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show commands do not tell link aggregation type

I am going to configure link aggrate between our switching core/distribution layer and one of our access switches. Both are cisco (3750 and 2960).

We have implemented link aggregation in other parts of our network and I would like to use the same standard for conistency.

However when I run show commands the Protocol feild is always just "-". I wish to know if it is LACP or PAgP. I have tried this on all switches that have link aggregation on them but get the same result each time.

Here is an example:

CPCore001#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: 7
Number of aggregators:           7

Group  Port-channel  Protocol    Ports
------+-------------+-----------+-----------------------------------------------
1      Po1(SU)          -        Gi4/0/1(P)  Gi4/0/2(P)
2      Po2(SU)          -        Gi1/0/3(P)  Gi1/0/4(P)
3      Po3(SU)          -        Gi1/0/5(P)  Gi1/0/6(P)
25     Po25(SU)         -        Gi2/0/9(P)  Gi2/0/10(P)
26     Po26(SD)         -        Gi2/0/11(D) Gi2/0/12(D)
37     Po37(SD)         -        Gi1/0/17(D) Gi1/0/18(D)
39     Po39(SU)         -        Gi4/0/7(P)  Gi4/0/8(P)

CPCore001#

Is there a way I can tell what link aggregation type is being used?

17 Replies 17

Leo Laohoo
Hall of Fame
Hall of Fame

What IOS are you using?

I'm running 12.2(58)SE2 and ...

2      Po2(SU)         LACP Gi1/0/10(P) Gi1/0/12(P) Gi2/0/11(P)

If I use  15.0(1)SE (2960S) and 12.2(55)SE4 (3750G) then I get the same result as yours.

The core switching stack has verison 12.2(25)SEE2

The access switch has version 12.2(44)SE6

If your 3750 has 16 mb of flash then the highest IOS you can go is 12.2(55)SE and later.  Your 2960 should be able to load 12.2(58)SE.  Try this IOS.

I'm not looking to upgrade or change the IOS.

I am simply looking to find out what type of link aggregation is in use so that I use the same (LACP or PAgP) when I set up the new link aggregation tonight.

Oh.  Ok.  Use the default.

"channel-group 1 mode on"

Hi Steven,

You can just check the running configuration on ports within port-channel.

E.G. sh run int Gi4/0/1. So based on channel mode configured you can get the protocol used - active (lacp), desirable (PAGP), on (none used - just Po forced to come up).

Hope this helps,

Nik

HTH,
Niko

glen.grant
VIP Alumni
VIP Alumni

  I think show etherchannel  detail might give it to you . 

darren.g
Level 5
Level 5

steven.crutchley wrote:

I am going to configure link aggrate between our switching core/distribution layer and one of our access switches. Both are cisco (3750 and 2960).

We have implemented link aggregation in other parts of our network and I would like to use the same standard for conistency.

However when I run show commands the Protocol feild is always just "-". I wish to know if it is LACP or PAgP. I have tried this on all switches that have link aggregation on them but get the same result each time.

Here is an example:

CPCore001#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: 7
Number of aggregators:           7

Group  Port-channel  Protocol    Ports
------+-------------+-----------+-----------------------------------------------
1      Po1(SU)          -        Gi4/0/1(P)  Gi4/0/2(P)
2      Po2(SU)          -        Gi1/0/3(P)  Gi1/0/4(P)
3      Po3(SU)          -        Gi1/0/5(P)  Gi1/0/6(P)
25     Po25(SU)         -        Gi2/0/9(P)  Gi2/0/10(P)
26     Po26(SD)         -        Gi2/0/11(D) Gi2/0/12(D)
37     Po37(SD)         -        Gi1/0/17(D) Gi1/0/18(D)
39     Po39(SU)         -        Gi4/0/7(P)  Gi4/0/8(P)

CPCore001#

Is there a way I can tell what link aggregation type is being used?

show interface poX etherchannel

Gives me an output like this

Port-channel1   (Primary aggregator)

Age of the Port-channel   = 28d:19h:09m:34s

Logical slot/port   = 10/1          Number of ports = 2

HotStandBy port = null

Port state          = Port-channel Ag-Inuse

Protocol            =   LACP

Port security       = Disabled

Ports in the Port-channel:

Index   Load   Port     EC state        No of bits

------+------+------+------------------+-----------

  0     00     Te1/1/1  Active             0

  0     00     Te2/1/1  Active             0

Time since last port bundled:    28d:19h:05m:09s    Te2/1/1

it's more time consuming, since you have to do each port-channel interface, but it should get you what you want to know.

Mind you, show etherchannel summary gives me an output like this

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: 3

Number of aggregators:           3

Group  Port-channel  Protocol    Ports

------+-------------+-----------+-----------------------------------------------

1      Po1(SU)         LACP      Te1/1/1(P)  Te2/1/1(P)

2      Po2(SU)         LACP      Te1/1/2(P)  Te2/1/2(P)

3      Po3(SU)         LACP      Gi1/0/1(P)  Gi2/0/1(P)

which clearly shows LACP in use on all ether channels - so I don't know why you're not gettign that - could be IOS version.

Cheers

Cheers.

I just found out that if you get the "-" under protocol it means that you are using NEITHER PAGp nor LACP.   You get this result(s) when using the "mode on" option.

My understanding was that there is either LACP or PAgP and that there is no other option.

According to my CCNP book using "channel-group 1 mode on" is a command used for PAgP.

But if I am understanding you correctly LACP and PAgP merely refers to the communication or negotiation of an EtherChannel and that "channel-group 1 mode on" is essentially forcing the channel up without using either protocol.

Am I understanding correctly?

Steven,

The CCNP book (I can't remember the author of mine, but it's the Cisco Press book) is a bit confusing in this section.  Note that the author includes the "on" command for both PAgP and LACP sections, but mentions in the text that "on" means the links are simply aggregated and no negotiation takes place.  This is further demonstrated when configuring the aggregation in IOS - you don't explicitly select PAgP, LACP, or "none", but rather you choose either a PAgP mode, LACP mode, or "on".

Thank you all for your responses. They have all been useful.

To complicate things further I attempted the EtherChannel configuration last night and, whilst nothing went disastrously wrong, the EtherChannel did not come up.

I used the following commands on both switches

Switch(config)# interface range gi0/47-48

Switch(config-if-range)# channel-protocol pagp

Switch(config-if-range)# channel-group 6 mode desirable non-silent

After some minor issues with making sure the port details were correct (same vlans etc) both interfaces on both switches were bundled into their respective channel-groups successfully.

HOWEVER

The on the core switch the interface po6 did not come up (notconnect). The interfaces were bundled into the EtherChannel. CDP could even detect the switch at the other end.

But when I went to the access layer switch (all the way down the other end of the compound ) the ports were also succcessfully bundled into the EtherChannel but po6 was up.

I checked trunk types, encapsulation types, shutdown commands, speeds everything - but for some reason the core etherchannel refused to come up. I changed the core Etherchannel not to be non-silent thinking that if both were waiting for the other nothing would happen. Again this did not work. Finally I tried channel-group 1 mode on on both ends but to no avail.

I think I am missing something fundamental about how EtherChannels work. I'm feeling pretty frustrated as I have a CCNP SWITCH exam coming up soon and this does not instil me with confidence.

Any help or suggestions would be appreciated.

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