Hi,
We have ACE 30 module context in bridged mode.
Everything works fine, but the probes to the real server on the Standby are in a Failed state. After troubleshooting for a while, I have found, that this is somehow related to L2 and ARP responses.
- Routing on the client side is pointing to 10.126.120.1 (this is a HSRP IP where 10.126.120.2 and .3 are real IP addresses) - this is vlan 2750
- Routing on server side is pointing to 10.126.120.4 (this is a HSRP IP where 10.126.120.5 and .6 are real IP addresses) - this is vlan 2751
- On Active ACE module, I can ping all of the addresses, i.e. 10.126.120.1-6
- On Standby ACE module, I can ping only client side IP addresses, i.e. 10.126.120.1-3.
- On Standby ACE, I cannot ping server-side router interfaces, i.e. 10.126.120.4-6 and there is no entry in the ARP table for these IPs.
- Routers are able to ping Active ACE BVI interface IP address 10.126.120.10
- Routers are unable to ping Standby ACE BVI interface IP address 10.126.120.11
- Routers don't receive ARP for Standby ACE BVI IP address.
- When i manually trigger the ACE module failover, probes start working just fine on both ACE modules until ARP times out.
Is this an expected behaviour?
Do you have an explanation about this behaviour?
From loadbalancing perspective, everything is working fine.
From the Probe perspective, I expect, that the probe on Standby ACE unit is using Standby BVI IP address 10.126.120.11, it is unable to get ARP for the corresponding server route and hence fails the probe.
Here comes the relevant config and state from the Standby ACE module:
0cc1-ace12/dclb# show arp
Context dclb
================================================================================
IP ADDRESS MAC-ADDRESS Interface Type Encap NextArp(s) Status
================================================================================
10.126.120.1 00.00.0c.07.ac.01 vlan2750 GATEWAY 39 182 sec up
10.126.120.2 e0.2f.6d.2c.23.c0 vlan2750 LEARNED 37 5961 sec up
10.126.120.3 e0.2f.6d.2c.23.80 vlan2750 LEARNED 35 5957 sec up
10.126.120.10 e0.5f.b9.ab.8c.35 vlan2750 LEARNED 40 5955 sec up
10.126.120.4 00.00.00.00.00.00 bvi1 GATEWAY - * 3 req dn
10.126.120.11 e0.5f.b9.ab.8c.11 bvi1 INTERFACE LOCAL _ up
================================================================================
Total arp entries 6
0cc1-ace12/dclb#
0cc1-ace12/dclb#
0cc1-ace12/dclb# show run interface
Generating configuration....
interface vlan 2750
description >MSFC:dc
bridge-group 1
fragment min-mtu 28
access-group input BPDU
access-group input ACL
no shutdown
ip route inject vlan 2750
interface vlan 2751
description >MSFC:dclb
bridge-group 1
fragment min-mtu 28
access-group input BPDU
access-group input ACL
no shutdown
interface bvi 1
ip address 10.126.120.11 255.255.255.224
peer ip address 10.126.120.10 255.255.255.224
Relevant router ARP table:
0cc1-s11#show ip arp vrf dclb 10.126.120.11
Protocol Address Age (min) Hardware Addr Type Interface
Internet 10.126.120.11 0 Incomplete ARPA
0cc1-s11#show ip arp vrf dclb 10.126.120.10
Protocol Address Age (min) Hardware Addr Type Interface
Internet 10.126.120.10 1 e05f.b9ab.8c35 ARPA Vlan2751
Regards,
Alexander
