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Etherchannel opinions and best practices
- Thread starter uzumaki
- Start date
Let the switch negotiate the link and don't force it on . Use the channel-group X mode desirable" command on each of the etherchannel interfaces . I always try to to keep the same channel group number on each end of the link though it is not a requirement, it makes it easier to troubleshoot if there is a problem . Usually if configured correctly there are very few issues with a etherchannel. You can also choose how the channel load balances useing either source or dest mac address or source and dest ip address or both . Sometimes people misunderstand how it works , while etherchannel gives you more bandwidth to run your traffic across , a given ip conversation will always flow down just one of those pipes even if you have say a 8 port etherchannel . You have to keep this in mind if troubleshooting because a given conversation to a site might have a problem while a different conversation might not because that conversation is flowing down a different port in the channel . We have run into stuff like this before and it can take awhile to find if say for instance you have a dirty fiber or copper link in your channel bundle.
The latest SRND ( recommends hard-coding EtherChannels as it slightly decreases the convergence time. If available on the platform use IP Source & Destination as the load-sharing algorythm to achieve the best load-sharing.
HTH
Andy
HTH
Andy
We have seen more than once when you force the channel on it can say it channelling but it won't pass traffic if something is not configured right and this can cause spanning tree loops which doesn't happen when you use pagp . In another cisco doc it says to use pagp to aggregate the links so its whatever you feel comfortable . The added convergence time is minor. The only time this will make any difference will be if you have to reload the box. This is a specific cisco warning when using "on" mode as opposed to pagp or lacp to create the channels/
EtherChannel On Mode
EtherChannel on mode can be used to manually configure an EtherChannel. The on mode forces a port to join an EtherChannel without negotiations. The on mode can be useful if the remote device does not support PAgP or LACP. In the on mode, a usable EtherChannel exists only when the switches at both ends of the link are configured in the on mode.
Ports that are configured in the on mode in the same channel group must have compatible port characteristics, such as speed and duplex. Ports that are not compatible are suspended, even though they are configured in the on mode.
Caution You should use care when using the on mode. This is a manual configuration, and ports on both ends of the EtherChannel must have the same configuration. If the group is misconfigured, packet loss or spanning-tree loops can occur.
EtherChannel On Mode
EtherChannel on mode can be used to manually configure an EtherChannel. The on mode forces a port to join an EtherChannel without negotiations. The on mode can be useful if the remote device does not support PAgP or LACP. In the on mode, a usable EtherChannel exists only when the switches at both ends of the link are configured in the on mode.
Ports that are configured in the on mode in the same channel group must have compatible port characteristics, such as speed and duplex. Ports that are not compatible are suspended, even though they are configured in the on mode.
Caution You should use care when using the on mode. This is a manual configuration, and ports on both ends of the EtherChannel must have the same configuration. If the group is misconfigured, packet loss or spanning-tree loops can occur.
- Thread starter
- #6
Hi Vipergg,
I've been trying to use the "On mode" on my switches, i dont have any idea if it works but the LEDs are all in green state on both switches. I've been watching CBT nuggets on BCMSN and the trainer also recommends to hardcode it to "On"
These are my step by step procedures:
Switch#config t
Switch(config)#int range F0/45-48
Switch(config-if-range)#speed 100
Switch(config-if-range)#duplex full
Switch(config-if-range)#channel-group 1 mode on
I also use the same config on the other side, successful creation have been made. However when I do the following command bellow:
Switch#show etherchannel
Channel-group listing:
----------------------
Group: 1
----------
Group state = L2
Ports: 4 Maxports = 8
Port-channels: 1 Max Port-channels = 1
Protocol: -
The "Protocol" listed above is blank. Is this normal? I mean if im connecting 2 Cisco switch this should be PagP right? What is my protocol then if this is the case? Am i using PagP already by default?
According to CBT nuggets trainor the "Channel-protocol pagp" is my negotiation protocol and should not be using this command if im going to use the "On mode" which is practically true because i was denied to create a channel when doing this on my Lab. If im not gonna be using this command what protocol am I using if I did the configuration above?
I've been trying to use the "On mode" on my switches, i dont have any idea if it works but the LEDs are all in green state on both switches. I've been watching CBT nuggets on BCMSN and the trainer also recommends to hardcode it to "On"
These are my step by step procedures:
Switch#config t
Switch(config)#int range F0/45-48
Switch(config-if-range)#speed 100
Switch(config-if-range)#duplex full
Switch(config-if-range)#channel-group 1 mode on
I also use the same config on the other side, successful creation have been made. However when I do the following command bellow:
Switch#show etherchannel
Channel-group listing:
----------------------
Group: 1
----------
Group state = L2
Ports: 4 Maxports = 8
Port-channels: 1 Max Port-channels = 1
Protocol: -
The "Protocol" listed above is blank. Is this normal? I mean if im connecting 2 Cisco switch this should be PagP right? What is my protocol then if this is the case? Am i using PagP already by default?
According to CBT nuggets trainor the "Channel-protocol pagp" is my negotiation protocol and should not be using this command if im going to use the "On mode" which is practically true because i was denied to create a channel when doing this on my Lab. If im not gonna be using this command what protocol am I using if I did the configuration above?
If you force the channel on then pagp is not used . To verify the channel use the "show etherchannel detail " command and make sure all links show as up on both sides of the channel . This will give you detailed info on how the channel is working and whether or not it is working or "bundled " correctly and all sorts of info pertaining to any created port channels. The leds just mean you have a good physical layer connection on your switches . There is no negotiation protocol used when you force it on . If you let the switch negotiate the channel then PAGP or LACP is used to automatically negotiate the channel depending on how you configure the channel . PAGP is a cisco proprietary protocol and LACP is the IEEE network standard that everyone uses .
If you want use negotiated protocols then you can use this setting. Do this on both sides. This setting uses PAGP as the negotiation protocol.
interface xxx
speed 100
duplex full
channel-group 1 mode desirable non-silent
-------------------------------------------------------------
For lacp protocol
interface xx
speed 100
duplex full
channel-group 1 mode active
interface xxx
speed 100
duplex full
channel-group 1 mode desirable non-silent
-------------------------------------------------------------
For lacp protocol
interface xx
speed 100
duplex full
channel-group 1 mode active
- Thread starter
- #9
If you force the channel on then pagp is not used"
"There is no negotiation protocol used when you force it on . If you let the switch negotiate the channel then PAGP or LACP is used to automatically negotiate the channel depending on how you configure the channel."
----- so how does this link work? as you said there in no protocol being used. How do etherchannel technology communicate with the other switch? Does it work because of the existing trunking configuration that i set? Is this just a "literal Bundling of Port" TECHNOLOGY a.k.a Etherchannel?
As far as I know the bundles are all OK, but if you will observe the "protocol" used, it is also blank. See all outputs bellow.
Switch#show etherchannel detail
Channel-group listing:
----------------------
Group: 1
----------
Group state = L2
Ports: 4 Maxports = 8
Port-channels: 1 Max Port-channels = 1
Protocol: -
Ports in the group:
-------------------
Port: Fa0/45
------------
Port state = Up Mstr In-Bndl
Channel group = 1 Mode = On/FEC Gcchange = -
Port-channel = Po1 GC = - Pseudo port-channel = Po1
Port index = 0 Load = 0x00 Protocol = -
Age of the port in the current state: 00d:00h:00m:46s
Port: Fa0/46
------------
Port state = Up Mstr In-Bndl
Channel group = 1 Mode = On/FEC Gcchange = -
Port-channel = Po1 GC = - Pseudo port-channel = Po1
Port index = 0 Load = 0x00 Protocol = -
Age of the port in the current state: 00d:00h:01m:07s
Port: Fa0/47
------------
Port state = Up Mstr In-Bndl
Channel group = 1 Mode = On/FEC Gcchange = -
Port-channel = Po1 GC = - Pseudo port-channel = Po1
Port index = 0 Load = 0x00 Protocol = -
Age of the port in the current state: 00d:00h:01m:07s
Port: Fa0/48
------------
Port state = Up Mstr In-Bndl
Channel group = 1 Mode = On/FEC Gcchange = -
Port-channel = Po1 GC = - Pseudo port-channel = Po1
Port index = 0 Load = 0x00 Protocol = -
Age of the port in the current state: 00d:00h:01m:07s
Port-channels in the group:
---------------------------
Port-channel: Po1
------------
Age of the Port-channel = 00d:00h:01m:24s
Logical slot/port = 1/0 Number of ports = 4
GC = 0x00000000 HotStandBy port = null
Port state = Port-channel Ag-Inuse
Protocol = -
Ports in the Port-channel:
Index Load Port EC state No of bits
------+------+------+------------------+-----------
0 00 Fa0/45 On/FEC 0
0 00 Fa0/46 On/FEC 0
0 00 Fa0/47 On/FEC 0
0 00 Fa0/48 On/FEC 0
Time since last port bundled: 00d:00h:01m:23s Fa0/48
Switch#show ip int brief
FastEthernet0/45 unassigned YES unset up up
FastEthernet0/46 unassigned YES unset up up
FastEthernet0/47 unassigned YES unset up up
FastEthernet0/48 unassigned YES unset up up
Port-channel1 unassigned YES unset up up
"There is no negotiation protocol used when you force it on . If you let the switch negotiate the channel then PAGP or LACP is used to automatically negotiate the channel depending on how you configure the channel."
----- so how does this link work? as you said there in no protocol being used. How do etherchannel technology communicate with the other switch? Does it work because of the existing trunking configuration that i set? Is this just a "literal Bundling of Port" TECHNOLOGY a.k.a Etherchannel?
As far as I know the bundles are all OK, but if you will observe the "protocol" used, it is also blank. See all outputs bellow.
Switch#show etherchannel detail
Channel-group listing:
----------------------
Group: 1
----------
Group state = L2
Ports: 4 Maxports = 8
Port-channels: 1 Max Port-channels = 1
Protocol: -
Ports in the group:
-------------------
Port: Fa0/45
------------
Port state = Up Mstr In-Bndl
Channel group = 1 Mode = On/FEC Gcchange = -
Port-channel = Po1 GC = - Pseudo port-channel = Po1
Port index = 0 Load = 0x00 Protocol = -
Age of the port in the current state: 00d:00h:00m:46s
Port: Fa0/46
------------
Port state = Up Mstr In-Bndl
Channel group = 1 Mode = On/FEC Gcchange = -
Port-channel = Po1 GC = - Pseudo port-channel = Po1
Port index = 0 Load = 0x00 Protocol = -
Age of the port in the current state: 00d:00h:01m:07s
Port: Fa0/47
------------
Port state = Up Mstr In-Bndl
Channel group = 1 Mode = On/FEC Gcchange = -
Port-channel = Po1 GC = - Pseudo port-channel = Po1
Port index = 0 Load = 0x00 Protocol = -
Age of the port in the current state: 00d:00h:01m:07s
Port: Fa0/48
------------
Port state = Up Mstr In-Bndl
Channel group = 1 Mode = On/FEC Gcchange = -
Port-channel = Po1 GC = - Pseudo port-channel = Po1
Port index = 0 Load = 0x00 Protocol = -
Age of the port in the current state: 00d:00h:01m:07s
Port-channels in the group:
---------------------------
Port-channel: Po1
------------
Age of the Port-channel = 00d:00h:01m:24s
Logical slot/port = 1/0 Number of ports = 4
GC = 0x00000000 HotStandBy port = null
Port state = Port-channel Ag-Inuse
Protocol = -
Ports in the Port-channel:
Index Load Port EC state No of bits
------+------+------+------------------+-----------
0 00 Fa0/45 On/FEC 0
0 00 Fa0/46 On/FEC 0
0 00 Fa0/47 On/FEC 0
0 00 Fa0/48 On/FEC 0
Time since last port bundled: 00d:00h:01m:23s Fa0/48
Switch#show ip int brief
FastEthernet0/45 unassigned YES unset up up
FastEthernet0/46 unassigned YES unset up up
FastEthernet0/47 unassigned YES unset up up
FastEthernet0/48 unassigned YES unset up up
Port-channel1 unassigned YES unset up up
As indicated before the protocol will show blank when you use channel-group 1 mode on . If you use one of the others I indicated it will show up as either pagp or lacp for the negotiating protocol . Since you are not using a negotiated channel it shows blank . Your channel looks fine , all ports show as "up master in bundle" which is the correct state for your ports.
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