Hey all,
Having a bit of an issue with bridge-domains on ASR 1001 and dynamic ARP entries.
Looking through the packet captures, I see the following events
- DHCP request from CPE
- DHCP ACK and assignment from DHCP server to CPE
- Gratuitous ARP sent from CPE.
- Packets flow as normal.
- Something triggers dynamic ARP entry to timeout on the BNG (Cisco ASR 1001).
- a. Suspect this may be triggered by the DHCP Request renew or the following gratuitous ARP received.
- See the debug message on the ASR:
*Oct 15 18:18:29.376: IP ARP: rcvd rep src 10.0.30.11 5475.d0df.7f48, dst 10.0.30.11 BDI100
*Oct 15 18:18:29.376: ARP DB: ARP entry of key 10.0.30.11 found
*Oct 15 18:18:29.376: ARP TABLE: modifying entry 10.0.30.11/5475.d0df.7f48 on BD100 for Dynamic
*Oct 15 18:18:29.376: ARP DYNAMIC[N]: Dynamic timeout occurredtimeout = 14400000, refresh_token = 2,refresh_timeout = 60000
*Oct 15 18:18:29.376: ARP DB: ARP entry of key 10.0.30.11 found
- DHCP client on the CPE eventually sends through a DHCP request for the IP 10.0.30.11.
- DHCP server replies with ACK.
- Gratuitous ARP sent from CPE.
- Dynamic ARP entry is populated.
- Packets flow as normal.
If I attempt to ping manually from the CPE, the dynamic arp entry is restored on the ASR.
Further details:
Platform: ASR 1001
Software: 3.10a (asr1001-universalk9.03.10.00a.S.153-3.S0a-ext.bin)
Interfaces:
interface Port-channel2
description Uplink - <redacted>
mtu 2000
ip dhcp relay information option-insert
ip dhcp relay information check-reply none
no ip address
no ip unreachables
no negotiation auto
lacp fast-switchover
lacp max-bundle 1
service instance 1101 ethernet
encapsulation dot1q 80 second-dot1q 1101
rewrite ingress tag pop 2 symmetric
ip dhcp relay information option subscriber-id GCC-CPE-1-1
service-policy output pm_BNG-WAN-wVoice-Out-12Mbps
bridge-domain 100
!
service instance 1102 ethernet
encapsulation dot1q 80 second-dot1q 1102
rewrite ingress tag pop 2 symmetric
ip dhcp relay information option subscriber-id GCC-CPE-2-1
service-policy output pm_BNG-WAN-wVoice-Out-25Mbps
bridge-domain 100
interface BDI100
ip address 10.0.30.1 255.255.255.0
ip helper-address 2.2.1.2
GCC-BNG-1#sh run | i bridge
bridge-domain 100
bridge-domain 912
bridge irb
bridge-domain 100
bridge-domain 100
bridge 100 protocol vlan-bridge
bridge 100 route ip
Any ideas?
