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I have 2 cisco core switches and 3 access layer switches. I will be using 6 &nbsp;gigabit ports from the core switch to create 3 port channels , one for every access layer switch. <br />
My 3 questions are :<br />
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1. the first two ports on the core will form port channel group 1 , the other two port channel goup 2 and the next 2 , port channel group 3 , right ? Each group will have a different id number..<br />
2. where will i put the command switch port trunk allow vlan all... to the core or on the access switches , or on both ?<br />
3. On the access layer switch , when i create the port group what id will i be using ? I would assume it has to match the id on the core switch , right ?
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I have 2 cisco core switches and 3 access layer switches. I will be using 6  gigabit ports from the core switch to create 3 port channels , one for every access layer switch. 
My 3 questions are :

1. the first two ports on the core will form port channel group 1 , the other two port channel goup 2 and the next 2 , port channel group 3 , right ? Each group will have a different id number..
2. where will i put the command switch port trunk allow vlan all... to the core or on the access switches , or on both ?
3. On the access layer switch , when i create the port group what id will i be using ? I would assume it has to match the id on the core switch , right ?

question in port channels

A router is a networking device that forwards data packets between computer networks. Routers perform the "traffic directing" functions on the Internet. The most familiar type of routers are home and small office cable or DSL routers that simply pass data, such as web pages, email, IM, and videos between computers and the Internet. More sophisticated routers, such as enterprise routers, connect large business or ISP networks up to the powerful core routers that forward data at high speed along the optical fiber lines of the Internet backbone. Though routers are typically dedicated hardware devices, use of software-based routers has grown increasingly common.

Routers

A switch is a device that filters and forwards packets of data between LAN segments. Switches operate at the data link layer or the network layer of the Open Systems Interconnection (OSI) Reference Model and therefore support any packet protocol. LANs that use switches to join segments are called switched LANs or, in the case of Ethernet networks, switched Ethernet LANs. A hub is a connection point for devices in a network. Hubs are commonly used to connect segments of a LAN. A hub contains multiple ports; when a packet arrives at one port, it is copied to the other ports so that all segments of the LAN can see all packets.