12-22-2013 09:47 PM - edited 03-07-2019 05:12 PM
Hi ,
what are the port roles of the switch in the following scenario if it is connecting to some down stream switches and currently acting as a root bridge?
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12-23-2013 10:34 AM
Hi Bharad,
what are the port roles on the root bridge if two ports are inter connected to each other?
One of the ports is Designated Forwarding, the other is Backup Discarding.
Best regards,
Peter
12-23-2013 01:07 AM
What do you mean by self loop? Do you have two ports on that switch connected to each other?
Daniel Dib
CCIE #37149
12-23-2013 01:29 AM
Are you asking what the port states will be when you have an active loop in the network?
I would hope you would be using BPDGuard to prevent something like this...
12-23-2013 01:32 AM
Hello
If you have a switch (1) which is the root and 2 other switches (2 & 3 )connected to the root switch
Then the port roles will be:
Switch 1) all interconnected links designated forwarding
Switch 2 & 3 ) interconnected link to switch 1 - root ports -forwarding
Switch 2 & 3 ) will negotiate their interconnected links between each other and one port will be the designated port for this lan segment and the other will become a Blocked port as its neither a root or designated port
Res
Paul
Sent from Cisco Technical Support iPad App
12-23-2013 10:29 AM
Hi All,
what are the port roles on the root bridge if two ports are inter connected to each other?
Regards,
Bharad.
12-23-2013 10:34 AM
Hi Bharad,
what are the port roles on the root bridge if two ports are inter connected to each other?
One of the ports is Designated Forwarding, the other is Backup Discarding.
Best regards,
Peter
12-23-2013 05:54 PM
Hello,
if your scenario is looping f1 and f2 of Root Bridge, then
In case of pvst/rapid-pvst/mst
F1 --> will be the desiginated forwarding
F2 --> will be in backup bloacking
Reson for the above selection is, Root Bridge priority is tie / Root Bridge id is tie / and port path cost is tie / port priority is tie but the port identifier is different (Port identifier is the combination of port priority + the port number (this changes depends on the hardware)). please find the below example
Port 1 (GigabitEthernet1/0/1) of VLAN0001 is designated forwarding
Port path cost 4, Port priority 128, Port Identifier 128.1.
Designated root has priority 40961, address b4a4.e3f4.b000
Designated bridge has priority 40961, address b4a4.e3f4.b000
Designated port id is 128.1, designated path cost 0
Timers: message age 0, forward delay 0, hold 0
Number of transitions to forwarding state: 1
Link type is point-to-point by default
BPDU: sent 19, received 1
Port 2 (GigabitEthernet1/0/2) of VLAN0001 is backup blocking
Port path cost 4, Port priority 128, Port Identifier 128.2.
Designated root has priority 40961, address b4a4.e3f4.b000
Designated bridge has priority 40961, address b4a4.e3f4.b000
Designated port id is 128.1, designated path cost 0
Timers: message age 16, forward delay 0, hold 0
Number of transitions to forwarding state: 0
Link type is point-to-point by default
BPDU: sent 1, received 19
Regards
Azif
12-24-2013 02:43 AM
Hi All,
Thanks Alot for you help.
Regards,
Bharad.
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