Physical sub interface cannot get IP address automatic because the problem of version

Publication Date:  2012-09-10 Views:  175 Downloads:  0
Issue Description
Topology
DHCP-SERVER----router----SW--- private line-----USG---

1. It cannot get IP address after configuring DHCP CLIENT ENABLE in Physical sub interface, It can get the IP address normally when PC with VLAN label encapsulation replace USG. It is found that USG sends DHCP DICOVER packets, The other side does not send OFER packets.
Capturing analysis
USG


PC


TTL of USG is 1, TTL of PC is 64, there is a router among users’ DHCP SERVER and USG, make DHCP RELAY on the router, the router will reduce the value of TTL, that make USG cannot receive DISCOVERY sent by USG after the DHCP SERVER sending.
Alarm Information
NULL
Handling Process
It is normal after upgrading to V100R005C00SPC600.
Root Cause

1. Check the configuration of packet filtering, normal.
2. Check the configuration of DHCP, normal.
3. Doubt the version problem.
Suggestions
This failure appears before the V100R005C00SPC500 version, it suggested that upgrading to V100R005C00SPC600 if this demand was required.

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