From: Brant I. Stevens (branto@branto.com)
Date: Thu Oct 27 2005 - 12:23:44 GMT-3
In order for HSRP to work properly, routers in a given group would need
Layer 2 adjacency. In the case of an ASW-DSW link failing, the "other" link
connecting the access switch to the distribution would carry the traffic,
and HSRP would be happy.
Do you mean if the DSW-DSW link fails? In that scenario, HSRP would peer
across the access layer (if the links were either (a)trunks that carried the
management VLAN, or (b) in the same VLAN)
But both uplinks would have to be trunks in order for the access switch to
continue to have access to the separate management VLAN HSRP group and pass
user traffic at the same time.
-----Original Message-----
From: nobody@groupstudy.com [mailto:nobody@groupstudy.com] On Behalf Of
Carlos G Mendioroz
Sent: Thursday, October 27, 2005 11:07 AM
To: ccielab@groupstudy.com
Subject: OT: HSRP in multilayer switching architecture
Hi,
I'm back again with this topic, "HSRP backtraffic howto" so to say.
While reading (again) the campus network design paper, I see that you can
use HSRP to have default GW for ASWs (Access switches) to reach the world in
case of DSW (Distribution switch) failure.
So basically ASWs do have dedicated IP subnets (usually two for load
balancing) and then is a DSW goes down, the remaining DSW (they go in
pairs) takes the whole traffic.
Great.
But what happens if a ASW - DSW link goes down ?
HSRP still works because DSWs are linked by the failing link, so both
pretend to be active (isolated I guess) and the one talking to the ASW does
the job. But what about the traffic going to the ASW ? Both DSW are layer 3
active on that IP subnet, and unless there is hardware indication of the
link down at the switch, traffic will be half dropped.
Am I missing something ?
Regards,
-- Carlos G Mendioroz <tron@huapi.ba.ar> LW7 EQI Argentina
This archive was generated by hypermail 2.1.4 : Sun Nov 06 2005 - 22:00:54 GMT-3