topic RE: Bootp or UDP_profile , which has presidence when both configured. in Network Architecture & Design

Bootp or UDP_profile , which has presidence when both configured.

Rod_Robertson2 — Fri, 31 Mar 2017 14:59:00 GMT

I have just recently taken over a network , that has both bootp and UDP-profiles configured fro teh same vlans.
I have used both individually , aka old days we could only specify single IP address for DHCP server in Bootp , and udp-profile for choosing other DHCP servers , Mitel for example.

My question is , if both are configured for the same vlans , which takes presidence , and is there a " bun fight " between the two operations ..

RE: Bootp or UDP_profile , which has presidence when both configured.

Karthik_Mohando — Sat, 01 Apr 2017 09:42:00 GMT

Hi Rod, Did a quick test in lab and the DHCP packet is sent to both the IP's. configure bootprelay add 10.1.1.81 UDP-profile destination-ipaddress 10.1.1.2

RE: Bootp or UDP_profile , which has presidence when both configured.

Patrick_Koppen — Sat, 01 Apr 2017 21:58:00 GMT

Hi Rod,

ExtremeXOS 22.1 User Guide, page 1235

If UDP Forwarding is used for BOOTP or DHCP forwarding purposes, do not configure or use the existing bootprelay function. However, if the previous bootprelay functions are adequate, you may continue to use them.

It seems not supported to use both, so you should not rely on this...

Regards
Patrick

RE: Bootp or UDP_profile , which has presidence when both configured.

David_Choi — Mon, 03 Apr 2017 06:06:00 GMT

Adding to Patrick's finding,
I would also like to add followings (found from 22.1 User guide also):

"The following rules apply to UDP broadcast packets handled by this feature:
• If the UDP profile includes BOOTP or DHCP, it is handled according to guidelines specified in RFC
1542.
• If the UDP profile includes other types of traffic, these packets have the IP destination address
modified as configured, and changes are made to the IP and UDP checksums and TTL field
(decrements), as appropriate.
If UDP Forwarding is used for BOOTP or DHCP forwarding purposes, do not configure or use the
existing bootprelay function. However, if the previous bootprelay functions are adequate, you may
continue to use them.

[Note]
When using udp-profile to forward dhcp request, the behavior will be different from
bootprelay. Where bootprelay will forward the dhcp packet with the client vlan IP as source IP,
udp-profile will forward the dhcp packet with the source IP of the egress vlan towards the
destination server.
UDP Forwarding only works across a Layer 3 boundary and currently, UDP Forwarding can be
applied to IPv4 packets only, not to IPv6 packets."

It seems like there is no precedence between bootprelay and UPD-profile with Karthik's local test result but the behavior looks a bit different...

RE: Bootp or UDP_profile , which has presidence when both configured.

Rod_Robertson2 — Tue, 04 Apr 2017 17:53:00 GMT

Many thanks I will disable the bootp and check ..