Cisco Switching/Routing :: VTP Traffic Not Seen On SPAN Port On 3750

Dec 12, 2011

Been dealing with a strange problem for several days now.  It started out with a problem that I thought was VTP related but ended up being something else.  I setup a span port on a 3750 that I am connected to that was mirroring the trunk connection coming into the switch.
Never saw an VTP traffic come across the connection but doing a sh vtp status indicated the traffic was arriving and getting processed.  When I found some debug commands (debug sw-lan vtp), I was also able to see the packets go between switches.  Seeing this issue concerns me that there is other traffic that isnt showing up during a span session.
I know that doing a span on a switch, especially using a trunk port as a source, isnt a good idea.  Since I didnt have a TAP at time, this was my only choice.  I have since borrowed a NetOptics TP-CU3 tap from a good friend and was able to confirm the VTP traffic was going across the trunk connection between switches.
All of my 3750's are running 12.2.55.SE.

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Cisco Switching/Routing :: SPAN Port Configuration On 3750?

May 23, 2012

I'm trying to configure a mirror port on a 3750. This configuration needs to replicate data from local ports, but I need that also act as a regular access port.
With the initial configuration, SPAN port, there is no problem, all the data of the configurated ports is replicating in the configurated port. On the port configurated as mirror there is a PC connected for audio recording. When the port is not operating as SPAN there is communications without problem over the LAN. But when I configure the port as SPAN, communication is interrupted.
Here is the actual configuration:
SWITCH1-PISO7#sh monitor session 1
Session 1
Type                   : Local Session


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Cisco Switching/Routing :: 1433 - Span Port Configuration To Listen To Specific Traffic Only?

Nov 2, 2011

Is it possible to configure the span(switch port analyzer) port and restrict it to only listen to ingress and egress of TCP/1433 from the source port?

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Cisco Switching/Routing :: 3750 - How To Isolate Fiber Port Traffic

Jun 18, 2012

We would like to setup a link to our DR site that is separate from our main network traffic.  This link will be used by an EMC VNX SAN for replication traffic.  The SAN will be plugged into a fiber port on a 3750 switch and going out from the same switch (going in as multimode, going out as single mode) into a patch panel that runs over to the DR site (about a mile away).  At the DR site it will go from the fiber panel into another 3750 switch which ends up going back out of that switch into our DR SAN.
I'm wondering what the best way would be to configure the fiber ports to accomplish this.  I'm affraid that the replication traffic will find it's way over through another route and congest our main network unless configured appropriately.

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Cisco Switching/Routing :: SPAN Configuration In Catalyst 3750

Dec 31, 2011

I have CISCO catalyst with VLANs (VLAN ID 33, 36, 40-53) configured. I need to configure port mirroring in Switch 3750 for NAC (Network Access Control).  I need to Monitor all the VLANs. Here is the SPAN configuration of switch: [code] Monitor session 1 source vlan 33 , 36 , 40 – 53.Monitor Session 1 destination interface fa 1/0/8  (here I am not able to set encapsulation dot1q ) because the error occurred saying %one or more dest port do not support the encapsulation%.

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Cisco Switching/Routing :: 3750 - SPAN Configuration For Websense

Jul 3, 2012

I have configured SPAN in cisco 3750 switch as below mentioned. but the destination port protocol is down.
Network Diagram:
switch(config)#monitor session 1 source interface gigabitethernet1/0/1switch(config)#monitor session 1 destination interface gigabitethernet1/0/11 ingress vlan 1


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Cisco Switching/Routing :: Not Capturing Span Traffic On WS-4510 / SupervisorV / 12.2(54)SG1

Mar 22, 2012

I have configured Span port on our 4510. We have an application 5view server to monitor trafic connected to G9/17 Since we have changed the network connection from physical Giga port and add a Port-channel instead, we don't see any more trafic from the new Port-channel to G9/17
We have the configuration below on our 4510 :
monitor session 1 source interface Gi4/6
monitor session 1 source interface Po20
monitor session 1 filter vlan 311 - 312 , 375
monitor session 1 destination interface Gi9/17
From the commands show, we don't see the trafic duplication from the source to the destination port :
Port Source
4510-5567#sh int po20
Port-channel20 is up, line protocol is up (connected)
Hardware is EtherChannel, address is 0016.9de2.a818 (bia 0016.9de2.a818)


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Cisco Switching/Routing :: Catalyst 6500 - Cannot See Return Traffic On SPAN Session?

Jan 31, 2012

On a Catalyst 6500, we configured a SPAN session with VLAN 300 as a source. We configured the session bi-directional ("both" keyword). We connect a sniffer on the SPAN destination port.
Strangely enough, we only see the traffic from the VRF to the firewall, but not the reverse traffic ! What can be the problem ?

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Cisco Switching/Routing :: 5596 VLAN Traffic Span Across Vpc Peer-link

Apr 22, 2013

I have pair of 5596 switches in vPC. One host say "HOST A" is connected to the primary vPC peer and other "HOST B" on secondary vPC peer.Both are in same VLAN 10. Both hosts are vpc orphan ports as their NIC is configured in active/standby mode.I have configured span session on both vPC peers with span source as VLAN 10 in rx mode.Span destination is connected to secondary vPC peer. The issue here is that I am not able to capture the traffic originating from HOST A destined to HOST B which is traversing vPC peer-link.Same issue occurs for the traffic in reverse way and span destination on primary vPC peer. In a nutshell, any traffic which crosses vPC peer-link is not getting captured.
What could be the issue and is there any solution for it. Below mentioned is the span config and relevant interfaces. [code]

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Cisco Switching/Routing :: 2960 -Destination Port Not Responding Over SPAN

Jun 8, 2012

i have configured SPAN over cisco 2960 to monitor source port traffic but after configuration i dont able to get response from destination port  as my NMS is attached on destination port so i lost its web interface.
Configuration is as under.
monitor session 1 source interface gigabitEthernet0/5  (Source Port on Vlan 100) monitor session 1 destination interface gigabitEthernet0/1 (Destination Port on Vlan 200)

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Cisco Switching/Routing :: NEXUS 7k Span Session Getting Twice Data To Port

Jun 9, 2013

I'm setting up a montitor session on a NEXUS 7K as below.we are receiving in 150M of data and 0 data going out port 9/25.but port 4/24 shows 300M to the span port?

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Cisco Switching/Routing :: Creating A Span Port On Router 3640

Oct 1, 2012

i am running c3640-is-mz.124-21.bin on a cisco router 3640. i am trying to create a monitor session in the CLI and everytime i type the command Router(config)#monitor session 1 interface ethernet2/1 % Invalid input detected at '^' marker. Router(config)#monitor session 1 interface ethernet2/1 ^% Invalid input detected at '^' marker. i get the error invalid input ?

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Cisco Switching/Routing :: Configuring Span Port On 6513 Switch

Mar 2, 2012

I have two servers, connected on two(Different) 6513 directly connected switches. Both these servers are in the same Vlan.
I have to monitor communication these two servers. I have a system connected on one of the 6513 switch, where network tool wireshark is installed.
How to configure span port.
switch 6513-1# show run int Gi10/43  --------------------Server 1 is connected
switch 6513-2# show run int Gi9/45 ------------------------Server 2 is connected
switch 6513-2# show run int Gi9/46 ------------------------System on which network tool wireshark is installed.

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Cisco Switching/Routing :: Effects Of SPAN Port Configuration On 4507R+E Switch?

Oct 29, 2011

I read quite a few documents on configuring SPAN on a cisco switch but none of them mention any limitations or any kind of CPU load it can have on a switch. I need to configure this on one of our switches and would like to know if there are any implications related to SPAN.

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Cisco Switching/Routing :: SPAN / Monitoring Destination Port Behaviour - 2960 LAN

Jan 16, 2012

In s SPAN session , normally the destination prt is used for monitoring purpose only. But could destination port be used to access the equipement or PC connected to that port , for a 2960 LAN BASE image  switch .

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Cisco Switching/Routing :: CAT6500 / Duplicate Multicast Packets On A Span Session Port?

Apr 17, 2013

If I monitor a trunkport on the rootbridge in both directions  I get Duplicate Multicast Packets on the perticular VLAN.   The first guess is, that this is worked as designed and not a IOS Bug (Platform CAT6500 SUP720 IOS 12.2(33)SXI9 ) Until know I only found an old Cisco press link from 2002 with this subject.

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Cisco Switching/Routing :: Replacing 3750 24 Port With 3750 48 Port?

May 21, 2012

We have a stack of switches that is at the max number of members allowed in the stack. Problem is we are running out of port density and need to add more ports. So instead of adding a whole new stack I would rather replace 2 of the 24-port swicthes with 48-port switches.
If the two 24-port swicthes we are removing are stack members and neither of them are the stack master, I should be able to replace the 24-port switches with the 48-port switches without bringing the master offline? If the new 48-port switches are running the same IOS version as the current 24-port swicthes, they should add themselves to the stack?Would I have to tell the new 48-port swicthes what switch numbers they are replacing in order for them to be added to the stack since we are at the max number of members?Also since the 48-port swicthes are replacing 24-port switches will the master give the 48-port switches the configuration for only the 24-ports?

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Cisco WAN :: 871 SPAN Want To Monitor The Wan Port Using Span

Apr 4, 2011

I am having some problems creating a SPAN port on my Cisco 871 (running IOS 12.4-11T).  My 871 is connected to a DSL modem, and uses "IP Negotiated" to get its dynamic ip address.I want to monitor the WAN port (FastEthernet4) using SPAN, but when I type "monitor session 1 source interface FastEthernet4" into the cli, it is rejected.  I can successfully use any of the other FastEthernet ports, as well as Vlan1 as a source for the SPAN session. I have tried to use Dialer0 instead of FastEthernet4, but it still doesnt work.

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Cisco Switching/Routing :: 3825 ISR - Traffic Route From Switch Port To Router Port

Jun 5, 2013

I'm fairly new to Cisco products am in the process of developing my network knowledge on a deeper level.  I have a 3825 with a HWIC-4ESW and I'm struggling to fully understand how the two "see" each other.  I've setup a V LAN with a layer 3 address on the HWIC and added the switch ports to it.  This seemed to allow devices connected to the switch ports to talk to the built-in router ports.  I thought this was all making sense until i applied an access-list to the router port.  It's a simple ACL i'm just using for testing and the only thing it does is blocks telnet from anywhere.  I know the ACL is setup properly because if I connect a device directly to the router port i cannot telnet to the port.  However, if i connect a device to one of the switch ports, i am able to telnet to the router port successfully. 

It seems that I'm missing something with how traffic flows from the switch port to the router ports and how the two "see" each other. 

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Cisco Switching/Routing :: 3750 - Only Allow Specific Traffic To VLAN

Oct 10, 2012

Have a quick question regarding inter-vlan routing on a 3750.  Overview of network is ISP --> ASA --> 3750 (acting as my core and default gw).  I have 5 vlan interfaces on my 3750, all w/ 192.192.x.x subnets, a 6th w/ 192.168.100.x, and a 7th w/ 192.168.200.x.  I have enabled "ip routing" on the switch and can successfully ping from subnet A to subnet B as long as both devices are using the correct DG for their vlan, which is the switch.  I have a few ports that are trunked as well that go to ESX hosts which break out the vlans according to the subnet the vm should be attached to.  The ASA is set to nat internal traffic for all the vlans.
Now my question:  short of applying an ACL to each vlan interface to block traffic from other 192.192.x.x subnets is there a better way to accomplish this?  I want my 192.168.10.x subnet to be able to reach all the subnets, but don't want 192.192.10.x to be able to talk to 192.192.20.x for example.  I was thinking to create an acl like this:
access-list 120 permit ip access-list 120 deny ip 120 permit ip any
and then applying this to the interface for the appropriate vlan. 

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Cisco Switching/Routing :: Keep Traffic Local Between Two Sub-nets Using 3750-X

Nov 13, 2011

We have a remote office with a Cisco 3750-X switch with the IP-Services feature set connected via dark-fiber to a 6509-E at the corporate office. We plan on migrating the remote office to a new network (new acquisition) to subnet on VLAN 20 which has an existing  subnet of and we would like to run both in parallel using their existing switches (Dell) and the new 3750-X.
I’m curious as to the best way to keep the traffic local between the two subnets using the 3750-X and if necessary put the network on a VLAN. I thought about routing between the two networks via IP routing on the 3750-X but the new workstations default gateway is the 6509-E and existing workstations is a SonicWALL within the remote office. The default gateway for the new workstations can be moved from the 6509-E as a last resort.

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Cisco Switching/Routing :: Traffic Within 3750 Slow / But Fast Outside Of It

Jul 15, 2012

I have 2 new 3750g devices in a small environment.  switch1 acts as our collapsed core and has ip routing enabled, and is connected to a ASA 5510. There are 3 HP l2 switches connected to switch1 as well.   switch2 is simply a server switch.  switch1 and switch2 have a 2port etherchannel between them, and a vlan trunk carrying 4 vlan's.  traffic between any 2 hosts on switch2 (same vlan) are slow. (average 300Mbits/sec)  If I move one of those hosts to switch1, speeds increase by 3 times.  (average 900 Mbits/sec).  Additionally, traffic between any 2 hosts on switch1 are quick. testing is done with iperf as well as timing 1gig file transfers.
I don't see any errors or drops anywhere, and there are no other symptoms other than slow transfer beteween hosts on switch2. I just got 2 more of these 3750's to put in a 2nd site that we have, put a quick configuration on them, and have the same result.  Other than switch1 having ip routing enabled, the configs are pretty much identical.

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Cisco Switching/Routing :: 3750 - Tagging Traffic By IP Source And Destination?

Dec 2, 2012

I want to know if there is way to tag traffic with DCSP tags without having to do all the other requirments of QOS setup.  All i want to do is just tag traffic at different DCSP values via source and destination IPs.  We do not have a need to be priortizing traffic on out internal switches.  We just want to tag the traffic so our MPLS provider can distinguish the different types of traffic.
Our environments is primarily 3750s in all offices.

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Cisco Switching/Routing :: 3750 Switches Doesn't See Traffic From Other Network

May 21, 2012

we have three separated network segments going to one Cisco 3750 switch all is L2 .. from this switch is 100 mbit uplink.we need to apply some Qos mechanism not to saturate line by traffic from one network.. Configuration from various reason CANNOT be done on switch where 100Mbit line is terminated.. so all must be done on SW1,2,3..Correct me if iam wrond but as switches doesnt see traffic from other network iam affraid only think we can do  is limit bandwidth on links going into SW1,2,3 to 33 Mbit.I found commad srr-queue bandwidth limit.But links going to SWs are 1Gbit so if i force bandwidth to 10% (minimum what command allows) its  100 Mbit..If I force speed on those links to 100Mbit and than apply  srr-queue bandwidth limit to 30% doest it work.??. Will  srr-queue bandwidth limit speed to 30Mbit?? Or srr-queue bandwidth limit is calculated from maxim speed of interface?

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Cisco Switching/Routing :: 3750 Cannot Mark Http Traffic With DSCP

Mar 14, 2012

I am trying to mark http packets from a web server with DSCP ef, but when I am doing a traffic capture all http packets have tos 0x0.I am able to mark UDP and ICMP packets originated from this server, but not any TCP traffic.The web server is in VLAN 20This is my config mls qos ip access-list extended MARK-HTTP-ACL  permit tcp host eq www. [code]

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Cisco Switching/Routing :: Traffic Policy Is Not Working On Catalyst 3750?

Jan 28, 2013

Unable to limit traffic on catalyst 3750 gigabit ports it has fiber modules,
I want to limit traffic 2mb per port
I have tried srr-queue and policier but it is not working and there is no ratelimit command under any interface, Applying policy to output is not supported of the interface
policy-map rate-limit
class class-default
police 2000000 8000 exceed-action drop
int gi1/0/3
service-policy input rate-limit 
still when I start download it goes to 10 mbps

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Cisco Switching/Routing :: 3750 / How To Identify Broadcast Traffic Source

Feb 23, 2012

We have 2 switches split across 2 datacentres connected via an interconnect.  Over the past couple of days the interconnect provider's Cisco kit has shut down our port (err-disabled) due to a broadcast storm.  They had the level set at 1 which I thought was a bit low.  They say they tried to set to 2, then 5 but still kept tripping the storm-control feature so they set at 10.  They say they've always had it set at 1% (on a 100Mb switch) and so we must be generating more broadcast traffic.
I'm trying to identify where the broadcast traffic is coming from.  On our Cisco 3750 I've clear interface counters and when I do a sh run | i broadcasts there are a few ports which have what seems like a high broadcast count.  The one port that is especially high and the only one tripping the storm-control feature (I've enabled on all our ports to try to identify where the traffic is coming from) is the port connected to the 100Mb interconnect.  I've mirrored that port to another port and connected a server with wireshark so I can capture all the traffic across that port. 
What I'm struggling to find is the source of the broadcast traffic.I have a few questions are these broadcasts layer 3 or layer 2 broadcasts.  Also in the output below when it says broadcasts received is this inbound to the port i.e. from the connected device or is this a total of inbound and outbound broadcasts.
When I use wireshark and filter the capture on broadcasts (ff:ff:ff:ff:ff:ff) I see only 200-300 compared to the thousands the switch is reporting.If I filter on the broadcast IP address I also don't see the numbers corresponding to what I see in the show interface output.
GigabitEthernet1/0/1 is up, line protocol is up (connected)
  Hardware is Gigabit Ethernet, address is 0014.a93f.7401 (bia 0014.a93f.7401)
  Description: Interconnect
  MTU 1500 bytes, BW 100000 Kbit, DLY 100 usec,
     reliability 255/255, txload 4/255, rxload 44/255
  Encapsulation ARPA, loopback not set

also I'm currently doing : monitor session 1 source int g1/0/1 both, and also tried just rx incase I just need to be looking at receive traffic but still nothing is standing out.

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Cisco Switching/Routing :: 3750 - Route Traffic From Server To End User?

Jun 3, 2013

Actually i have a design from my customer who have ( Cisco core switch 3750 (allports fiber ports) which is connected to L2 switches , these switches carry servers and end users .the only routing protocol on the access switches is static route ,
My question how can i route the traffic from the server to the end user , as the the server is not direct connect to the core switch.

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Cisco Switching/Routing :: Switch 3750 / Policy Inbound Traffic Per IP?

Mar 2, 2012

We are using Cisco 3750 switches in our environment as distribution switches.We currently use to police inbound traffic, but we need to find a solution to limit inbound traffic per IP.Something like this “Inbound traffic for each IP can be maximum 1 Mbps” This can be done having, one ACL and one class-map for each IP, but in my situation is not a practical solution, because we have more than 500 IP’s on that site.
Is any way to accomplish this without writing 500 ACLs and 500 class-map?

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Cisco Switching/Routing :: Capturing Traffic Flows From 3750 To 6509 Then To Netflow

Aug 6, 2012

I am aware that the 3750 switches are not able to support Netflows, so I have created a SPAN port and spanning traffic from a specific port. I would like to create a seperate VLAN and trunk the traffic from the SPAN port down to the 6509 switch and then capture all the traffic for that VLAN on the 6509.

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Cisco Switching/Routing :: Block / Permit Intra Vlan Traffic On 3750

Feb 21, 2013

I have One switch 3750 and many switch 2960 c.I use one ASA 5510 to reach emote branche site (vpn conexion).I use one router 1841 for internet conexion.Router 1841, ASA and catalyst 2960 are connected on the 3750.Default gateway of all user is ASA IP
I configured Vlan 3750 and it work.Now I need to implement security : permit/block specific traffic between vlan [code] From vlan 72 I cannot have remote access on computer in vlan 34 and I cannot ping computer in vlan 34.

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Cisco Switching/Routing :: Setup VLan To Allow Video Traffic Between 2960 And 3750?

Nov 13, 2011

I am trying to setup a network using Cisco 2960 switches with vlans configured.  One vlan will handle video coming from four cameras that are connected to another 2960.
We have four cameras feeeding one port each on a 2960, that 2960 in turn feeds one port on the main 2960 which is the video vlan for that site.  From the site it goes back to a Cisco 3750 to be sent over to a Sonicwall firewall. If we connect to the 2960 that the camera are connected to we can see the video, but not on the main site 2960.

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Cisco Switching/Routing :: 3750 Switch - Routed Interface / Traffic Composition

Feb 21, 2012

On a router I can use IP Accounting or Netflow to see what kind of traffic is moving over an interface.  Are there any tools on a 3750 switch with a routed interface which would tell you who is hogging the bandwidth on that interface?

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