There are a few towns in my state where ISP’s are setting up city wide hotspots for municipalities. These towns are small (under 6000 population). They are blanketing the towns with 30-40 routerboards/pcboards. I’m also interested in doing this for smaller towns.
I was interested in network topologies. The few ISP’s that I’ve talked to are running private routed addresses on the routerboards with OSPF between each node. Then they are laying a bridged network on top of this with EOIP and RSTP using public IP addresses. I beleive they are running hotspot on top of that. So basically it’s meshed and roamable.
I guess my question is; is there are reason for putting the routable network underneath the bridged network? Does it limit broadcast traffic to do it this way? Or maybe it limits other types of overhead? What are the pluses and minues?
In this configuration customers communicate in layer 3 with edge router.
Tell me if I’m wrong, PPPOE connection are not allowed in this scenario, only PPTP are routed to the back bone. Or there is a way to bridge only the PPPOE request to the edge between two network?
I belive there are a lot of us out here trying to do this very thing but trying to get educated how to do it has been the most difficult and time consuming process I have ever done.
At this time I am simply doing a routed ip network. Mikrotik unit on the roof has both 2.4ghz and 5.8ghz card. Route ip from 5.8ghz to the next base station. And each 2.4ghz card has it’s own ssid and authenticates clients using hotspot or ppoe (both setup thorugh radius).
I have seen diagrams but no real “how to” instructions. I would really like to see all of my 2.4ghz links on the same ssid and support full roaming.
I understand the RSTP part. If there are multiple paths on the bridged network to the same device then you get a nasty bridging loop that will shut the network completely down. Regular Spanning Tree Protocol took way too long to converge. I have not done much with Rapid Spanning Tree, but I’m pretty sure it hardly looses a packet. This makes it ideal for wireless meshed/bridged networks.
Its the bridged network layed on top of the routed network that I’m not quite understanding the pros and cons versus a plain bridged network.
“Poor man’s MPLS” explains it quite well imo. Just read the abundant info about MPLS and you’ll see where the switched/routed network concept comes in handy.
What problems does MPLS solve?
The initial goal of label based switching was to bring the speed of Layer 2 switching to Layer 3. Label based switching methods allow routers to make forwarding decisions based on the contents of a simple label, rather than by performing a complex route lookup based on destination IP address. This initial justification for technologies such as MPLS is no longer perceived as the main benefit, since Layer 3 switches (ASIC-based routers) are able to perform route lookups at sufficient speeds to support most interface types.
However, MPLS brings many other benefits to IP-based networks, they include:
Traffic Engineering - the ability to set the path traffic will take through the network, and the ability to set performance characteristics for a class of traffic
VPNs - using MPLS, service providers can create IP tunnels throughout their network, without the need for encryption or end-user applications
[li]Layer 2 Transport - New standards being defined by the IETF’s PWE3 and PPVPN working groups allow service providers to carry Layer 2 services including Ethernet, Frame Relay and ATM over an IP/MPLS core
Elimination of Multiple Layers - Typically most carrier networks employ an overlay model where SONET/SDH is deployed at Layer 1, ATM is used at Layer 2 and IP is used at Layer 3. Using MPLS, carriers can migrate many of the functions of the SONET/SDH and ATM control plane to Layer 3, thereby simplifying network management and network complexity. Eventually, carrier networks may be able to migrate away from SONET/SDH and ATM all-together, which means elimination of ATM’s inherent “cell-tax” in carrying IP traffic.