![]() Mac address flooding cisco code#This is first available starting with 2.1(1h) and all code after.After 3.0, this can be enabled by going to System > System Settings > Endpoint Control > IP Aging (look to the right for this tab).Prior to 3.0, this can be enabled by going to Fabric > Access Policies > Global Policies > IP Aging Policy.At 75% of the endpoint retention timer, a directed ARP is sent to the IP component of the endpoint, and if unanswered, ACI will allow the IP endpoint to age out. This feature will age each IP separately to address that scenario. Cosmetically, this is undesirable in scenarios where DHCP enabled hosts get a new IP address but both IP’s are still shown within the EPG operational tab as tied to that MAC. Mac address flooding cisco mac#When IP Aging is not enabled (which is the default), if multiple IP’s are learned on a single MAC, then as long as the MAC is active then all IP’s will stay learned on the fabric.After 3.0, this can be disabled (or enabled) by going to System > System Settings > Endpoint Controls > EP Loop Detection.Prior to 3.0, this can be disabled (or enabled) by going to Fabric > Access Policies > Global Policies > EP Loop Detection Policy.For this reason, I would disable EP Loop Detection. While the EP Loop Detection configuration has good intentions, (i.e., finding a loop, and killing it), I have found that it is triggered as often (or more) by false positives, such as Vmotions of VMs, as it finds true loops.The workaround is to have the L2 BD configured for L2 Unknown Unicast = Flood. When Enforce Subnet is enabled, any Bridge Domains which are configured as L2-only -AND- have L2 Unknown unicast set to proxy will result in mac addresses not being learned from ARP/GARP packets. Be aware of CSCvh17285 (fixed in 3.2(1l) and later).When enabled, we will not learn the IP component at the VRF level as well. This can be problematic, and thus, the need for the Enforce Subnet configuration option. The packet can still be learned on a leaf that does not have the BD configured (i.e., a border leaf). “Limit IP Learning to subnet” does NOT drop the packet, it just stops it from being learning on the BD. You might remember that the “Limit IP Learning to subnet” BD configuration option prevents the learning of IP endpoints if they are not a subnet configured on the BD. Enforce Subnet Check is somewhat like “Limit IP Learning to subnet”, but on steroids.First available for 3.0 starting with 3.0(2k) and after.This is first available starting with 2.2(2q) and all 2.2(x) code after.Enforce Subnet Check (will only work on -EX and -FX based leafs).This bug will allow remote EP learns on border leaf switches even if Disable Remote EP learn is configured when the switch receives packets with src/dst of tcp 179. Be aware of CSCvi11291 (fixed in 3.2(1l) and later).This is first available starting with 2.2(2e) and all code after.After 3.0, this can be enabled by going to System > System Settings > Fabric Wide Setting.Prior to 3.0, this can be enabled by going to Fabric > Access Policies > Global Policies > Fabric Wide Setting Policy.Disable Remote EP Learn – This will disable remote IP learning on border leaf switches.If you want to read more about, MCP, go check out this post!.Make sure and enable the “Enable MCP PDU per VLAN” option (available after 2.0(2)), which enables MCP to send packets on a per-EPG basis, otherwise, these packets will only be sent on untagged EPGs (which basically makes it useless from a loop-detection perspective).This can be enabled by going to Fabric > Access Policies > Global Policies > MCP Instance Policy default. ![]()
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