Cisco command line encapsulation dot1q
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Hello,
I am currently working on Packet Tracer and I wanted to know what the command line "encapsulation dot1q 5" represents in a Cisco router (5 being a VLAN number, I suppose). I also have another question: what is the difference between trunk mode and access mode in a switch? From what I understand, trunk is used to connect devices like routers and switches, while access is for connecting a PC.
If you could clarify this topic for me.
Thank you.
Configuration: Windows 7 / Firefox 10.0.2
I am currently working on Packet Tracer and I wanted to know what the command line "encapsulation dot1q 5" represents in a Cisco router (5 being a VLAN number, I suppose). I also have another question: what is the difference between trunk mode and access mode in a switch? From what I understand, trunk is used to connect devices like routers and switches, while access is for connecting a PC.
If you could clarify this topic for me.
Thank you.
Configuration: Windows 7 / Firefox 10.0.2
3 answers
Hello,
Not quite. The word "trunk" (this can be seen as VLAN multiplexing) is 100% Cisco terminology. Indeed, they were the pioneers of this mechanism (like other network protocols) and its standardization is heavily inspired by their ISL protocol. On Cisco routers, the command "encapsulation dot1q" (usually configured on a sub-interface of an interface connected to a switch) is just used to specify the type of encapsulation: dot1q = .q (in fr) refers to the standard of trunking, that is to say, the IEEE 802.1q standard.
So this command is only used to ensure continuity of a VLAN coming from a switch on a router via a trunk link. Inter-VLAN routing is enabled by the @IP/mask that you add to the next line.
Not quite. The word "trunk" (this can be seen as VLAN multiplexing) is 100% Cisco terminology. Indeed, they were the pioneers of this mechanism (like other network protocols) and its standardization is heavily inspired by their ISL protocol. On Cisco routers, the command "encapsulation dot1q" (usually configured on a sub-interface of an interface connected to a switch) is just used to specify the type of encapsulation: dot1q = .q (in fr) refers to the standard of trunking, that is to say, the IEEE 802.1q standard.
So this command is only used to ensure continuity of a VLAN coming from a switch on a router via a trunk link. Inter-VLAN routing is enabled by the @IP/mask that you add to the next line.
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Thank you very much for providing so much detail.
