Tuesday, January 27, 2009

Difference between a Trunk port and a Tunnel port

Trunk - physical port, dot1q or ISL protocol, encapsulates multiple VLAN's

Tunnel - logical port, can be layer 2 (L2TP) or layer 3 (GRE)

I would say trunk port can be configured to carry multiple vlan's.

Tunnel port will carry only 2 Vlan. Mainly used in service provider environment. say for example you have two switch

SW1(Trunk Port)---------(tunnel Port VLAN-ID 2)SW2

In the above example SW1 is at customer end can have any vlan configured but SW2 which is at SP end will have only one VLAN-ID 2 as access VLAN ok this VLAN-ID 2 will be dedicated for That perticular customer to segregate the traffic from that customer to SP network

Multiple VLANs from multiple customer sites can be transported through the Service Provider's network using 802.1Q tunneling. This is accomplished by adding an additional VLAN tag for each customer - when packets arrive at the edge switch, the VLAN tag assigned to that customer is removed, leaving the packets tagged as they were when they entered the Service Provider network.

Best Regards,
Deepak Arora

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