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New Member

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
Hall of Fame Super Gold

show commands do not tell link aggregation type

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)

Hall of Fame Super Gold

show commands do not tell link aggregation type

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

New Member

show commands do not tell link aggregation type

The core switching stack has verison 12.2(25)SEE2

The access switch has version 12.2(44)SE6

Hall of Fame Super Gold

show commands do not tell link aggregation type

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.

New Member

show commands do not tell link aggregation type

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.

Hall of Fame Super Gold

Re: show commands do not tell link aggregation type

Oh.  Ok.  Use the default.

"channel-group 1 mode on"

Hall of Fame Super Gold

show commands do not tell link aggregation type

Cisco Employee

show commands do not tell link aggregation type

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

Purple

show commands do not tell link aggregation type

  I think show etherchannel  detail might give it to you . 

Silver

show commands do not tell link aggregation type

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.

Hall of Fame Super Gold

show commands do not tell link aggregation type

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.

New Member

show commands do not tell link aggregation type

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?

show commands do not tell link aggregation type

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".

New Member

show commands do not tell link aggregation type

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.

Cisco Employee

show commands do not tell link aggregation type

Hello Steven and other friends,

Please allow me to join this discussion.

Regarding the channeling protocols, Leo is correct. If the show ether summary command says "-" in the Protocol column, the EtherChannel has been configured statically using the on mode, and no negotiation of port bundling takes place. Alternatives are active/passive for LACP and desirable/auto for PAgP. These modes are disjunctive - they cannot be combined on a single port. A port can be either on or active or passive or desirable or auto but never any combination of two or more of these modes. If a textbook suggests otherwise, it is most probably incorrect on this subject.

About the silent/non-silent modes in PAgP, they prove to be very confusing. Essentially, the silent/non-silent modes were devised as a primitive way of detecting unidirectional links, obviously before UDLD and L1 detection methods were more common. Without trying to go into much detail here, I suggest not specifying any of them when configuring PAgP (let the default value in place). Please also check the following two URLs for an in-depth discussion of the silent/non-silent:

http://www.cisco.com/en/US/tech/tk389/tk213/technologies_tech_note09186a00800949c2.shtml#silent

http://www.cisco.com/en/US/products/hw/switches/ps708/products_white_paper09186a00801b49a4.shtml#cg6 (scroll down a couple of pages to find the discussion about silent/non-silent)

Regarding the inability of the EtherChannel to come up, can we try to configure it once more? Please try using the desirable keyword on both ends and leave out any silent/non-silent keywords. Thanks!

Best regards,

Peter

New Member

show commands do not tell link aggregation type

Hi Peter,

Thanks for the advice.

Unforunately I cannot retest the creation of the EtherChannel until next week. The link in question connects to our DR site where our primary backup server lives. I need to follow regulation RFC processes and get it approved however I don't see this being refused.

I wil try what you suggest on my home network setup over the weekend and update this thread with my result and then again next week once I've tried again on the production environment.

Again thanks for the help.

New Member

Re: show commands do not tell link aggregation type

I have tried to configure EtherChannel excluding the non-silent keyword but to no avail.

I used the following commands:

CORE SWITCH

Switch1(config)# interface range gi40/4-5

Switch1(config-if-range)# channel-protocol pagp

Switch1(config-if-range)# channel-group 5 mode desirable

ACCESS SWITCH

Switch2(config)# interface range gi0/47-48

Switch2(config-if-range)# channel-protocol pagp

Switch2(config-if-range)# channel-group 5 mode desirable

As before the core EtherChannel po5 (I changed the port channel number to start fresh) did not come up, however it appeared as if the interfaces joined their respective port channels.

Below are some show commands:

Switch1# show interfaces po5

Port-channel5 is down, line protocol is down (notconnect)

  Hardware is EtherChannel, address is 001d.468c.df05 (bia 001d.468c.df05)

  MTU 1500 bytes, BW 2000000 Kbit, DLY 10 usec,

     reliability 255/255, txload 4/255, rxload 1/255

  Encapsulation ARPA, loopback not set

  Full-duplex, 1000Mb/s, link type is auto, media type is unknown

  Media-type configured as  connector

  input flow-control is off, output flow-control is unsupported

  Members in this channel: Gi4/0/4 Gi4/0/5

  ARP type: ARPA, ARP Timeout 04:00:00

  Last input 00:00:00, output never, output hang never

  Last clearing of "show interface" counters never

  Input queue: 0/75/0/0 (size/max/drops/flushes); Total output drops: 0

  Queueing strategy: fifo

  Output queue: 0/40 (size/max)

  5 minute input rate 1814000 bits/sec, 230127 packets/sec

  5 minute output rate 36987000 bits/sec, 643175 packets/sec

     3547625993 packets input, 2703375078 bytes, 0 no buffer

     Received 456706943 broadcasts (0 multicast)

     0 runts, 0 giants, 0 throttles

     53 input errors, 0 CRC, 0 frame, 0 overrun, 0 ignored

     0 watchdog, 73718023 multicast, 0 pause input

     0 input packets with dribble condition detected

     2204682451 packets output, 1550006496 bytes, 0 underruns

     0 output errors, 0 collisions, 8 interface resets

     0 babbles, 0 late collision, 0 deferred

     0 lost carrier, 0 no carrier, 0 PAUSE output

     0 output buffer failures, 0 output buffers swapped out

Switch1# show int po5 etherchannel
Age of the Port-channel   = 00d:00h:17m:44s
Logical slot/port   = 10/5          Number of ports = 2
GC                  = 0x00050001      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     Gi4/0/4  Desirable-Sl       0
  0     00     Gi4/0/5  Desirable-Sl       0

Time since last port bundled:    00d:00h:02m:18s    Gi4/0/5
Time since last port Un-bundled: 00d:00h:13m:24s    Gi4/0/5

After bringing down the EtherChannel from the CORE switch I checked the ACCESS switch. I noticed the po5 duplex and speed settings on the ACCESS switch were auto-duplex and auto-speed whereas the CORE switch had po5 as  full-duplex and 1000Mb/s.

When I tried to change the po5 interface to have a manual speed I got the following result:

Switch2(config-if)#speed 1000

Command rejected! GigabitEthernet0/47 in port-channel does not support speed change

I am not sure if this gives a clue as to why it is not working.

Again any help is appreciated.

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