Comments on: Cisco’s ip helper-address Too Forward? http://slaptijack.com/networking/ciscos-ip-helper-address-too-forward/ I’ve spent the last 10+ years hoarding network and system administration knowledge. Now, in an attempt to organize all the sticky notes and scraps of paper floating around my office, I’m steadily putting everything in one place. Not only does this site serve as my personal library of collected information, but it’s available to all admins — beginners and experts alike. Thu, 18 Mar 2010 03:55:26 +0000 http://wordpress.org/?v=2.9.2 hourly 1 By: Scott Hebert http://slaptijack.com/networking/ciscos-ip-helper-address-too-forward/comment-page-1/#comment-15294 Scott Hebert Fri, 08 May 2009 15:05:00 +0000 http://slaptijack.com/networking/ciscos-ip-helper-address-too-forward/#comment-15294 @Matthew - Of the two scenarios you describe, the first is probably the preferred. The local server will receive DHCP requests via broadcasts on the subnet. The router will pick up these broadcasts and forward them on to the remote DHCP server. Unfortunately, in both cases, you might have DHCP issues if the servers do not synchronize their DHCP lease information. (By the way, when you use multiple ip helper-address lines in your configuration, each DHCP request is forwarded to both servers.) @Matthew -

Of the two scenarios you describe, the first is probably the preferred. The local server will receive DHCP requests via broadcasts on the subnet. The router will pick up these broadcasts and forward them on to the remote DHCP server.

Unfortunately, in both cases, you might have DHCP issues if the servers do not synchronize their DHCP lease information.

(By the way, when you use multiple ip helper-address lines in your configuration, each DHCP request is forwarded to both servers.)

]]> By: Matthew http://slaptijack.com/networking/ciscos-ip-helper-address-too-forward/comment-page-1/#comment-15226 Matthew Thu, 07 May 2009 20:11:19 +0000 http://slaptijack.com/networking/ciscos-ip-helper-address-too-forward/#comment-15226 We are setting up MetaIP servers for our dhcp services at all sites. Each MetaIP server will "replicate" scopes, etc to a standby backup server at a remote site. Therefore, we will have a dhcp server at every site but want to have failover capabilities in case the local server goes offline and thus need to configure an ip helper-address for the remote "standby" dhcp server. In this situation, would you want to create just one ip helper: ip helper-address [remote standby server] or would you want to create 2: ip helper-address [local server] ip helper-address [remote standby server] Thank you in advance. We are setting up MetaIP servers for our dhcp services at all sites. Each MetaIP server will “replicate” scopes, etc to a standby backup server at a remote site. Therefore, we will have a dhcp server at every site but want to have failover capabilities in case the local server goes offline and thus need to configure an ip helper-address for the remote “standby” dhcp server. In this situation, would you want to create just one ip helper:
ip helper-address [remote standby server]
or would you want to create 2:
ip helper-address [local server]
ip helper-address [remote standby server]

Thank you in advance.

]]> By: cworld: Network Administration http://slaptijack.com/networking/ciscos-ip-helper-address-too-forward/comment-page-1/#comment-2920 cworld: Network Administration Wed, 01 Oct 2008 00:16:07 +0000 http://slaptijack.com/networking/ciscos-ip-helper-address-too-forward/#comment-2920 [...] ip helper-address: too forward [...] [...] ip helper-address: too forward [...]

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