Redundancy between 2 6850

[sacaminas]

Hello sir:
I have two 6850 and I have configured both of them with flat SPT using G1 and G2 ports for redundancy.
Testing the redundancy when I unplugged the G1 port all works without problems but when I unplugged the G2 ports the 6850 build the new amap and y lost some packets losting the conection around 10 seconds therefore the phone are rebooted.
Can Someone explain me how this time could be shorter ?
Thanks

[silvio]

If you would like to connect two 6850 via two ports why don't you use LACP? Then you have redundance and load balancing.
regards Silvio

[sacaminas]

Hello Silvio:
May be I don´t explain my problem .
I have two 6850 and now they are conected using G1 (red link) port with spanning tree mode Flat.
I would like conect the G2 (blue link) ports to make a backup connection and if the G1 connection fail the G2 will be forwarding.
It´s something like this.

Thanks

[devnull]

yes..
But why don't you connect both cables, and make an aggregate out of it. that will work fine, in normal times you can use both links (double the link bandwidth) if any of the links goes down the other will continue to work.
If it gets back it will be re - integrated in the LACP trunk/channel/lagg. So there is no need for spanning tree and your 10 seconds should not occur. This is because the lacp lagg s seen as one link.
Just take a look in the User guide and test!

[sacaminas]

Sorry again Silvio this was not the real scenario:
It´s this

I have three 6850, 1,2,3.
Link A and B are working fine, but now I would like Conect the C link for redundancy.
Link C work fine with spanning tree mode flat.
The problems araise when I unplugged the A link and the switch 3 must re-build the amap and I lost the connection around 10 seconds and the phone are rebooted.
I hope that this time I explain it better.

[silvio]

Hi,
I can't download the jpg (it is 0 byte). Try it again at this forum (don't understand spain ).
Also give us some outputs of the switches:
> show spanntree
> show spanntree 1
> show spanntree ports active

regards
Silvio

[sacaminas]

Hi Silvio, here is the information, if you need anything tell me:
Switch3

show spantree 1
Spanning Tree Parameters for Vlan 1
Spanning Tree Status : ON,
Protocol : IEEE Rapid STP,
mode : 1X1 (1 STP per Vlan),
Priority : 32768 (0x8000),
Bridge ID : 8000-00:e0:b1:8b:58:d6,
Designated Root : 1000-00:e0:b1:bc:8e:9b,
Cost to Root Bridge : 4,
Root Port : Slot 1 Interface 1,
Next Best Root Cost : 0,
Next Best Root Port : None,
TxHoldCount : 3,
Topology Changes : 18,
Topology age : 8 days and 01:27:53,
Current Parameters (seconds)
Max Age = 20,
Forward Delay = 15,
Hello Time = 2
Parameters system uses when attempting to become root
System Max Age = 20,
System Forward Delay = 15,
System Hello Time = 2

show spantree ports active
Vlan Port Oper Status Path Cost Role
-----+-----+------------+---------+-------
1 1/1 FORW 4 ROOT
1 1/47 FORW 19 DESG
9 1/1 FORW 4 DESG
9 1/2 FORW 19 DESG
9 1/47 FORW 19 DESG
10 1/1 FORW 4 DESG
10 1/2 FORW 19 DESG
10 1/47 FORW 19 DESG
11 1/1 FORW 4 DESG
11 1/2 FORW 19 DESG
11 1/47 FORW 19 DESG
12 1/1 FORW 4 DESG
12 1/2 FORW 19 DESG
20 1/1 FORW 4 DESG
20 1/2 FORW 19 DESG
20 1/47 FORW 19 DESG
22 1/1 FORW 4 DESG
22 1/2 FORW 19 DESG
22 1/45 FORW 19 DESG
22 1/47 FORW 19 DESG
24 1/1 FORW 4 DESG
24 1/2 FORW 19 DESG

show spantree
Spanning Tree Path Cost Mode : AUTO
Vlan STP Status Protocol Priority
-----+----------+--------+--------------
1 ON RSTP 32768 (0x8000)
9 ON RSTP 32768 (0x8000)
10 ON RSTP 32768 (0x8000)
11 ON RSTP 32768 (0x8000)
12 ON RSTP 32768 (0x8000)
20 ON RSTP 32768 (0x8000)
22 ON RSTP 32768 (0x8000)
24 ON RSTP 32768 (0x8000)
26 ON RSTP 32768 (0x8000)
28 ON RSTP 32768 (0x8000)
30 ON RSTP 32768 (0x8000)
32 ON RSTP 32768 (0x8000)
40 ON RSTP 32768 (0x8000)
100 ON RSTP 32768 (0x8000)
101 ON RSTP 32768 (0x8000)
102 ON RSTP 32768 (0x8000)
103 ON RSTP 32768 (0x8000)
104 ON RSTP 32768 (0x8000)
107 ON RSTP 32768 (0x8000)
108 ON RSTP 32768 (0x8000)
112 ON RSTP 32768 (0x8000)
150 ON RSTP 32768 (0x8000)
151 ON RSTP 32768 (0x8000)
200 ON RSTP 32768 (0x8000)
201 ON RSTP 32768 (0x8000)
202 ON RSTP 32768 (0x8000)
203 ON RSTP 32768 (0x8000)
204 ON RSTP 32768 (0x8000)
205 ON RSTP 32768 (0x8000)
206 ON RSTP 32768 (0x8000)
207 ON RSTP 32768 (0x8000)
208 ON RSTP 32768 (0x8000)
209 ON RSTP 32768 (0x8000)
210 ON RSTP 32768 (0x8000)
333 ON RSTP 32768 (0x8000)

[devnull]

For which switch is this? And for the other switches? Which ports are connected?

[sacaminas]

switch 1:

show spantree 1
show spantree 1
Spanning Tree Parameters
Spanning Tree Status : ON,
Protocol : IEEE Rapid STP,
mode : FLAT (Single STP),
Auto-Vlan-Containment: Enabled ,
Priority : 4096 (0x1000),
Bridge ID : 1000-00:e0:b1:bc:8e:9b,
Designated Root : 1000-00:e0:b1:bc:8e:9b,
Cost to Root Bridge : 0,
Root Port : None,
Next Best Root Cost : 0,
Next Best Root Port : None,
TxHoldCount : 3,
Topology Changes : 17,
Topology age : 6 days and 03:47:34,
Current Parameters (seconds)
Max Age = 20,
Forward Delay = 15,
Hello Time = 2
Parameters system uses when attempting to become root
System Max Age = 20,
System Forward Delay = 15,
System Hello Time = 2

show spantree ports active
show spantree ports active
Bridge Port Oper Status Path Cost Role
------+-----+------------+---------+-------
1 1/1 FORW 4 DESG
1 1/2 FORW 4 DESG
1 1/3 FORW 4 DESG
1 1/4 FORW 4 DESG
1 1/5 FORW 4 DESG
1 1/6 FORW 4 DESG
1 1/7 FORW 4 DESG
1 1/8 FORW 4 DESG
1 1/9 FORW 4 DESG
1 1/10 FORW 4 DESG
1 1/15 FORW 4 DESG
1 1/16 FORW 4 DESG
1 1/18 FORW 4 DESG
1 1/19 FORW 4 DESG
1 1/22 FORW 4 DESG

show spantree
Spanning Tree Path Cost Mode : AUTO
Bridge STP Status Protocol Priority(Prio:SysID)
------+----------+--------+--------------------
1 ON RSTP 4096 (0x1000:0x0000)


switch 2


show spantree 1
Spanning Tree Parameters
Spanning Tree Status : ON,
Protocol : IEEE Rapid STP,
mode : FLAT (Single STP),
Auto-Vlan-Containment: Enabled ,
Priority : 8192 (0x2000),
Bridge ID : 2000-00:e0:b1:bc:8b:c3,
Designated Root : 1000-00:e0:b1:bc:8e:9b,
Cost to Root Bridge : 4,
Root Port : Slot 1 Interface 1,
Next Best Root Cost : 4,
Next Best Root Port : Slot 1 Interface 2,
TxHoldCount : 3,
Topology Changes : 37,
Topology age : 6 days and 05:06:22,
Current Parameters (seconds)
Max Age = 20,
Forward Delay = 15,
Hello Time = 2
Parameters system uses when attempting to become root
System Max Age = 20,
System Forward Delay = 15,
System Hello Time = 2

show spantree ports
Bridge Port Oper Status Path Cost Role
------+-----+------------+---------+-------
1 1/1 FORW 4 ROOT
1 1/2 BLK 4 ALT
1 1/3 BLK 4 ALT
1 1/4 DIS 0 DIS
1 1/5 FORW 4 DESG
1 1/6 FORW 4 DESG
1 1/7 DIS 0 DIS
1 1/8 DIS 0 DIS
1 1/9 DIS 0 DIS
1 1/10 DIS 0 DIS
1 1/11 DIS 0 DIS
1 1/12 DIS 0 DIS
1 1/13 DIS 0 DIS
1 1/14 DIS 0 DIS
1 1/15 DIS 0 DIS
1 1/16 DIS 0 DIS
1 1/17 DIS 0 DIS
1 1/18 DIS 0 DIS
1 1/19 DIS 0 DIS
1 1/20 DIS 0 DIS
1 1/21 DIS 0 DIS
1 1/22 DIS 0 DIS
1 1/23 FORW 4 DESG
1 1/24 FORW 4 DESG
1 1/25 DIS 0 DIS
1 1/26 DIS 0 DIS

show spantree
Spanning Tree Path Cost Mode : AUTO
Bridge STP Status Protocol Priority(Prio:SysID)
------+----------+--------+--------------------
1 ON RSTP 8192 (0x2000:0x0000)


Conections
switch 1 conected to switch 2 port 1/4
switch 1 conected to switch 3 port 1/7
I would like conect switch 2 port 1/4 to switch 3

Thanks a lot Silvio

[silvio]

Hi,
now I can see the scenario.

Switch 3 has bridge mode 1x1 (per vlan). This has to be changed to flat mode.
and all connections between the switches has to be in vlan 1.

Your givven connections are apparently not correct:

switch 2 has two connections with costs 4 (= gig) to root bridge: 1/1 = root port and 1/2 = blocked
So I assume that both ports parallel connected to switch 1 (root bridge).
There you should use LACP instead (like devnull and I have already written).

switch 3 is at port 1/1 connected to switch 1 - but on which port to switch 2 (I can't see next best root)?
Is this port in vlan 1?

regards
Silvio