Integrated switch - supports STP/RSTP? (Spanning Tree Protocol)

Greetings all..
As this device includes a 3-port switch, which can be integrated with the rest of the network, does it support either Spanning Tree Protocol (802.1d) or Rapid Spanning Tree Protocol (802.1w)?
Neither protocol is terribly difficult to implement, and since these things are so heavily marketed in the education space, it seems like it's a feature that should be there.
That said, when I look at the switch port that the AEBS is connected to (in bridge mode, obviously), there is no interaction with STP or RSTP. Is there some sort of "friendly" name for the option in the AirPort Utility that's eluding me?
While I'm not going to create loops in the network by cabling this up, I can't count on someone else coming behind me doing the wrong thing...

I have had sniffers on LAN ports off various AirPort AP before, never a sign of a BPDU. I am fairly certain that it does not support Spanning Tree.

Similar Messages

  • SF 300 Serires switch not participating in spanning tree?

    I just purchased an SF300-24 managed switch and I am running it in layer3 mode. I am testing it out right now and have it connected to two 2950 switches. The SF300 is connected to each 2950 with a four port etherchannel running LACP. When looking at spanning tree all three switches are configured the same when it comes to hello, forward, max age and all three are in RSTP mode. I adjusted the priorities so that the SF300 would be the root but that is not happening.
    I only have one VLAN as of right now set up and connectivity between the three switches is fine. The only problem seems to be that the two 2950 switches are the only two switches involved in the determination of the root bridge. Additionally it was the same way before I configured the etherchannel and had the switches connected over single trunk lines.
    I would appreciate if someone can expain to me why this is?
    Thanks in advance.

    /* Style Definitions */
    table.MsoNormalTable
    {mso-style-name:"Table Normal";
    mso-tstyle-rowband-size:0;
    mso-tstyle-colband-size:0;
    mso-style-noshow:yes;
    mso-style-priority:99;
    mso-style-parent:"";
    mso-padding-alt:0in 5.4pt 0in 5.4pt;
    mso-para-margin-top:0in;
    mso-para-margin-right:0in;
    mso-para-margin-bottom:10.0pt;
    mso-para-margin-left:0in;
    line-height:115%;
    mso-pagination:widow-orphan;
    font-size:11.0pt;
    font-family:"Calibri","sans-serif";
    mso-ascii-font-family:Calibri;
    mso-ascii-theme-font:minor-latin;
    mso-hansi-font-family:Calibri;
    mso-hansi-theme-font:minor-latin;
    mso-bidi-font-family:"Times New Roman";
    mso-bidi-theme-font:minor-bidi;}
    Thanks for your help but know I still cannot get the three devices to talk MST either,it is getting frustrating. If i add a redundant link and directly connect the two 2950's they immediately talk and configure MST. But when I remove that link no info is passed and both 2950's think they are the root even though the SF 300 priority is 0 on all three MST instances. On the SF300 I have the following settings:
    Spanning tree: enabled
    STP Operation Mode: Multiple STP
    BPDU Handling: Flooding
    Path Cost: Long
    Region name: test
    Revision: 1
    Max Hops: 20
    Max-age: 20
    Hello Time: 2
    Forward Delay: 15
    MST instance 1 Vlan 100
    Bridge Priority 0
    Designated Root Bridge: Self
    Root port: 0
    Root path cost: 0
    MST instance 2 Vlan 2-5
    Bridge Priority 0
    Designated Root Bridge: Self
    Root port: 0
    Root path cost: 0
    MST instance 0 all vlans not in instance 1 and 2
    Bridge Priority 0
    Designated Root Bridge: Self
    Root port: 0
    Root path cost: 0
    For MST interface Settings (both LAGs/instances are thesame)
    Int Priority: 128
    Path Cost: 20000
    Port State: Boundary
    Mode: RSTP
    Type: Boundary
    Designated port ID: 128
    Designated Cost: 0
    Remain Hops: 20
    Forward Transitions: 1
    The 2950 switches: (The only difference on the other switch is that the priority is 8192, and the MACs of course)
    MST00 is executing the mstp compatible Spanning Treeprotocol
      Bridge Identifierhas priority 4096, sysid 0, address 000b.460e.e040
      Configured hello time 2, max age 20, forward delay 15
      Current root haspriority 0, address 6c50.4dcb.334b
      Root port is 65 (Port-channel1), cost of root path is 50000
      Topology change flag not set, detected flag not set
      Number of topology changes 7 last change occurred 00:18:54 ago
              from Port-channel1
      Times:  hold 1, topology change 35, notification 2
              hello 2, max age 20, forward delay 15
      Timers: hello 0, topology change 0, notification 0
    Port 65 (Port-channel1) of MST00 is root forwarding
       Port path cost 50000, Port priority 128, Port Identifier 128.65.
       Designated roothas priority 0, address 6c50.4dcb.334b
       Designatedbridge has priority 0, address 6c50.4dcb.334b
       Designated port id is 128.1000, designated path cost 0
       Timers: message age 4, forward delay 0, hold 0
       Number of transitions to forwarding state: 1
       Link type ispoint-to-point by default, Boundary RSTP
       BPDU: sent 571,received 568
    MST01 is executingthe mstp compatible Spanning Tree protocol
      Bridge Identifierhas priority 4096, sysid 1, address 000b.460e.e040
      Configured hello time 2, max age 20, forward delay 15
      We are the root of the spanning tree
      Topology change flag not set, detected flag not set
      Number of topology changes 9 last change occurred 00:18:55 ago
              from Port-channel1
      Times:  hold 1, topology change 35, notification 2
              hello 2, max age 20, forward delay 15
      Timers: hello 0, topology change 0, notification 0
    Port 65 (Port-channel1) of MST01 is boundary forwarding
       Port path cost 50000, Port priority 128, Port Identifier 128.65.
       Designated root has priority 4097, address 000b.460e.e040
       Designated bridge has priority 4097, address 000b.460e.e040
       Designated port id is 128.65, designated path cost 0
       Timers: message age 0, forward delay 0, hold 0
       Number of transitions to forwarding state: 1
       Link type ispoint-to-point by default, Boundary RSTP
       BPDU: sent 598,received 0
    MST02 is executingthe mstp compatible Spanning Tree protocol
      Bridge Identifierhas priority 4096, sysid 2, address 000b.460e.e040
      Configured hello time 2, max age 20, forward delay 15
      We are the root of the spanning tree
      Topology change flag not set, detected flag not set
      Number of topology changes 9 last change occurred 00:19:50 ago
              from Port-channel1
      Times:  hold 1, topology change 35, notification 2
              hello 2, max age 20, forward delay 15
      Timers: hello 0, topology change 0, notification 0
    Port 65 (Port-channel1) of MST02 is boundary forwarding
       Port path cost 50000, Port priority 128, Port Identifier 128.65.
       Designated root has priority 4098, address 000b.460e.e040
       Designated bridge has priority 4098, address 000b.460e.e040
       Designated port id is 128.65, designated path cost 0
       Timers: message age 0, forward delay 0, hold 0
       Number of transitions to forwarding state: 1
       Link type ispoint-to-point by default, Boundary RSTP
       BPDU: sent 611,received 0
    I notice that on MST01 and 02 they are not receiving BPDU’s,but I am not sure why or if that is the problem. It appears that the SF 300 is not sending BPDU packets for MST01 and 02, but is sending them for MST00. I also attached a capture. I captured the VLAN info for VLAN 100 which is in MST1. on the SF300, it appears that the SF 300 is recieving STP traffic but not generating any.

  • ESW 500 Spanning Tree Protocol

    Hi:
    I have designed my network as Follows:
    Cisco Catalyst 3750G Stack as the Core Switches
    Cisco ESW 500 Switches as the Edge switches
    I am trying to configure Spanning tree on my network with The Core Switches as the root. But i am having a problem with that.
    I set the Catalyst 3750 as the root Bridge for all Vlans. But i am having a hard time to configure that on the ESW 500 Switches, as there is no place to configure Per VLAN spanning tree.
    Once I configure trunk Ports between the Core and the Edges. The Edge Switches don't consider the the Catalyst 3750G as the root, although it is configured with 0 Periority.
    Can you please help me with that?

    Hi Mohamed,
    Thank you for participating in the Small Business support community. My name is Nico Muselle from Cisco Sofia SBSC.
    The reason for this not to work is the following : The ESW switches do not support PVST(+) or PVRST like the 3750G does, on the other hand, they support STP, RSTP, and MSTP (MSTP is not supported on the 3750)
    So, keeping this in mind, it will not be possible to implement your STP per vlan. In this scenario however, where you set the 3750 as a root bridge for all VLANs, you could easily use RSTP, which is functional on both 3750 and ESW500 switches.
    Hope this helps.
    Best regards,
    Nico Muselle
    Sr. Network Engineer - CCNA

  • Redundant connection, spanning tree protocoll

    Between two buildings i want to establish a redundant network connection. If one of the connections fails, the other connection shall transport the network data automatically. There is a SRW2024 in every building. They are connected by a fibre-cable between the miniGBIC ports 24 of every switch. This combination exists two times.
    In one building (Keller in the appended pdf-file) there is a rack with MPEG4 codecs. This rack has a built in unmanaged switch with two ports. This ports are patched to one port of the SRW2024.
    In the other building (Pforte) there is a PC which receives the MPEG4 streams. It is connected to a fifth SRW2024 which receives the streams of the two connections on ports 1 and 2.
    In my first try i have enabled the spanning tree protocoll in all 5 switches. The PC received the MPPEG4 streams. But when i disconnect one of the fibre connections the system comes to an unstable condition where the MPEG4 streams are interrupted sometimes and no network connection is possible.
    Even if i reconnect the fibre, the system switches the streams off and on and was not stable.
    Where is my fault, is it enough to configure only the fifth switch for spanning tree ?
    It would be glad if anyone has an idea to solve the problem.
    Michael

    Hi Michael,
    I have no experience with the series, but I see in the documentation that you can stack the switches. If you stack they, I think they will work as one logical one like a 3750 e.g. and you can use a Port-channel configuration.
    If I`m wrong, we should take a close look to the STP config, to make sure which one will be the root and which ports are up to make the situations "controlled"
    regards,
    Sebastian

  • Which spanning tree protocol is preferred PVST or rapid-PVST and why?

    I have WS-C2960G-24TC-L and Cisco 3750G switches, I have option to configure PVST spanning tree or rapid-pvst. Please let me know which is better and why? also send me some document explaining both protocols in detail.

    Disclaimer
    The Author of this posting offers the information contained within this posting without consideration and with the reader's understanding that there's no implied or expressed suitability or fitness for any purpose. Information provided is for informational purposes only and should not be construed as rendering professional advice of any kind. Usage of this posting's information is solely at reader's own risk.
    Liability Disclaimer
    In no event shall Author be liable for any damages whatsoever (including, without limitation, damages for loss of use, data or profit) arising out of the use or inability to use the posting's information even if Author has been advised of the possibility of such damage.
    Posting
    As Alex has noted, normally rapid-PVST should be preferred.
    Depending on needs (and device support), MST might be better yet.

  • Spanning Tree Protocol

    Fellas, I was wondering if someone can help me out here. I need to know if anyone out there in a metro ethernet or campus environment is running STP/MST/RSTP at a large scale. Large scale meaning about 200 switches. Can anyone point me to a link for a case study or a company doing this preferabley with Cisco gear but any gear would suffice.
    Also, any links on STP scaling and free standards downloads?
    I am searching myself but I recall this site has a tremendous amount of good folks.
    Any help would be appreciated thanks..

    STP as a standard recomends seven switches in a ring topology and RSTP may go up to 14 again recomended.There is no hard and fast rules as to how many switches to be accomodated in a ring.However my practical experience recomends the above. With RSTP typically the convergence is 600 msecs . This could be lowered by running multiple instances of STP in a ring through the use of VLANs (MSTP). In some cases it really can go up seconds unless the BPDY flooding accross rings or accross VLANs are not prevented through somemechanism.You can refer to cisco site for RSTP ,MSTP white papers. All metro providers (Reliance Infocomm,Tata telecomm.) are using MSTP in the rings with a maximum of 7 to 8 switches in a ring.

  • Different spanning tree protocols behavior

    Hi,
    This is my first time posting a question, so apologies if I missed something.
    My question is...
    I noticed a weird setup at my workplace and i'm unsure of how STP will interact. We have about 15 switches spread around the network, and I have noticed some run PVST and others run RSTP. I also noticed that there will two root bridges for a particular VLAN. However one root bridge will be running PVST and the other one will be running RSTP. What happens in that time of scenario?
    Is it that only PVST switches will look at the root bridge running PVST and the ones running RSTP will look at the root switch running PVST.

    It usually happens when people add additional switches over time and configure them using RSTP.
    You then end up with a mix of the two.
    As Reza has said, schedule a maintenance window and get them all over to RSTP (or Per Vlan-RSTP). There could well be a blip during this time so I would avoid doing it unless you have advised users of potential down time.
    You may find things improve after you change it, you could well have some sub optimal traffic flows if you have root bridges all over the place. 

  • How to implement uplink redundancy and spanning tree in SFP-300 switches

    We have several Small Business 300 Series Managed Switches, the 10/100 ones with PoE, the first generation ones.
    We've been advised to implement uplink redundancy and spanning tree on these switches.
    I'm sure spanning tree is a checkbox somewhere in the web interface.
    How does one implement uplink redundancy besides interconnecting the switches plus turning on spanning tree (RSTP)??
    Thank you, Tom
    P.S. I also tried to file a service request but it does not work, I get: "Error 500: Request processing failed; nested exception is java.lang.NullPointerException"

    Hello Thomas,
    Thanks for using the Cisco Small Business eSupport Community. I've looked through the articles that are available in our Knowledge Base and found a few that I hope will be able to assist you in setting up spanning tree and link redundancy on your SFP300s:
    In regards to link redundancy, the following article on LAG can hopefully provide some guidance:
    Link Aggregate Group (LAG) Configuration on 200/300 Series Managed Switches
    And for your question on setting up STP, here are a few articles with additional information:
    Configure Spanning Tree Protocol (STP) Status and Global Settings on 200/300 Series Managed Switches
    Setup Spanning Tree Protocol (STP) on a Interface on the 300 Series Managed Switches
    I hope that this information helps! Please remember to mark your question as answered and rate if this solves your problem.
    Best,
    Gunner

  • Blocked Stack Ports on 2960X-48FPD-L Stack (Unstable Switch Stack!) Spanning Tree?

    I am having an issue where 2 2960X-48FPD-L Switches in a redundant flexstack (stack port 1 SW1 to port  2 SW2 and port 2 SW1 to port 1 SW2) ring. 
    At first running the 15.0(2).EX5 (and earlier EX3, and EX4) version IOS yielded all the ports on the stack master switch refusing to run spanning tree and would only link in amber and not pass any traffic other than CDP information (the slave switch linked in fine). 
    I upgraded to 15.2(3)E and this solved the problem of the ports not linking in green and participating in spanning tree. 
    Now, however, about every week or two I lose connectivity to the switch stack and I was able to go to the switch stack locally and found that for some reason the switch stack is blocking and unblocking VLANs on StackPort1 frequently (see below).  When I was at the site, I sometimes had connectivity, sometimes not.  A stack hard reboot brought everything back up, but this is the second time this has occurred and I would expect the same problem in the next week or so. 
    Has anyone else run into these issues, and have you found a solution?
    I'm guessing that if I either get rid of the redundancy on the switch stack or stack using Ethernet cables between switches the problem will go away, but then what is the point of using stackable switches in a non redundant low speed stack.  It seems to me that Spanning tree thinks that I have a spanning tree loop going on with the stack ports which I didn't even think was possible.   
    What do you think?
    Jim
    _BAD_TLV: Received SSTP BPDU with bad TLV on StackPort1 VLAN1.
    Mar 11 09:02:59: %SPANTREE-2-UNBLOCK_CONSIST_PORT: Unblocking StackPort1 on VLAN0307. Port consistency restored.
    Mar 11 09:03:16: %SPANTREE-2-RECV_BAD_TLV: Received SSTP BPDU with bad TLV on StackPort1 VLAN1.
    Mar 11 09:03:27: %SPANTREE-2-BLOCK_PVID_PEER: Blocking StackPort1 on VLAN0307. Inconsistent peer vlan.
    Mar 11 09:03:42: %SPANTREE-2-UNBLOCK_CONSIST_PORT: Unblocking StackPort1 on VLAN0307. Port consistency restored.
    Mar 11 09:03:46: %SPANTREE-2-RECV_BAD_TLV: Received SSTP BPDU with bad TLV on StackPort1 VLAN1.
    Mar 11 09:03:47: %SPANTREE-2-BLOCK_PVID_PEER: Blocking StackPort1 on VLAN0307. Inconsistent peer vlan.
    Mar 11 09:04:12: %SPANTREE-2-UNBLOCK_CONSIST_PORT: Unblocking StackPort1 on VLAN0307. Port consistency restored.
    Mar 11 09:04:22: %SPANTREE-2-RECV_BAD_TLV: Received SSTP BPDU with bad TLV on StackPort1 VLAN1.
    Mar 11 09:04:56: %SPANTREE-2-RECV_BAD_TLV: Received SSTP BPDU with bad TLV on StackPort1 VLAN1.
    Mar 11 09:05:13: %SPANTREE-2-RECV_PVID_ERR: Received BPDU with inconsistent peer vlan id 207 on StackPort1 VLAN307.
    Mar 11 09:05:13: %SPANTREE-2-BLOCK_PVID_LOCAL: Blocking StackPort1 on VLAN0307. Inconsistent local vlan.
    Mar 11 09:05:30: %SPANTREE-2-RECV_BAD_TLV: Received SSTP BPDU with bad TLV on StackPort1 VLAN1.
    Mar 11 09:06:00: %SPANTREE-2-RECV_BAD_TLV: Received SSTP BPDU with bad TLV on StackPort1 VLAN1.
    Mar 11 09:06:04: %SPANTREE-2-UNBLOCK_CONSIST_PORT: Unblocking StackPort1 on VLAN0307. Port consistency restored.
    Mar 11 09:06:32: %SPANTREE-2-RECV_BAD_TLV: Received SSTP BPDU with bad TLV on StackPort1 VLAN1.
    Mar 11 09:07:02: %SPANTREE-2-RECV_BAD_TLV: Received SSTP BPDU with bad TLV on StackPort1 VLAN1.
    Mar 11 09:07:03: %SPANTREE-2-RECV_PVID_ERR: Received BPDU with inconsistent peer vlan id 207 on StackPort1 VLAN307.
    Mar 11 09:07:03: %SPANTREE-2-BLOCK_PVID_LOCAL: Blocking StackPort1 on VLAN0307. Inconsistent local vlan.
    Mar 11 09:07:34: %SPANTREE-2-RECV_BAD_TLV: Received SSTP BPDU with bad TLV on StackPort1 VLAN1.
    Mar 11 09:07:45: %SPANTREE-2-UNBLOCK_CONSIST_PORT: Unblocking StackPort1 on VLAN0307. Port consistency restored.

    Jim,
    We have also the same problem with our 2960-X switches (access) connecting to a pair of 4500x (VSS) except our issue is with Portchannel with 2 physical links connecting the 2960xs to the 4500.
    If we disconnect one of the physical links from the portchannel everything works fine, but when we connect the same physical link back all users lose connectivity and the physical link starts flapping. Here are some of the messages we see in the logs when both physical links are in the portchannel:
    Mar 10 18:00:43 EST: %SPANTREE-2-RECV_PVID_ERR: Received BPDU with inconsistent peer vlan id 1 on Port-channel5 VLAN90.
    Mar 10 18:00:43 EST: %SPANTREE-2-BLOCK_PVID_PEER: Blocking Port-channel5 on VLAN0001. Inconsistent peer vlan.
    Mar 10 18:00:43 EST: %SPANTREE-2-BLOCK_PVID_LOCAL: Blocking Port-channel5 on VLAN0090. Inconsistent local vlan.
    Mar 10 18:00:58 EST: %SPANTREE-2-UNBLOCK_CONSIST_PORT: Unblocking Port-channel5 on VLAN0001. Port consistency restored.
    Mar 10 18:00:58 EST: %SPANTREE-2-UNBLOCK_CONSIST_PORT: Unblocking Port-channel5 on VLAN0090. Port consistency restored.
    Mar 10 18:01:29 EST: %LINEPROTO-5-UPDOWN: Line protocol on Interface TenGigabitEthernet1/0/1, changed state to down
    Mar 10 18:01:37 EST: %LINEPROTO-5-UPDOWN: Line protocol on Interface TenGigabitEthernet1/0/1, changed state to up
    Mar 10 18:01:48 EST: %LINEPROTO-5-UPDOWN: Line protocol on Interface TenGigabitEthernet1/0/1, changed state to down
    Mar 10 18:01:51 EST: %LINEPROTO-5-UPDOWN: Line protocol on Interface TenGigabitEthernet1/0/1, changed state to up
    We have upgraded to 15.0(2a).EX5 and still have the same issue.
    We have a ticket open with Cisco and have sent them all the logs and debugs and waiting to hear back from IOS developers.
    HTH

  • What is the command to check the changes in the spanning-tree topology?

    What is the command to check the changes in the spanning-tree topology?

    Hi,
    Few commands which would help are:
    1- Show spanning-tree detail
    2-show spanning-tree detail | in ieee|from|occur|is exec  >> This will give from were the changes occuring- Ex:
    C6K1#show spanning-tree detail | in ieee|from|occur|is exec  
     VLAN0001 is executing the rstp compatible Spanning Tree protocol
      Number of topology changes 9536 last change occurred 00:00:29 ago
              from GigabitEthernet4/6
    3- show spanning-tree active  *& show spanning-tree root >> Will give you the root information.
    4-  show spanning-tree inconsistentports >> If there are any port which are inconsistent state due to STP features.
    STP running MST:
    ===============
    show spanning-tree mst configuration  >> Need to check and match the same outputs with the other switches running in the same MST domain/region.
    show spanning-tree mst detail
    show spanning-tree mst <name of the region>
    Debug on STP:
    ============
    debug spanning-tree events/bpdu >> would be good but to be run with more cautious.
    HTH
    Inayath
    *Plz rate if this info is usefull.

  • Why did we really need this "spanning-tree extend system-id" command?

    Folks,
    On the Spanning tree protocol I understood how does this spanning-tree extend system-id command work.
    But I have not understood why it is in place? or why do we really need it?
    Regards,
    Nikhil Kulkarni.

    Hi Nikhil,
    The STP and RSTP standard specifications mandate that each switch running STP/RSTP must have a unique Bridge ID (BID). Because Cisco runs STP or RSTP in each VLAN separately (called PVST and RPVST or PVRST), in each VLAN, the switch behaves like a standalone (albeit virtual) switch and thus, each STP/RSTP instance is required to have a unique BID to comply with the standard. Simply, having X VLANs means having X separate STP/RSTP instances and X unique BIDs.
    The question now is how to make sure the BIDs of STP/RSTP instances run on the same switch in different VLANs are truly unique. Older switches actually had a large reserve of MAC addresses. As new VLANs were created, these switches allocated a new MAC address for each new STP/RSTP instance in a new VLAN (recall that the BID originally consisted of the priority and the MAC address), making the BIDs unique.
    However, the consumption of MAC addresses this way was simply too large and ineffective. At the same time, having 65536 different values for priority in the BID was largely useless. So IEEE came with the idea of Extended System ID in which they reused a part of the priority field for a unique instance identifier. In Cisco's implementation, this field is populated with the VLAN number the STP/RSTP instance runs in. This easily and effectively makes the BID unique - even with the same priority for all VLANs on a single switch, and a single switch MAC address, multiple STP/RSTP instances running on this same switch with the same priority have different BIDs thanks to different VLAN numbers embedded into the BID.
    Some switch platforms actually allowed you to deactivate the Extended System ID and revert to the older style of assigning unique MAC addresses to individual STP/RSTP instance BIDs. That is why the command spanning-tree extend system-id exists in the first place. However, removing this command is only possible on those switching platforms which are equipped with 1024 MAC addresses for their disposal. Most new switching platforms have only 64 MAC addresses for their internal use, and while the spanning-tree extend system-id command is present in their configuration, you can not remove it. It is simply there to inform you that the Extended System ID is being used but you can not really deactivate it.
    Read more here:
    http://www.cisco.com/en/US/docs/switches/lan/catalyst6500/ios/12.2SXF/native/configuration/guide/spantree.html#wp1096536
    Best regards,
    Peter

  • Rapid Spanning Tree, 802.1w

    Do any SBTG switches support Rapid Spanning Tree? It appears the 3560x does, but looking for more "cost effective" solution.

    Hi Art,
    The new and improved  300 series  (SRWxxx-K9-NA) which is a refresh for the older SRW series,  shows that it supports STP,   RSTP and    MSTP.
    http://www.cisco.com/en/US/products/ps10898/prod_models_comparison.html
    regards and seasons greetings
    Dave Hornstein

  • 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
    IEEE 802.1Q defines a single instance of spanning tree running on the native VLAN for all the VLANs in the network which is called Mono Spanning Tree (MST). This lacks the flexibility and load balancing capability of PVST available with ISL. However, PVST+ offers the capability to retain multiple Spanning Tree topologies with 802.1Q trunking.
    IEEE 802.1Q defines a single instance of spanning tree running on the native VLAN for all the VLANs in the network which is called Mono Spanning Tree (MST). This lacks the flexibility and load balancing capability of PVST available with ISL. However, PVST+ offers the capability to retain multiple Spanning Tree topologies with 802.1Q trunking.
    http://networking.ringofsaturn.com/Certifications/BCMSN.php
    Per-VLAN Spanning Tree (PVST) ? A Cisco proprietary method of connecting through 802.1Q VLAN trunks, the switches maintain one instance of the spanning tree for each VLAN allowed on the trunk, versus non-Cisco 802.1Q switches which maintain one instance for ALL VLANs. This is the default STP used on ISL trunks.
    http://www.informit.com/content/images/1587051427/samplechapter/1587051427content.pdf
    The 802.1Q standard defines one unique Spanning Tree instance to be used by all VLANs in the network. STP runs on the Native VLAN so that it can communicate with both 802.1Q and non-802.1Q compatible switches. This single instance of STP is often referred to as 802.1Q Mono Spanning Tree or Common Spanning Tree (CST). A single spanning tree
    lacks flexibility in how the links are used in the network topology. Cisco implements a protocol known as Per-VLAN Spanning Tree Plus (PVST+) that is compatible with 802.1Q CST but allows a separate spanning tree to be constructed for each VLAN. There is only one active path for each spanning tree; however, in a Cisco network, the active path can be
    I could not get exactly what these Terminology (PVST, instance, PVST+, MST, etc) trying to achieve ?
    Any URL and online resource help me to do some extar reading to clarify these terminology

    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
    Now for point 1, we have the IEEE standard 802.1q, which mentions how multiple vlans can be carried across a link. As per this standard a 4 byte tag will be inserted in the ethernet packet, ( inserted between the Destination mac address field and the ethertype field)
    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.
    Now for point 2, again we have IEEE standards like 802.1d ( common/mono spanning tree), 802.1w/RSTP ( Rapid spanning tree) and 802.1s/MSTP.
    In 802.1d, there will be only one spanning tree process/instance running for the whole network, irrespective of how many vlans are involved in the network. Hence the whole network is treated as one common domain by the STP protocol.
    So, there can be only one root bridge in the network and other bridges will intelligently block the redundant links, we wont have much control to effectively utilise the redundant links.
    IEEE 802.1w/RSTP also works in the same fashion, but the convergence time is very fast in this protocol.
    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

  • How many BGP peers does the 3548 switch support?

    Is it possible to run more than 40 peers on a single switch? What is the limitation if not?

    Hi ,
     You can have 40 BGP peers , IPV4 unicast routes handled by hardware is only 24000 .Enusre all your BGP peering routing updates is within this limits . 
    http://www.cisco.com/c/en/us/products/collateral/switches/nexus-3548-switch/data_sheet_c78-707001.html
    Table 7. Hardware Specifications Common to Both Switches
    Mode
    Normal Mode
    Warp Mode
    Hardware tables and scalability
    Number of MAC addresses
    64,000
    8000
    Number of IPv4 unicast routes
    24,000
    4000
    Number of IPv4 hosts
    64,000
    8000
    Number of IPv4 multicast routes
    8000
    8000
    Number of VLANS
    4096
    Number of ACL entries
    4096
    Number of spanning-tree instances
    Rapid Spanning Tree Protocol (RSTP): 512
    Multiple Spanning Tree (MST) Protocol: 64
    Number of EtherChannels
    24
    Number of ports per EtherChannel
    24
    Buffer size
    6 MB shared among 16 ports; 18 MB total
    Boot flash memory
    2 GB
    HTH
    Sandy

  • Nexus spanning tree pseudo configuration

    Hi
    I am trying to understand the pseudo configuration commands in a Nexus hybrid topology.
    I have vlans a, b and c only in the vPC side of the topology.  I have peer switch configured and the same stp priority on both switches.
    In the standard Spaning-tree topology I have completely seperate vlans x, y and z.
    What should I be configuring in the pseudo config section ?  Do I define a pseudo root priority for all vlans a, b, c and x, y, z or just for the standard spanning tree vlans x, y and z.  I need to avoid and, even short, spanning tree outages if I take one Nexus out of service for a short time.
    My thinking is that if one Nexus is out of service the physical mac will be used and potentially reduce the root priority of the vPC vlans causing a TCN and STP recalculation in vlans a, b and c.  This can be avoided by configuring a pseudo root priority for all Vlans lower than the current spanning tree priority shared by the vPC peers.  Is this correct ?  However, since I have a shared priority of 8192 on current vPC vlans will configuring, for example, a pseudo root priority of 4096 on those vPC vlans won't this also cause the TCN and recalculation I am trying to avoid ?  Is the benefit of the pseudo root config only obtained if it is configured at the start when the vPC is formed and prior to the peer switch command being issued ?
    Thanks, Stuart.

    Hi Ajay,
    It is recommended that switch-to-switch links are configured with the spanning-tree port type normalcommand. The one exception is the vPC peer-link which is recommended to configure with the spanning-tree port type network command.
    Take a read of the Best Practices for Spanning Tree Protocol Interoperability from page 56 of the vPC Best Practice Design Guide for further information on this.
    Regards

Maybe you are looking for