ROOT Bridge identification

Team:
I am very perplexed by one CCNA question, this is a simulation. The simulation allows you to console into one switch and asks what bridge is the root bridge, how do you tell?

boy, spanning tree is too fundu for ccna. Even understanding VTP is a tough time at ccna level, bcoz many people who appear for ccna are not experienced or have hands-on over devices. But they are taking a chance, hoping to get a profile where they get to work on these devices.
however, heres the command:
show spanning-tree
The output shows Root bridge MAC & priority, as well as self MAC & priority. If both are same, then that switch itself is the root bridge. otherwise "sh arp" can give u a corresponding Ip add of root switch against rootbridge mac add.

Similar Messages

  • How to find out Secondary STP Root bridge in cisco switche network

    Hi, i need to find out Root Primary and Root Secondary bridge in all my offices.
    sh spanning-tree summary command can tell me which switch is root bridge primary, but how can i find secondary root easily with some simple command?
    sh spanning-tree summary
    Switch is in pvst mode
    Root bridge for: VLAN0001-VLAN0002, VLAN0005, VLAN0008, VLAN0031

    I'm not sure if there is a simple way of finding the bridge with the SECOND best priority.

  • 1300 Root-Bridge and Non-Root Bridge setup

    I have two 1300s that I am trying to set up as Root Bridge and Non-Root Bridge, however, everytime i specify one of them as a Non-Root bridge, the radio0 interface becomes disabled. The only option that i am able to pick that enables the radio0 interface is "Access Point", which is what am trying to avoid it being.
    Can anybody help me figure out how to go about this

    A non-root's radio will show as disabled if it cannot find the root AP to associate to. Make sure you have "infrastructure-ssid" configured under the SSID on both the root and non-root bridges. Also depending on code versions you may have to configure the distance command under the radio interface on the root.

  • 7920 associates to root bridge but not to non-root bridge

    I have 7920s using open authentication with WEP128 cipher. I have two 1300 root AP's (with client support) and three non-root AP's (also client support) in the same lab area. The root AP's and non-Root AP's associate and link to each other no problem. However, the 7920's will only associate with the Root APs. If I power down the root APs, the 7920s show "no AP found". I've verified SSID and WEP128 keys. I've also noted that the root AP does have a channel specified under dot11radio0 but the non-roots do not. Do the 7920's just scan for any channel until it finds an association or do I need to specify a channel in the non-root bridges?
    Thanks,
    Mike.

    With static WEP, the authentication is happening at the AP level. Will want to ensure non-root is associated to a root though otherwise the interface may be in "reset" state.
    The 7920 will look at these 2 as individual APs regardless of channel. Non-roots should have the same channel as the root, otherwise will not be able to communicate.

  • Can one Root Bridge support multiple non-root bridges?

    Hey gang,
    I have a pretty simple question here I think
    I have a wireless bridge currently setup to support a separate office building on our property about 200 yards away from the main building.  The wireless bridge has been working great and was a much cheaper solution when compared to the cost of making a fiber drop to this building.  The needs of our business have changed (go figure), to include a warehouse building also on the backside of the property.  It's not feasible to run a cable between these two building either.  So I need to create another wireless bridge to this back warehouse as well.  My question is can I just use another non-root bridge to link to the root bridge already in place, or does each wireless bridge require one root bridge and one non-root bridge?
    I have good LoS to both buildings from where the current root bridge is, so if two non-root bridges can talk to one root bridge I should be able to just an additional non-root bridge and be good to go.  But if wireless bridges are meant to be a one to one setup, then I'll need to setup an additional root bridge to link to the new non-root bridge?
    It seems like you should be able to have one root bridge link to multiple non-root bridges but I haven't been able to find any clear examples of this being done.
    Thanks in advance for the help!

    That was just too easy.
    I copied the configuration from the working non-root bridge to my laptop.  I changed out the ip address of the BVI interface.  I uploaded the configuration to the new 1300 bridge.  I plugged it in and pointed the yagi antenna in the general direction of the original root bridge and started pinging the new 1300.  Success!
    I'll use my spare 1300 to get service up and running in the warehouse by the end of the week and I'll just need to order one more 1300 to make sure I have spare on hand if needed.
    Thanks again!

  • Two root bridge in same network

    Dear Team,
    As I checked, there are two root bridge in the same LAN.
    We have 6500 which is manually configured as root bridge and this is showing root for all the vlans in the network. Once switch connected to 6500 through 4500 is showing root for the vlans that not assigned to any of the port. Please help to clear it.
    Setup
    Cisco 6500 -- Cisco 4500 -- Cisco3560 -- Cisco 3560
    Cisco 6500
    CORE_SW#show spanning-tree root detail
    VLAN0001
      Root ID    Priority    24577
                 Address     0025.84d9.ac80
                 This bridge is the root
                 Hello Time   2 sec  Max Age 20 sec  Forward Delay 15 sec
    VLAN0002
      Root ID    Priority    24578
                 Address     0025.84d9.ac80
                 This bridge is the root
                 Hello Time   2 sec  Max Age 20 sec  Forward Delay 15 sec
    Cisco 3560 Second
    Access#show spanning-tree root de
    VLAN0001
      Root ID    Priority    24577
                 Address     0025.84d9.ac80
                 Cost        16
                 Port        28 (GigabitEthernet0/4)
                 Hello Time   2 sec  Max Age 20 sec  Forward Delay 15 sec
    VLAN0002
      Root ID    Priority    32770
                 Address     000a.b8ff.be00
                 This bridge is the root
                 Hello Time   2 sec  Max Age 20 sec  Forward Delay 15 sec
    Here, I have not assigned any port in vlan 2 and this is showing root bridge for vlan 2. In which cases such thing can happen?
    Thank You,
    Abhisar.

    By default, Cisco switches run one spanning tree instance per VLAN and negotiate the topology with other connected switches. If your 3560 believes it is the root for VLAN 2 and there are no ports using VLAN 2, it will consider itself the to be the root because it hasn't been able to negotiate a topology for this VLAN with any other devices. This is normal. Once ports are connected to VLAN 2 and the 3560 can talk to the other switches, the spanning tree will be renegotiated and should behave as you expect.
    If you want to have a single spanning tree topology for all VLANs and avoid this behaviour, consider moving to a single-instance MSTP configuration.

  • Root Bridge vs. AP

    I presently have a point to multi-point wireless network using an AP350 at the wired central connection point. I would like to upgrade the access point with a BR1310. Should I configure the BR1310 as an AP or as a root Bridge? There are about a dozen client locations which use both BR1310s (presently in WGB mode) and WGB350s to connect to the central AP. I beleive that the 1310's and the WGB350s are all compatible with the central BR1310 as either an AP or a Root Bridge. Is there any advantage to using the central BR1310 configured as a root bridge versus an AP? The path length from the central point to the clients is about 12 miles. Thanks.

    this link answers some questions about the WGB
    http://www.cisco.com/warp/public/102/wlan/workgroup-bridge-faq.pdf
    which the following is one.
    With which devices can a Workgroup Bridge associate?
    Workgroup Bridge to Access Point (AP)
    Workgroup Bridge to Bridge (in AP mode)
    Workgroup Bridge to Base Station (in AP mode)
    Workgroup Bridge to AP in repeater mode, if the repeater is associated with a root AP
    hope this helps.
    Bill

  • Root Bridge vs. Non-Root Bridge

    Hi,
    I want to understand the Root Bridge vs. the Non-Root Bidge when using Autonomous 1131 AP's on the same /24 network. Does that command matter in Autonomous? I have many devices working without issues on the same /24 network and all have the Root Bridge set,
    Clearly confused...
    Thanks,

    The command is used on point to point links deployments
    A non root bridge becomes a client and connect to another ap in order to do wireless bridging.
    Sent from Cisco Technical Support iPhone App

  • 1230AG non-root bridge not associating

    Hello everyone,
    I am new at setting up root and non-root bridges. I am trying to set-up three 1230ag devices.
    One as the root and the othe two as non-root, I copied the config txt from the root and
    copied that into the two I am going to use for the non-root. That way the ssid's are the
    same. When I set the role to non-root the radio is not enabled and I get a message saying
    Interface Dot11Radio0,cannot associate:No Response
    Does any know what I am doing wrong, and how to fix it
    Thanks

    The radio interface will go down in response to being configured as a non-root bridge, so that much is working.  But there must be a configuration error if it won't associate.  Can you post the configs so we can review them?
    Are the bridges mounted, or are they on your desk?

  • Using root bridge as a fallback radius server for WPA and EAP

    From reading the different documentation out there, it seems that one should be able to configure a root bridge as a fallback radius server in case a primary radius server were to be unreachable. Has anyone encountered this situation? And could they share the steps and configuration statements to apply the bridges (1310 or 1410) in order to make this happen?
    Many Thanks and Regards,
    Giles -

    Yes, you have to first configure a root bridge as a fallback radius server in case a primary radius server were to be unreachable

  • Root Bridge can see NonRoot Bridges but does not Associate

    This is a point-to-multipoint bridging LAN for networking eight serial devices (air quality monitors) to a central Windows box for real-time wireless data acquisition.  Thus far, I have configured a single Aironet 1310 as the root bridge (RB:  150.100.0.2, 255.255.0.0) at the Windows box (PC: 150.100.0.1, 255.255.0.0) and three Aironet 1310s as non-root bridges (NRB1:  150.100.0.3; NRB2:  150.100.0.4; NRB3:  150.100.0.5).  When the system's working, each of the NRBs will connect to an ethernet-to-serial device server with its own IP, and the serial devices will connect to the device servers as COM2-COM9, respectively.  Each node in this network has an external antenna, an omni at the RB and directional/Yagi antennae at the NRBs.  Distances are short, hundreds of meters, so power will not be the limiting factor.  (We could have done this with Zigbee but decided to overdesign for reliability.)
    After assigning IP addresses to all four bridges using the command-line interface, and with the RB connected to an ethernet hub/switch, we configured each of the NRBs by connecting them to the same hub/switch and using the browser interface.  We used the document at
    http://www.cisco.com/application/pdf/paws/68087/bridges_pt_to_pt.pdf
    and followed it to the letter to configure first the RB, then the NRBs.
    After configuring all four bridges, and while all four were still hard-wired together through the hub/switch, all four bridges showed the proper associations in the "State" column of the web interface under "Association."  To test the wireless links we disconnected the three NRBs from the hub/switch by removing the ethernet cables, leaving the RB connected to the hub/switch (naturally) to maintain connection to the host PC.  We then refreshed all associations.
    On the RB web interface, all three NRBs showed up with the proper IP addresses, but the "State" fields showed "Attempting Association" or something like that rather than "EAP-Associated."
    All three NRB web interfaces disappeared because the links were lost.  I tried to PING each of the IP addresses using a DOS command, but all three timed out.
    So, in short, the RB can "see" all three NRBs and "knows" they're there; but the association does not complete.  What are my options for diagnosing the problem?
    Thanks in advance...
    Brent Auvermann
    Amarillo, TX

    Chieu Dinh,
    For the non-root bridge, is there a way to set the scan? I can see in the log file shows that the scan is starting when I changed from Install to non-root bridge. Once I am on the non-root bridge role, I don't see any more the log for scanning.
    I don't know about any command that controls the scanning interval when the bridge is in non-root mode. I also don't think it logs every time it goes into a scan cycle because I think they're pretty close together, maybe at most a few seconds.
    My question is "is there some ways that I can initiate the scan on the non-root bridge?
    You can shut/no-shut the non-root bridge radio interface. Every time you do this it intiates a new scan immediately.
    can I use the "parent" command on the point-to-multipoint environment?
    As far as I know, yes. I think the only mode parent doesn't work in is repeater mode. For repeaters, you don't configure a list of parents, you only configure one single MAC peer.
    An added thought: if you are having trouble with the bridge link coming up, then there is likely either a signal or a configuration issue (and chasing the scan interval probably won't net you any solutions). I've found that a great way to narrow the troubleshooting is to configure the bridges on the ground at close range (maybe 50-100 feet apart, not right up against each other) to control for signal. Once you have a working configuration and you know for sure that the bridges will come up, then install them in your outdoor locations. Keep in mind that when outdoors, a lot of factors can play into signal claritiy and usability (trees/foliage, distance, LOS/fresnel, earth curvature, weather, noise and interference, etc.). Also, unfortunately for the 1310s, the 2.4GHz space is really congested in most populated areas so they are not a reliable solution unless you're out in the country. Always survey first.
    Justin

  • Need to reboot root bridge for RF connectivity

    We have installed RF connectivity with Cisco Aironet 1300 between two sites.The distance is 1 km.
    The connectivity is intermittent and shows radio errors in logs.
    After rebooting the root bridge at one site the connectivity is restored.
    We have not been able to locate the problem . Plz Help
    the configs are as below :
    Site 1 :
    ROOT BRIDGE
    ip subnet-zero
    aaa new-model
    aaa group server radius rad_eap
    aaa group server radius rad_mac
    aaa group server radius rad_acct
    aaa group server radius rad_admin
    cache expiry 1
    cache authorization profile admin_cache
    cache authentication profile admin_cache
    aaa group server tacacs+ tac_admin
    cache expiry 1
    cache authorization profile admin_cache
    cache authentication profile admin_cache
    aaa group server radius rad_pmip
    aaa group server radius dummy
    aaa authentication login eap_methods group rad_eap
    aaa authentication login mac_methods local
    aaa authorization exec default local
    aaa accounting network acct_methods start-stop group rad_acct
    aaa cache profile admin_cache
    all
    aaa session-id common
    dot11 activity-timeout client default 99999
    dot11 activity-timeout repeater default 99999
    dot11 activity-timeout workgroup-bridge default 99999
    dot11 activity-timeout bridge default 99999
    dot11 ssid yyyy
    authentication open
    dot11 network-map
    bridge irb
    interface Dot11Radio0
    bandwidth inherit
    no ip address
    no ip route-cache
    ssid yyyy
    speed basic-1.0 basic-2.0 5.5 6.0 9.0 basic-11.0 12.0 18.0 24.0 36.0 48.0 54.0
    no preamble-short
    station-role root bridge
    cca 75
    concatenation
    distance 2
    antenna gain 14
    infrastructure-client
    bridge-group 1
    bridge-group 1 port-protected
    bridge-group 1 spanning-disabled
    interface FastEthernet0
    no ip address
    no ip route-cache
    full-duplex
    bridge-group 1
    bridge-group 1 spanning-disabled
    interface BVI1
    ip address 10.1.254.252 255.255.255.248
    no ip route-cache
    ip default-gateway 10.1.254.249
    ip http server
    no ip http secure-server
    ip radius source-interface BVI1
    radius-server attribute 32 include-in-access-req format %h
    radius-server vsa send accounting
    control-plane
    bridge 1 route ip
    Site 2 :
    aaa new-model
    aaa group server radius rad_eap
    aaa group server radius rad_mac
    aaa group server radius rad_acct
    aaa group server radius rad_admin
    aaa group server tacacs+ tac_admin
    aaa group server radius rad_pmip
    aaa group server radius dummy
    aaa authentication login eap_methods group rad_eap
    aaa authentication login mac_methods local
    aaa authorization exec default local
    aaa accounting network acct_methods start-stop group rad_acct
    aaa session-id common
    dot11 activity-timeout client default 99999
    dot11 activity-timeout repeater default 99999
    dot11 activity-timeout workgroup-bridge default 99999
    dot11 activity-timeout bridge default 99999
    dot11 ssid yyyy
    authentication open
    infrastructure-ssid
    bridge irb
    interface Dot11Radio0
    bandwidth inherit
    no ip address
    no ip route-cache
    ssid yyyy
    short-slot-time
    cca 75
    concatenation
    speed basic-1.0 basic-2.0 basic-5.5 6.0 9.0 basic-11.0 12.0 18.0 24.0 36.0 48.0 54.0
    station-role workgroup-bridge
    antenna gain 14
    keepalive 9999
    infrastructure-client
    bridge-group 1
    bridge-group 1 port-protected
    bridge-group 1 spanning-disabled
    interface FastEthernet0
    no ip address
    no ip route-cache
    bridge-group 1
    bridge-group 1 spanning-disabled
    interface BVI1
    ip address 10.1.254.253 255.255.255.248
    no ip route-cache
    ip default-gateway 10.1.254.249
    ip http server
    no ip http secure-server
    ip radius source-interface BVI1
    radius-server attribute 32 include-in-access-req format %h
    radius-server vsa send accounting
    control-plane
    bridge 1 route ip

    Hi Sanjay,
    Nothing is jumping out from the config all seems fairly standard. Points more to an RF problem.
    Can you post the error logs/messages from the radios.
    How much clearence above obstacles do you have between the link? At that distance on 2.4GHz there should be around 6m free space.
    What antennas are you using? Have you performed a spectrum analysis at either end of the link to determine potential interference on the channel used?
    From each end could run the following command and post the output:
    show dot11 stat cli
    show dot11 carrier busy
    Thanks
    Mat

  • Network Design - Root and Non root bridges

    Hi,
    We have a network set-up as the below image. Where the switches have STP enable to handle the muliple paths for the data to flow.
    What I would like to know is should the 2 bridges plugged into the same switch e.g Switch A (Bridge A and Bridge B) both be root bridges and (Bridge C and Bridge D) both be non root.
    Or should for example, Bridge A be a root and Bridge C a non root and Bridge B a non root and Bridge D the root?
    Similarly with the rest of the other bridges E, F, G and H
    Thanks

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    Posting
    Ah, I think I understand.  So the wireless bridges are "transparent" to the rest of the network.  They just convert wired to wireless and back again.
    If I have that right, we can ignore them and just consider your switches.
    In that case, it appears you have two L2 loops, those formed by the dual paths between switches A and B and between switches C and D.  From a topology standpoint, it doesn't seem to matter what switch you select as root and secondary root.  However, as switches B and C are the interior switches, I would suggest those as your root and secondary root switches.

  • Non-root bridges associating with each other.

    We have a point to multi-point bridge setup with 3 BR1310s. One is set to be a root bridge and the other two are set to be non-root bridges. From past experience (not to mention Cisco documentation) I would expect the 2 non-roots to associate to the root. What is happening is that one of the non-roots associates with the root and the other non-root associates with the first non-root. The good bit is that everything still works, the puzzling bit is why this is happening, the bridges are physically in a V pattern so there's no reason for the second non-root to behave as it is, even if we force it off the first non-root it just jumps right back in there again. Bridges are all running 12.3.4-JA.

    Configurations of both non-root bridges attached. I've just found out that the customer has mounted the second non-root bridge in such a way that there is probably no line of site to the root bridge (failing to follow clear instructions!) which explains why we can't get it to associate with the root bridge but doesn't explain how it can associate with the other non-root. The only thing I can think of is that both are "non-root with clients" and the second bridge is being accepted as a client rather than a bridge.

  • Set Up of Backup Root Bridge (for resilience purpose)

    Hi,
    I've a wireless link with 2 Aironet 1240, one as Root Bridge connected to backbone network, the other one as Non Root Bridge.
    I would like to setup another Aironet 1240 as Root Bridge with backbone network connection for resilience purpose, any special parameters need to be taken care of?
    Will I need to configure the 'Root Parent Timeout Value' & 'Root Parent MAC'?
    Thanks.

    Yes you can configure parent in this and you are right.. Configure parent with the MAC address.. your Parent Number will decide which one is promary and which one is backup..
    Example..
    parent 1 1111.1111.1111
    parent 2 3333.3333.3333
    In this case.. the Non Root will try to associate to Parent 1 , if this fails then this goes to parent 2..
    Lemme know if htis answered your question
    Regards
    Surendra

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