Problem in STP?

[Senthil Rajendra]

Dear All,

In this connectivity,I configured,HSRP For, VLAN 23 & VLAN-24  in  Edge Router 7604 PE1,

1.If i am configuring like this, i will be  getting flopping in PE2.

2.Then i changed the  connectivity,

PE1--VLAN24---> DLinkswitch2

PE2--VLAN24---> Dlink Switch1

That time my both the routers CPU utilization will be very high(100%)

3.If i am removing the cable between D-Link,

That time i cant able to reach the Servers which is connected to Switch.

In this case, what i have to do?

Thanks in Advance

Tks&Rgds

Senthil

[chris.rae07]

Hi Senthil,

Just a few things.

You may want to  add the following to your HSRP config to make it more deterministic -:

standby  1 timers 1 3
  standby 1 priority 110

It doesn't solve the STP issue,  but fixing inconsistancies helps.

I notice that you are running MST.

MST is backward compatible with CST and will create a CST instance if the dlinks

don't support MST.

If the dlinks are manageable I would check and see if they support MST.

I also notice that you have your two VLANs in the default MST instance 0.

When you create a VLAn this is the default MST instance that VLAns will get dumped into.

To solve your problem I would run the following commands on the PE's as it will resolve any spanning

tree loops with MST -:

PE1:

PE1(config)#spanning-tree mst 0 root primary

PE2(config)#spanning-tree mst 0 root secondary

This runs a macro that calculated what STP priority it needs to win the root bridge election.

The root secondary command will cause PE2 to calculate the bridge priority to become the secondary root bridge.

This should fix it in theory, but if there is no real MST running on the dlink, it wont.

Let me know how it goes.

Chris

[Senthil Rajendra]

Dear Chris,

As Per your suggestion, i have configured the Priority and Timers in both Edge routers..

For VLAN 23, PE1-Active, PE2-Standby

For VLAN 24, PE2-Active, PE1-Standby

After that,i cant able access the internal vlan which is configured in the D-Link.

(Actually i configured the three VLAN in D-Link Switch, But physically i connected with two vlans only..

PE1(4/32)-->D-Link1(VLAN23)

PE2(4/33)-->D-Link2(VLAN24)

PE1(4/32)-->D-Link2(VLAN23)

PE2(4/33)-->D-Link1(VLAN24),

Then i configured Dlink1(1/48)--Dlink2(1/48) port as a trunk and tagged all the VLAN.

When i am configuring mst primary in PE1, i am getting this errors..

Now what to do?

PE1(config)#spanning-tree mst 0 root primary
% Failed to make the bridge root for mst 0
% It may be possible to make the bridge root by setting the priority
% for some (or all) of these instances to zero.

Then i cant able to access VLAN 25 which is in both D-Link...This is the complete scenerio.

Now what i will do ?

Tks&Rgds

Senthil

[ramji_avinash]

Dear Senthil Rajendra,

There is some serious problem with your HSRP config, i think it should be like this ,

PE_1 ---int vlan 23

standby 1 ip 10.237.16.61

standby 1 preempt

standby 1 priority 150

int vlan 24

standby 2 ip 10.237.16.125

standby 2 preempt

standby 2 priority 140

PE_2--int vlan 24

standby 2 ip 10.237.16.125

standby 2 preempt

standby 2  priority 150

standby 1 ip 10.237.16.61

standby 1 preempt

standby 1  priority 140

make sure that u allow all vlans , make sure whether u have created port channel command like int port channel ,switchport enclapuslation etc