From: Victor Cappuccio (cvictor@protokolgroup.com)
Date: Tue Jan 10 2006 - 22:28:53 GMT-3
Hello People..
Please help me to clarify this blur that I have:
www.cisco.com/univercd/cc/td/doc/product/lan/c3550/12225seb/scg/swvlan.htm#w
p1150302
By default, a trunk port sends traffic to and receives traffic from all
VLANs. All VLAN IDs, 1 to 4094, are allowed on each trunk.
Switch#show int trunk
<..>
Port Vlans allowed on trunk
Fa0/1 1-4094
<..>
Switch#show run interface fastEthernet 0/1
Building configuration...
Current configuration : 132 bytes
!
interface FastEthernet0/1
switchport trunk encapsulation dot1q
switchport trunk allowed vlan 2-4094
switchport mode trunk
end
Switch#show int trunk
<..>
Port Vlans allowed on trunk
Fa0/1 2-4094
<..>
Also says that: To reduce the risk of spanning-tree loops or storms, you can
disable VLAN 1 on any individual VLAN trunk port by removing VLAN 1 from the
allowed list. This is known as VLAN 1 minimization.
ohh my god this make life a little bit harder.. Is there any hidden concept
here about trunking, Q in Q or something similar?
When you remove VLAN 1 from a trunk port, the interface continues to send
and receive management traffic, for example, Cisco Discovery Protocol (CDP),
Port Aggregation Protocol (PAgP), Link Aggregation Control Protocol (LACP),
Dynamic Trunking Protocol (DTP), and VLAN Trunking Protocol (VTP) in VLAN 1.
Why Sending then all this Management Traffic??
Now it continues down, to a lot of stuff I could not process :D
But Ok the concept is simple, helps reducing traffic, and increasing network
bandwidth.
But my question is then what is the difference between Pruning-Eligible List
and removing Traffic from the vlans? Is there something bigger ??
Thanks
Victor.
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