Hi guys. Some time ago in my company we moved one of our datacenter to another location.
This is a very basic draw of the connection between the 2 sites.
SW-DC1 <---- Link 1------> SW-DC2
|<----Link 2 ----->|
SW-DC1 are two 4500x in vss mode
SW-DC2 are two 4500x in vss mode
All with the same firmware version.
Before the migration the scenario was the same, the two links were 2 fiber between 2 sites managed by us, and running link agregation protocol to high availability in trunk mode with multiple vlans.
Now the links are:
Link 1 is a 10gbps fiber, provided by local ISP
Link 2 is a 10gbps fiber, provided by local ISP too.
But our ISP told us that we cannot do a link agregation between the 2 links due to the difference delay between the 2 links. I don't know if true, I'm not sure how it works LAGP in deep. So we have the 2 links in trunk mode with multiple vlans.
All vlans has been passed in the 2 links and we use spanning-tree vlan cost command to make a kind of load balance.
We are running rapid-pvst protocol.
If I remove a vlan from one link, the traffic trough this vlan it automatically passed to the other link with practically no downtime (running a ping, sometime just loss 1 packet)
But if we have a link failure it took more than 20 seconds to move all the traffic from one link to another.
This is the configuration in the 2 switches:
----------------------------------------
show spanning-tree summary
Switch is in rapid-pvst mode
Root bridge for: VLAN0001, VLAN0090, VLAN0100, VLAN0333, VLAN0500-VLAN0502
VLAN0504-VLAN0508, VLAN0727, VLAN0900, VLAN0909, VLAN0912, VLAN0916
VLAN0925, VLAN0990, VLAN1000-VLAN1001, VLAN1024-VLAN1037, VLAN1042-VLAN1045
VLAN1096, VLAN1202, VLAN1299, VLAN2000, VLAN2014-VLAN2015, VLAN2017-VLAN201
VLAN2222, VLAN2500
Extended system ID is enabled
Portfast Default is disabled
PortFast BPDU Guard Default is disabled
Portfast BPDU Filter Default is disabled
Loopguard Default is disabled
EtherChannel misconfig guard is enabled
UplinkFast is disabled
BackboneFast is disabled
Configured Pathcost method used is short
---------------------------------
I was reading about this, and I found the backbonefast and uplinkfast commands. But in the cisco site I found this too,
"You do not need to configure backbone fast with RSTP or IEEE 802.1w because
the mechanism is natively included and automatically enabled in RSTP"
But in the command above it seems to be disabled.
I've to execute spanning-tree backbonefast? In this case, if this command disruptive? If this feature is enable, will improve the perfomance
in case of link failure or in rstp this 20seconds is the minimun time?
Thanks in advance
