Port-Channel options they are many? how to choose?

itdaddyitdaddy Senior MemberMember Posts: 2,089 ■■■■□□□□□□
what does it matter what you use? do you use one over the other?
I know if say a net app san uses LACP you have to use LACP on both ends. I get that but do you try different port-channeling if something goes wrong with say Etherchannel ON ? and then try another port-channel protocol on both ends to see if it fixes the issue. The reason I ask this is because we are having an issue with channel-group 1 mode on and had to take it off
and go back to a single trunk. Do you think if say I tried PagP alone on both ends or LACP on both ends along with saying
switchport mode trunk? it would possiblly fix my issue. Just wondering why so many options? Maybe for different systems and to use other mode in case of issues like I have?

sw-ch-core1(config-if)#channel-group 1 mode ?
active Enable LACP unconditionally
auto Enable PAgP only if a PAgP device is detected
desirable Enable PAgP unconditionally
on Enable Etherchannel only
passive Enable LACP only if a LACP device is detected

sw-ch-core1(config-if)#channel-group 1 mode

Comments

  • networker050184networker050184 Mod Posts: 11,962 Mod
    No you don't just keep trying different things until it works! You find the real problem and fix it.

    As far as which one to choose, PAgP is probably never the one you want to go with. The LACP mode or static (on) depends on what's on the other side. Usually it's safer to have it negotiate and not not form a channel in case the other end is hosed.
    An expert is a man who has made all the mistakes which can be made.
  • techfiendtechfiend Member Posts: 1,481 ■■■■□□□□□□
    Unrelated to Cisco and port channels but today I read documentation stating to try different things until communication works for official software, I chuckled at first. Six hours later, it still didn't work, I was getting frustrated. Ended up going with unofficial software that instantly communicated.

    In such a technical industry filled with highly intelligent humans I'm shocked to see so many things that don't have specific fixes. In the long run I guess that employs support and gives companies reasons to charge for it.
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  • itdaddyitdaddy Senior Member Member Posts: 2,089 ■■■■□□□□□□
    well I did just that. hahaahah We have old 12-15 year old 4500 cat switches huge monsters and I was using the Mode ON on both ends with a newer 2960 DMZ switch and we had issues with the DMZ..i felt it was a port-channel compatablility issue so I put LACP on booth ends of the 2 link port channel and BAM BOOOM works perfect now with dual DMZ and Dual ASA firewalls. not sure but my gut was saying old switch use LACP on both ends and it did work. I used logic and used the different options until it worked. Just had a gut feeling...yeah! I am a genius! hahaha not yet! getting there..thanks men!
  • networker050184networker050184 Mod Posts: 11,962 Mod
    techfiend wrote: »
    In such a technical industry filled with highly intelligent humans I'm shocked to see so many things that don't have specific fixes. In the long run I guess that employs support and gives companies reasons to charge for it.

    Everything does have a specific fix. Whether or not everyone understands it is a different story!
    An expert is a man who has made all the mistakes which can be made.
  • IristheangelIristheangel CCIEx2 (Sec + DC), CCNP RS, CCNA V/S/R/DC, CISSP, CEH, MCSE 2003, A+/L+/N+/S+, and a lot more from m Pasadena, CAMod Posts: 4,133 Mod
    PAGP/LACP are negotiation protocols for port channeling. The benefit of using them is detection of misconfiguration - i.e. if you accidentally connect ports on one side to a non-port channel port or a port belonging to another port channel, it'll shut down and prevent looks and other issues. LACP is more of the accepted protocol - most server NIC cards, vendor switches, etc all support this. PAGP is Cisco-proprietary and it seems like Cisco is doing away with it since some of the newer Cisco switches (especially data center switches) don't support PAGP.

    Static mode on bypasses all negotiation and bring up the port channel immediately regardless of whether there is misconfiguration on the other side. This is NOT best practice but sometimes it's necessary if the NIC card or switch doesn't support negotiation
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  • Danielh22185Danielh22185 Member Posts: 1,195 ■■■■□□□□□□
    PAGP/LACP are negotiation protocols for port channeling. The benefit of using them is detection of misconfiguration - i.e. if you accidentally connect ports on one side to a non-port channel port or a port belonging to another port channel, it'll shut down and prevent looks and other issues. LACP is more of the accepted protocol - most server NIC cards, vendor switches, etc all support this. PAGP is Cisco-proprietary and it seems like Cisco is doing away with it since some of the newer Cisco switches (especially data center switches) don't support PAGP.

    Static mode on bypasses all negotiation and bring up the port channel immediately regardless of whether there is misconfiguration on the other side. This is NOT best practice but sometimes it's necessary if the NIC card or switch doesn't support negotiation

    ^^ Iris beat me to the punch.

    So with that said it sounds like you had a port-channel configuration problem.
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  • itdaddyitdaddy Senior Member Member Posts: 2,089 ■■■■□□□□□□
    Okay. It was not misconfiguration, it was and old CAT switch and a new 2960 switch not agreeing on something.
    I saw no issues when running show commands. Some traffic did work.

    I saw no issues. We use etherchannel mode on on many of our connections and they work fine. But I changed it to the accepted LACP and boom things worked great. Thanks guys!
  • theodoxatheodoxa Member Posts: 1,340 ■■■■□□□□□□
    LACP Active or Passive

    PAgP can only be used if both sides are Cisco. LACP can be used between Cisco and other vendors' equipment. Static Etherchannel risks the ports being err-disabled by Etherchannel Misconfig Guard.
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  • FrankGuthrieFrankGuthrie Member Posts: 245
    Isn't that explained in the CCNA curriculum, the differences in LACP and PaGP and their respective mode?
  • IristheangelIristheangel CCIEx2 (Sec + DC), CCNP RS, CCNA V/S/R/DC, CISSP, CEH, MCSE 2003, A+/L+/N+/S+, and a lot more from m Pasadena, CAMod Posts: 4,133 Mod
    Yes it is, Frank. But Itdaddy took it years ago and he just got his first network engineer job recently if I recall correctly. Very possible he may have forgotten in all that time of not using it
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  • kohr-ahkohr-ah Member Posts: 1,277
    Isn't that explained in the CCNA curriculum, the differences in LACP and PaGP and their respective mode?

    It is but the way they redid the exams they recap a lot of things. Also depends on when the CCNA was taken (when I took it, it wasn't on there).

    As for what we have always done is we always use LACP and never use ON.
  • itdaddyitdaddy Senior Member Member Posts: 2,089 ■■■■□□□□□□
    omg what did I forget? I said there was issues between an Old old cat 4500 switch and a new 2960 switch and I was using channel-group 1 mod on vs the channel group 1 mode active (for LACP on both ends)..what part did I miss and screw up? I am kind of lost. I have no idea what it did but it now works like it suppose to when I change to LACP on both ends. I wish I new granular wise what happened. But what did I mess up I am clueless can someone explain stupidity? for forgetting what CCNA topics. Both devices are Cisco so I used etherchannel not LACP and it didnt work like I expected. I did all the show commands for etherchannel and they looked normal and good. But I could not get to certain DMZ public addresses. It was weird. I just tried LACP on both ends even though I know this is a standard for NON cisco. I know all this. I was just trying anything to see what could fix it. So hello dudes what did I messup in? What stupid thing did i say that makes you think i operate at CCENT level??? hahahahaahh

    And believe it or not I am rebuilding a County's Data center and doing a great job of it according to this CCIE who comes in and checks my work ;) I always have CDW-G come in and check my work..I miss crap like anyone. It is always good to get your friendly CCIE to come in and check my design and configurations. Sometimes I may sound juvenille in my words by I don't speak about everything in my blog posts maybe I should work on sounded more text book I am sure it would help you guys think I am not and idiot haahah ;) I know I know dudes thanks for help anyways but i got it working with LACP on both ends with dual DMZ switches ;)


    Static Etherchannel risks the ports being err-disabled by Etherchannel Misconfig Guard.user-offline.png
    Isn't that explained in the CCNA curriculum, the differences in LACP and PaGP and their respective mode?



    Okay okay..but the reason I used channel-group 1 mode on on both ends of my cisco switches is it works many other places and these are both Cisco switches like other port-channels we have working nicely. Maybe there are many reasons for many things but I doubt you will remember all the fine things about everything. I am not a genius but I am pretty dam n good. I left my IT manager job doing network engineer, got job at Fiserv data center worked 1 year as BGP MPLS cloud engineer and now I am working as a Network Admin for a county. and I can tell you I dont remember everything off the top of my head and I doubt any of you will..But I know how to ask the right question and get things done :) now i am building a new data center and move a data center and working direct with CDW and they seem confident in my abilities and even they ask other peers on things they forget. None of us experts remembers everything when you get in the real world the best avenue is networking with peers! CCIE r/s network with the voice CCIE etc...it is just common if you work in the field long enough like I have .

    cheers mates. merry Christmas and happy new year men! and ladies!!!!!!!
  • IristheangelIristheangel CCIEx2 (Sec + DC), CCNP RS, CCNA V/S/R/DC, CISSP, CEH, MCSE 2003, A+/L+/N+/S+, and a lot more from m Pasadena, CAMod Posts: 4,133 Mod
    I don't think he was saying you forgot something. I think he was more commenting on the fact that you were confused on which port-channeling negotiation protocol to use or not to use and that fact that you were asking about why there were so many types. A lot of that was covered in the CCNA R&S as well as the CCNP Switch exams.

    I would refer back to what Networker said: Don't just try different things until you make it work. Figure out what the root cause it. Use your debug commands to capture what's happening in real time if the configs and show commands look good to you. When in doubt, call TAC and try to have them walk you through it. Don't just assume old switch == the root cause. I once watched a senior network engineer spend an entire 2 hour change window trying to reconfigure static port channels to LACP port channels over and over again only to have them errdisable. Turned out, he didn't shut the ports first so it was all happening in real time and errdisabling on one side before he had the chance to configure the other. All because he didn't shut the ports. Little things like that will sometimes bite you in the butt.

    No one is calling you an idiot, IT. You've been studying networking for awhile but I remember you mentioning this is your first networking job. It's nothing bad but there's been a bit of time between the time you took your tests and now without you actually applying that knowledge daily. Again, nothing wrong with it but it does seem like you're weaker in the foundations from some of the recent posts (i.e. Posts about ACL logic, QoS, etc). There is nothing wrong with this - Just things you know to improve in. I would recommend regoing through some of the core concepts + pick up a copy of Network Warrior to start drilling through.

    Take this as a learning experience. One challenge you might do for yourself in your own personal studies while you lab is to prevent yourself from using show run as a means to troubleshoot. Seriously. Forgot the command exists and just use debugs and other show commands. Train yourself to learn to troubleshoot and diagnose through debug output. This will make you a better engineer.

    Have a good holidays, Itdaddy
    BS, MS, and CCIE #50931
    Blog: www.network-node.com
  • theodoxatheodoxa Member Posts: 1,340 ■■■■□□□□□□
    Yes it is, Frank. But Itdaddy took it years ago and he just got his first network engineer job recently if I recall correctly. Very possible he may have forgotten in all that time of not using it

    Etherchannel wasn't on the CCNA until the 2013 revision. It was a CCNP (SWITCH) topic before that.
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  • IristheangelIristheangel CCIEx2 (Sec + DC), CCNP RS, CCNA V/S/R/DC, CISSP, CEH, MCSE 2003, A+/L+/N+/S+, and a lot more from m Pasadena, CAMod Posts: 4,133 Mod
    I guess it depends on the study material you used. I know it's at least gone over in Todd Lammle's CCNA 7th edition (640-802) and Jeremy Ciora's Exam Cram (640-802). I don't have the copy of my old Wendell Odom books but I think I remember them covered there as well. I guess it really doesn't matter since itdaddy did actually pass his CCNP Switch some time ago as well so it would have been covered in more detail there too. I think this is just a case of Itdaddy having a gap of time between the time he passed his exams and the time he started applying that knowledge. Happens to the best of us. :) If you asked me to help you with Citrix, pen testing, or forensics these days, I'd probably be pretty horrible at it. Just sounds like he needs a good refresher at the foundations.
    BS, MS, and CCIE #50931
    Blog: www.network-node.com
  • itdaddyitdaddy Senior Member Member Posts: 2,089 ■■■■□□□□□□
    agreed Merry Christmas...yes I do need a refresher...thank you for you replies always welcomed dudes. I still have lots to learn....
  • joelsfoodjoelsfood Member Posts: 1,027 ■■■■■■□□□□
    The answer to the original question is always use lacp unless you absolutely can't. It's a rare bird these days that doesn't support lacp.
  • itdaddyitdaddy Senior Member Member Posts: 2,089 ■■■■□□□□□□
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