandwidth links as the traffic needs of the network increase. All Cisco switches have the ability to support EtherChannel.
When an EtherChannel is configured all adapters that are part of the channel share the same Layer 2 (MAC ) address. This makes the EtherChannel transparent to network applications and users because they only see the one logical connection; they have no knowledge of the individual links.
EtherChannel aggregates the traffic across all the available active ports in the channel. The port is selected using a Cisco-proprietary hash algorithm, based on source or destination MAC addresses, IP addresses or TCP and UDP portnumbers. The hash function gives a number between 0 and 7, and the following table shows how the 8 numbers are distributed among the 2 to 8 physical ports. In the hypothesis of real random hash algorithm, 2, 4 or 8 ports configurations lead to fair load-balancing, whereas other configurations lead to unfair load-balancing.
LIMITATION OF ETHERCHANNEL:
Iis that all the physical ports in the aggregation group must reside on the same switch, although exceptions do exist on stackable switches such as Cisco's 3750 series. Nortel's SMLT protocol removes this limitation by allowing the physical ports to be split between two switches. Cisco's Virtual Switching System allows the creation of a Multichassis Etherchannel (MEC) allowing ports to be aggregated towards different physical chassis that conform a single "virtual switch" entity.
EtherChannel technology was invented by Kalpana in the early 1990s. They were later acquired by Cisco Systems in 1994. In 2000 the IEEE passed 802.3ad which is an open standard version of EtherChannel.
BENEFITS OF ETHERCHANNEL:
EtherChannel technology provides incremental scalable bandwidth. Standards-based:
Cisco EtherChannel technology builds upon IEEE 802.3-compliant Ethernet by grouping multiple, full-duplex point-to-point links together. EtherChannel technology uses IEEE 802.3 mechanisms for full-duplex auto negotiation and auto sensing, when applicable.
MULTIPLE PLATFORMS: Cisco EtherChannel technology is flexible and can be used anywhere in the network that bottlenecks are likely to occur. It can be used in network designs to increase bandwidth between switches and between routers and switches—as well as providing scalable bandwidth for network servers, such as large UNIX servers or PC-based Web servers.
INCREASED BANDWIDTH: Use EtherChannel and combine two or four links into one logical link. It will double or quadruple your bandwidth. For example, four 100Mb Fast Ethernet connections bonded into one could provide you up to 800Mb/second, full duplex.
Cisco EtherChannel technology provides bandwidth aggregation in multiples of 100 Mbps, 1 Gbps, or 10 Gbps, depending on the speed of the aggregated links. For example, network managers can deploy EtherChannel technology that consists of pairs of full-duplex Fast Ethernet links to provide more than 400 Mbps between the wiring closet and the data center. In the data center, bandwidths of up to 800 Mbps can be provided between servers and the network backbone to provide large amounts of scalable incremental bandwidth.
PROVIDES REDUNDANCY: Since there are many Ethernet links combined into one logical channel, it automatically allows more available links in case one or more links go down.
When a link fails, Cisco EtherChannel technology provides automatic recovery by redistributing the load across the remaining links. When a link fails, Cisco EtherChannel technology redirects traffic from the failed link to the remaining links in less than one second. This convergence is transparent to the end user—no host protocol timers expire, so no sessions are dropped.
COMPATIBLE WITH CISCO IOS: Software Cisco EtherChannel connections are fully compatible with Cisco IOS virtual LAN (VLAN) and routing technologies. The Inter-Switch Link (ISL) VLAN Trunking Protocol (VTP) can carry multiple VLANs across an EtherChannel link, and routers attached to EtherChannel trunks can provide full multi protocol routing with support for hot standby using the Hot Standby Router Protocol (HSRP).
LOAD BALANCE TRAFFIC: EtherChannel balances the traffic load across the links, thereby increasing efficiency on your networks.
Cisco EtherChannel technology is composed of several Fast Ethernet links and is capable of load balancing traffic across those links. UNICAST, BROADCAST,
UNDERSTANDING LOAD BALANCING: EtherChannel balances traffic load across the links in a channel by reducing part of the binary pattern formed from the addresses in the frame to a numerical value that selects one of the links in the channel. EtherChannel load balancing can use either MAC addresses or IP addresses and either source or destination or both source and destination addresses. The selected mode applies to all EtherChannel configured on the switch.
Use the option that provides the greatest variety in your configuration. For example, if the traffic on a Channel is going only to a single MAC address, using the destination MAC address always chooses the
Same link in the channel; using source addresses or IP addresses may result in better load balancing
ETHERCHANNEL COMPONENTS: EtherChannel Is Made Up Of The Following Key Elements:
ETHERNET LINKS: EtherChannel works over links defined by the IEEE 802.3 standard, including all sub-standards. All links in a single EtherChannel must be the same speed.
COMPATIBLE HARDWARE : The entire line of Cisco Catalyst switches as well as Cisco IOS software-based routers support EtherChannel. Configuring an EtherChannel between a switch and a computer would either require special network interface cards (NICs) such as the model pictured here, or support built into the operating system. FreeBSD, for example, supports EtherChannel via LACP on standard NICs.
Multiple EtherChannels per device are supported; the number depends on the type of equipment. Catalyst 6500 and 6000 switches support a maximum of 64 EtherChannels.
CONFIGURATION: An EtherChannel must be configured using the Cisco IOS on switches and router, and using specific drivers when connecting a server. There are two main ways an EtherChannel can be set up. The first is by manually issuing a command on each port of the device that is part of the EtherChannel. This must be done for the corresponding ports on both sides of the EtherChannel. The second way is using Cisco Port A.
TWO PROTOCOLS USED FOR THE LINK AGGREGATION:
- Cisco’s proprietary Port Aggregation Protocol (PAgP).
- IEEE standard Link Aggregation Protocol (LACP)
PAgP (PORT AGGREGATION PROTOCOL):
- Cisco proprietary
- Forms EtherChannel only if ports are configured for identical static VLANs or trunking
- Will automatically modify interface parameters on all ports of the bundle if one the the interfaces is changed.
Example: If speed, VLAN, or duplex mode of a port in an establish bundle is modified, PAgP reconfigures that parameter for all other ports in the bundle.
- STP sends packets over only one physical link in a PAgP bundle. Because STP’s algorithm uses the lowest port priority (priority + port ID), if defaults are set, STP will always use the lowest number port for BPDUs.
Port aggregation protocol (PAgP) aids in the automatic creation of Fast EtherChannel links. PAgP packets are sent between Fast EtherChannel-capable ports in order to negotiate the forming of a channel.
PAgP HAS THREE MODES:
- ON
- DESIRABLE such as-
-
- DESIRABLE: Places an interface into an active negotiating state, in which the interface initiates negotiations with other interfaces by sending PAgP packets.
- ON FORCES: The interface to channel without PAgP. With the on mode, a usable EtherChannel exists only when an interface group in the on mode is connected to another interface group in the on mode.
Both the AUTO AND DESIRABLE modes allow interfaces to negotiate with partner interfaces to determine if they can form an EtherChannel, based on criteria such as interface speed and, for Layer 2 EtherChannel, trunking state and VLAN numbers.
Interfaces can form an EtherChannel when they are in different PAgP modes as long as the modes are compatible. For example:
- An interface in desirable mode can form an EtherChannel successfully with another interface that is in desirable or auto mode.
- An interface in auto mode can form an EtherChannel with another interface in desirable mode.
- An interface in auto mode cannot form an EtherChannel with another interface that is also in auto mode, because neither interface will initiate negotiation.
PAgP - FAMILIARIZE WITH THE FOLLOWING COMMANDS;
Switch(config)# interface fa 1/1/2
Switch(config-if)# channel-protocol pagp
Switch(config-if)# channel-group number mode {on | {{auto | desirable} | [non-silent]}}
By default, PAgP operates in silent submode – allowing ports to be added to the EtherChannel, even if it does not hear anything from the far end. This allows a switch to form an EtherChannel with a non-PAgP devices such as a network analyzer or server. It is best practice to aways use non-silent mode when connecting two switches together.
1.This lab uses two Cisco Catalyst 3750 Series Switches and connects the cables of the appropriate switches according to the topology.
2. It is recommended to set the interfaces Fa1/0/1 – 22 in shutdown status in order to assure the lab of success.
3. Check the STP information on SW1 and SW2
SW1#show spanning-tree
VLAN0001
Spanning tree enabled protocol ieee
Root ID Priority 32769
Address 0014.a8e2.9880
Cost 19
Port 25 (FastEthernet1/0/23)
Hello Time 2 sec Max Age 20 sec Forward Delay 15 sec
Bridge ID Priority 32769 (priority 32768 sys-id-ext 1)
Address 0014.a8f1.9880
Hello Time 2 sec Max Age 20 sec Forward Delay 15 sec
Aging Time 300
Interface Role Sts Cost Prio.Nbr Type
Fa1/0/23 Root FWD 19 128.25 P2p
Fa1/0/24 Altn BLK 19 128.26 P2p
4. Although STP can avoid loops in the network, it can’t make full use of the bandwidth of the redundant links. The link aggregation protocol PAgP can be used to solve the link bandwidth problems.
5. The configurations on SW1 and SW2 are as follows:
SW1(config)#interface range fastEthernet 1/0/23 – 24
SW1(config-if-range)#switchport
SW1(config-if-range)#channel-protocol pagp
SW1(config-if-range)#channel-group 1 mode desirable
Creating a port-channel interface Port-channel 1
SW1(config-if-range)#exit
SW1(config)#exit
SW2(config)#interface range fastEthernet 1/0/23 – 24
SW2(config-if-range)#sw
SW2(config-if-range)#switchport
SW1(config-if-range)#channel-protocol pagp
SW2(config-if-range)#channel-group 1 mode auto
Creating a port-channel interface Port-channel 1
SW2(config-if-range)#exit
SW2(config)#exit
6. The interface in the Descirable mode of PAgP will actively enter the negotiation status, while in the Auto mode it will passively enter the negotiation status.
7. After configuring the two switches properly, IOS will show the following information in the process of configuration.
00:32:28: %LINEPROTO-5-UPDOWN: Line protocol on Interface FastEthernet1/0/23, changed state to down
00:32:28: %LINEPROTO-5-UPDOWN: Line protocol on Interface FastEthernet1/0/24, changed state to down
00:32:37: %LINEPROTO-5-UPDOWN: Line protocol on Interface FastEthernet1/0/23, changed state to up
00:32:38: %LINEPROTO-5-UPDOWN: Line protocol on Interface FastEthernet1/0/24, changed state to up
0:37:18: %LINK -3-UPDOWN: Interface Port-channel1, changed state to up
00:37:19: %LINEPROTO-5-UPDOWN: Line protocol on Interface Port-channel1, changed state to up
8. Check the aggregation information on the interface of SW1.
SW1#show interfaces fastEthernet 1/0/23 etherchannel
Port state = Up Mstr In-Bndl
Channel group = 1 Mode = Desirable-Sl Gcchange = 0
Port-channel = Po1 GC = 0×00010001 Pseudo port-channel = Po1
Port index = 0 Load = 0×00 Protocol = PAgP
Flags: S – Device is sending Slow hello. C – Device is in Consistent state.
A – Device is in Auto mode. P – Device learns on physical port.
d – PAgP is down.
Timers: H – Hello timer is running. Q – Quit timer is running.
S – Switching timer is running. I – Interface timer is running.
Local information:
Hello Partner PAgP Learning Group
Fa1/0/23 SC U6/S7 H 30s 1 128 Any 5001
Partner’s information:
Partner Group
Port Name Device ID Port Age Flags Cap.
Fa1/0/23 SW2 0014.a8e2.9880 Fa1/0/23 20s SAC 10001
Age of the port in the current state: 00d:00h:06m:53s
SW1#
9. Use the show etherchannel port-channel command to check the aggregation group information
SW1#show etherchannel port-channel
Channel-group listing:
Group: 1
Port-channels in the group:
Port-channel: Po1
Age of the Port-channel = 00d:00h:15m:37s
Logical slot/port = 10/1 Number of ports = 2
GC = 0×00010001 HotStandBy port = null
Port state = Port-channel Ag-Inuse
Protocol = PAgP
Ports in the Port-channel:
Index Load Port EC state No of bits
0 00 Fa1/0/23 Desirable-Sl 0
0 00 Fa1/0/24 Desirable-Sl 0
Time since last port bundled: 00d:00h:10m:27s Fa1/0/24
SW1#
10. Check the summary information of the aggregation link.
SW1#show etherchannel summary
Flags: D – down P – in port-channel
I – stand-alone s – suspended
H – Hot-standby (LACP only)
R – Layer3 S – Layer2
U – in use f – failed to allocate aggregator
u – unsuitable for bundling
w – waiting to be aggregated
d – default port
Number of channel-groups in use: 1
Number of aggregators: 1
Group Port-channel Protocol Ports
1 Po1(SU) PAgP Fa1/0/23(P) Fa1/0/24(P)
SW1#
11. Check the spanning-tree information.
SW1#show spanning-tree
Interface Role Sts Cost Prio.Nbr Type
Po1 Root FWD 12 128.616 P2p
SW1#
12. Configure IP addresses of VLAN1 on SW1 and SW2, test the tolerance of the aggregation link.
SW1(config)#interface vlan 1
SW1(config-if)#ip address 192.168.1.1 255.255.255.0
SW1(config-if)#no shutdown
SW1(config-if)#exit
SW2(config)#interface vlan 1
SW2(config-if)#ip address 192.168.1.2 255.255.255.0
SW2(config-if)#no shutdown
SW2(config-if)#exit
13. Use the Ping command on R1 to test the connectivity between the two switches.
SW2#ping 192.168.1.1
Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 192.168.1.1, timeout is 2 seconds:
!!!!!
Success rate is 100 percent (5/5), round-trip min/avg/max = 1/1/1 ms
SW2#
14. Use the extended ping command on SW2 to send ICMP data packets to SW1 continuously to test the redundant tolerance of the aggregation ports.
SW2#ping
Protocol [ip]:
Target IP address: 192.168.1.1
Repeat count [5]: 1000000
Datagram size [100]:
Timeout in seconds [2]:
Extended commands [n]:
Sweep range of sizes [n]:
Type escape sequence to abort.
Sending 1000000, 100-byte ICMP Echos to 192.168.1.1, timeout is 2 seconds:
15. Manually shutdown the interface Fastethernet 1/0/24 or Fastethernet 1/0/24 of aggregation group on SW1 and observe the ping feedback information on SW2. It is found that the Ping data packets will not be interrupted, which indicates that the link aggregation can effectively avoid instability of the topology of the single link and solve the problems that link bandwidth can be used completely and achieve load balancing due to spanning tree under redundant link.
16. The previous configuration is of the Layer2 PAgP link aggregation, the following configuration will show us how to configure the Layer3 PAgP link aggregation.
17. Delete the previous Layer2 PAgP configuration.
18. Configure SW1 and SW2 as follows.
SW1(config)#interface port-channel 1
SW1(config-if)#no switchport
SW1(config-if)#ip address 192.168.1.1 255.255.255.0
SW1(config-if)#no shutdown
SW1(config-if)#exit
SW1(config)#
SW1(config)#
SW1(config)#interface range fastEthernet 1/0/23 – 24
SW1(config-if-range)#no switchport
SW1(config-if-range)#channel-protocol pagp
SW1(config-if-range)#channel-group 1 mode desirable
SW1(config-if-range)#exit
SW1(config)#exit
SW1#
00:12:15: %EC-5-L3DONTBNDL1: Fa1/0/23 suspended: PAgP not enabled on the remote port.
00:12:16: %EC-5-L3DONTBNDL1: Fa1/0/24 suspended: PAgP not enabled on the remote port.
SW2(config)#interface port-channel 1
SW2(config-if)#no switchport
SW2(config-if)#ip address 192.168.1.2 255.255.255.0
SW2(config-if)#no shutdown
SW2(config-if)#exit
SW2(config)#
SW2(config)#interface range fastEthernet 1/0/23 – 24
SW2(config-if-range)#no switchport
SW2(config-if-range)#channel-protocol pagp
SW2(config-if-range)#channel-group 1 mode desirable
SW2(config)#exit
SW2#
00:20:02: %LINEPROTO-5-UPDOWN: Line protocol on Interface FastEthernet1/0/23, changed state to up
00:20:02: %LINEPROTO-5-UPDOWN: Line protocol on Interface FastEthernet1/0/24, changed state to up
00:20:03: %LINK -3-UPDOWN: Interface Port-channel1, changed state to up
00:20:04: %LINEPROTO-5-UPDOWN: Line protocol on Interface Port-channel1, changed state to up
17. Check the information of the aggregation links
SW2#show etherchannel summary
Flags: D – down P – in port-channel
I – stand-alone s – suspended
H – Hot-standby (LACP only)
R – Layer3 S – Layer2
U – in use f – failed to allocate aggregator
u – unsuitable for bundling
w – waiting to be aggregated
d – default port
Number of channel-groups in use: 1
Number of aggregators: 1
Group Port-channel Protocol Ports
1 Po1(RU) PAgP Fa1/0/23(P) Fa1/0/24(P)
SW2#
18. Use the Ping command to test
SW2#ping 192.168.1.1
Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 192.168.1.1, timeout is 2 seconds:
.!!!!
Success rate is 80 percent (4/5), round-trip min/avg/max = 1/1/1 ms
19. Use step14 and step15 to test the tolerance of the Layer3 PAgP aggregation link. The detailed steps will not be listed.
20. End
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LAB EXAMPLE -2: FOR PAgP:
Step 1 . – Configure ESW1’s Fa0/10, Fa0/11 and Fa0/12 interfaces to aggressively attempt to form a PAgP EtherChannel.
For this you’ll use the channel-group # mode desirable command in interface or interface range configuration mode as shown below;
ESW1 con0 is now available
Press RETURN to get started.
ESW1>enable
ESW1#configure terminal
Enter configuration commands, one per line. End with
ESW1(config)#interface range f0/10 - 12
SW1(config-if-range)#channel-group 1 mode desirable
Creating a port-channel interface Port-channel 1
ESW1(config-if-range)#no shut
ESW1(config-if-range)#end
ESW1#
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Step 2. – Configure ESW2’s Fa0/10, Fa0/11 and Fa0/12 interfaces to form a PAgP EtherChannel when a device attempts to negotiate a PAgP EtherChannel only.
For this you’ll use the channel-group # mode auto command in interface or interface range configuration mode as shown below;
For this you’ll use the channel-group # mode auto command in interface or interface range configuration mode as shown below;
ESW2 con0 is now available
Press RETURN to get started.
ESW2>enable
ESW2#configure terminal
Enter configuration commands, one per line. End with
ESW2 (config)#interface range f0/10 - 12
ESW2 (config-if-range)#channel-group 1 mode auto
Creating a port-channel interface Port-channel 1
ESW2 (config-if-range)#no shut
ESW2 (config-if-range)#end
ESW2#
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Step 3. – Verify that interfaces Fa0/10, Fa0/11 and Fa0/12 on SW1 formed a PAgP EtherChannel correctly.
To verify your configuration you can use either the show etherchannel summary or show etherchannel detail command in user or privileged mode as shown below;
ESW1#show etherchannel summary |
Flags: D - down P - bundled in port-channel
I - stand-alone s - suspended
H - Hot-standby (LACP only)
R - Layer3 S - Layer2
U - in use f - failed to allocate aggregator
M - not in use, minimum links not met
u - unsuitable for bundling
w - waiting to be aggregated
d - default port
Number of channel-groups in use: 1
Number of aggregators: 1
Group Port-channel Protocol Ports
------+-------------+-----------+-----------------------------------------------
1 Po1(SU) PAgP Fa0/10(P) Fa0/11(P) Fa0/12(P)
SW1#
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Step 4. – Ping R2′s FastEthernet0/0 interface from R1 to verify communications between the switches as shown below;
R1#ping 10.1.1.2
Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 10.1.1.2, timeout is 2 seconds:
.!!!!
Success rate is 80 percent (4/5), round-trip min/avg/max = 1/2/4 ms
R1#
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*******************************************************************
LACP (LINK AGGREGATION CONTROL PROTOCOL) / 802.3AD LINK :
- An open standard to PAgP
- IEEE 802.3ab
- Uses priority system for end switches
- Switch with the lowest system priority (2 byte value followed by
- Uses port priority to determine which ports to place in standby mode if a hardware limitations do not allow all ports to participate in the EtherChannel.
- Most leave the system and port priority to defaults
Link Aggregation Control Protocol (LACP) is part of an IEEE specification (802.3ad) that allows you to bundle several physical ports together to form a single logical channel. LACP allows a switch to negotiate an automatic bundle by sending LACP packets to the peer. It performs a similar function as Port Aggregation Protocol (PAgP) with Cisco EtherChannel.
Because LACP is an IEEE standard, it can be used to facilitate etherchannels in mixed-switch environments.
PASSIVE: The switch does not initiate the channel, but does understand incoming LACP packets. The peer (in active state) initiates negotiation (by sending out an LACP packet) which we receive and reply to, eventually forming the aggregation channel with the peer. This is similar to the auto mode in PAgP.
ACTIVE: We are willing to form an aggregate link, and initiate the negotiation. The link aggregate will be formed if the other end is running in LACP active or passive mode. This is similar to the desirable mode of PAgP.
ON: The link aggregation is forced to be formed without any LACP negotiation .In other words, the switch will neither send the LACP packet nor process any incoming LACP packet. This is similar to the on state for PAgP.
LACP uses two types of port modes; active and passive. LACP active mode unconditionally forms a LACP dynamic ether-channel whereas passive will only accept LACP negotiation attempts from a device set to active.
LACP - FAMILIARIZE WITH THE FOLLOWING COMMANDS;
CHANNEL-GROUP # mode active – This command when executed in interface configuration mode sets the channel-group number and LACP mode to aggressively attempt to form a LACP EtherChannel. If negotiations fail, the EtherChannel will not pass traffic.
CHANNEL-GROUP # mode passive – This command when executed in interface configuration mode sets the channel-group number and LACP mode to listen for LACP packets but not aggressively and unconditionally form an EtherChannel using LACP.
LACP - ETHERCHANNEL INTERFACE CONFIGURATION:
Switch(config)# lacp system-priority number (optional)
Switch(config)# interface fa 1/1/3
Switch(config-if)# channel-protocol lacp
Switch(config-if)# channel-group number mode {on | passive | active}
Switch(config-if)#lacp port-priority number (optional)
It’s important to note that EtherChannel can operate at layer 2 and 3. The configuration is a bit different between the two, so it is important to recognize what type you need before you begin your configurations. Layer 2 EtherChannel links are simply a bundled switch link that acts as one logical link. This is most commonly used for trunked links between switches.
Step 1 . – Configure ESW1′s Fa0/10, Fa0/11 and Fa0/12 interfaces to aggressively attempt to form a LACP EtherChannel.
For this you’ll use the channe
l-group # mode active command in interface or interface range configuration mode as shown below;
ESW1 con0 is now available
Press RETURN to get started.
ESW1 >enable
ESW1 #configure terminal
Enter configuration commands, one per line. End with
ESW1 (config)#interface range f0/10 - 12
ESW1 (config-if-range)#no shut
ESW1 (config-if-range)#channel-group 1 mode active
Creating a port-channel interface Port-channel 1
ESW1 (config-if-range)#end
ESW1#
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Step 2. – Configure ESW2′s Fa0/10, Fa0/11 and Fa0/12 interfaces to form a PAgP EtherChannel only when a device attempts to negotiate a LACP EtherChannel only.
For this you’ll use the channel-group # mode passive command in interface or interface range configuration mode as shown below;
ESW2 con0 is now available
Press RETURN to get started.
ESW2 >enable
ESW2#configure terminal
Enter configuration commands, one per line. End with
ESW2 (config)#interface range f0/10 - 12
ESW2 (config-if-range)#no shut
ESW2 (config-if-range)#channel-group 1 mode passive
Creating a port-channel interface Port-channel 1
ESW2 (config-if-range)#end
ESW2#
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Step 3. – Verify that interfaces Fa0/10, Fa0/11 and Fa0/12 on SW1 formed a LACP EtherChannel correctly.
Step 4. – Verify that interfaces Fa0/10, Fa0/11 and Fa0/12 on SW1 formed a LACP EtherChannel correctly.
To verify the EtherChannel LACP configuration you can use either the show etherchannel summary or show etherchannel detail command in user or privileged mode as shown below;
ESW1#show etherchannel summary
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Step 5. – Verify IP communication over the newly formed LACP Ether-Channel by pinging R2′s Fa0/1 IP Address from R1 as shown below;
R1#ping 10.1.1.2
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This Article Written Author By: Premakumar Thevathasan. CCNA, CCNP, CCIP, MCSA, MCSE, MCSA - MSG, CIW Security Analyst, CompTIA Certified A+.
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