If you want switch level redundency, then You can go for two switches at central side. Each link from a site will go to seperate switch. Both these switches can be interconnected. Hence you will get full redundency.
I advise you against bridging for the design. Etherchannell has not be designed for WAN use and you would find yourself doing something very uncommon,plus this solution would not provide QoS and all the features you want on WAN links.
A regular design would use a router with two G.703 circuits at the branches, and one bigger one at the center, eliminating the "converters" (bridges). For example, 1841 with VWIC-2MFT, and a 7200 with 2 x PA-MC-8TE1 at the center. This is the only solution that will effectively bond the 2 x E1 lines in a single virtual pipe of 4 Mbps.
If this is too expensive, then all an ethernet router can be used, retaining the bridges, By shaping the traffic at 4 Mbps you can still have QoS. For example, 871 with "advanced ip services" at the branches (better would be 1811), and 1801 plus a vlan-capable switch at the data center.
In any case,Ip routing would take care of redundancy and laod sharing over the lines.
This is actually a pretty cool feature, i didn't even know it existed until I was looking for a solution to advertise a subnet (prefix in BGP talk), only if a certain condition existed. This is exactly what conditional advertisements does
j ai une question j ai achete un routeur cisco 887VA-k9 , je le configuré avec la configuration ci- dessous
si je le lier avec mon pc portable sur l un de ses ports directement ça marche toute est bien ( la connexion internet + m...
Attached policy provides CLI access to the Cisco 4G router over text messaging. Two files are in the attached .tar file:
2. PDF with instructions on how to load and use the .tcl file.