Etherchannel Question
Hey guys. I have a question regarding etherchannel. It seems when using both PAgP and LACP, as soon as I force the ports of the channel to be 1000/Full, the channel won't form. It works perfectly with auto/auto.
Here's the config and show etherchannel summary for both switches.
Switch 1:
Switch 2:
When I add the following, the channel goes down and doesn't come back up.
Switch 1:
Switch 2:
As I understand it, both sides have to match on speed/duplex (among other things). In this case, they match but still won't form a channel.
Both switches are Catalyst 2960Gs running the same version of IOS.
What am I missing?
Thanks.
Here's the config and show etherchannel summary for both switches.
Switch 1:
DSW1_CiscoLab#sh run int po1
Building configuration...
Current configuration : 31 bytes
!
interface Port-channel1
end
DSW1_CiscoLab#sh run int gi0/1
Building configuration...
Current configuration : 102 bytes
!
interface GigabitEthernet0/1
channel-protocol pagp
channel-group 1 mode desirable non-silent
end
DSW1_CiscoLab#sh run int gi0/2
Building configuration...
Current configuration : 102 bytes
!
interface GigabitEthernet0/2
channel-protocol pagp
channel-group 1 mode desirable non-silent
end
DSW1_CiscoLab#sh run int gi0/3
Building configuration...
Current configuration : 102 bytes
!
interface GigabitEthernet0/3
channel-protocol pagp
channel-group 1 mode desirable non-silent
end
DSW1_CiscoLab#sh run int gi0/4
Building configuration...
Current configuration : 102 bytes
!
interface GigabitEthernet0/4
channel-protocol pagp
channel-group 1 mode desirable non-silent
end
DSW1_CiscoLab#sh etherchannel sum
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 Gi0/1(P) Gi0/2(P) Gi0/3(P)
Gi0/4(P)
Switch 2:
DSW2_CiscoLab#sh run int po1
Building configuration...
Current configuration : 66 bytes
!
interface Port-channel1
switchport mode dynamic desirable
end
DSW2_CiscoLab#sh run int gi0/1
Building configuration...
Current configuration : 137 bytes
!
interface GigabitEthernet0/1
switchport mode dynamic desirable
channel-protocol pagp
channel-group 1 mode desirable non-silent
end
DSW2_CiscoLab#sh run int gi0/2
Building configuration...
Current configuration : 137 bytes
!
interface GigabitEthernet0/2
switchport mode dynamic desirable
channel-protocol pagp
channel-group 1 mode desirable non-silent
end
DSW2_CiscoLab#sh run int gi0/3
Building configuration...
Current configuration : 137 bytes
!
interface GigabitEthernet0/3
switchport mode dynamic desirable
channel-protocol pagp
channel-group 1 mode desirable non-silent
end
DSW2_CiscoLab#sh run int gi0/4
Building configuration...
Current configuration : 137 bytes
!
interface GigabitEthernet0/4
switchport mode dynamic desirable
channel-protocol pagp
channel-group 1 mode desirable non-silent
end
DSW2_CiscoLab#sh 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 Gi0/1(P) Gi0/2(P) Gi0/3(P)
Gi0/4(P)
When I add the following, the channel goes down and doesn't come back up.
Switch 1:
DSW1_CiscoLab#sh run int po1
Building configuration...
Current configuration : 56 bytes
!
interface Port-channel1
speed 1000
duplex full
end
DSW1_CiscoLab#show etherchannel sum
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(SD) PAgP Gi0/1(D) Gi0/2(D) Gi0/3(D)
Gi0/4(D)
Switch 2:
DSW2_CiscoLab#sh run int po1
Building configuration...
Current configuration : 91 bytes
!
interface Port-channel1
switchport mode dynamic desirable
speed 1000
duplex full
end
DSW2_CiscoLab#sh etherchannel sum
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(SD) PAgP Gi0/1(D) Gi0/2(D) Gi0/3(D)
Gi0/4(D)
As I understand it, both sides have to match on speed/duplex (among other things). In this case, they match but still won't form a channel.
Both switches are Catalyst 2960Gs running the same version of IOS.
What am I missing?
Thanks.
CCNP Progress
ROUTE [X] :: SWITCH [X] :: TSHOOT [X]
ROUTE [X] :: SWITCH [X] :: TSHOOT [X]
Comments
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networker050184
Mod Posts: 11,962 Mod
I believe you need the speed/duplex to match on the physical interfaces and the port-channel.An expert is a man who has made all the mistakes which can be made. -
iproute
Member Posts: 269
Thanks for the reply. By applying the commands to the port channel interface, it applies them to the member interfaces as well.
Switch 1:DSW1_CiscoLab#sh run int po1 Building configuration... Current configuration : 56 bytes ! interface Port-channel1 speed 1000 duplex full end DSW1_CiscoLab#sh run int gi0/1 Building configuration... Current configuration : 127 bytes ! interface GigabitEthernet0/1 speed 1000 duplex full channel-protocol pagp channel-group 1 mode desirable non-silent end DSW1_CiscoLab#sh run int gi0/2 Building configuration... Current configuration : 127 bytes ! interface GigabitEthernet0/2 speed 1000 duplex full channel-protocol pagp channel-group 1 mode desirable non-silent end DSW1_CiscoLab#sh run int gi0/3 Building configuration... Current configuration : 127 bytes ! interface GigabitEthernet0/3 speed 1000 duplex full channel-protocol pagp channel-group 1 mode desirable non-silent end DSW1_CiscoLab#sh run int gi0/4 Building configuration... Current configuration : 127 bytes ! interface GigabitEthernet0/4 speed 1000 duplex full channel-protocol pagp channel-group 1 mode desirable non-silent end
Switch 2:DSW2_CiscoLab#sh run int po1 Building configuration... Current configuration : 91 bytes ! interface Port-channel1 switchport mode dynamic desirable speed 1000 duplex full end DSW2_CiscoLab#sh run int gi0/1 Building configuration... Current configuration : 162 bytes ! interface GigabitEthernet0/1 switchport mode dynamic desirable speed 1000 duplex full channel-protocol pagp channel-group 1 mode desirable non-silent end DSW2_CiscoLab#sh run int gi0/2 Building configuration... Current configuration : 162 bytes ! interface GigabitEthernet0/2 switchport mode dynamic desirable speed 1000 duplex full channel-protocol pagp channel-group 1 mode desirable non-silent end DSW2_CiscoLab#sh run int gi0/3 Building configuration... Current configuration : 162 bytes ! interface GigabitEthernet0/3 switchport mode dynamic desirable speed 1000 duplex full channel-protocol pagp channel-group 1 mode desirable non-silent end DSW2_CiscoLab#sh run int gi0/4 Building configuration... Current configuration : 162 bytes ! interface GigabitEthernet0/4 switchport mode dynamic desirable speed 1000 duplex full channel-protocol pagp channel-group 1 mode desirable non-silent end
CCNP Progress
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phoeneous
Member Posts: 2,333 ■■■■■■■□□□
Are you plugging into the dual-purpose ports? What happens when you try the etherchannel on ports gi3 and gi4 and set speed and duplex? Just curious what happens. -
networker050184
Mod Posts: 11,962 Mod
Do the ports come up when not in the etherchannel? Any messages in the log? Have you tried bouncing the etherchannel after changing both sides?An expert is a man who has made all the mistakes which can be made.
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creamy_stew
Member Posts: 406 ■■■□□□□□□□
Interesting, I'm looking to implement etherchannel in a production environment. This scares me
Have you looked for err-disabled ports? Especially due to etherchannel misconfig.
edit: this is probably not an etherchannel issue. I now remember I had a problem adding an additional 2960G. I would get some sort of VTP error logs (all switches running transparent) When I switched to auto, the logs went away. Not really a problem, except ALL the other switches were hard set to 1000/full. -
mikej412
Member Posts: 10,086 ■■■■■■■■■■
What kind of cable are you using? Auto-MDIX is disabled when you manually set the speed or duplex -- so if it's copper and straight through that could be an issue.
Checking for err-disable is another good idea. If you changed the config while the ports were no shut, you may not have been fast enough making the configuration changes on both sides.:mike: Cisco Certifications -- Collect the Entire Set! -
iproute
Member Posts: 269
What kind of cable are you using? Auto-MDIX is disabled when you manually set the speed or duplex -- so if it's copper and straight through that could be an issue.
Hey all - been away for a few. This is the most likely cause. I'm using straight through cables relying on auto MDIX (basically, I have to make cross-overs if I want them). I'll try some crossover cables and check this tomorrow (my lab is at work, I am at home).
Thanks for all the responses.CCNP Progress
ROUTE [X] :: SWITCH [X] :: TSHOOT [X] -
iproute
Member Posts: 269
Confirmed. With a cross over cable, the port comes right up (I tried it only with one as I don't see a need to make 4 cross over cables for this test).
DSW1_CiscoLab#sh 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 Gi0/1(P) Gi0/2(D) Gi0/3(D) Gi0/4(D) DSW1_CiscoLab#
Thanks Mike for this valuable nugget of info.
Thanks for all the replies.CCNP Progress
ROUTE [X] :: SWITCH [X] :: TSHOOT [X] -
chrisone
Member Posts: 2,278 ■■■■■■■■■□
creamy_stew wrote: »Interesting, I'm looking to implement etherchannel in a production environment. This scares me
Shouldn't be a problem even if you brought down the switch, as long as you don't implement it during business hours. Ask for a scheduled downtime "network maintenance" and you should be solid to work free of stress.Certs: CISSP, EnCE, OSCP, CRTP, eCTHPv2, eCPPT, eCIR, LFCS, CEH, SPLK-1002, SC-200, SC-300, AZ-900, AZ-500, VHL:Advanced+
2023 Cert Goals: SC-100, eCPTX
