From: L. Jankok (lj@2u2.nu)
Date: Wed Jul 02 2008 - 17:07:03 ART
Hi,
I have three switches.
SW1 <-> SW2 <-> SW3
On SW1 I have a port-channel towards SW2 like this:
interface Port-channel10
switchport trunk encapsulation dot1q
switchport mode trunk
end
On SW3 I have a port-channel towards SW2 like this:
interface Port-channel10
switchport trunk encapsulation dot1q
switchport mode trunk
end
on SW2 I have for the ports to SW1 and SW3 this
interface FastEthernet0/13
switchport access vlan 100
switchport mode dot1q-tunnel
l2protocol-tunnel cdp
l2protocol-tunnel stp
l2protocol-tunnel point-to-point pagp
l2protocol-tunnel point-to-point lacp
no cdp enable
end
This results on both SW3 and SW1 in this:
Device ID Local Intrfce Holdtme Capability Platform Port ID
Rack1SW1 Fas 0/16 151 S I WS-C3750G Gig
1/0/13
Rack1SW1 Fas 0/18 151 S I WS-C3750G Gig
1/0/15
Rack1SW1 Fas 0/17 140 S I WS-C3750G Gig
1/0/14
Number of channel-groups in use: 1
Number of aggregators: 1
Group Port-channel Protocol Ports
------+-------------+-----------+-----------------------------------------------
10 Po10(SU) PAgP Fa0/16(P) Fa0/17(P) Fa0/18(P)
Question:
Eventought the protocol of the etherchannel is PAgp if I disable
"l2protocol-tunnel point-to-point lacp"
on SW2 on the respective interfaces the etherchannel between SW1 and SW3
will go down.
The switches SW1 and SW3 will still see eacht other through cdp but the
etherchannel will be down.
Why is this happening?. It seems that LACP is needed eventhough PAgP is
used.
Regards,
LJ
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