RE: Spanning-tree link-type point-to-point or portfast trunk

Reni,

Point-to-point allows for a fast transition to forwarding when one side becomes designated in rstp, trunk ports are typically set to this without configuring anything. Spanning-tree portfast trunk would be used for a router on a stick implementation to switch the port to an edge port, meaning no forwarding / proposal delay.

!
interface FastEthernet0/6
 switchport trunk encapsulation dot1q
 switchport trunk allowed vlan 67,146
 switchport mode trunk
end

Rack1SW2#show spanning-tree interface f0/6

Vlan Role Sts Cost Prio.Nbr Type
------------------- ---- --- --------- -------- --------------------------------
VLAN0067 Desg FWD 19 128.8 P2p
VLAN0146 Desg FWD 19 128.8 P2p

*Mar 4 18:40:01.793: %LINK-3-UPDOWN: Interface FastEthernet0/6, changed state to up
Rack1SW2(config-if)#
*Mar 4 18:40:04.620: RSTP(67): initializing port Fa0/6
*Mar 4 18:40:04.620: RSTP(67): Fa0/6 is now designated
*Mar 4 18:40:04.620: RSTP(146): initializing port Fa0/6
*Mar 4 18:40:04.620: RSTP(146): Fa0/6 is now designated
*Mar 4 18:40:04.628: RSTP(67): transmitting a proposal on Fa0/6
*Mar 4 18:40:04.628: RSTP(146): transmitting a proposal on Fa0/6
.
.
.
Rack1SW2(config-if)#
*Mar 4 18:40:34.634: RSTP(67): Fa0/6 fdwhile Expired
*Mar 4 18:40:34.634: RSTP(146): Fa0/6 fdwhile Expired

!
interface FastEthernet0/6
 switchport trunk encapsulation dot1q
 switchport trunk allowed vlan 67,146
 switchport mode trunk
 spanning-tree portfast trunk
end

*Mar 4 18:41:17.601: %LINK-3-UPDOWN: Interface FastEthernet0/6, changed state to up
Rack1SW2(config-if)#
*Mar 4 18:41:20.201: RSTP(67): initializing port Fa0/6
*Mar 4 18:41:20.201: RSTP(67): Fa0/6 is now designated
*Mar 4 18:41:20.201: RSTP(146): initializing port Fa0/6
*Mar 4 18:41:20.201: RSTP(146): Fa0/6 is now designated

Rack1SW2(config-if)#do show spann int f0/6

Vlan Role Sts Cost Prio.Nbr Type
------------------- ---- --- --------- -------- --------------------------------
VLAN0067 Desg FWD 19 128.8 P2p Edge
VLAN0146 Desg FWD 19 128.8 P2p Edge

HTH,

-ryan

-----Original Message-----
From: nobody_at_groupstudy.com [mailto:nobody_at_groupstudy.com] On Behalf Of Rene
Sent: Wednesday, May 13, 2009 2:38 PM
To: Amarnath Mamidi
Subject: Spanning-tree link-type point-to-point or portfast trunk

HI folks,

just playing arround with spanning-tree,

can someone declare what the differents between the interface cmd
"spanning-tree link-type point-to-point" and "spanning-tree portfast trunk"
is ?

cheers Reni

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Received on Wed May 13 2009 - 15:42:17 ART