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Good evening - I am setting up a network in Packet Tracer and I'm not sure why I am getting this error.

The setup: I have 5 edge switches representing 5 floors of an office. I want to connect an Etherchannel group from one switch to a Master switch and a Backup switch, then a channel from MasterSW to BackupSW. MasterSW will connect to Master router and Backup router, while BackupSW will connect to Backup router and Master router.

I'm using 2 ports for Etherchannel from each floor to the MSW and 2 to the BSW, then using 4 ports for the connection between MSW and BSW.

Port Channel    Devices     Port Connections    Type    Mode        
1               SW1 to MSW  f0/23 to f0/23      LACP    Active
                            f0/24 to f0/24
2               SW1 to BSW  f0/21 to f0/23      LACP    Active
                            f0/22 to f0/24
3               SW2 to MSW  f0/23 to f0/21      LACP    Active
                            f0/24 to f0/22
4               SW2 to BSW  f0/21 to f0/21      LACP    Active
                            f0/22 to f0/22
5               SW3 to MSW  f0/23 to f0/19      LACP    Active
                            f0/24 to f0/20
6               SW3 to BSW  f0/21 to f0/19      LACP    Active
                            f0/22 to f0/20
7               SW4 to MSW  f0/23 to f0/17      LACP    Active
                            f0/24 to f0/18
8               SW4 to BSW  f0/21 to f0/17      LACP    Active
                            f0/22 to f0/18
9               SW5 to MSW  f0/23 to f0/15      LACP    Active
                            f0/24 to f0/16
10              SW6 to BSW  f0/21 to f0/15      LACP    Active
                            f0/22 to f0/16
11              MSW to BSW  f0/1 to f0/1        LACP    Active
                            f0/2 to f0/2
                            f0/3 to f0/3
                            f0/4 to f0/4

From channel group 1 through 6 I can set up fine, but once I try 7 or 8, I get Invalid input detected at channel group number marker.

The switches I am using are the 2960s. Is this a config oversight issue I am missing, or 2960 limit, or an issue w/ PT?

Thanks for your input.

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  • Please add the switch configurations to your question (in text format, using the editor's {} preformat option). Generally, do not create chains or rings with Ethernet. The natural topology is a tree, so you'd connect each access switch to MSW and for redundancy to BSW (don't forget STP). Any reason you use PAGP between MSW and BSW but LACP otherwise? Commented Oct 7 at 7:12
  • Sounds good, I'll change it to reflect a tree. My bad w/ the PAGP, it was supposed to have been changed as well to LACP, but my sleepy brain overlooked it. Originally they were all PAGP, but then it was felt that the edge switches may not necessarily be all Cisco devices, so they were all changed to LACP. I thought I may as well change them all to LACP, but I forgot to change the M to B connection. Commented Oct 7 at 11:42

2 Answers 2

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once I try 7 or 8, I get Invalid input detected at channel group number marker.

The maximum number of Etherchannel link aggregation groups for Catalyst 2960 switches is 6. You can't use 7 or 8.

https://www.cisco.com/c/en/us/td/docs/switches/lan/catalyst2960/software/release/12-2_55_se/configuration/guide/scg_2960/swethchl.html

Possibly, that's also the maximum total number for Packet Tracer - keep in mind that it's a tool for studying for and passing CCNA exams and it largely only supports what it needs to. You might need to use a better simulator, but we can't make any product recommendations here.

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  • To that point, Cisco has better simulators; they just don't give them to CCNA students. (or for free.) Commented Oct 7 at 14:10
  • True, but that is 6 per device, not for the entire network - unless that is a PT limit. Each edge switch only has 2 channels - one to MSW and one to BSW. And those two have a channel to each other which makes 6 for them. Commented Oct 7 at 15:12
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After more research into it, it looks as if PT does have a limit to the number of Etherchannels you can create total. Ah well. I may have to spring for one o' the Pro network simulators.

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