[c-nsp] ASR9K HSRP over L2VPN

[James Jun]

On Fri, Feb 11, 2022 at 02:45:28PM +0000, Mati wrote:
> Hi,
> 
> Is it possible to have HSRP on L3 BVI's with an mpls pseudowire to access
> switches? Would HSRP failover correctly?
>

Yes, you can.  Traditionally, you add a BVI (routed bridge domain) interface into your
l2vpn domain configuration, which makes it similar to having a 'Vlan' interface as if it
were an L3 switch.

BVI interface can then be added into protocol hsrp, just like any oither physical interface.

If L2VPN domain has outage in all of its subordinate neighbors, BVI will be signalled down,
causing HSRP failover.



However, BVI also represents a problem, as BVI interface has no ability for traffic shaping,
so you're going to have QoS related performance issues when downstream customer interface is
only 1GE and your BVI-bound router talking HSRP is connected to backbone at 10GE or higher.

For this exact reasons, a few customers (myself included) had asked Cisco tu support 
Pseudowire Head-End (PWHE) interface to be supported under HSRP, since PWHE can shape.
This feature should have been added in recent eXR versions (7.x), but I haven't looked
for it myself yet.

James