connction between devices, and routed port question

[daniel4579329]

1. wanted to know what is the connction  i need /smart to do between 

router and router

router and L3 switch 

L3 switch and L2 switch 

2. pretty much related to the previous question, is it smart to connect L2 switch and L3 switch and make the L3 switch a routed port

thanks for the help :)

[Seb Rupik]

Hi there,

1)

Router to Router : use either routed switchports or routed sub-interfaces

Router to L3 switch: routed sub-interfaces to trunk switchport and SVIs

L3 switch to L2 switch: trunk to trunk

2) If you are using a L3 switch I would always suggest using SVIs as they provide more flexibility in making a VLAN available across multiple switchports.

cheers,

Seb.

[Martin L]

My answer is similar to Seb's but from perspective of cisco exam taker:
Router to Router: mostly routed ports are used. Never seen sub-interfaces used here on cisco exam.
Router to L3 switch: routed port is used to access port on sw; L3 switch will do routing using its SVIs among vlans and routing to/from router via SVI;
* Router to L2 switch is where routed sub-interfaces of a router to L2 switch trunk switchport is needed. this is called ROAS -router-on a stick who does routing (since L2 sw cannot)
L3 switch to L2 switch: trunk to trunk

Regards, ML
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[Martin L]

alternatively, you can use routed port on both switch and router to routing traffic; you can take any L3 switch port and convert it to be a routed port, then add IP; example

interface GigabitEthernet1/0/7
no switchport
ip address 10.1.1.1 255.255.255.252
duplex auto
speed auto

not likely scenario for ccna level exam; only seen this option used on ccie lab exam;

[daniel4579329]

Maybe a bit stupid question but which link/cable would you use for all of these devices that i mantion 

thanks for the halp (:

[Seb Rupik]

Hi there,

in the past you would have need to carefully select the correct UTP cable when connecting router-router, router-switch, etc. Connecting devices on the same type required a crossover cable, in all other scenarios a straight through cable was used. Then came along auto-MIDX which meant you didn't really need to worry and crossover cables were banished to box of network voodoo along with vampire taps!

Nowadays it is more common to connect infrastructure together with fibre or twinax.

cheers,

Seb.

[Martin L]

not stupid question; auto-MIDX will take care cables in real world but I am not sure if it is still on exam (it was when I took it);  check ccna book, if cables types are mentioned, it might be on exam.

As I remember Cross-over cables:

PC to router

PC to PC

sw to sw

router to router

hub to hub and hub to sw

Regards, ML
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