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Cisco Bug: CSCvi53117 - Command "ip dhcp snooping information option replace" doesn't work properly

Last Modified

Jun 07, 2018

Products (1)

  • Cisco Catalyst 6000 Series Switches

Known Affected Releases

15.4(1.1.24)SY4

Description (partial)

Symptom:
End host --- 3560 --- 6880 with IA --- DHCP server

3560 - L2 switch with DHCP snooping
6880 - DHCP relay

End host is not able to get IP from DHCP when running version 154-1.SY4 with enabled command "ip dhcp snooping information option replace"

When 6880 is running c6880x-adventerprisek9-mz.SPA.154-1.SY4.bin, end host is not able to get IP address while command "ip dhcp snooping information option replace" is enabled on 6880.

End host is able to get IP address if 6880 is running c6880x-adventerprisek9-mz.SPA.152-1.SY3.bin and c6880x-adventerprisek9-mz.SPA.152-1.SY5.bin.

After removing "ip dhcp snooping information option replace", end host is able to get IP address.

Debug messages during the issue:

*Mar 16 12:44:31.086: SW1: fm_dhcps_intercept_tx_process_path(): Not a DHCP Packet, vlan = 100, returning
*Mar 16 12:44:32.474: SW1: DHCPS-DEBUG: fm_dhcps_intercept_rx_interrupt_path: Packet with exc cause[0x501] on vlan[100], input port[Gi101/1/0/10] passed to snooping process
*Mar 16 12:44:32.474: SW1: DHCP_SNOOPING: received new DHCP packet from input interface (GigabitEthernet101/1/0/10)
*Mar 16 12:44:32.474: SW1: dhcp_snooping_platform_adjust_vlan(): pak->vlan_id = 100 
*Mar 16 12:44:32.474: SW1: dhcp_snooping_platform_adjust_vlan(): Returning vlan_id = 100 , l3hwidb = 0x241B5D88
*Mar 16 12:44:32.474: SW1: DHCP_SNOOPING: process new DHCP packet, message type: DHCPDISCOVER, input interface: Gi101/1/0/10, MAC da: ffff.ffff.ffff, MAC sa: cc46.d6e0.14d1, IP da: 255.255.255.255, IP sa: 0.0.0.0, DHCP ciaddr: 0.0.0.0, DHCP yiaddr: 0.0.0.0, DHCP siaddr: 0.0.0.0, DHCP giaddr: 0.0.0.0, DHCP chaddr: cc46.d6e0.14d1
*Mar 16 12:44:32.474: SW1: dhcp_snooping_process_pak(): Not a routed packet
*Mar 16 12:44:32.474: SW1: dhcp_snooping_is_port_trusted(): GigabitEthernet101/1/0/10 is Layer 2 intf
*Mar 16 12:44:32.474: SW1: dhcp_snooping_is_port_trusted(): GigabitEthernet101/1/0/10 is Layer 2 intf, dhcpsb->data.trust = 0
*Mar 16 12:44:32.474: SW1: dhcp_snooping_process_pak(): Not a Trusted port : GigabitEthernet101/1/0/10
*Mar 16 12:44:32.474: SW1: dhcp_snooping_is_port_trusted(): GigabitEthernet101/1/0/10 is Layer 2 intf
*Mar 16 12:44:32.474: SW1: dhcp_snooping_is_port_trusted(): GigabitEthernet101/1/0/10 is Layer 2 intf, dhcpsb->data.trust = 0
*Mar 16 12:44:32.474: SW1: dhcp_snooping_need_binding_update(): Returning  Binding update required  = 0
*Mar 16 12:44:32.474: SW1: dhcp_snooping_is_port_trusted(): GigabitEthernet101/1/0/10 is Layer 2 intf
*Mar 16 12:44:32.474: SW1: dhcp_snooping_is_port_trusted(): GigabitEthernet101/1/0/10 is Layer 2 intf, dhcpsb->data.trust = 0
*Mar 16 12:44:32.474: SW1: dhcp_snooping_check_and_replace_option82: Replace current option 82 with new option 82
*Mar 16 12:44:32.474: SW1: dhcp_snooping_check_and_replace_option82: option 82 is the last option in the packet. Blank it
*Mar 16 12:44:32.474: SW1: DHCP_SNOOPING: add relay information option.
*Mar 16 12:44:32.474: SW1: DHCP_SNOOPING: could not create relay information template.
*Mar 16 12:44:32.474: %DHCP_SNOOPING-SW1-4-OPTION82_INSERTION_FAIL: The interface Gi101/1/0/10 is not able to insert opt82 into the packet
        because of insufficient space in the packet
*Mar 16 12:44:32.474: SW1: Error in option82 replace.Packet dropped

Conditions:
Issue is observed when DHCP snooping is enabled on 6880 with "ip dhcp snooping information option replace" command.
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