!dx » Ср апр 05, 2006 1:56 pm
должно помочь:
Код: Выделить всё
SuperStack 3 Switch 4900 - Some devices fail to get a DHCP address via UDP Helper
Problem: Some devices frequently fail to get a DHCP address
Problem: Some clients on VLANs unable to get DHCP Addresses
Problem: Cannot get IP address from DHCP server
Fact: SuperStack 3 Switch 4924
Fact: SuperStack 3 Switch 4950
Fact: SuperStack 3 Switch 4900 12-Port
Fact: SuperStack 3 Switch 4900 12-Port 1000BASE-SX
Fact: Switch 4050
Fact: Switch 4060
Fact: Switch 4070
Fact: Dynamic Host Configuration Protocol (DHCP)
Fact: DHCP
Fact: UDP Helper
Fact: Multiple Subnets
Fact: ESD14354
Fact: Apple
Cause:
This occurs where there are Multiple Subnets on one VLAN.
The client device DHCP Request has the BOOTP Broadcast flag = 0 (i.e. instructs the DHCP server to unicast DHCP offer to it).
When the Switch 4900 UDP Helper forwards the DHCP request it cannot know the subnet the offer will put the device in, and selects one of the IP addresses allocated to the VLAN. Where this guess is wrong the Switch 4900 cannot unicast the reply, but an incorrect entry is added to the ARP table. This ARP entry causes further DHCP offers to be lost until it is aged out, or flushed from the table.
The greater the number of subnets on one VLAN, the higher the failure rate.
Fix:
This has been fixed in software version 3.12 and software version 4.12 for the Switch 49xx and the Switch 40x0 family.
Fix: Restrict devices that require a unicast DHCP offers to VLANs with a single IP address, and subnet.
Fix: Change the DHCP client device configuration to request broadcast DHCP offers.
должно помочь:
[code]SuperStack 3 Switch 4900 - Some devices fail to get a DHCP address via UDP Helper
Problem: Some devices frequently fail to get a DHCP address
Problem: Some clients on VLANs unable to get DHCP Addresses
Problem: Cannot get IP address from DHCP server
Fact: SuperStack 3 Switch 4924
Fact: SuperStack 3 Switch 4950
Fact: SuperStack 3 Switch 4900 12-Port
Fact: SuperStack 3 Switch 4900 12-Port 1000BASE-SX
Fact: Switch 4050
Fact: Switch 4060
Fact: Switch 4070
Fact: Dynamic Host Configuration Protocol (DHCP)
Fact: DHCP
Fact: UDP Helper
Fact: Multiple Subnets
Fact: ESD14354
Fact: Apple
Cause:
This occurs where there are Multiple Subnets on one VLAN.
The client device DHCP Request has the BOOTP Broadcast flag = 0 (i.e. instructs the DHCP server to unicast DHCP offer to it).
When the Switch 4900 UDP Helper forwards the DHCP request it cannot know the subnet the offer will put the device in, and selects one of the IP addresses allocated to the VLAN. Where this guess is wrong the Switch 4900 cannot unicast the reply, but an incorrect entry is added to the ARP table. This ARP entry causes further DHCP offers to be lost until it is aged out, or flushed from the table.
The greater the number of subnets on one VLAN, the higher the failure rate.
Fix:
This has been fixed in software version 3.12 and software version 4.12 for the Switch 49xx and the Switch 40x0 family.
Fix: Restrict devices that require a unicast DHCP offers to VLANs with a single IP address, and subnet.
Fix: Change the DHCP client device configuration to request broadcast DHCP offers.[/code]