[c-nsp] FHRP selection within Nexus

Andrew Miehs andrew at 2sheds.de
Wed Nov 13 14:12:20 EST 2013


On Thu, Nov 14, 2013 at 6:03 AM, Gert Doering <gert at greenie.muc.de> wrote:

>
> "forwarding to the active HSRP device" and "only the active HSRP interface
> answers ARP request" doesn't particularily sound "active-active" to me :-)
>
> *This* is what happens on any 6500 that does HSRP on a SVI...
>
> GLBP is active-active in that both L3 routers will accept packets to the
> world, instead of L2-forwarding them to the other one inside the SVI.
>
>
>
Maybe I am missing something, but I understand the below text to indicate
that both the primary and secondary HSRP peers will accept the packet to
their "local" svi - rather than pushing it across the link...  (Continued
on page 25)

<quote>

The most significant difference between the HSRP implementation of a
non-vPC configuration compared with a vPC
configuration is that the HSRP MAC addresses of a vPC configuration are
programmed with the G (gateway) flag on
both systems, compared with a non-vPC configuration where only the active
HSRP interface can program the MAC
address with the G flag.

Given this fact, routable traffic can be forwarded by both the vPC primary
device (where HSRP is primary) and the
vPC secondary device (where HSRP is secondary), with no need to send this
traffic to the HSRP primary device.
Without this flag, traffic sent to the MAC address would not be routed.

</quote>


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