DHCP and ACE in Bridge Mode

[David Martinez Garcia]

Hi guys!

I have a n ACE20 in bridge mode.

The servers behind the bridge interface didn't receive DHCP offers form DHCP server. Any idea if the BVI interface needs some config?

The schema is.

DHCP SERVER ----------FWSM(default gateway)--------------------BVI-------------SERVER

Thanks in advance!

[Kanwaljeet Singh]

Hi David,

The ACE does not support DHCP relay for DHCP packets received on shared VLANs between contexts or on bridged interfaces. Please go the link  below for more details.

http://www.cisco.com/en/US/docs/interfaces_modules/services_modules/ace/vA5_1_0/configuration/rtg_brdg/guide/dhcp.html

Regards,

Kanwal

[David Martinez Garcia]

Hi Kanwal.

are you saying that I can't use dhcp-configured server when the ACE is in bridge mode

That server won't receive the dhcp offer packet anymore?

Thanks!

[Kanwaljeet Singh]

Hi David,

I haven't done or tested this configuration before but the above link which is "Routing and Bridging guide for A510"  clearly states that it does not support DHCP relay for DHCP packets coming in on Bridged interfaces .

Further research shows that there has been a DDTS logged for this and is supposed to be in fixed in A512c.

CSCuc40400:  ACE DHCP relayed packets get dropped by the ACE in bridge mode

Regards,

Kanwal

[Kanwaljeet Singh]

Hi David,

I looked more about the issue and it seems that older guides doesn't have the restriction plus we have that above DDTS which means that DHCP relay should work through ACE in bridged mode. Please ensure that proper configuration is in place for the same. Also, i just realized you are talking about ACE20 and not 30.

Here's the link for your reference :

http://www.cisco.com/en/US/docs/interfaces_modules/services_modules/ace/v3.00_A2/configuration/rtg_brdg/guide/dhcp.html

Regards,

Kanwal

[David Martinez Garcia]

Hi Kanwal.

Yes, we are running ACE20, so I was thinking about it and....do we need some ACL to DHCP work properly?

Thanks in advance!

[Kanwaljeet Singh]

Hi David,

You can try putting in ip any any and see if that helps. There must already be an ACL in place on interface. But you should have proper configuration for DHCP as mentioned in link above. Do you see the correct outputs when you execute the commands as mentioned in above document?

show ip dhcp relay conf

show ip dhcp relay information policy

show ip dhcp relay statistics—Displays the DHCP relay statistics

Regards,

Kanwal