Options
Negotiate a Trunk
up2thetime
Member Posts: 154
in CCNA & CCENT
Does anyone know how i can set ports on a 2924 to auto-negotiate a trunk?
I cannot figure out the command even with ios help...
I figured out how to set either ISL or dot1q... but the port still has "Negotiating of Trunking: Disabled"
I cannot figure out the command even with ios help...
I figured out how to set either ISL or dot1q... but the port still has "Negotiating of Trunking: Disabled"
Comments
-
Options
mikej412
Member Posts: 10,086 ■■■■■■■■■■
The 2900 XL switches didn't/don't support DTP.
Check out DTP in Table 2. The 2900XL's are the first column.
Catalyst 2950 Series Software Feature Comparison--SI and EI [Cisco Catalyst 2950 Series Switches] - Cisco Systems:mike: Cisco Certifications -- Collect the Entire Set! -
Options
bigheadx
Member Posts: 36 ■■□□□□□□□□
What he said ^^!WIP: CCNA, BS Sys/Net Admin
Taking one byte out of computers, one bit at a time!
College Fund: [-/
] (15000)
-
OptionsAlexMR
Member Posts: 275
Also, you can't have both switchports set to dynamic auto because they will always become an access port. One of them must be configured as a trunk...or dynamic desirable.Training/Studying for....CCNP (BSCI) and some MS.
-
Options
ColbyG
Member Posts: 1,264
Also, you can't have both switchports trying set to dynamic negociate auto because they will always become an access port. One of them must be coonfigured as a trunk.
wat...? -
Options
Bl8ckr0uter
Inactive Imported Users Posts: 5,031 ■■■■■■■■□□
Also, you can't have both switchports trying set to dynamic negociate auto because they will always become an access port. One of them must be coonfigured as a trunk.
By default the ports are to Dynamic Auto. So they will become trunks by default since Dynamic auto will become trunks if neighbor ports are set to Auto/Desirable/Trunk. I believe that if the neighbor port is set to access the port will become access. I know that this applies to the 2950 but I am not sure about any others.
I pulled this from my notes, which were based on the CCNA study guide. -
Optionsrwwest7
Member Posts: 300
The whole point of the dynamic thing is so people can pull switches out of the box, plug them in, and be trunking without knowing even what trunking is.Also, you can't have both switchports trying set to dynamic negociate auto because they will always become an access port. One of them must be coonfigured as a trunk. -
Options
luke_bibby
Member Posts: 162
Also, you can't have both switchports trying set to dynamic negociate auto because they will always become an access port. One of them must be coonfigured as a trunk.
I think what you meant was that if two connected switches are configured as "dynamic auto" then neither switch will send a DTP frame to negotiate the trunk, and thus no trunk will be formed. If one is configured as "trunk" or "dynamic desirable" then a trunk will form with the other being set to "dynamic auto"By default the ports are to Dynamic Auto. So they will become trunks by default since Dynamic auto will become trunks if neighbor ports are set to Auto/Desirable/Trunk. I believe that if the neighbor port is set to access the port will become access. I know that this applies to the 2950 but I am not sure about any others.
Two "dynamic auto" configurations will not form a trunk. 2950's also default to "dynamic desirable" by the way :P -
Optionsrwwest7
Member Posts: 300
Cisco Certification Exam Review Trunking Modes 2950 Switchdynamic desirable: Default for many new Cisco switches, a port in this mode is actively attempting to form a trunk via Dynamic Trunking Protocol (DTP).
dynamic auto: A port in this mode will form a trunk, but is not actively attempting to negotiate trunking, so DTP frames are not transmitted. -
OptionsAlexMR
Member Posts: 275
Ok. It was late, I was tired from studying like 100 hours for the CCNA voice and I mistyped "trying". Now I edited my post and i think it is correct.The whole point of the dynamic thing is so people can pull switches out of the box, plug them in, and be trunking without knowing even what trunking is.
I'm pretty sure this is incorrect. They negotiate a trunk out of the box because they are dynamic/desirable by default. I might be wrong about it but I doubt I am.luke_bibby wrote: »I think what you meant was that if two connected switches are configured as "dynamic auto" then neither switch will send a DTP frame to negotiate the trunk, and thus no trunk will be formed. If one is configured as "trunk" or "dynamic desirable" then a trunk will form with the other being set to "dynamic auto"
Two "dynamic auto" configurations will not form a trunk. 2950's also default to "dynamic desirable" by the way :P
You got it right, Luke.Training/Studying for....CCNP (BSCI) and some MS. -
Optionsmikej412
Member Posts: 10,086 ■■■■■■■■■■
The question was about a 2924 switch. It doesn't support DTP so there are NO negeotion options.
The only trunking options on the 2924 are setting the encapsulation and statically configuring the interface so that it forms a trunk.
Answering a question that wasn't asked is confusing when people search the forum for 2924 and trunking or DTP and find information in the thread that isn't relevant.
If you want to discuss dynamic desirable and dynamic auto -- it's been done recently in this thread
http://www.techexams.net/forums/ccna-ccent/46821-does-tagging-encapsulation-always-occur.htmlISL Trunks will always tag traffic
Trunking depends on the switches.
2924-XL-EN switches don't support DTP, so you have manually tell a port to trunk.
2950 switches will attempt to trunk by default -- but only support dot1q. I assume the 2960 is the same.
3550 switches default to dynamic desirable -- so they will trunk with other 3550 switches -- and 3560 switches and 3750 switches which default to dynamic auto.
3560 (and 3750) default to dynamic auto -- and 2 dynamic auto switches will NOT negotiate a trunk. You'd have to change the default configuration on at least one switch to get it to trunk.:mike: Cisco Certifications -- Collect the Entire Set! -
Optionsrwwest7
Member Posts: 300
You say I'm wrong, then you say the same thing I did. They negotiate trunk out of the box. Thank you.I'm pretty sure this is incorrect. They negotiate a trunk out of the box because they are dynamic/desirable by default. I might be wrong about it but I doubt I am. -
Optionsncsugrad2002
Member Posts: 131
You say I'm wrong, then you say the same thing I did. They negotiate trunk out of the box. Thank you.
lol, i was thinking the same thing.. you guys said the exact same thing but were disagreeing? haha.
and yes, that is correct--FOR SWITCHES THAT SUPPORT TRUNKING. the 2924 does not. -
OptionsAlexMR
Member Posts: 275
LOL. I sent him a PM. I was trying to quote the preceding post.Training/Studying for....CCNP (BSCI) and some MS.
-
OptionsMorty3
Member Posts: 139
ncsugrad2002 wrote: »lol, i was thinking the same thing.. you guys said the exact same thing but were disagreeing? haha.
and yes, that is correct--FOR SWITCHES THAT SUPPORT TRUNKING. the 2924 does not.
Haha, for switches that support dynamic trunking. The 2924 does not. It does support trunking, though it is a lil different on these switches. I think it is called like "Multi" or something. Not sure on this, I remember it was different though. Had a few in my schools lab.CCNA, CCNA:Sec, Net+, Sonicwall Admin (fwiw). Constantly getting into new stuff.
