CSS Bridging and Spanning-tree

Greetings:
I have a configuration where I have two CSS attached to two WS 3550 switches. I'd like to connect an interface from each VLAN on each CSS to both 3550 switches (see attached). I have a problem when both of the interfaces are active in a VLAN. The spanning tree breaks down (both CSS see themselves as the root and one of the 3550's becomes the root for the two 3550's). Additionally, I had a situation where the ISL link between the 3550's shut down due to excessive spanning-tree errors.
I looked into using unconditional bridging, but that would cause problems on the "outside" interfaces as we can't predict how the VLAN's will be configured on that side of the CSS. We actually have a split situation where layer-3 path forwarding decisions are preferable on hte outside and layer-2 path forwarding descisions are preferable inside.

Wiwells,
Honestly, when I look at what you are doing, I feel you are making it overly redundant on the bridged side of things.
Why not simply connect each load balancer to only one switch rather than cross-connecting everything and then put a APP session between the load balancers?

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    Hello Thomas,
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  • SGE2010 switches, VLAN's and a blocked port in spanning-tree

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  • Discussion for spanning tree

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  • E100 & E1000 Spanning tree and VLAN reuse

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  • Cisco Switches and HP Interoperability with Spanning-Tree (RSTP)

    Hello All.
    I read a lot of information from this forum about Spaning-Tree interoperability between HP Switches and Cisco Switches.
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      0    32768.cc3e-5f3a-2939  0           0
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      0        GigabitEthernet1/0/47        DESI  FORWARDING    NONE
      0        GigabitEthernet1/0/48        DESI  FORWARDING    NONE
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    -------[CIST Global Info][Mode RSTP]-------
    CIST Bridge         :32768.cc3e-5f3a-2939
    Bridge Times        :Hello 2s MaxAge 20s FwDly 15s MaxHop 20
    CIST Root/ERPC      :32768.cc3e-5f3a-2939 / 0
    CIST RegRoot/IRPC   :32768.cc3e-5f3a-2939 / 0
    CIST RootPortId     :0.0
    BPDU-Protection     :enabled
    Bridge Config-
    Digest-Snooping     :disabled
    TC or TCN received  :17
    Time since last TC  :0 days 0h:1m:52s
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     Spanning tree enabled protocol rstp
     Root ID    Priority    32768
                Address     cc3e.5f3a.2939
                Cost        4
                Port        26 (GigabitEthernet0/2)
                Hello Time   2 sec  Max Age 20 sec  Forward Delay 15 sec  Bridge ID  Priority    61441  (priority 61440 sys-id-ext 1)
                Address     001b.54db.7200
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    Gi0/1            Altn BLK 4         128.25   P2p
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                Address     cc3e.5f3a.2939
                Cost        4
                Port        26 (GigabitEthernet0/2)
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                Address     001b.0cbc.4300
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    Gi0/1            Desg FWD 4         128.25   P2p
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    Hello, David.
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  • VLAN spanning-tree root and VLAN L3 SVI

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                 Address     6400.f1ee.c140
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                 Address     0015.f960.9ac0
                 Hello Time   2 sec  Max Age 20 sec  Forward Delay 15 sec
                 Aging Time 300
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    Gi1/1            Root FWD 4         128.1    P2p
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    Hi Tojackson, I guess this depends on how stuff is interconnecting. It's obvious gi1/1 is forwarding and gi1/2 is blocking. So from the furthest access switch, what path must it take to reach gi1/1? That is the number of hops involved for normal traffic.
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    Please mark answered for helpful posts

  • Mutiple spanning-tree root bridges

    We've started installing some new 3650 switches (replacing 3560's at the access layer) running XE 03.03.05SE. We've run into some problems as a result of "ip device tracking" being on by default, but in the process of debugging I've found that three separate switches all believe they are the spanning-tree root bridge for the same VLANs. The new switches are by default in rapid-pvst mode; the distribution switches are set to rapid-pvst as well. All 3650's are dual-homed.
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    Gi1/1/4             Desg FWD 4         128.52   P2p
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                 Aging Time  300 sec
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      Bridge ID  Priority    33767  (priority 32768 sys-id-ext 999)
                 Address     78da.6e6f.7180
                 Hello Time   2 sec  Max Age 20 sec  Forward Delay 15 sec
                 Aging Time  300 sec
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    Hi,
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    Thank you!
    Best regards,
    Peter

  • Mono spanning-tree and PVST

    Refering to these two links
    http://www.cisco.com/en/US/tech/tk389/tk390/technologies_tech_note09186a0080094665.shtml
    http://www.experts-exchange.com/Hardware/Routers/Q_21349385.html
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    http://networking.ringofsaturn.com/Certifications/BCMSN.php
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    http://www.informit.com/content/images/1587051427/samplechapter/1587051427content.pdf
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    Hi,
    The URLs that you have provided all explains the same technical details in different fashion.
    I will summarise them here for better clarity.
    There are two separate technologies that needs clarity.
    1) Method of Trunking many vlans across a link
    2) Spanning tree
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    This tag will contain the vlan identifier info and some other details ( available in the urls that you have highlighted)
    Cisco has a proprietary technology called ISL which effectively does the same job in a different fashion but can only be used in cisco devices.
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    Here also there is only one spanning tree instance involved.
    In both the above STP protocols, there is only one instance/process of the protocol running in the network, which is common for all vlans. Hence these protocols consume only very less CPU utilisation.
    In 802.1s/ MSTP ( multiple spanning tree), extends the 802.1w Rapid Spanning Tree Protocol (RSTP) to have multiple STP instances. In this protocol, we can group the desired vlans in to one Instance of the protocol.
    Say for example, lets assume a typical campus network with multiple access switches, 2 distribution/core switches.
    Access switches having dual connectivity to the distribution/core switches.
    In this topology if we deploy 802.1d or 802.1w, the redundant links from the access switches to the distribution/core switches will be blocked. Only one uplink from the access switch to the distribution layer will be working at any point.
    In this network, only one distribution/core switch will be root bridge for the entire network.
    But if we deploy 802.1s for this network, we can design it as follows.
    We can split the vlans in to two groups,
    Group1 => vlan 1 to 50
    Group2 => vlan 51 to 100
    We can create two instance of MSTP protocol with the following mappings
    Instance 1 => for Group 1, with one distribution/core switch as the root bridge
    Instance 2 => for Group 2, with another distribution switch as the root bridge
    --Continued

  • Spanning Tree and Admin mac address issues srw2048

    Ok, I have a somewhat complex problem and hopefully someone may shed some light or have an idea as to whats wrong.
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