[j-nsp] MC-LAG spanning-tree to be or not to be?
Sukhjit Hayre
sukhjit.hayre at googlemail.com
Mon Apr 27 19:10:26 EDT 2015
hi list
I am confused on juniper terminology with regards to whether we really need
to run any spanning-tree variants when I have created mc-lag with mc-ae's
in family bridge mode....
guide here suggests not:
http://www.juniper.net/techpubs/en_US/junos14.1/topics/concept/multichassis-link-aggregation-ex.html
"Multichassis link aggregation groups (MC-LAGs) enable a client device to
form a logical LAG interface between two MC-LAG peers (for example, EX9200
switches). *An MC-LAG provides redundancy and load balancing between the
two MC-LAG peers, multihoming support, and a loop-free Layer 2 network
without running STP*."
latter steps 9,10 and 11 here suggest if we're dual homing into a non
spanning-tree device then block any bpdu's which I understand:
http://www.juniper.net/techpubs/en_US/junos14.1/topics/usage-guidelines/interfaces-configuring-multi-chassis-link-aggregation.html
my understanding would be the following, block any stp bpdu's to any dual
homed devices whether they run spanning-tree or not (where not would be a
safety net just in case)
by default the mc-lag peer's set the DL & DR flags for man-addresses learnt
D -dynamic MAC
L -locally learned
&
D -dynamic MAC
R -Remote PE MAC
where one of the MC-LAG peers with the D & R flags will use the ICL-PL
(Inter-Chassis-Link Protection-Link) to ensure a L2 loop free path
would that be correct?
I also have the following two questions:
1.what decides the DL and DR flags? is it hash internal algorithm?
2.what are the re-convergence timers i.e hold/flush timers should the
mc-lag peer with the D&L flags have his link broken so that the mc-lag peer
with the D&R link changes it to D&L
thanks in advance for any replies
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