PAgP dinamically modifies parameters?

Unanswered Question
May 6th, 2010

I read the following: PAgP also dynamically modifies parameters of the EC if one of the bubdled ports is modified. Example, if the configured VLAN, speed, or duplex mode of a port in an established bundle is changed, PAgP reconfigures that parameter for all ports in the bundle.

I changed the speed in one of the two ports in my bundle and it was suspended because it was not compatible with the other one.... I thought by changeing the speed in one port the other port would be changed aswell dynamically as the book says but it didnt.... any explanation on this subject?

This is what i have (changed the speed of Fa 0/2 to 10 Mbps):

interface FastEthernet0/2
speed 10
channel-group 5 mode desirable non-silent
channel-protocol pagp
!
interface FastEthernet0/3
channel-group 5 mode desirable non-silent
channel-protocol pagp

This is what I got:

SW-HC#
00:20:36: %EC-5-CANNOT_BUNDLE2: Fa0/2 is not compatible with Fa0/3 and will be suspended (speed of Fa0/2 is 10M, Fa0/3 is 100M)

SW-HC#
SW-HC#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 - unsuitable for bundling
        U - in use      f - failed to allocate aggregator
        d - default port

Number of channel-groups in use: 1
Number of aggregators:           1

Group  Port-channel  Protocol    Ports
------+-------------+-----------+-----------------------------------------------
5      Po5(SU)         PAgP      Fa0/2(s)    Fa0/3(Pd)

I have this problem too.
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Edison Ortiz Thu, 05/06/2010 - 13:33

PAgP also dynamically modifies parameters of the EC if one of the bubdled ports is modified.

That's incorrect. Please refer to the book name and page number, please.

Ganesh Hariharan Fri, 05/07/2010 - 00:09

PAgP also dynamically modifies parameters of the EC if one of the bubdled ports is modified.

That's incorrect. Please refer to the book name and page number, please.

Hi Edison,

I just came across this link with Document ID: 12023 about the statement on PAgp and restriction also :-

PAgP does not group ports that operate at different speeds or port           duplex. If speed and duplex change when a bundle exists, PAgP changes the port           speed and duplex for all ports in the bundle.

http://www.cisco.com/en/US/tech/tk389/tk213/technologies_tech_note09186a0080094714.shtml#prereq

Even i thought the same that PAgp dont do but as per the above link i am confused now !!

Ganesh.H

ssreejesh Sat, 11/08/2014 - 01:30


Page 113, chapter 6, CCNP  SWITCH 642-813 official CErtification Guide, ciscopress.com, David Hucaby, CCIE No.4594

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