Cisco Switching/Routing :: 2921MS DHCP NACK With DHCP Relay?
Nov 11, 2012
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 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.
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.
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 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'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 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?
I am actually more of a 3Com guy than Cisco but I like to think I know my stuff and having just discovered this site I hope to join in as it looks a good place.I have a question about the general theroy underneath DHCP relay (IP Helper in the Cisco world I believe!)I've always put the DHCP server in VLAN1 only. A few weeks ago, I repatched the DHCP server in one of our offices (small site, single switch) into a different port by mistake. A few days ago I noticed (when doing something entirely unrelated) that I had left it in a port on both VLANs meant for PC's/phones. So, untagged on VLAN1, tagged on the voice VLAN. It had continued to work properly all that time however.By contrast, at a larger site, a new DHCP server came online and was put on a switch elsewhere in the building and was also put into a port on both VLANs - however things didn't work at all - of course we noticed immediately and changed the port setting to VLAN1 only, and it came back.In the second example, the server was on a different switch to where the main L3 switch for the Voice VLAN was (which also does the DHCP relay), and was connected over a fibre trunk link.Is there any reason why it should work on a single switch on a port on both VLANs, but not when connected over a trunk link? The server does not understand tagging. In the case where it worked, the phones were getting an IP from the correct scope; so the relay obviously must have been working with the server issuing an address based on the GIADDR field.
DHCP Relay on a SGE2000 switch.I have configured two VLANs on the switch, VLAN2 (192.168.10.x/24) and VLAN3 (192.168.9.x/24). I have the switch in Layer 3 mode. I have configured the DHCP relay server of 192.168.10.4 and the DHCP Interfaces as VLAN3. All of the IP Static Routes were generated by the switch.
If I put a client computer on a port that is Untagged VLAN 3 and try to get a DHCP address from the server on an Untagged VLAN 2 port I never get a response back.I have done some packet captures and here is what I have found:
I see the DHCP broadcast on the client computerI see the DHCP Request on the DHCP server coming from the IP assiged to the switch on VLAN 3 (192.168.9.254)I see the DHCP server respond with a DHCP OfferThe DHCP offer never gets to the client computer I can't seem to get a DHCP address to any system not on the same VLAN as the DHCP server. Option 82 is disable and I did try enabling it, which made no difference.
My network is set up such that I have a Wireless Network in VLAN 1, which is the primary network that we use. The subnet is 10.5.1.x.
My goal is to set up a completely isolated Guest Wireless Network, however it would work best. What I am trying to do now is I created a seperate VLAN (VLAN 2, IP range 10.5.2.x) and turned on DHCP on the WRVS4400N. However, in the Guest Network, it is always picking up a 10.5.1.x IP which is handed out by the DHCP server (10.5.1.5, Win 2003) and still routing all of the traffic to/from our private network.
Here's What I have set:
Wireless>Security Settings>Guest Network (SSID 2) Wireless Isolation (between SSID w/o VLAN): EnabledWireless Isolation (within SSID): EnabledSetup>LAN>VLAN 1 Router IP 10.5.1.1, WLAN IP 10.5.1.3DHCP Relay for 10.5.1.5Setup>LAN>VLAN 2 Router IP 10.5.2.1DHCP Enabled for 10.5.2.x subnetDHCP Relay option is grayed out (not sure why)Setup>Advanced Routing Inter-VLAN Routing: Disabled Any way to solve this would be fine. I just do not want traffic routing through our internal network. Ideally, if I could get the Windows server to hand out 10.5.2.x addresses, that would be perfect, but I'm not sure how to configure it for such.
Here is the high-level question, please only respond if you have a conclusive answer with documentation to back it up. It seems simple, but all my research on forums and things have been confusing and conflicting.
When "ip helper-address" is used to enable the dhcp-relay function, will the DHCP packets get relayed through the VPN tunnel (if thats where the DHCP server is?) This question applies to Cisco IOS Routers and VPN appliances which have a Site-to-Site IPSEC VPN Tunnel to a place that hosts a DHCP server.
I'm using the Cisco 880 and 1800 series routers. I've already got DHCP relaying through IPSEC tunnels, but so far I've only set it up where my 2960 switch relays the DHCP messages to the VPN router on site (which is a separate device). I want to know if the router can pickup and relay through it's own tunnel natively.
We have a SBS 2003 server with two NIC's, one for the internal LAN and the other connecting to the WAG160Nv2 that is hooked up to the internet.The internal LAN clients are all getting IP addresses from the DHCP server in the SBS Server (192.168.16.XXX). The DHCP server is sat at 192.168.16.2.The only thing connected to the LAN ports on the WAG160Nv2 is the Internet facing NIC from the server.What I want to do is to get the WAG160Nv2 to give IP addresses to Wireless connections going through the router, can I configure the DHCP relay option on the WAG160Nv2 to do this, I have looked at the DHCP relay option but it doesn't seem to work, my wireless connections are getting private 169.254.xxx.xxx addresses.Also is there anything I can do to make the wireless more Apple friendly, iPhones and iPads drop of the wireless frequently, that's why I trying a different approach.
I am having some issues with getting DHCP Relay to fuction properly over our SG300-20 Switch.Out current layout is as follows. Hanging off the SG300-20 are a pair of Clustered Checkpoint Gateways with VLAN'ed interfaces in Both of our 2 VLANs, a 3COM 4200G In VLAN1 which has the DHCP server (And all the other Servers) connected to it, and a Pair of HP Procurve 2520's Stacked in VLAN 2 to provide PoE for our Phones/connectivity for our PCs.The problem is I cannot get the DHCP Relay to fuction from VLAN 1 to VLAN 2. If I assign an address in VLAN 2 manually to a device connected to the Procurves, everything works fine. I am able to reach both VLAN 1 and VLAN 2, but DHCP aquisition fails even if the device is connected directly to a port assigned to VLAN 2 on the SG300. The SG300 is running at Layer 3 currently also.
Here is a copy of the running config: -------------------------------------------------------------------------------------------------------------- switch4db24f#show running-config vlan database vlan 2 exit interface range gi8,gi16 switchport default-vlan tagged
I have a Cisco 7200 acting as the DHCP relay agent on my network. From a security standpoint, I want to disable the bootp server, with 'no ip bootp server'. What bearing, if any, does 'no ip bootp server' have on DHCP activity?
I have two Cisco RV220W routers and I would like to realy DHCP from the home office to the remote office accross the IPsec Tunnel. Is this possible and if so how?
I have already gone into the IPv4 LAN (Local Network) settings on the remote router and set the DHCP mode to "DHCP Relay" providing the internal ip address of the home office router as the remote DHCP server.
Site1: On the Cisco 877: Cryptomaps:permit 192.168.200.0 192.168.2.0 (original crypto)permit 192.168.200.21 192.168.1.2 (added)permit 192.168.200.21 192.168.2.1 (added). What NAT entries do I need to use on the ASA and 877 ?
I have this Cisco 1941 router with two Ethernet ports g0/0 and g0/1. The g0/0 is connected to office LAN with internet access. As my office LAN is DHCP, it will assigned a IP address for g0/0 since this g0/0 is configured as "ip address dhcp". Now my question is that i have a group of 5 pcs, namely PC1, PC2, PC3, PC4 and PC5 that is connected to the switch and one of the ports of this switch is connected to g0/1 of Cisco 1941. Is it possible that let say PC2 and PC3 (both DHCP enabled) could access the internet access from g0/0 and at the same time, the office LAN assigned IP address for PC2 and PC3 automatically?
Office Lan with internet access (DHCP) (Default gateway 10.0.0.1) | | g0/0 (DHCP enable) (DHCP assigned IP address 10.0.0.138) Cisco router 1941 g0/1 | | HP Switch | PC1 PC2 PC3 PC4 PC5
Is this operation possible? if possible, how to configure inside the router 1941 to achieve this objective?
I disconnected and reconnected the powercable while holding on to the setup button until system, alert, setup go amber. The system led light began blinking green. I waited until one of the leds lights on the ports starts blinking green I then connected the ethernet cable connected to my pc. I made sure my lan connection on my computer was set to dhcp.In the docs claim it should take about 1 minute to grab a new ip address. After a few minutes i check the ipconfig on my pc and I get the apipa address.The setup light on the switch remains green while system is amber. The led for port 1 stopped blinking and remains green.My pc is not grabbing an ip address I don't know what else to do.
We are looking to avoid the need to install an additional device in our network as our core 6509s are not being pushed by any stretch. However, we are having an issue getting the 6509 to assign DHCP addresses and perform NAT.
Most interfaces and V LAN's on the 6509 are using public IPs and have BGP routing at the edge. We have a trunk up link coming into the 6509 on a ws-6816 card via a SMF GBIC in slot 9, port 2 that feeds a wifi link where we are looking to provide guest access to our network.
We created 2 V LAN s on the switch 20 and 21. We assigned a private IP and network to the VLAN20 interface and assigned a new public /30 sub net ip to the V LAN 21 interface. The following configuration was applied which I thought was the required configuration based on how we would typically configure ISR routers for the same services...
ip dhcp excluded-address 10.200.200.1 ! ip dhcp pool WiFi_Pool network 10.200.200.0 255.255.255.0 default-router 10.200.200.1 dns-server 4.2.2.1 4.2.2.2 [ code]...
What am I missing in this configuration? Note that if I create an access switch port for v LAN 20 on the switch and plug a laptop in directly to the 6509, the laptop is unable to receive a DHCP address. If I assign the laptop an address in the 10.200.200.0 /24 range manually, I can ping 10.200.200.1 from the laptop, however, the laptop will not get to the internet as it appears to be failing to perform nat.
I am a newbie to Cisco. I am trying to setup NAT with DHCP in our office on CISCO 819 router. I am having a problem with DHCP not assigning an IP on vlan1. I cannot figure out what i'm doing wrong. Below is my config and debug from DHCP.
router#sh config Using 4328 out of 262136 bytes ! ! Last configuration change at 05:56:39 UTC Mon May 13 2013 by cisco ! NVRAM config last updated at 05:57:16 UTC Mon May 13 2013 by cisco [Code]....
I have this message "DHCP Timeout"on few cisco IP Phones .try to assign IP manually and it's working fine.. seems DHCP not giving IP's to those.. 6500 have configured as DHCP pool.
