[c-nsp] Physical Port Redundancy

Nassess, George (Contractor) George.Nassess at gmacrfc.com
Wed Nov 16 15:57:48 EST 2005


Hello List, 
 
I am looking for a way to connect to redundant physical switches from
one physical device. Our IP enabled PBX communicates (to itself and with
IP trunks to other PBXs) via two Cisco 2950 switches with dual fiber Gig
uplinks to the core. The PBX architecture was supposed to be totally
redundant on each switch (hence using 2950's in the first place) but
during a recent incident we found this not to be the case. In the event
of a switch failure (or multiple fiber trunk failure, like we
experienced this time) our control network fails to the devices on the
other switch, but media resources on the remaining switch are
insufficent for call processing since this is a virtual call center. 
 
So, to make a long story short, I need to make sure that my media
devices (which of course have only one physical port, and can only use
one IP address) are always connected in the event of a switch failure. I
am pretty sure that my 2950s will have to go somewhere else, but I want
the most redundant and available replacement we can manage. We could
migrate to a Cisco 6500 with redundant switching fabric, but this again
brings to a single point of failure again in event of an IOS Bug or
unforseen switch behavior. I know its unlikely, but we woudl have some
serious explaining to do if this is the solution we propose. 
 
Around 2000 or so at an ASP I worked for we deployed some switches with
Y-Cable taps that connected a single device to two switches. The
switches then had a heartbeat/monitor cable between them to detect a
failure and failover to the standby switch. Unfortunately this was not
my project, and I can;t even remember the manufacturer. 
 
Does Cisco or anyone else still make a solution of this type? 
If not, what is the most redundancy/availability given that I can only
have single connectivity of connected devices?
 
George "Gus" Nasses
Network Analyst
GMAC/RFC 
952-857-8165
 


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