hoogen82 wrote: » I am not sure about why you want to run OSPF all the way till your access....That's probably not a good solution... Would love to hear your theory here though...
The many potential advantages of using a Layer 3 access design include the following: •Improved convergence •Simplified multicast configuration •Dynamic traffic load balancing •Single control plane •Single set of troubleshooting tools (for example, ping and traceroute) Of these, perhaps the most significant is the improvement in network convergence times possible when using a routed access design configured with EIGRP or OSPF as the routing protocol. Comparing the convergence times for an optimal Layer 2 access design (either with a spanning tree loop or without a loop) against that of the Layer 3 access design, you can obtain a four-fold improvement in convergence times, from 800-900msec for the Layer 2 design to less than 200 msec for the Layer 3 access. (See Figure 4.)
Although the sub-second recovery times for the Layer 2 access designs are well within the bounds of tolerance for most enterprise networks, the ability to reduce convergence times to a sub-200 msec range is a significant advantage of the Layer 3 routed access design. To achieve the convergence times in the Layer 2 designs shown above, you must use the correct hierarchical design and tune HSRP/GLBP timers in combination with an optimal L2 spanning tree design. This differs from the Layer 3 campus, where it is necessary to use only the correct hierarchical routing design to achieve sub-200 msec convergence. The routed access design provides for a simplified high availability configuration.
mikej412 wrote: » Sounds like you're doing a routed access solution. The Juniper solution doesn't look to different from the Cisco solution -- only the hardware and configs have changed (and no EIGRP routing option ). You'll be routing down to the wiring closets. The VLANs (and subnets) should be contained in the individual wiring closets -- preferably to individual switches (or your virtual chassis). You should be able to get some configuration ideas from this Juniper IMPLEMENTING L3 AT THE DATA CENTER ACCESS LAYER ON JUNIPER NETWORKS INFRASTRUCTURE PDF.
kronicklez wrote: » But in this URL it use MX. Is it same if i use EX8208 as a core Switch.
mikej412 wrote: » When I checked the EX4200 and EX8208 data sheets to see what they could do, the 4200s looked like they'd act like a stack of Cisco 3750s and the 8208 looked like they'd take the Cisco 6500 role. You'd be using BFD to achieve the sub-second OSPF routing, so as long as we don't try a hybrid Cisco/Juniper solution, I don't see why the 8208s couldn't do it. Since that PDF I did find on the Juniper site was for a data center solution, on the Cisco side we might use the Nexus Switches in the data center running NX-OS rather than the 6500s running IOS, so our configs would be different -- but the logic should stay the same. You might need to translate if there are differences between Juniper MX JUNOS and the EX's -- but you'd need someone more well versed in JUNOS (and Juniper hardware) than me to help you with that. The most work would be if you're currently just running an L2 core with the EX8208s. If you're already running an L3 core with the EX8208s (OSPF area 0), then it should be easy bring L3 down to each individual wiring closet (each one is a separate OSPF area). Just make sure you've got a solution for any applications that are used across different floors that may require users being in the same VLAN or subnet. Same with security -- don't forget about any changes to any current security policies/configurations that could be needed as you isolate VLANs & subnets to individual wiring closets.
