Trunking a cat3750 stack with 3850 or cat9300

[prakavi]

Hi, 

I have  a set of 3 cat 3750 switches  stacked  together with a single ip. I want to add one more switch  , like cat 3850  or cat 9300. Stacking is ruled out. So to  get  the maximum  throughput  can  I trunk ,  the  3850  or 9300 with (10 g)sfp  trunks ? 

[Seb Rupik]

Hi there,

Assuming you are talking about 3750X switches the best you could acheive would be a 60G port-channel, this would reuqire three C3KX-NM-10G modules installed in each switch. That is the highest density SFP+ module the 3750X supports.

Of course you would probably want some of those SFP+ interfaces for uplinks to your core...

cheers,

Seb

[prakavi]

Hi, 

Thank you for the reply. All of the  switches have  10 g capability  and  one 10g  sfp port is used to trunk it to the  core .  Since the switches are stacked and  using a single ip , can I trunk   the sfps from any switch  to the new 3850 or 9300.? FYI  ,  on one floor   suddenly  more users were added .  this floor has  two cat3750 48port switches and one cat3750  24 port switch. This stack is  using a trunk to the core using   a 10 g sfp . Now  I want to add one more switch  either 3850 or 9300  . If I trunk it with  a normal 1 g port  I am losing  a lot. Since I cant stack  with 3850 or 9300 ,  have to use  the TE2   port to trunk. Two TE2  ports   are free . Can I use any one of them to trunk ?

Regards

[Seb Rupik · Accepted solution]

Yes, you can use any free 10G ports you have to connect a 3850/ n9k providing the corresponding 1G interface on the network module is not in use. Check the installation guide:

https://www.cisco.com/c/en/us/td/docs/switches/lan/catalyst3750x_3560x/hardware/install/notes/net_mod_note.html#wp138200

Ideally you will create a port-channel on the 3750 with member interfaces residing on different switches, ie:

Te1/1/1 and Te2/1/1

cheers,

Seb.

[prakavi]

Hi, 

Thank you for the  quick reply. I have a 10 g link  on one switch and 1g  back up link  on one switch. So One switch is  free .  I can use the  10 g port on that switch  to trunk  it with cat3850 . Only thing is that  whether the   same type of sfps can be used  in 3850/ 9300 and 3750  is the concern . 

Regards

[Joseph W. Doherty]

If they are Cisco SFPs, Cisco documents what SFPs work on what Cisco devices with which IOS versions. (Good chance, in your case, the answer is yes.)

[Seb Rupik · Accepted solution]

If it is a short distance (10m or less) then I recommend using twinax cables ( eg: SFP-H10GB-ACU7M, SFP-10G-AOC10M) :

https://www.cisco.com/c/en/us/products/collateral/interfaces-modules/transceiver-modules/data_sheet_c78-455693.html

Check compatablity of SFPs here:

https://www.cisco.com/c/en/us/td/docs/interfaces_modules/transceiver_modules/compatibility/matrix/10GE_Tx_Matrix.html

cheers,

Seb.

[prakavi]

Hi, 

Thank you. One more query. If  I have only one switch 3750   and  one 10 g up link and one 1gb  backup link  to the core, can  I use the  free 10G   to  create a trunk  to add another  switch like 3850/ 9300? will it work ? 

Regards

[Seb Rupik · Accepted solution]

Assuming you are using a C3KX-NM-10G , then if you are using both 10G interfaces, you will not be able to use the other 1G interfaces, so in your scenario you would loose your backup 1G link to the core

Gi1/1/1, Gi1/1/2  or  Te1/1/1

Gi1/1/3, Gi1/1/4  or  Te1/1/2

cheers,

Seb.