The C6500 series switches uses DCEF instead of regular CEF Switching. The "DCEF" means distributed CEF Switching, meaning the CEF table is populated to all line cards once the Switch Starts up. This also means the hardware is Actually perform the Switching, so according to your output its the "Distribute Cache" output.   just to highlight, the "Route Cache" is a fast switching mechanism and its not CEF Switching.  those route cache is a switching mechanism that build tables on demand for switching unlike the CEF which is topology driven.   BR, Mohamed ... View more

Hi, 740W capable Switch differs from 370W one by the the total power can be delivered by the Switch. meaning at a time , the Switch can deliver up to 740W or 370W maximum. Now, Choosing the appropriate PoE Switch depends on the power consumption of the end devices. for example, some IP phones requires only 7watts to operate, others with enhances features requires more , Access points also varies. Your decision to choose the correct Switch depends on the devices that will be connected to the Switch and how much power they would need. check the Data sheet of the devices that will be connected to the switch , calculate the sum of the power required and choose your switch accordingly.   BR, Mohamed ... View more

Hello, Yes it should be Ok to establish an IPSec tunnel with one point having static IP address and the other is dynamic. Please not this Option allows Only one end to initiate the IPSec to the other end not from both ways. Unfortunately, DMVPN is an option but not in this case. DMVPN is designed for Hub and Spoke topology not a point to point connection. OSPF cant be established if the neighbours are not directly connected.      BR, Mohamed ... View more

Donal, I hope we can we help you out here!  Please note that having a Service Contract is good for you not only in terms of the current issue you are facing, but because predicting from any future hardware or Software problems. The Cisco Service Contract  ensures you have adequate hardware/Software replacement upgrades at the time is needed. Ferdenand might have something to elaborate on this specific platform, however, my general recommendation would be to protect your investment what so ever its with Cisco smart contracts that is also affordable to get.   Now, Coming to your issue, your Config of both routers seems OK, but its missing two important things: 1- You need to set the correct MTU and MSS Value on both routers. this should eleminate any cause of drops due to fragmentation and hence impact your VOIP between Sites. Please set the MTU Value on both router dialer interfaces to a value of 1439. Please Set the tcp MSS value on the Vlan 1 interface of both routers to 1399 on both routers. 2- Check your VOIP session after the modifications, if its still there, then I would recommend having Quality of Service in place to ensure your SIP gets the required priority when there is a congestion. this ensures your VOIP gets the right QoS treatment if there is Bandwidth usage at the DSL lines.   Let us know your feedback,   BR, Mohamed ... View more

My questions are: What is the implication in disabling all BFD in routers' interface and sub interface? Answer:  the implication would be eliminating sub-second millisecond convergence. BFD detect failure at the link layer very fast , once detected it informs the upper layer protocol about the failure causing it to converge immediately.    Will this improve recalculation of OSPF routes in cause of link flaps or it will totally ignore the link flaps? Answer: if your Provider experiencing intermittent flaps, then yes it will be advisable to turn BFD off. this however doesn't totally ignore the link flaps, once the upper protocol detect the failure based on the dead interval parameter on OSPF, it will recalculate OSPF routes again.  Keep in mind, if you have redundant or more links to your provider , then I wouldn't recommend disabling BFD , as it should improve Convergence and you shouldn't notice the failure.    Will the routers only recognize a "full down" status of the interface? Answer: disabling BFD allows the router recognize a full down status once the upper protocol dead interval occurs or full down status of interface. which ever occurs the earliest.   How can we Disable BFD in multiple Router Sub interfaces that participates in OSPF in a faster way? Or do we have to do this one by one? You can disable it one by one. or if you have configuration management software, it allows you to do it for all nodes at a time. but this depends if you have it or not.   Please consider not to disable BFD if you have multiple OSPF links towards your provider from any branch, as it shouldn't impact your VMs, it should rather improve Convergence at milliseconds which is absolutely not noticeable.   BR, Mohamed    ... View more

  Hello, This is the state where BGP peers exchange open messages which contains Basic parameters of the BGP peers before it goes into established state neighbour-ship. This means your TCP is active but the neighbour is not reaching open confirm state due to lack of basic parameters not being received during open message exchange & therefore not reaching the established state. A BGP notification message indicates an error in the neighbour ship adjacency establishment.  Can you make sure there is no congestion or a sudden link failure that could result in this issue.   BR, Mohamed ... View more

Hi Mitchen, If your branches are connected through an IPSec tunnels over ADSL or 3G, then you should modify their MTUs on the dialer to be 1500-61 = 1439. (The 1439 takes into account all overheads. its the correct value). Like wise, their LAN side should be modified to 1439-40 = 1399. (Also this takes into account the TCP overhead. its the correct value). If most of your links are connected as above, make it standard config template and apply it to all. Or you can tailor them per branc basis if they have different type of connection or if they are not using IPSec tunnels.   With the above, you shouldn't worry about the performance, as it should enhance it and make sure your connectivity is not impacted by fragmentations/drops on the WAN that could result in the symptoms your experiencing.   Regards, Mohamed ... View more

Mitchen,   As you done the testing already and experiment on this behaviour, allow me to elaborate on one possible cause you have not stated. Your Sites are connecting to your DC over an IPSec tunnels using ADSL or 3G connections. Please note of the following overheads that should be considered over the current links which can negatively result in drops. The IPSec itself adds additional (53 Bytes) header to the Original packets. And the PPP adds the (8 Byte) header as well to the Original packets. The Total overhead for the Original packets would be 61 bytes. Accordingly, I would recommend you to set the dialer interfaces to some thing like 1500-61 = 1439, apply this to your both dialer interfaces, although the 3G connection doesn't incurred the additional 8 byte PPP header. On the Other hand, the TCP maximum Segment Size (MSS) should be tailored to 1399. this is because of the TCP header of 40 bytes lower than the modified MTU , and this should be applied on all branch LAN interface. I believe this should solve your issue, and eliminate the performance degradation you are facing.     HTH Mohamed ... View more

You need to assign your Public IPs to the router WAN in order to establish the IPsec tunnel.   Regards, Mohamed ... View more

  You need to route traffic through a L3 interface, an interface not assigned a L3 IP doesnt process any Packets.   Your config of both routers of the default route should be corrected as follows: ip route 0.0.0.0 0.0.0.0 Serial1/0.16     Regards, Mohamed ... View more

  If there is a routing through Vlan 120, then you MUST see input and output counters for the Vlan interface. That means, no routing for Vlan 120 exist.      Regards, Mohamed ... View more