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STP - Link cost

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Camels
Occasional Advisor

STP - Link cost

Hi,

Just a simple query (hopefully), I have setup STP between procurve 2524,2512 and a Cisco 3560.

When I run "sh spanning-tree" on the procurve I see that the port cost on 10/100tx links are 10

The cisco shows it as 200 000.

From what i have read, the port cost displayed on the procurves should be 19.

Any idea's why this is displaying as 10?
10 REPLIES
cenk sasmaztin
Honored Contributor

Re: STP - Link cost

hi
normaly pach cost must have (for 10/100interface) 200 000

please send me sh tech print your procurve switch
cenk

cenk sasmaztin
Honored Contributor

Re: STP - Link cost

did you change with manually patch cost on procurve switch
cenk

Camels
Occasional Advisor

Re: STP - Link cost

I haven't changed the port costs.

Im having trouble uploading the file with the info your requested. It just keeps timing out...
Camels
Occasional Advisor

Re: STP - Link cost


FYI - st info


Status and Counters - Spanning Tree Information

Protocol Version : STP
STP Enabled : Yes

Switch Priority : 32768 Hello Time : 2
Max Age : 20 Forward Delay : 15

Topology Change Count : 68
Time Since Last Change : 5 hours

Root MAC Address : 001185-286300
Root Path Cost : 0
Root Port : This switch is root
Root Priority : 32768

Port Type Cost Priority State | Designated Bridge
---- --------- ----- -------- ---------- + -----------------
1 10/100TX 10 128 Forwarding | 001185-286300
2 10/100TX 10 128 Disabled |
3 10/100TX 10 128 Disabled |
4 10/100TX 10 128 Disabled |
5 10/100TX 10 128 Disabled |
6 10/100TX 10 128 Disabled |
7 10/100TX 10 128 Disabled |
8 10/100TX 10 128 Disabled |
9 10/100TX 10 128 Disabled |
10 10/100TX 10 128 Disabled |
11 10/100TX 10 128 Disabled |
12 10/100TX 10 128 Disabled |
13 10/100TX 10 128 Disabled |
14 10/100TX 10 128 Disabled |
15 10/100TX 10 128 Disabled |
16 10/100TX 10 128 Disabled |
17 10/100TX 10 128 Disabled |
18 10/100TX 10 128 Disabled |
19 10/100TX 10 128 Disabled |
20 10/100TX 10 128 Disabled |
21 10/100TX 10 128 Disabled |
22 10/100TX 10 128 Disabled |
25 100FX 10 128 Forwarding | 001185-286300
26 100 128 Disabled |
Trk1 10 64 Forwarding | 001185-286300
cenk sasmaztin
Honored Contributor

Re: STP - Link cost

Camels
Occasional Advisor

Re: STP - Link cost

Hi Cenk,

I have read through this document previously.

Spanning tree is actually working as intended.

Im just confused as to why the port costs are 10.

If i remove the Cisco out of setup, I still see the same results, the cost still appears as 10.

Any idea's why this may be?
Camels
Occasional Advisor

Re: STP - Link cost

Running conf of the root sw..

Running configuration:

; J4813A Configuration Editor; Created on release #F.05.72

hostname "2524"
cdp run
snmp-server community "public" Unrestricted
vlan 1
name "DEFAULT_VLAN"
untagged 1-26
ip address dhcp-bootp
exit
no aaa port-access authenticator active
spanning-tree protocol-version stp
spanning-tree
Ardon
Trusted Contributor
Solution

Re: STP - Link cost

Hi Camels,

So you are running the 2524 in 802.1d mode.
Per IEEE http://speed.cis.nctu.edu.tw/~ydlin/course/cn/exp/Exp_NBL/stp/802.1D-1998.pdf

Tabe8-5 these are allowed Path Costs.

Parameter Link Speed Recommended
value
Recommended
range Range
Path Cost 4 Mb/s 250 100â 1000 1â 65 535
Path Cost 10 Mb/s 100 50â 600 1â 65 535
Path Cost 16 Mb/s 62 40â 400 1â 65 535
Path Cost 100 Mb/s 19 10â 60 1â 65 535
Path Cost 1 Gb/s 4 3â 10 1â 65 535
Path Cost 10 Gb/s 2 1â 5 1â 65 535

Sorry for the lousy format but as can be seen a link of 100Mb is allowed a range from 10-60.

You say Cisco shows it as 200,000. That could be but then the Cisco is running 802.1W or 802.1s.

Why are you still running 802.1d the 2524 as the Cisco will the fall back to 802.1d as well (remember 802.1w is backwards compatible with 802.1d but 802.1d is of course not forward compatible with 801.1w :-)

Just change the STP Version on the 2524 to RSTP (requires reload to take effect I think). Then you will see a Path Cost of 200000 as well.

Hope this helps.

ProCurve Networking Engineer
Camels
Occasional Advisor

Re: STP - Link cost

Awesome, Thanks for the clarifying that.

I have changed the procurves to run RSTP and now the port costs are displayed as 200 000.

The cisco is running MSTP which, from what ihave read is backwards compatible with RSTP and STP, is this correct?

my other option on the cisco is selecting PVST and rapid PVST however im led to believe these are proprietary and not compatible with other vendors.

Appreciate your assistance! :) TY
Ardon
Trusted Contributor

Re: STP - Link cost

Hi Camels,

Awesome, Thanks for the clarifying that.

The cisco is running MSTP which, from what ihave read is backwards compatible with RSTP and STP, is this correct?

Yes, you have to be sure however, depending on the Cisco IOS, that indeed 802.1s is supported. In older Cisco IOS version there was MSTP but based on a draft and not compatible with IEEE 802.1s.

my other option on the cisco is selecting PVST and rapid PVST however im led to believe these are proprietary and not compatible with other vendors.

PVST is indeed Cisco although some other vendors have it as well. PVST also uses a different Layer 2 multicast Address to send BPDUs. Not really recommended as it indeed run one instance of Spanning Tree and therefore more CPU intensive. MSTP (802.1s) is preferred the more as it also an industry standard.

Appreciate your assistance! :) TY
ProCurve Networking Engineer