This section provides information about auto-learn-mac-protect and restrict-protected-src discard-frame features.
VPLS solutions usually involve learning MAC addresses in order for traffic to be forwarded to the correct SAP/SDP. If a MAC address is learned on the wrong SAP/SDP, traffic would be redirected away from its intended destination. This could occur through a misconfiguration, a problem in the network, or by a malicious source creating a DoS attack, and is applicable to any type of VPLS network; for example, mobile backhaul or residential service delivery networks. The auto-learn-mac-protect feature can be used to safeguard against the possibility of MAC addresses being learned on the wrong SAP/SDP.
This feature provides the ability to automatically protect source MAC addresses that have been learned on a SAP or a spoke/mesh SDP and prevent frames with the same protected source MAC address from entering into a different SAP/spoke or mesh SDP.
This is a complementary solution to features such as mac-move and mac-pinning, but has the advantage that MAC moves are not seen and it has a low operational complexity. If a MAC is initially learned on the wrong SAP/SDP, the operator can clear the MAC from the MAC FDB in order for it to be relearned on the correct SAP/SDP.
Two separate commands are used, which provide the configuration flexibility of separating the identification (learning) function from the application of the restriction (discard).
The auto-learn-mac-protect and restrict-protected-src commands allow the following functions:
the ability to enable the automatic protection of a learned MAC using the auto-learn-mac-protect command under a SAP/spoke or mesh SDP/SHG context
the ability to discard frames associated with automatically protected MACs instead of shutting down the entire SAP/SDP as with the restrict-protected-src feature. This is enabled using a restrict-protected-src discard-frame command in the SAP/spoke or mesh SDP/SHG context. An optimized alarm mechanism is used to generate alarms related to these discards. The frequency of alarm generation is fixed to be, at most, one alarm per MAC address per forwarding complex per 10 minutes in a VPLS service.
If the auto-learn-mac-protect or restrict-protected-src discard-frame feature is configured under an SHG, the operation applies only to SAPs in the SHG, not to spoke-SDPs in the SHG. If required, these parameters can also be enabled explicitly under specific SAPs/spoke-SDPs within the SHG.
Applying or removing auto-learn-mac-protect or restrict-protected-src discard-frame to/from a SAP, spoke or mesh SDP, or SHG, clears the MACs on the related objects (for the SHG, this results in clearing the MACs only on the SAPs within the SHG).
The use of restrict-protected-src discard-frame and both the restrict-protected-src [alarm-only] command and with the configuration of manually protected MAC addresses, using the mac-protect command, within a specified VPLS are mutually exclusive.
The following rules govern the changes to the state of protected MACs:
Automatically learned protected MACs are subject to normal removal, aging (unless disabled), and flushing, at which time the associated entries are removed from the FDB.
Automatically learned protected MACs can only move from their learned SAP/spoke or mesh SDP if they enter a SAP/spoke or mesh SDP without restrict-protected-src enabled.
If a MAC address does legitimately move between SAPs/spoke or mesh SDPs after it has been automatically protected on a specified SAP/spoke or mesh SDP (thereby causing discards when received on the new SAP/spoke or mesh SDP), the operator must manually clear the MAC from the FDB for it to be learned in the new/correct location.
MAC addresses that are manually created (using static-mac, static-host with a MAC address specified, or oam mac-populate) are not protected even if they are configured on a SAP/spoke or mesh SDP that has auto-learn-mac-protect enabled on it. Also, the MAC address associated with an R-VPLS IP interface is protected within its VPLS service such that frames received with this MAC address as the source address are discarded (this is not based on the auto-learn MAC protect function). However, VRRP MAC addresses associated with an R-VPLS IP interface are not protected either in this way or using the auto-learn MAC protect function.
MAC addresses that are dynamically created (learned, using static-host with no MAC address specified, or lease-populate) are protected when the MAC address is learned on a SAP/spoke or mesh SDP that has auto-learn-mac-protect enabled on it.
The actions of the following features are performed in the order listed.
Restrict-protected-src
MAC-pinning
MAC-move