Cisco :: Why Wouldn't Use Spanning - Tree Portfast On Trunk Port Other Than Trunk Between Two Switches

Apr 11, 2013

Is there really any reason why you wouldn't use spanning-tree portfast on a trunk port other than a trunk between two switches? We have it enabled on all ports except for the fiber trunk between two non-stacked switches and the trunk ports connected to our Astaro firewall.I'd like to enable it on the ports to the firewall unless that would cause issues.

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Routers / Switches :: Trunk Port Connecting But Network Tree Not Available On Pc

Jun 26, 2012

trunk port connecting but not allowing access to tree; i connected 4506 port to 3550 port; and i set both to switchport mode dynamic desirable; the 4506 port was set with switchport mode access and switchport mode access vlan ?; i used the command default switchport access vlan to remove the vlan; the ports are up but as I stated I cannot connect ot our workgroup tree

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Cisco Switches :: SGE2010 Switches / VLANs And A Blocked Port In Spanning-tree?

Aug 20, 2012

I have 2 switch groups.
2 SGE2010's with VLAN's defined as 10,20 and 30
Vlan 10 is the management VLAN, and it uplinks to our border router.Vlan 20 is the workstation VLAN, and all workstations point to the switch as their default GW? Vlan 30 is the ip phone VLAN, and all phones use this as their gateway.
I would like to put a LAG between said switches, we have some servers on the ip phone switch that need to be accessed by the workstation clients, and the single 100mb link through the router is probably not going to be enough.As I understand it, because the switches have different networks on them, a simple lag will not work. I did create a lag, and assign ip addresses to each side, however in that mode, it doesn't appear I can block vlan 10 from transiting the LAG, and with out that block I will end up with a logical loop, and spanning-tree will block one of the uplinks, or the LAG itself.

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Cisco Switches :: SGE2010p VLAN Trunks Spanning Tree And A Port Blocked

Jul 21, 2012

We are upgrading out internal office network. I have setup 4 switches and 1 router using the following config.
-2 SGE2010p's are stacked together forming vlan 30 (to be used for phones)

-2 SGE2010's stacked for workstation's under vlan 20
Both switches are apart of vlan 1 (the default)Ports 1 on each stack are connected to a Cisco 890 (port fe2 and fe3) in trunk mode. Ports 2 and 3 are in an LAG group and connected to the neighboring stack (I have attached a diagram), and are also in trunk mode).At this point one port (port 1 on either stack) goes into blocking mode, and I get why ,it's a physical loop.I need more than a 100mb link between switches (which is what pulling the LAG between switches gets me), but I don't want to route phone traffic through my workstation switches to get out of the LAN.Is it possible using these switches and router to have a LAG between stacks and a link to the router for traffic to ?

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Cisco WAN :: Port Security Between Two Switches 3750 Or 3560 Using Trunk

Sep 2, 2012

Is it possible to use Port Security mechanism between two switch (3750 or 3560) ports while trunk has been configured? If it's not possible, is there any other way to ensure that no other Switch can be connected other then the one switch which has been configured/placed by a network engineer?

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Cisco Switching/Routing :: 3560 Multiple Switches One Trunk Port

Sep 21, 2012

We have 7 3560's in 7 different locations connected to our providor for wan access.  Our provider has given us a copper cable at each point and we have connected it directly to our 3560 switch at each location.  Each port is configured the same way at each location.  Each switch is running eigrp.All of the switch ports on each switch are configured as a trunk and vlan 299 had the ip address for the eigrp connection: [code] This setup is working as each switch see's all of the other switches as an eigrp neighbor.  We have also made sure that the switch at our head office has spanning tree priority for vlan 299.
So the problem is, if there is a change in the topology at one of the locations it usually causes one or more of the other connections to go down for some reason.  We just cannot pinpoint what is causing this change.  There are no log's or anything other than an eigrp hold time expired message.?

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Cisco Switching / Routing :: WC2948G - Configure LACP Trunk And Multiple Trunk

Feb 12, 2012

we recently aquired a managed services job and have to do a overhaul of the vlan configs and have a whole dozen WC2948G's trunk between a set of ports as well as trunk out a LAG channel setup to non cisco equipment. the deal is the lacp-channel works properly on both ends but no routing of vlans between ports and between the lag trunk are working.
theres alot of settings in the config and im planning on clearing it and starting from scratch but before i do i want to know where my problem lies.


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Cisco :: Spanning Tree Between Switches Accordingly

Nov 18, 2012

Do switches learn link state information from routers and optimise the spanning tree between the switches accordingly ?

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Cisco WAN :: How Spanning Tree Works On L3 Switches

Oct 25, 2012

I've got a bit of a query regarding how spanning tree works on L3 switches?So say we have a few 3550's connected together and spanning tree has converged and everything is looking ok. We then introduce routing into the network, does STP still operate in the same way or is this layer 2 feature now redundant because routing has taken over?I just couldn't figure out if STP still operates at layer 2 to prevent loops and routing sits on top to route the traffic?

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Spanning Tree Protocol For Extreme Switches?

Feb 28, 2011

download speed is getting slower in lan, file and print sharing also take long time.

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Cisco WAN :: 2 X 3750 Configure Spanning Tree On All Switches

Jan 8, 2013

I have a question in regards to configuration I'm planning to implement. I currently have 2 x 3750 running in a stack. I would like to add 1 x 870 router connected to both switches.It's important for me that 870 is always available (it will only be used as a backdoor for our management network through WAN) but I don't want it to participate in any switching (including switching for management network unless it's going through this backdoor WAN). Do I need to configure spanning tree on all switches or stack is automaticly working as a 1 logical unit?As router is only using 100MB/s connection, how I can prevent this router from switching packets with other switches?

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Cisco :: Spanning-tree Every Port Go Into Listening / Learning State

Apr 4, 2012

Ages ago I was shadowing someone making a change on the network. I cannot remember which spanning tree version was running and cannot remember the config of any port either. What I do remember is that every switch port on the 2960 switch went orange and an outage occured, where the ports went into listening / learning mode. I assume that the STP was just the default ieee 802.1D.

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Cisco Firewall :: 3750-x Stack Port Acl And Spanning Tree

Oct 3, 2011

I have a pair of 3750-x switches stacked together. Using spanning tree with our upstream provider I have an active line in port GigE 1/0/25 and a blocked redundant line in GigE 2/0/25. I have setup a port based acl as below on 1/0/25 which is a port on the current master switch. Do I need to manually set this on 2/025 as well? Just wondering what would happen if the line to the master switch was to disappear or if the master disappeared completely whether the acl would automatically be applied to 2/0/25.

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Cisco Switching/Routing :: 5500g 3com Switches - Spanning Tree

Jan 10, 2013

I have problems too when I connect 3com and Cisco.
I have 2 5500g 3com switches connected with 2 links. If LACP is disable, this causes serious problems and STP not works.
Logically , the link, is a port trunk with all the vlans permitted. One switch has STP enable and the other RSTP. Why this not works fine? I need to configure MSTP maybe? PVSTP is not allowed on this switches.

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Cisco Switching/Routing :: 8192 / Spanning Tree Port Priority Value?

Sep 19, 2012

Why is it when I set the port priority for example to 8192 and I then do a show spanning-tree vlan 1 it shows as 8193, does it add the vlan number?  so if it was vlan 10 it would be 8202?

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Cisco :: Core Layer Switches After A Spanning-tree Topology Change Occurs

Mar 24, 2013

I've been taught/under the impression that vlans and stp stay in the access layer to prevent bridging loops and broadcast storms from taking down the whole network. Well I was reading about backbonefast and how it "Enables fast convergence in the networkbackbone or core layer switches after a spanning-tree topology change occurs." Now I thought that from the distribution layer up we use a routing protocol.

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Cisco Switching/Routing :: 2960 Switch Stack Spanning Tree Recalculate From Port One

Feb 23, 2012

2960 switch stack (flex) Spanning tree re-calculate from stack port one?I need to identify with port in the stack is causing the re-calc  I have four 48 port switches and show spanning detail only indicates stack port 1.

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Cisco Switching/Routing :: Lose Lot Of Bandwidth Over Trunk Port (vs Access Port) 3750g

Feb 18, 2013

I have a 3750g connected to a "core" switch stack of 7 other 3750g's via 2 GigE ports in a trunk.  This is currently in a switchport mode access port- channel so only the default vlan data is sent over. Now we have a need due to physical location of these switches, to allow vlan20 (DMZ) from this 3750g to the switch stack.  I will configure a few ports on the switch stack for vlan20 and they need to be able to talk to the stand alone 3750g.To do this I will change the port channel on both endpoints to

-switchport trunk ecapsulation dot1q

-switchport mode dynamic desirable
also making the appropriate change on the interfaces belonging to this trunk.My question is, now that its a trunk port that carries multiple VLANs, how much is the bandwidth reduced on that 2gbps link?I have a very active VLAN (10) on the stand alone switch, but on the core I'm not going to be assigning VLAN 10 to any ports.  So does traffic from VLAN10 even come across the trunk (wasting bandwidth) if no ports on the core side are assigned to it?  I really just need vlan 1 and 20 (for now).

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Cisco Switches :: QoS On Trunk Ports ESW 500 And SF 300

Mar 27, 2012

How does the ESW 500 or SF300 line guarantee QoS of voice traffic when trunking switch to switch? I have (2) ESW 500 series switches in series. The phone on switch 1 have no audio issues, but the phones on switch 2 (the last in the series) have intermittent voice quality issues when dialing across a WAN circuit to another office. The phone on switch 1 do not have that issue though they traverse the same circuit. They are all using the same VLAN 100.

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Cisco Wireless :: Trunk Port On WAP 321?

Feb 12, 2013

i have plan to deploy cisco WAP321 on my customer, and after rading the document about WAP321, it said the WAP321 support for VLAN ID feature, but i cant find whether it support for trunk port because i would like to connect the WAP 321 LAN port to the cisco SMB switch SG300/SG200. is the trunk port already enable on the WAP 321 LAN port so i dont need to configured it or not ?

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Cisco :: How To Configure A Trunk Port As Network Port

Feb 27, 2012

What is network port ? I want to configure a trunk port as network port, so that the trunk port becomes the network port for all the VLAN associated to the port.

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Cisco :: Cannot Trunk With Allied Telesis Switches

Oct 29, 2012

I'm working with an established Network, which has 2 Allied Telesis Switches (1)&(2).I must add another Allied Telesis (3), and a Cisco Switch.If I connect just the Cisco Switch, and the AT(3), it works ok. I mean it trunks. It also works ok if I connect the AT(3) with AT (1) and AT (2). But if I want to connect the Cisco SW with AT(1) and AT(2), or AT(1), AT(2) and AT(3) It doesn´t trunk. Even if I set the Cisco Switch port I use, as a trunk port.I think I have a problem with the vlans already created on AT1 and AT2. But the problem is that I cannot access to the AT console mode.

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Cisco Switches :: Set Up Trunk Between SG200 And SRV2048?

Apr 14, 2013

I'm trying to set up a trunk between an SG200 and a SRV2048.. I am attaching my configuration that not works..
I test to ping an host that is open on Vlan 22 on Swich01 from the other switch, SWITCH02 , from a port 26 that I opened on VLAN 22 in untagged mode but nothing works..

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Cisco :: Obtaining Vlan On Trunk / Port

Jun 29, 2012

I'm trying to obtain the vlans on a trunk and also whether the port is a trunk. Ive seen VTP mib, but these dont appear present on my switch (2950).

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Cisco WAN :: 2801 And Switch Trunk Port

Apr 20, 2012

1- Cisco Router
Eth0/0 : Ip address /24   == connected my laptop of
 /1: Ip address : /24   = connected cisco swith

2 - Cisco Switch
VLAN 2 Name : Sales : ip address 192.168.3. 1 = connected computer
VLAN 3  Name : Marketing : ip addres = connected computer

So I want my laptop that connected the router Eth0/0 Interface should access both VLAN 2 and VLAN 3 computers

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Cisco :: Customizable Trunk Port Group In LMS 4.0?

Jul 19, 2011

How can I add devices onto the customizable group1?  I am trying to creat a group of trunk ports and monitor just the up/down.

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Cisco AAA/Identity/Nac :: NAC 4.1.6 Managing Trunk Port?

Sep 1, 2011

Running Cisco NAC 4.1.6 OOB on the LAN.  For some reason in the middle of the night, the snmp trap mac-notification added command appeared on the trunk uplink port of one of our switches. 

I don't know exactly when the command was added but at 2am when the backup of the config was taken, it was there.  At around 4:30am, the uplink went off-line.  Is there anything within NAC that would push a change like that automatically to a switch.  We do have NAC Profiler running on the network also.The problem was in a branch office so I only got the information second hand what was on the switch itself.  We moved the uplink to a different port which allowed the switch to show up on the CAM again, however when I viewed it, the uplink port was set to controlled! 
Does this make any sense?

how long devices will stay in the certified device list if no timer is configured to clear it out?

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Cisco Switches :: Possible To Trunk SF300 With 3750 Switch

May 4, 2011

Is it possible to trunk a SF300 switch with a 3750 switch?  If so how?  Whenever I turn trunking on the 3750 port I lose connection to the SF300.

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Cisco Switches :: SG300 Trunk With 3com 4800G?

Oct 25, 2012

Our company currently have a 3com 2816 connected to a 3com 4800G through a trunk.  The 4800G connects to the PBX and to the ip phones/computers. We are currently using vlan1 (192.168.100.n) for data and vlan 3 (192.168.101.n) for voice , Ip addresses are being issued by a DHCP server. Each user has an assigned IP phone and it has an ethernet port that connects to each computer. This setup has been working properly until I purchased an SG300 and replaced the 3com 2816.
The ip phone is showing a bad gateway and the PC are getting an ip address of 192.168.101 (which is for voice). Theoretically it should work, but what is weird is, it seems the SG300 trunking with the 3com 4800G is not working. Is it possible that it is on ISL mode rather than dot1q?I also saw its running RSTP, should I changed it to classic STP?How do I fix this or what troubleshooting should i do?
The SG300 is configured as a layer 2 switch. Configuration for the trunk below:
interface gigabitethernet27
spanning-tree link-type point-to-point
switchport trunk allowed vlan add 3-4
macro description switch
macro auto smartport type switch $native_vlan 1

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Cisco WAN :: 1800 Router - Trunk Port L2 Switch

Feb 24, 2011

Currently I have a 4510-48g HP3COM switch as a core switch for my 4 VLAN network (which I hope to send back cause it doesn't do what I wanted it to do... PBR, which is what I need to route specific VLAN's to specific interfaces on the sonicwall,.. cause sonicwall dont understand trunk or spanning tree,. meh!) This may not happen so I've dug out an old CISCO 1800 sdsl router that has 1 FE0 port and 8 other ports, FE 1-8.
The first thing I need to do is get everything to talk to each other. So I plugged the switch into it via its configured trunk port, and configured 4 sub interfaces on the router 1800 and all seemed happy as larry and working. The problem I have is I dont seem to be able to create sub interfaces on the other ports!?


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Protocols / Routing :: SIP Trunk Port Range (VOIP)

Aug 14, 2012

I've recently set up a PC-based IP PBX in our small business which uses a SIP Trunk for up to 3 simultaneous voice calls. Ports needed to operate include 5060 (SIP-UDP) and then a huge range of high-number UDP ports which I believe is for the 'media' or audio. Let's call the range UDP 49,152 to 64,512. I only know a little about the SIP protocol but my understanding is that each call will randomly use a few ports from this range across which will pass audio, Is there a need to have such a wide range of ports open? If my SIP trunk is only capable of 3 simultaneous calls then it seems only 9 or so of those open ports could get used at once. Could I not just open, say a range of 100 ports and be fine, thereby reducing the security risk?

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Cisco :: Switches Are Complaining About Duplex Mismatches On Trunk Interfaces

Jun 19, 2012

I've noticed that a couple of switches are complaining about duplex mismatches on trunk interfaces. When I took a closer look, two switches (switches 1 & 3) are reporting that they have a duplex mismatch to a device connected to a downstream switch (switch 2). Basic topology is switch 2 has a 1G fiber link to both switch 1 & 3.

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Cisco Switching/Routing :: Two 3750 L3 Switches Connected Via Trunk

Jan 29, 2012

I have client who has two distant offices with 3750 L3 as core (do all vlan routing for local office) and multiple L2 access switches with multiple VLAN’s connected to it. First 3750 is hub also connected to internet, second 3750 is spoke and acting as a router on stick. We have eigrp configured on both side ISP provided client 100Mbps link as a trunk with two vlan; vlan10 for voice and vlan20 for data. We assigned two small subnets to these vlans and Hub addresses are and respectively. How to force voice over VLAN10 and data via vlan20, but still do some load balancing? How to setup default route on second (router on stick) switch?

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