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).
we have a scenario that consists of a Cisco 4507 series core switch with more than 20 vlans which is connected to a C2960G switch( in a nearby building) using a trunk by a fiber connection. Up to this point everyhting is fine . VTP domain is configured on the core switch and we have all of the 20 vlans present correctly on the edge 2960G wich is part of course of this same VTP domain.the fiber connection goes from core switch to a "in the middle location" where we have a fiber patch panel that is connected in a jumper style to another fiber patch panel going to the destination building where the C2960G sits.
Now imagine that Fiber connection from this middle location to the destination C2960 edge switch is down for any possible reason meanwhile the fiber connection from Core switch 4507 to the middle location is still intact.In the same time, in this middle location , we do have a wireless connection which links 1 Cisco 3750G switche ( a different infrastructure and different VTP domain) to another C3560G switch which sits on the same Room in the nearby destination building where we have the edge C2960G, An idea came to me is to connect one of the fiber port (core) in the intact fiber patch panel coming from Core switch 4507 TO an access vlan configured switchport in the 3750G switch ( this switchport will belong to a vlan designed only to trasmit the vlans on the trunk coming from 4507 core switch say VLAN 10) then connect one VLAN 10 access switchport to the destination C2960 edge switch ( the switchport on the c2960G is still a trunk)Will this solution work and all of the 20- 4507 core switch vlans arrive to the destination C2960G ? Or we do need something that tags the 2 VLAN 10 switchports like switchport dot1q tunnel like QinQ
I have a 48-port 3750G switch (model # WS-C3750G-48TS-S). How do I determine which ports are grouped per ASIC on the 3750G switch? For example, is the grouping ports 1-8 is serviced by ASIC 1, ports 9-16 is serviced by ASIC 2, ports 17-24 is serviced by ASIC 3, etc. If it exists, what is the IOS command to show the mapping of ports to ASIC?
I am trying to run TDR tests on a 3750G (ver12.2). The switch ports have 3502 series access points attached to them. When ever I run the test the results all show "Not Completed". I understand that this means the test failed but this happens with any port I try.
I have 2 Cisco 6509 switches linked together via single Fibre as a trunk.I want to change this to a port channel where I will add another 3 fibre ports to the port channel but what order do I do this to minimise any disruption.
1-Configure PortChannel and add the 3 new ports, this will bring up the Port Channel but what effect will this have on traffic currently going over the single Trunk link? Will spanning tree go mad, how will switches react?
2-Convert existing Trunk link to Portchannel then add in new ports to PortChannel, I guess in doing this there will be a small hit on traffic as it changes to a port channel.
I have a stack of 3750G's where the connection between switch 1 port 1 and switch 2 port 2 are down
Stack Port Status Neighbors Switch# Port 1 Port 2 Port 1 Port 2 -------------------------------------------------------- 1 Down Ok None 3 2 Ok Down 3 None 3 Ok Ok 1 2
I have ruled out the stackwise cable as the problem but would like to know which switch has the problem
can i have 4 links from an ESX server to 6500 , each link represents a trunk link carries each the same 2 VLAN , 100 and 101 , keep port-channel out of the picture , does it work well?
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.?
I have a pair of 3560's configured with dot1q trunks between them carrying a number of VLANs.
Once deployed there will be a requirement for these physical trunks to be disconnected from time to time. Knowing that this is inevitable I am trying to minimise the period of time for the trunks to recover once the physical connectivity is reinstated.
All of the VLANs on the switches are configured for Spanning Tree Rapid PVST. Current time for the trunks/VLANs to come up is around the 4 second mark.
Is it possible to rate limit on a L2 trunk port on a 3750?
current port config and ios are as follows;
interface GigabitEthernet1/0/50 description *** Connection to Fiber Link *** switchport trunk encapsulation dot1q switchport trunk allowed vlan 1,172 switchport mode trunk end flash:c3750-advipservicesk9-mz.122-46.SE.bin
i was wondering if the "srr-queue bandwidth limit 10" command would work to limit the output from this interface to be 10 % of the port bandwidth and then the same command could be done on the other side.
We have a 3750G 12S that is connected to its clients with 1000 Mb SFPs. On the switch is a simple Vlan all the ports are assigned to. The ports are auto-sensing gig connection speed and full duplex when I run the show interface command.What happens is that if a client workstation is restarted or shut down and powered back up, the client cannot reconnect to the switch unless we cycle the switch itself (power off and back on)I know only the very basics of switch configuring and finding it difficult to source any trouble shooting info on issues like this.
I've run in to this on 3750G's in a various sized stacks. We apply port security for a mac address on a single port (not existing on more than one port - that's a different issue that appears in multiple posts already).In this case:
1) We do a 'sho mac address-table and see that the device with the mac address in question lives on one port, port 1/0/x.
2) We apply mac port security for this exact same mac address to the same port it is already attached to. switch(config)#int g2/0/2 switch(config-if)#switchport port-security mac-address 001a.1ec8.abcd
3) Get this error: 'Found duplicate mac-address 001a.1ec8.abcd'.We again confirm that that is the only port on the entire switch that has this mac-address.Try the command again, same error.
4) We do a bunch of show commands, get in and out of the switch, go back and then try it again, and now it works, same command, same port and same mac address.
-Aging is default 300 -These are Cisco wireless AP's attached to the switch -This occurs on different switches with different ports using different mac addresses, always same symptoms.
I have several closets with Cisco 3560 on the edge that I'd like to change the vlan that's used for the management vlan on each. In the core I have a Cisco 6509 with Sup720's.
I'd like to do this by changing the native vlan on the trunk port on the core 6509 interface that connects to the 3560. and leave the management vlan on the 3560 as vlan 1.
Seems trivial but what I tried didn't work and I didn't have the window to troubleshoot. I'll paste the simplified configs for the interfaces below
So I took a laptop with wireshark and plugged it into a nexus 5000 port that is configured as a trunk with 3 vlans allowed on it. The laptop was seeing all kinds of traffic on the wire, most of it was not involving my laptop.
For example: Server A VLAN 10= 10.10.10.1 Server B VLAN 20= 10.20.20.1 and wireshark laptop is plugged into a trunk port which is allowing those vlan's. The vlan's are routable.
10.10.10.3 is seeing the entire conversation when 10.10.10.1 backs up 10.20.20.1 even though it has no reason to see it. It is as if the trunk is spanning traffic to the laptop port. No span is setup however. It's really weird. This is not just broadcast traffic, but actual tcp taffic between Server A and B. Why would a trunk port see traffic between 2 other servers talking to each other on the vlan.
I need adding a vlan to the trunks bundled in port channel. I know how to add v lans to a port channel with Cisco IOS but with CAT OS.
I have 2 ports bundled to form ether channel in switch which is running CAT OS. There are already few v lans allowed in the trunk of each interface. now I need to add one more v lan.
For Example:- v lan 135 needs to be added in addition to the existing v lans.
clear trunk1/2 1-112,115,117-134,136-4094 set trunk 1/2 on dot1q 113-114,116,135
and similarly on the 2nd interface
so if I add vlan135 to the trunk one after another will it cause any service disruption?
We had a core switch (Cisco 4503), distribution switches(Cisco 3750) and access switches in our network and consists of many vlans. Almost all vlans uses DHCP Pools. But for few vlans DHCP is not yet configured due to initial design poblems. Recently one of the rogue user in vlan 1 connected to one of the access switch send rogue arp packets to the network (suspecting arp packet with interface vlan 1 ip of core switch with wrong mac-address (gateway ip of vlan 1)) and resulted in a prolonged network outage for the vlan 1. Any way we are going to seggregate vlan 1 into different vlans, but before that we need a temporary plan to block such kinds of attack like enabling DAI in the switch. I have checked the DAI implemenation feasibility with my knowledge and found that it is not possible to configure to the access switches(Cisco 2960) in which the user directly connected. But found that Distribution switch connected to that particular access switch seems to be able to configure since DAI commands are available to configure in switch.
Is it possible to block ARP packets with the interface vlan 1 IP Address with rogue mac-address by configuring DAI in the above mentioned Distribution switch and the port connected to the mentioned access switch?
I'm trying to trace a host and I'm getting stuck at the port channel mac addresses. I need to find out where the server is connected to and the switch it lives on.
Please read below:
Step 1) Log into the core (MSFC): Code...
How do I find out where this physical server lives? I keep getting the mac for the trunk ports which is being used for all VLANs.
The server is hanging off some switch but I need to track it down to the last end.
I have a Cisco Wireless LAN Controller WCL2112 model. It's currently plugged into an HP Procurve switch on a trunk port. That HP switch is plugged into my Cisco stack on a trunk port. I can reach the WCL just fine through the LAN. But when I plug the WCL directly into the Cisco stack on a trunk port, I can't reach the WCL at all, unless I connect to it over wireless. The interface shows it's conneccted and up/up. But no communications are sent across the line. I did a wireshark and can see only ARP request from the WCL. The trunk port on the stack is set to:
Any way to test in a lab what would happen if a tech mistakingly added "switchport voice vlan XX" to a trunk port? I am try to do some RCA on an issue and this has been identified as a possible cause by one of my techs.
The config is Switch1------Switch2--------Switch3 Each interswitch connection is configured as a dot1q trunk with all vlans allowed. The link between switch2 and 3 is where switchport voice vlan 10 was added. Switch1 is a 3750 and 2/3 are 3560's.
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.
I want to configure switch port bandwidth limit for my Catalyst 2960-48, is there any hardware / ios limitation? can I configure it at all 48 switch ports?
I'm intending to purchase a switch for work,and I need to limit the bandwidth of one of the ports to 25 Mbit upload and 25 Mbit download (we have 100/100 Mbit connection and the customer is only paying for 25). I been trying to find information on how this could be "properly" done and what kind of switch I need to buy. As far as I have understood, most L2+ switches support outbound rate limiting, but not inbound, and as I only want the customer to have 25 mbit up and down, I need both.
I been looking at a Cisco Catalyst 3560 switch, and I'm first and foremost wondering if I can limit the inbound AND outbound bandwidth on this switch? Perhaps it can even be done on a simpler, cheaper, switch - as I rather not spend more money then necessary?
Lastly, how to do it, limit the inbound and outbound bandwidth on a single port (perhaps on the above mentioned switch, if possible), to 25 Mbit?
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.
I have configured a few 3750G switches with trunks and I want to test the throughput. In your experience is iperf the best tool? If so what settings do you use?
Can I configure the Port at the ASA 5050 from Mode: access Port to trunk during the FW is running in a production area without console access ?As I know at the 5505 ist should work?
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?
On the supervisor card of a cisco 6500 series, according to the following link, [URL] it only has 2 uplink ports on the card. Would I be correct in assuming that I only have those to ports that I can configure IP addresses on?
The cisco that is being devlivere is coming with a 48 port switch and 24 port fibre switch. Could I change any of those ports into a router port and configure IP addresses on those?
The supervisor card is a ws-sup-720-3b the 48 port switch is a ws-x6748-ge-tx the 24 port fibre switch is ws-x6724-sfp
I'm trying to enable port security on several 4507R's. When I try to configure a range of ports the switch will randomly put 1 or 2 in err-disable. It's different every time I apply the config to the same group of ports. However if I do them one at a time it seems to work. But I really don't want to configure 6 fully populated switches one port at a time. We also have a lot of 3750's and they gave me no problem using a port range. [code]
We just installed a hosted VOIP system using Cisco 7900 series IP phones. We are having a strange issue with a few computers where they pull DHCP information from our VOIP provider's DHCP server on the Internet and not our LAN DHCP server.
The switchports areconfigured as: switchport mode access
My rationale behind this is that the phones would use CDP to get their VLAN info from the providers Cisco router and the PCs would just ride on the default VLAN. But this is not the case. Computers randomly keep getting DHCP info from the provider's router. Do I have to use voice vlan x and make the switchports trunks?
is it possible to shutdown a specific port on my 3750x and monitor this port at the same time .for example , im dealing with a mac authenticated network using port security , i want to shut down all the ports that are not used at the moment , however , if some one gets connected to the one of the shutdown ports i want to know the mac address of the user or atleast to know that i have someone who is just plugged in to the one of the shutdowned ports .
