Chciałbym poruszyć pewne zagadnienie związane z LACP oraz PAGP, który ostatnio mnie zaintrygowało.
Szukając różnic pomiędzy PAGP i LACP znajduję głównie informacje w stylu "PagP is cisco proprietary, LACP is standards based itp...". W praktyce jednak znalazłem moim zdaniem inną bardzo ważną różnicę, która poskutkowała odcięciem jednej z moich lokacji.
Do rzeczy: Z moich testów wynika, że w przypadku gdy po jednej stronie będzie skonfigurowany portchannel, a na drugim swichu nie, to
- PAGP nie wynegozjuje etherchannela i potraktuje porty jako niezależne. Nie odetnie tym samym przełącznika i będzie działać na jednym linku (spanning-tree shutnie redundatne linki).
- LACP wyłączy (suspended) porty i tym samym "odetnie" przełącznik podłączony tym channelem
W tym konkretnym przypadku, można pokusić się o stwierdzenie, że PAGP jest bardziej bezpieczny..?/..
SW1 = SW2
Kod: Zaznacz cały
SW2#sh run int f0/14
Building configuration...
Current configuration : 161 bytes
!
interface FastEthernet0/14
switchport trunk encapsulation dot1q
switchport trunk allowed vlan 10
switchport mode trunk
channel-group 1 mode desirable
end
SW2#sh run int f0/15
Building configuration...
Current configuration : 161 bytes
!
interface FastEthernet0/15
switchport trunk encapsulation dot1q
switchport trunk allowed vlan 10
switchport mode trunk
channel-group 1 mode desirable
end
SW2#sh run int po 1
Building configuration...
Current configuration : 126 bytes
!
interface Port-channel1
switchport trunk encapsulation dot1q
switchport trunk allowed vlan 10
switchport mode trunk
end
SW2#sh etherchannel summary
Flags: D - down P - in port-channel
I - stand-alone s - suspended
H - Hot-standby (LACP only)
R - Layer3 S - Layer2
U - in use f - failed to allocate aggregator
u - unsuitable for bundling
w - waiting to be aggregated
d - default port
Number of channel-groups in use: 1
Number of aggregators: 1
Group Port-channel Protocol Ports
------+-------------+-----------+-----------------------------------------------
1 Po1(SD) PAgP Fa0/14(I) Fa0/15(I)
SW2#sh spanning-tree vlan 10
VLAN0010
Spanning tree enabled protocol ieee
Root ID Priority 8202
Address 001b.d5e2.f100
Cost 19
Port 16 (FastEthernet0/14)
Hello Time 2 sec Max Age 20 sec Forward Delay 15 sec
Bridge ID Priority 32778 (priority 32768 sys-id-ext 10)
Address 001b.d48a.0980
Hello Time 2 sec Max Age 20 sec Forward Delay 15 sec
Aging Time 300
Interface Role Sts Cost Prio.Nbr Type
---------------- ---- --- --------- -------- --------------------------------
Fa0/14 Root FWD 19 128.16 P2p
Fa0/15 Altn BLK 19 128.17 P2p
Kod: Zaznacz cały
Current configuration : 129 bytes
!
interface FastEthernet0/14
switchport trunk encapsulation dot1q
switchport trunk allowed vlan 10
switchport mode trunk
end
SW1#sh run int f0/15
Building configuration...
Current configuration : 129 bytes
!
interface FastEthernet0/15
switchport trunk encapsulation dot1q
switchport trunk allowed vlan 10
switchport mode trunk
end
SW1#sh spanning-tree vlan 10
VLAN0010
Spanning tree enabled protocol ieee
Root ID Priority 8202
Address 001b.d5e2.f100
This bridge is the root
Hello Time 2 sec Max Age 20 sec Forward Delay 15 sec
Bridge ID Priority 8202 (priority 8192 sys-id-ext 10)
Address 001b.d5e2.f100
Hello Time 2 sec Max Age 20 sec Forward Delay 15 sec
Aging Time 300
Interface Role Sts Cost Prio.Nbr Type
---------------- ---- --- --------- -------- --------------------------------
Fa0/14 Desg FWD 19 128.16 P2p
Fa0/15 Desg FWD 19 128.17 P2p
Kod: Zaznacz cały
SW2#sh run int f0/14
Building configuration...
Current configuration : 158 bytes
!
interface FastEthernet0/14
switchport trunk encapsulation dot1q
switchport trunk allowed vlan 10
switchport mode trunk
channel-group 1 mode active
end
SW2#sh run int f0/15
Building configuration...
Current configuration : 158 bytes
!
interface FastEthernet0/15
switchport trunk encapsulation dot1q
switchport trunk allowed vlan 10
switchport mode trunk
channel-group 1 mode active
end
13:23:43: %EC-5-L3DONTBNDL2: Fa0/15 suspended: LACP currently not enabled on the remote port.
13:23:43: %EC-5-L3DONTBNDL2: Fa0/14 suspended: LACP currently not enabled on the remote port.
SW2#sh etherchannel su
Flags: D - down P - in port-channel
I - stand-alone s - suspended
H - Hot-standby (LACP only)
R - Layer3 S - Layer2
U - in use f - failed to allocate aggregator
u - unsuitable for bundling
w - waiting to be aggregated
d - default port
Number of channel-groups in use: 1
Number of aggregators: 1
Group Port-channel Protocol Ports
------+-------------+-----------+-----------------------------------------------
1 Po1(SD) LACP Fa0/14(s) Fa0/15(s)
SW2#sh spanning-tree vlan 10
Spanning tree instance(s) for vlan 10 does not exist.
SW2#sh int f0/14
FastEthernet0/14 is up, line protocol is down (suspended)
