Cisco Switching/Routing :: 3750 Has IP Conflict With Another Device?
May 2, 2012
I just found out that one of our 10 3750's has been assigned with an IP Address that is in conflict with a PC that has been in production long before this 3750 was deployed in our environment. Good thing it is servicing devices on a separate vlan. The conflict IP Address is assigned to the default vlan of the switch so we can connect to it from the core.If I change the IP Address of the switch, will it reboot and momentarily disconnect the devices connected to it?
I have switch 2960 and router that connect with one interface to that switch. the link is trunk and Router function is inter vlan routing between 4 vlan. This netwrok has only one ip address space that is 10.10.2.0/24 and work without problem. We connect cisco switch 2960 with optic link to another switch that in stack 3750 which configured as trunk link and allowed only 3 vlan between them. In the other side netwrok which consist the switch 3750 we have different subnet ip address that switch working in layer 3 too. the problem is that when I permit vlan 210 in the switch 2960 only layer 2 between this switch and the 3750 in network that consist th ip address 10.10.2.0/24 devices, if I disconnect and then connect pc to network he says that he has ip conflict and in the log he show mac address of router that has vlan 210 subinterface configured with 10.10.2./24 subnet. But how I gibe back vlan 210 from permited vlan in trunk devices start normaly working. If I again put vlan 210 to permit vlan in that trunk devices again said that there are conflict ip address and show mac address vlan 210 router subinterface.
I'm looking to configure a syslog server for all of my cisco device logging. I've had a look at CNA and can't find any options to define a syslog server for my switches.
What's the best way to define a syslog server and the severity of the notifications? Also, i'm looking to clear all previous Syste mmessages fon my devices?
3750 can not support multiple subnets in it's DHCP server pool config.
Is this an issue that can be fixed with a different iOS or is there a different Cisco switch that I can replace the 3750 with that will handle multiple subnets within an individual pool?
We have VSS configured between Cat-6509 switches (s72033-advipservicesk9-mz.151-1.SY.bin)..For the voice vlans,dhcp scope is configured within VSS and ip addresses are assigned to ip phones from these pools configured within VSS.Cat 3750 stack is connected with dual links to this vss. IP phones are connected to cat 3750 switches and desktop is connected back to IP phone. For data vlans IP addresses are assigned from external dhcp server.
Currently we are facing lot of ip conflicts for ip phones and after clearing the dhcp conflicts, IP phones starting getting IP addresses..(sufficient IP's do available in the dhcp scope for IP address assignment). (What exactly the role of no ip dhcp conflict logging command......)
I had problem with IP conflit address from cisco router 2911 , all the time the router respond with ARP reply (duplicate use of IP : x.y.z.t with the same Mac Address ) and the IP subject of conflit dosen't appear in any router's interfaces configuration (basic configuration without dhcp) ,the problem was solved problem when I desactivete proxy arp but I can't understand this behavior , why arp proxy respond to all IP address with same Mac even the IP dosen't exist in router ?
I have a network topology which you can see on image. All routers are Cisco 3745 with IOS (C3745-ADVENTERPRISEK9-M), Version 12.4(12). SW1 is L3- switch Cisco Catalyst WS-C3560E-24TD with IOS (C3560E-UNIVERSALK9-M 12.2(58)SE2). [code] After that I have problem. When PC with OS Windows 7 begins to work in corporate network, it sees "coflict ip addresses" and doesn't work with network. I've used wireshark and seen, when the PC send arp request a SW1 always send arp reply (see attached file). I think problem with command "ip sla responder", but I haven't searched information about it and I want understand this is bug or normal functioning.
I configured an DHCP server on cisco 3750 switch . Wher in w3750 gets connected to plain l2 switch 2960 on floor and machine gets connected to 2960 port. [code] Below is the description of problem:
-> The Cisco 3750 switch is the DHCP server. VLAN 108 is named as internet vlan.
-> Ports in Cisco 2960 switch has been configured with "switchport access vlan 108".
-> There were no problems at all and everything had been working smoothly.
-> 3 days back, users started complaining that they couldn't access the internet. Up on troubleshooting the issue, I found out that there was an issue with the DHCP server as the computer couldn't get any IP address at all. After setting static IP address, the internet started working again.
If I bind IP to MAc address reservation on core 3750 switch for some time of moment it works but after that machine gets unreachable .I restarted the 3750 switch and also all the 2960 switches over the weekend, however, the issue still hasn't been resolved yet. I did issue the command "clear ip dhcp conflict *", clear ip dhcp binding * but no joy at all.
I'm looking at adding a Cisco 3750-X switch running c3750e-universalk9-mz.122-55.SE1 (IP base license) into a stack of 3750-G switches running c3750-ipbasek9-mz.122-55.SE1.bin Given that the version and feature sets are the same I don't forsee any compatibility issues. Would there be any reason why a universal image wouldn't stack correctly with other switches running the single .bin file?
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?
I have a 3560E with 2 vlans that I want to route between. one device with 2 vlans and route between.Interfaces are configured as such:
int g0/11 switchport mode access switchport access vlan 10 int g0/12 switchport mode access switchport access vlan 11
[code]...
Laptops on each port with 10.10.10.2 and 10.10.11.2 configured on them. I can ping from 10.10.10.2 to 10.10.11.1, but not to 10.10.11.2.What do I have to configure to be able to get the 2 laptops to talk to each other?
Problem with a conflicting IP address. Basically on a normal running day my wireless is switched on and connected perfect to my internet, however if i want to download any large files i plug my Ethernet to my laptop and disable the wireless from my laptop, instantly then the LAN connection kicks in and im on the internet again as i find download speeds are faster through a LAN. However today my wireless is fine but the second i switch to LAN the ! symbol appears and a message says their is an IP conflict.
some of our switches have the switchport mode trunk command configured between the 3750 switches but other 3750 switches connected to our 6509 core switch do not have the switchport mode trunk command to permit Vlans from going across the swtiches instead it has an ip address and says no switchport what is the difference between does two. Is trunking used only for Layer 2 and L3 is used to route interface vlans?
I have a network with a Catalyst 3750 as the main switch and then some Catalyst 2960 switches that are plugged in to that. I have a server running windows server 2008 with a couple of virtual machines running in Hyper-V. I created 4 VLANS listed below and gave the 3750 the following IP Address.I would like the 3750 to only be configurable from VLAN 40 but currently every VLAN can connect to it, I noticed in the standard web page settings there was a setting for "Management VLAN" but it was set to 1 and would not let me change it, I kinda assumed that was for the management port in the back.-Now the tricky part, I was trying to set up routing between the VLANs and so far I have only been able to get a sort of "all or nothing" routing to work. I can turn IP routing on and add two or more VLANs to the routing and it works fine. But what I was hoping to do is create a couple of "junction vlans" that would only route to one or two other vlans. For instance, I wanted to create a VLAN 100 that routed to VLAN 20 and 30 but nothing else. I also want to route VLAN 1 just to VLAN 30, and so on. I am able to do each one of the cases but only one, it seems like the switch only supports one "routing table" am I missing something or is this just a limitation of the switch?
Is a 3750 sw capable of handling full routing tables and what can you recommend in a small mutihomed BGP router or switch capable of handling full routing tables?
I have a network with several catalyst 2960 switches and one catalyst 3750. I have created two VLAN and set up the proper routing and everything is working fine there. I have a client/server application that used multicast in the initial start up for the client to determine available servers, the issue is one of my clients is on a different VLAN then the server. I am able to route the multicast using MVR as long as both the server and the client are plugged into the 3750 by creating a static route, making the server a source port and the client a receive port. Unfortunately I need the client and the server plugged in to different 2960s. My question is how do I establish multicast routing between the two and perferably do it dynamically (always route multicast traffic from one VLAN to another).
I have been looking into this for a while and I can't seem to figure out why my 2nd vlan is not able to connect properly to the net.
My switch has 12 ports where my devices connects directly, they are all on Vlan 1 and they all work perfectly. on Port 12 I have a dlink router that is connected to a cable modem. the dlink router has an Ip address of 192.168.0.20
I created a second vlan (vlan2) and enabled dhcp relay on it. then I assigned port 9 on the switch to (vlan2)my laptop which is connected to port 9 seems to get an ip address fine and able to ping only some devices on my network (vlan1) and is not able to go out to the internet. I think it has to do with the routes. [code]
I have the task of replicating the router config on a 3825 router on a 3750 switch. Reason is we are taking out the router and replacing it with the switch to make use of the router for other functions.
Below is main part of the router config:
! ip source-route ip cef ! ! multilink bundle-name authenticated ! license udi pid CISCO3825 sn FCZxxxxxxx ! vlan internal allocation policy ascending
[code].....
The 3750 switch I have runs C3750E-UNIVERSALK9-M, Version 12.2(55)SE3 on a LAN BASE license.
The first thing I have done is to order for a license upgrade to IP BASE which would give the support for OSPF routing.I do not see much of an issue with the Interface configs, however, I am not too sure about replicating the routing config on the switch.
My question is can I run the commands as shown for the OSPF routing on the switch? If not, can I get suggestions on how best to set this up on the switch?
In 3750 switch,I have configured intervlan routing.I have three vlans Vlan 10,vlan 20,Vlan 30 and I have assigned IP address for that Vlan.In vlan 10,I have connected one systen gigabitethernet 0/1 interface.From my system I am able to ping vlan 10 ip address but I can't able to ping other vlan ip address (vlan 20,vlan 30).Is it possible to up the protocol for all that time.
For intervlan routing, Is 'IP routing' command enabled by default on a 6500 series switches based on the IOS?and on 3750 switches, do we need to enable the "ip routing" command manually for intervlan routing?
I am using a 3750 as a default gateway for multiple Vlans on a few 2960 switches. The trunk lines are configured and working and I have assigned ip addresses to each of the Vlan interfaces on the 3750. My issue is that I can only ping the ip address on the Vlan interface of the 3750 if I have a working computer plugged directly into the Vlan on the 3750. I only have 3 vlans on the 3750 that have hosts directly connected (vlans 2, 10 and 40) the other vlans ( 20 and 70) don't have any clients plugged into them on the 3750 but the hosts reside on 2 different 2960s that connect via trunk ports. How do I keep the vlan interface on the 3750 switch pingable when I don't have hosts directly connected in that vlan on the 3750? (yes, I have enabled ip routing on the 3750)
I have a simple design with 3750. I configured a route-map which define a next hop. I defined this route-map on a policy on a vlan interface.When I test some ping and a debug ip policy and it seems that my policy never match.Is there any mechanism that prevent the switch from using PBR? I think of CEF .
In our datacenter we have a 3750 stack with IP base image. I have enabled PBR and reloaded the switch. Show sdm prefer says i am using default template. The reason i want to use PBR is that we have 2 firewalls on the same work and want to be able to have granular control over which gateway out of the network they use but still be able to access all internal resouces accross wan and locally.
Created access list to identify traffic:
access-list 10 permit 10.2.3.59 (test workstation on vlan 3)
Created policy:
route-map TestASA permit 10 match ip address 10 set ip next-hop 10.2.0.3
Assigned policy to the user vlan3:
ip policy route-map TestASA
Results:It changed the default gateway to the above gateway but i could not access any resources on any other vlan, could not access resouces accross wan.
I have been looking into this for a while and I can't seem to figure out why my 2nd vlan is not able to connect properly to the net. My switch has 12 ports where my devices connects directly, they are all on Vlan 1 and they all work perfectly. on Port 12 I have a dlink router that is connected to a cable modem. the dlink router has an Ip address of 192.168.0.20,I created a second vlan (vlan2) and enabled dhcp relay on it. then I assigned port 9 on the switch to (vlan2),my laptop which is connected to port 9 seems to get an ip address fine and able to ping only some devices on my network (vlan1) and is not able to,go out to the internet.
I have a simple design with 3750.I configured a route-map which define a next hop.I defined this route-map on a policy on a vlan interface.When I test some ping and a debug ip policy and it seems that my policy never match.Is there any mechanism that prevent the switch from using PBR?
I'm running into what seems a basic ip routing config problem with a Catalyst 3750 (IP Base) switch. I have several VLANS configured on the switch with IP routing enabled, and the switch is connected to the inside interace of a new ASA 5520 as follows:
ASA5520 IP (Default gateway): 192.168.1.1Switchport Gi1/0/1 is configured as a routed port, IP address 192.168.1.3 255.255.255.0Example VLAN is VLAN 100, IP address 192.168.100.1 255.255.252.0 From the switch CLI, I can ping all VLAN addresses, as well as the ASA5520, and the client laptop I'm testing with from VLAN 100.
From the client laptop on VLAN 100, I can ping all switch interface and VLAN addresses (inter-VLAN routing is working), including 192.168.1.3, but I CANNOT ping the default gateway at 192.168.1.1.
Here is the relevant configuration information on the 3750:
! no aaa new-model switch 1 provision ws-c3750x-24 system mtu routing 1500
I have a Cisco 3750 with private VLANS configured.. VLAN 2 is the "primary", VLAN 3 is "isolated" and VLAN 4 is "community". This is all working correctly, however I now have the need to another VLAN called "production". I need the production VLAN to be able to reach all the private VLAN hosts (community and Isolated), and vice versa
For intervlan routing, Is 'IP routing' command enabled by default on a 6500 series switches based on the IOS?hes, do we need to enable the "ip routing" command manually for intervlan routing?
I have 2 ISP connected to Router A and Router B.Both the routers are connected to the core 3750 switch.. I want to send the traffic from the switch that goes to router A to router B..[code]
I am using a cisco 3750 in my network as a gateway, and above it I use a squid machine for caching my internet. My network is like this:
Basically I have two VLANs on my network which are VLAN10 and VLAN100, VLAN10 is the cooperate network of my office. VLAN100 is the management VLAN which i use for the switches. I keep the squid as well the client in VLAN10.
squid (192.168.1.50)---->cisco 3750(192.168.1.123)---->Distribution Switch(cisco 2960)---->client PC (192.168.1.5)
I have done nating on squid and internet is working pretty fine when I use the client gateway as the squid, but when I use the cisco 3750 as my gateway after adding route maps for forwarding the internet traffic coming to the cisco 3750 to squid it disconnects me from internet as well I cannot even reach the switches from the corporate network. These are the only Lines I used for the routing:
! route-map proxy-redirect permit 10 match ip address 110
I have a quick query which i need ratified before proceeding. I have the following scenario -
Two Cisco 3750v2 switches with stackwiseISP allocated block of /26 (64 addresses)8 customers each with a VLAN and SVIInternet facing VLAN and SVIDefault route to ISP router Lets say the ISP has given me the network range 10.10.10.0/26 (we'll assume this is routable on the internet for the purposes of this example) and a default gateway to the internet of 10.10.10.1 within this range. I have configured a public facing VLAN as follows -
VLAN 300 name PUBLIC int VLAN 300 IP Address 10.10.10.2 255.255.255.252
I have then created a default route as follows -
ip route 0.0.0.0 0.0.0.0 10.10.10.1
With this configured, the switch can successfully route upstream to the internet with no problems. I have then moved onto the customers and depending on what service they have purchased, I have subnetted the 10.10.10.0/26 range into smaller subnets. See as follows -
Customer A - 10.10.10.4/30 Gateway IP - 10.10.10.5 Useable IPs - 10.10.10.6 Customer B - 10.10.10.8/29 Gateway IP - 10.10.10.9 Useable IPs - 10.10.10.10 - 10.10.10.14
This continues for each customer depending on how many IP's the have purchased. I have then assigned these IP ranges to a customer VLAN and SVI as follows -
Customer A VLAN 10 name CUST-A-VLAN int VLAN 10 ip address 10.10.10.5 255.255.255.252
[code].....
It is then up to the customer as to what equipment they use and how they NAT or firewall their internal networks.
