I'm troubleshooting a network issue with an appliance that isn't getting on our
network. We've already solved one problem (hash-collision causing the MAC not
to be learned), and JTAC is working on that. However, even with that worked
around, the equipment isn't getting a DHCP address. We suspect this is an
issue with the device (not the switch), and I have a question for the list:
Does the QFX5100 dhcp-relay or EX4200 DHCP snoop have any built-in feature that
drops non-compliant DHCP packets?
The device is being worked on, so I can't have it in the failure state right
now to take a trace. I'm hoping someone might know off the top of their head.
The device is giving itself an auto-assigned IP (169.254.36.130). Nothing
wrong with that, but it's using that address as the source of its DHCPDISCOVER
packets:
18:19:51.846671 00:10:7f:5b:a0:d4 > ff:ff:ff:ff:ff:ff, ethertype IPv4 (0x0800),
length 342: (tos 0x0, ttl 128, id 23, offset 0, flags [none], proto UDP (17),
length 328)
169.254.36.130.49152 > 255.255.255.255.67: [udp sum ok] BOOTP/DHCP, Request
from 00:10:7f:5b:a0:d4, length 300, xid 0x7bad5324, Flags [Broadcast] (0x8000)
Client-Ethernet-Address 00:10:7f:5b:a0:d4
Vendor-rfc1048 Extensions
Magic Cookie 0x63825363
DHCP-Message Option 53, length 1: Discover
Client-ID Option 61, length 7: ether 00:10:7f:5b:a0:d4
Parameter-Request Option 55, length 7:
Subnet-Mask, Default-Gateway, Domain-Name-Server, Domain-Name
Netbios-Name-Server, Netbios-Node, Netbios-Scope
Hostname Option 12, length 15: "DMPS3-A0D4-BHDH"
END Option 255, length 0
PAD Option 0, length 0, occurs 21
Per RFC 2131:
"DHCP messages broadcast by a client prior to that client obtaining its IP
address must have the source address field in the IP header set to 0."
So, does anyone know if this might cause the packets not to get relayed?
Also, any opinions on the client behavior? Doesn't seem RFC-compliant, but
there's plenty of that to go around so I'm not sure if that's the root cause
here.
Thanks for any help; I'll try to get a full trace at some point when the tech
for the equipment is available to fail it back to DHCP (we have it set to
static temporarily as a workaround).
Thanks,
Jason
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