D2s 1.LAG.pdf

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Section 2 · Module 1 · Page 25

• LAG sub-group

• IPD supports grouping of links for a given LAG into a "subgroup" and amongst the subgroups within a LAG, one subgroup is chosen to be "Active" and within this chosen subgroup links become Active links (the other subgroup's links are either Standby or failed)

LAG b ill t b t d i th fi t l t NANT D• LAG sub-group will not be supported in the first release at NANT-D



• Alarms

• LAG down alarm will be supported

• LAG will be down when all links are down or number of active links reaches/goes below a configured threshold

• A new alarm-type: LAG, and alarm-index should identify the LAGyp , y



• Each LAG instance has its own id and is considered as a new, logical port in all later configuration, the LAG can be referred to as:

lag-<lag-id>

LACP (Link Aggregation Protocol)

• Both active and passive LACP is supportedp pp

• LACP periodic transmission machine supports both the fast (1s) and the slow (30s) periodic time





















Resiliency is the ability to recover from a failure.

• The term may be applied to hardware, software or data

Resiliency always matters when many users are impacted upon failure, so it was always crucial in aggregation and edge networks:

• non-stop forwarding / graceful restart / MPLS…p g g

Historically it was less important in access networks, but that changes now: especially when triple plays takes off, resiliency is crucial in access networks too!



Equipment protection switching protects the system against hardware failures:

e.g. if NT-A fails, there’s a switchover to NT-B. For the NT I/O there’s no redundant equipment (there’s less need for a redundant board, since it contains basically passive components with little chance of failures).

APS = Automatic protection switching

The NE supports line protection and EPS. If a second – redundant – NT unit is installed, EPS provides protection against internal failures of the active NT.

In HighCap NT boards the switching is only impacting OAM (SNMP, CLI, database and software management) while traffic shared between both NT boards in active/active modemanagement), while traffic shared between both NT boards in active/active mode.

Remark: even though the link protection is not exactly the same as the SDH/SONET APS, it is sometimes also called APS.



A/A: Active/Active

A/S: Active/Standby

• From the perspective of resilience, load-sharing can be seen as a generalization of redundancy, since in case of failure of one board the remaining board takes all load.y, g

• Since the regular links on HiCap NT boards are always working in load-sharing mode for user traffic, Link Protection Switching (LPS) is fully decoupled from Equipment Protection Switching (EPS).

• External management traffic can be transmitted via the regular links of both NT boards, though it is processed on the active NT board, as part of such OAM processes as CLI, SNMP, database and software management., g

• The craft connection only works on the active NT board.

• In HighCap NT boards the combined use of Redundancy and Load-sharing (when protection is unlocked) is subject to an ISAM Feature license in the AMS, for which the NE provides the counter.



h l d h d l h h d d h k The slide shows a dual homing scenario where a device is connected to the network via two independent access points (points of attachment). One access point is the primary connection; the other is a standby connection that is activated in case the primary connection fails.

802.1w Rapid Spanning Tree Protocol runs over ISAM uplinks

RSTP runs over ISAM network links, not over subtending links or user links.

RSTP protects against:

• link failure

• aggregation node failure

RSTP doesn’t offer load balancing!

• RSTP can be combined with link aggregation (LACP offers load balancing between the links in a LAG).

• In that case, combined link and NT protection recommended (forced switch-over to “full” backup LAG instead of bandwidth drop upon failure of a defined number of links in the LAG – you can configure the threshold for switchover how many links in the



in the LAG you can configure the threshold for switchover how many links in the LAG must always be operational?)

(Persistency of subscriber management characteristics in 7x50 nodes requires regular exchanging state info between both switches.)

This is also a dual homing situation.

In case of RSTP only one Ethernet switch is active for all VLANs. The other Ethernet switch is standby for all VLANs.

In case of MSTP both Ethernet switches can be active: one for VLAN A and the other for VLAN B.



This is also a dual homing situation.

In case of RSTP only one Ethernet switch is active for all VLANs. The other Ethernet switch is standby for all VLANs.

In case of MPLS again both Ethernet switches can be active: one for Service A and the other for Service B, with very fast recovery time (1000x faster than STP).



CLI: the command to enable/disable equipment protection switch:• configure equipment protection-group <1> admin-status <lock/unlock> eps-

quenchfactor <0..1440000>

• By locking protection-group 1, you disable NT protection.

• The EPS-quench factor is a timer value (in AMS expressed in seconds; in CLI in h d d f d ) Thi b d id li f NT A NT B d hundreds of seconds). This can be used to avoid toggling from NT-A to NT-B and back all the time. If there is a next failure before time out (t < quench timer), there will be no switchover.



CLI: the command to change the switchover mode:

• configure equipment protection-element nt-b redcy-ctrl-status forced_active

• Don’t forget to put it back to normal afterwards to allow automatic switchover



















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D2s 1.LAG.pdf