I have a business request to separate some of our systems across two geographically disperse sites. Some of the systems that need splitting use HSRP & VRRP as part of an automatic failover mechanism.
My question is, if we separated our pair of 6500's and pair of 4500's core switches and used WDM technology from a Service Provider to connect the switches together so that we can preserve the VLAN's across the two sites, what is the maximum distance that can be supported. (e.g. I know that the ZX GBIC's have a limit of 70km, presumably down a dark fibre).
I am aware that part of this limit is down to the optical path budget but I am also concerned if there are timeout limits (e.g. as a result of propogation delay etc) that will come into play and break the protocols.
Does anyone know what this maximum limit is as my search on the WWW & CCO has not revealed an obvious answer.
Propogation delay is unlikely to be a concern for protocols such as HSRP and VRRP, which usually use hello intervals of at least a second during which light can travel around 200,000km through fiber.
What you may want to think about instead is whether or not running HSRP/VRRP over a WAN is the best way to accomplish your failover goals. I mention this because it's a pretty rare practice (usually routing protocols are used), though it may indeed make the most sense in your case.
[toc:faq]The ProblemOn traditional switches whenever we have a trunk
interface we use the VLAN tag to demultiplex the VLANs. The switch needs
to determine which MAC Address table to look in for a forwarding
decision. To do this we require the switch to do...
[toc:faq]Introduction:Netdr is a tool available on a RSP720, Sup720 or
Sup32 that allows one to capture packets on the RP or SP inband. The
netdr command can be used to capture both Tx and Rx packets in the
software switching path. This is not a substitut...
IntroductionOSPF, being a link-state protocol, allows for every router
in the network to know of every link and OSPF speaker in the entire
network. From this picture each router independently runs the Shortest
Path First (SPF) algorithm to determine the b...