show commands do not tell link aggregation type

[steven.crutchley]

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?

[Peter Paluch]

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

[steven.crutchley]

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.

[steven.crutchley]

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.