Mlag reload-delay timers tunning

General rules:

• No.1 rule - side-way up first
• Peer-link up first. Recommended (if not must) to have an iBGP peering between MLAG peers. So always have a side-way. 
• Why need a side-way? Because there is for sure a gap between non-mlag (uplinks) and mlag (downlinks) ready to forward, in this case, there is a fire exit to avoid traffic drop. 
• No.2 rule - non-mlag relay < mlag delay
• "In a topology where non-mlag links are only L3 ports that want to reach hosts behind MLAG interface, then it is preferable to keep non-mlag reload-delay smaller compared to mlag reload-delay to have L3 protocols converge before the L2 links ( MLAG interfaces ) are brought up."
• Why? don't overwhelm the peerLink. Most of the time, servers's ingress << egress. 
• No.3 rule - if "lacp standby" enabled, mlag delay < non-mlag
• Bring up interfaces to allow hw programing. So non-mlag (uplinks) up first, N-S traffic in but downlinks not ready. 

Primary和Secondary最大的区别是STP，Sec上的STP is held.

MLAG reboot/SSO, all ports except peerlink are in err-disabled state。这个期间，系统需要bring up hardware，Mlag peer可以sync states.  From 4.15.2F (released Sep 2015), the default-relay is automatically adjusted based on platform, 1800s in Sand(Arad/J/J+) modular, 1200s in Strata(Trident/TH) modular and 300s fixed.

如果non-mlag links都是L3 ports，最好是non-mlag delay < mlag delay，所以uplink先起来，等Mlag converged了，S-N已经有routes ready了。但是这个时候，会Attract N-S traffic，但是我们peerlink已经up了，就走peerlink, no loss.

LACP-standby就是可以更新LAG成员表，MAC地址表，ports appear as linkActive. 如果这个是ON，那么Non-Mlag delay >= Mlag delay. 不如N-S traffic进来，以为Mlag ports up，就drop了

如果使用VRRP，就需要configure VRRP reload daly time higher than MLAG reload delay.

Z1554