Cisco Switching/Routing :: C3750 DHCP Relay Is No Longer Functioning For Client PCs
May 29, 2012
I have upgraded a C3750G-12S-E to c3750-ipserviceslmk9-tar.122-55.SE5This switch is a distribution layer switch for one of my remote sites. it contains an ip helper-address on the site vlan's SVI.DHCP relay is no longer functioning for client PCs. Static address assignment allows full network functionality. I enabled debug ip dhcp server packet. [code] Actually I am betting you upgraded your IOS from something before 12.2(50)SE to 12.2(50)SE or later. We added enhancement CSCso19800 which will validate DHCP options when we are a relay agent.
How to configure cisco 3560 to force the client only can get ip by dhcp-relay server ?
The company i am working in has 5 vlans which have been set an lay-3 switch(3560), uses the dhcp-relay server .(in svi configuration: ip helper-address X.X.X.X) well , that works ok~
Now , I got my problem: I need to force the client only can get ip by dhcp-relay server, that means if anyone set static IP manunally , he can't really access to anywhere (to provent anyone set static IP with malignancy )
I know if a h3c router , how to set this configuration n svi configuration : dhcp relay security address-check enable ) the how to configure on a cisco 3560 ?
I have some DHCP trouble since I subnetted my network with a 2921. My clinets are in 172.16.2.0/23 and DHCP servers are in 172.16.5.0/24.Sometimes, randomly I guess, I get NACK from my DHCP server, and if I look into DHCP logs I got something like this:
Have a client wanting to hand out public ip addresses to all clients from a PFSense Firewall terminating the internet connection.
How do I allow the Cisco Switches currently in place, configured with private ip addresses in the 10.10.x.x ranges and Vlans, where the main 3550 layer 3 has defined dhcp scopes for each vlan, to relay dhcp requests from all vlans to the PFSense firewall?
I assume I would take off the currently defined dhcp scopes for the vlans and configure each vlan/switch with the ip helper address and specify the PFSense firewall and that Nat would have to be disabled onthe firewall?
I am trying to get an understanding of some behaviour I am seeing on my N7Ks regarding DHCP relay.I have two identically configured Vlans interfaces both configured with the same two dhcp relay servers in the same order. The only difference between the two vlans is that one is HSRP active on the A side switch and the other is active on B side switch. All clients in Vlan136 (active on B side) are getting DHCP leases from the first of the two dhcp relay servers configured while all clients on Vlan 137 (active on A side) are getting DHCP leases from the second of the two dhcp relay servers. I would expect that all clients on both vlans would get leases from the first relay server configured unless that device was unavailable.
Would like to impliment VLAN's on Cisco IOS Software, C3560 Software (C3560-IPSERVICES-M), Version 12.2(25)SEB4...But I need a DHCP Realy to my Windows Based DHCP Server. How do I enable DHCP Relay on the 3560?
I have a 2921 with 4 segments: [code] My DHCP server is 172.16.5.2 and I need to serve clients from 172.16.2.0/23 by MAC address and only to that segment.
Windows Server 2008 R2 has two DHCP scopes 192.168.1.x (for data) and 192.168.2.x (for VOIP). The Catalyst 2960-S has Vlan1 for the Data V LAN and V lan 2 for the VOIP network. How do I setup DHCP relay for Vlan2 to get their IPs from the scope on the Windows server?
Used to doing ip helper-address x.x.x.x in other Catalyst switches, but not available here.
I can't seem to find any info on how to configure 2 DHCP server pools on a C3750, to use with 2 user vlans. The purpose is that users in vlan 1 should get an IP address from DHCP server1, and users in vlan 2 should get an IP address from DHCP server2. Both DHCP servers are configured in a stack of C3750 switches, which acts a a L2 switch.
I am trying to configure two 3845 routers to act as dhcp server and dhcp relay. Clients are connected to the router that relays all dhcp requests to the vrf instance which is used to connect it to the router wich is running dhcp server.
Router1 ip vrf dhcp_dns rd 8:1 int gi0/0 ip vrf forwarding dhcp_dns ip address 192.168.200.5 255.255.255.248
[code]...
So far I can see dhcp requests coming from the R1 and dhcp server on R2 replies with the dhcp offer but PC is not getting any ip.
I faced with issue on ME3800. [code] With that configuration there is no problem with DHCP Relay packets.But if I add on interface #xconnect 82.199.1 19.1 77 encapsulation mpls it will stop forward DHCP relay packets immediately. All other traffic transfers without problem.
I have a test setup of a C3750 stack as a core and some 2960's as access switches.[URL] - The switches at the bottom is the new network (VLANNED). The switches on the left is the current production network (10.1.1.0/24) From the C3750 to the router is a /30 network.
There will be 6 VLANs but at the moment I have one configured. VLAN50 - 10.5.1.0/24 From the C3750 I can ping my current production network, internet, other VLANs in the testsetup, ... Everything.From the C2960 I can ping other VLAN's, reach the gateway, reach the router, reacht the currenct production network. But I can't reach internet. I've configured "ip default-gateway 10.5.1.254" on the C2960. C3750 relevant config is down below.How is it that I can reach other networks connected to the router and not internet from the access switches? I'm just trying to ping 8.8.8.8.
! ip routing ! ! interface GigabitEthernet1/0/1 no switchport ip address 172.16.1.2 255.255.255.252
I need to configure public and private wireless access using an ASA 5505 and an Aironet AIR-AP1041N-A-K9. I need to be able to do this via ASDM and http if at all possible. I simply do not have the time to learn hundreds of lines of arcane CLI code. The Aironet connects to the ASA successfully, and receives an IP. I can then connect to the AP wirelessly, but do not receive an IP. I have setup a second SSIDVLAN on the AP, and can't connect to it at all.
I can ping [URL], from the router but not from a client attached to the router dhcp interface(10.1.3.1). When I turn on ip routing I cannot ping at all. Here is the config I have now that can ping the internet from the router.
sh runBuilding configuration... Current configuration : 1191 bytes!! No configuration change since last restart!version 12.3no service timestamps debug uptimeservice timestamps log datetime msecno service password-encryption!hostname
1 Cisco switch stack (SGE2010) in L3 mode, 2 Vlans.
Vlan 1 = 192.168.0.253/24, untagged on all ports except 14/15 Vlan 2 = 192.168.22.1/24, untagged on port 14 and 15 SGE2010 default route 0.0.0.0/0 next hop 192.168.0.1 (Checkpoint UTM) DHCP Relay enabled DHCP server set to 192.168.0.16 DHCP interface set to Vlan2
[code]....
Expanding the ICMP entry, it appears that the destination is the pc client since it shows a Dell mac address, and the source is the Checkpoint UTM (Sofaware).
I can ping and tracert from the Checkpoint to my static IP on Vlan 2. The same goes for the DHCP server to/from Vlan2, so I am confused as to why the routing is failing. I have tried adding Port Fast to the stack ports, but nothing changes.
i am not sure if this is something with my DHCP setup or not, but it certainly seems to be the culprit. I am running a 3560G and using it as DHCP and to do V LAN routing (Geiger protocol). I have 10 pools configured with a few static addresses per pool. Now to get down to the problem. I have a computer (and this problem seems to be a gremlin as it changes what computer is affected quite often) that will connect, get its IP, immediately disconnect, then send out a DHCP req again. The computer has a static assignment in the pool, and for the brief second that it connects, it gets the right address. If i move the computer to another v lan, all works right. If i delete the static entry it will get an address in the right v lan no problem. The command i have been using to add static entries is:
That seems to have been working on all my static routes except for a bank of computers in vlan3. I have went as far as to delete the pool and recreate it, heck i even recreated the v lan and i am still having issues. Below are some snippets of the running config for review.
The DHCP Pool for the affected LAN: ip dhcp pool Dev3 network 192.168.3.0 255.255.255.0 boot file bootx86wdsnbp.com next-server 192.168.1.78 dns- server 192.168.1.8 192.168.1.78 [Code] .....
I am trying to configure interface vlan1 to get an ip address from dhcp by entering the commnad ip address dhcp ios rejects the dhcp portion of my command as not recognised although it is referred to in Cisco manuals.my IOS version is c2950-i6k2l2q4-mz.121-22.EA14.bin.I get the same problem when I try to configure ip http secure-server on the switch. Is this a known bug or whether I have the correct IOS version for these commands?
Haveing issue with DHCP server handing out IP addresses to client connected to VLAN5 interface.ISP Router>Firewall -(WatchGuard Drop-in mode) I have several 3750 switches and one acting as a L3 switch. The L3 is configured as follow: [code]
If I connect a laptop to int fa1/0/10 I DO NOT get an IP address from the 10.100.0.8 scope. If I connect to another interface within the VLAN 1, I get an address from the 10.100.0.0 range.
I have a problem to solve in our data center, see attached drawing. HW: Our core switches consists of two stacked C3750 with ip routing. What I want to do is probably simple but I haven't been able to figure out the best method.
VLAN10 and VLAN20 should not be able to communicate with each other. (ACLs?)VLAN10 will have it's own default route/firewall. Both VLAN10 and VLAN20 should be able to send server backups to server in VLAN30. All 3 V LANs come in on a trunk from a pair of stacked C2960-S. I need it to be able to scale if we have 50 VLANs for instance, hopefully without long complicated ACLs. I've been considering VRF's, PBR but can't decide what's the simplest solution to this problem. I have never done this before so I would prefer to start off on the right foot.
I start configuring Cisco 2821 router for multicast . First short description and attached sheme explanation. Let we say I have small network with 100 users. One router and Cisco switch 3560. Two VLAN’s, one for data another for multicast. Data from internet works fine but now I want to connect multicast servers (or source of more multicast streams) from another subnet. Router have three interfaces.I expect there should be no problems with multicast configuration, but unfortunately it is not like I expect. What I did ?
First step: enable multicast routing
Second step: on both interfaces (Fe 0/1 and Fe 0/2) - ip pim sparse-mode
Third step: configure switch that users are connected to access port in VLAN 222 (temporary to see if multicast work)
When I start VLC on computer nothing happend. If I try to connect computer on same subnet where is source of multicast streams it works fine.What I am doing wrong ? Is there anything about routing ? All subnets are directly connected. RP is not needed if I have one router or ?
I'm having a problem getting DHCP working with an ASR9k as shown in this document. I've successfully implemented very similar setups with some Cisco IOS routers, but the IOS XR on the ASR seems to be defeating me. Router A (happens to be a 3750)A DHCP/BOOTP/TFTP server, connected to router ARouter B - this is the ASR, running software version 4.0.3.Router A and B are connected by a layer-3 link.Router C (happens to be a Broadcom embedded router). It's connected to Router B by a VLAN trunk link.Device 1, this one needs to get its configuration by DHCP/BOOTP/TFTP. It's connected to Router C by a VLAN trunk link.Device 2, this one doesn't need any DHCP/BOOTP/TFTP. It's connected to Router C by a VLAN trunk link (its port is the same as Device 1's) Device 2 works great - it can ping the DHCP/BOOTP/TFTP server (and vice versa) and everything else it needs.
I am having troubles to get 2 C3750-X switches WS-C3750-X-48P-L) to stack. They are both running iOS 15.0(2)-UNIVERSALK9, and are licensed for IP Base.
If I connect stack port 1 of switch 1 to stack port 2 of switch 1, and stack port 1 of switch 2to stack port 2 of switch 2 I get the following:
WS-C3750-X_STACK1_SW1>show switch stack-ports summary Switch#/ Stack Neighbor Cable Link Link Sync # InPort# Port Length OK Active OK Changes Loopback Status
[Code].....
I have tried restarting (powering off for about 1 min and turning back on) simultaneously, and powering off switch 1 for 1 min and switch 2 for 2 min. I have also tried both enabling the stack ports, and disabling followed by enabling.
I have a cable from an SFP module in a WS-C3750-48P with 12.2(55)SE1 running to a Gigabit port on a Cisco WLC. After the switch recovers from a power failure, the gigabit autonegotiation fails. The cure is a long drive to unplug and reseat the SFP. Note this happens at too many similar sites for this to be a loose connection. Interface shutdown then 'no shutdown' is not sufficient. The state is 'line protocol is down (not connected)'. Interface is configured for switchport mode trunk (auto speed, auto duplex). Command 'switchport nonegotiate' makes no difference. Is there a more powerful command than 'shutdown' which might toggle the interface signals? Is there some way of resetting the SFP? sh int gi 1/0/1 displays 'media type is 10/100/1000BaseTX SFP' and zero packets received.
I would like to apply policing on a C3750 interface, for all traffic matching 10.0.0.0 / 8, except for sub net 10.0.0.0 / 24. I plan to apply the following configuration, with an ACL that denies 10.0.0.0 / 24 then accept 10.0.0.0 / 8. I am quite sure of the answer but need a confirmation about the following configuration correct ? (10.0.0.0 / 24 will be not blocked, and no policing will be apply on it?)
ip access-list extended TEST deny tcp 10.0.0.0 0.0.0.255 any eq 5000 permit tcp any 10.0.0.0 0.255.255.255 any eq 5000 [code]....
I have a stack of 2 C3750-switches (WS-C3750G-24TS-1U) with IPBASE-firmware (12.2(52)SE).
When I ping to a machine (in this case a virtual one), the replies are always received on the port where the machine is connected, but on the port-channel connecting to the stack of the 'pinging device' the reply comes only for certain initiators, and not for all.
Setting: Gi1/0/6: Device/Server I want to connect too ; defined as access port Gi1/0/25 + Gi2/0/25, as Port-Channel 1: The location of the devices I connect (read as: the uplink to the stack of the PC's), defined for Dot1Q-trunking
Monitoring setup: Source ports: Both: Gi 1/0/6, Po1 (or Po1 replaced by both interfaces)
For the machines which can ping the server I see 2 echo (ping) requests, followed by 2 echo (ping) replies ... So once seen on the Po1, and once seen on the interface Gi1/0/6.
However for other machines, the 2nd reply is missing ; which must be caused by the dropping of these packets in the switch. At least, I my opinion this must be the reason... But I can't see any (change of) output drops at int Po1, nor at Gi1/0/6. The CPU doesn't seem to have high usage, and even then, I don't think the error would be constant, as it's always failing for some PC's, and never for others... (at least for a certain time, a few hours it can be constant, the problem dissapears from time to time).
I have a firewall that I want acting as a DHCP relay. This firewall has a number of VLAN interfaces serving clients. The DHCP relay destination is the IP address of a Windows 2012 Server running Microsoft DHCP which has multiple scopes configured, one for each client VLAN.What I'm finding confusing is how the DHCP will identify the client. Does the DHCP relay insert an identifier of some sort (opt. 54?) based on which VLAN the DHCPREQUEST comes from and then this identifier can be configured to be recognized on the DHCP server?
I have a data center with virtual desktops and other shared infrastructure serving remote sites, some of which are connected to the data center with GRE over IPsec.
IP address management including DHCP is centralized in my architecture, but I simply cannot figure out how to relay DHCP requests through GRE over IPsec to my DHCP server cluster. I am working with Cisco 800 series VPN peers, and the VPNs are terminated either on a 1841 or a Juniper SRX. Everything else is just fine and dandy, but DHCP is not forwarded across the GRE tunnel.
As a workaround I am forced to use local DHCP pools on the VPN peers, which is extra work from a management point of view, and also precludes static IP address assignment where a local DHCP pool is in a VRF. My LAN devices are mostly thin clients, so I don't care if DHCP stops working when the WAN link fails. As such local pools have no upsides, they are only a tremendous hassle.
My config is very basic, public WAN in global routing table and WAN + GRE tunnel in a VRF. NAT is not used. Here are the DHCP-related configs I have tried:ip helper-address on the LAN gateway, both with and without ip forward-protocol udp bootpcip dhcp pool with relay options configured
In every case, I can see the UDP broadcasts hit the LAN gateway, but relayed packets never arrive at the other GRE tunnel endpoint let alone the DHCP server.
I have defined several V LAN's and the corresponding IP Addresses on the SGE2000. The static routing works fine. On one V LAN there is a Windows 2003 DHCP Server which I have defined as DHCP Relay Server (Option 82), but no packets are relayed. Has anyone a functional setup, with dhcp relay?
We have existing stack of 3 units of WS-C3750-48TS-S ( 100 mbps ports with Gigabot uplinks). with IOS as follows, Can we add WS-C3750G-48PS-S in this same stack (this is 48 Gigabit ports)?
