Welcome
First of all, may I welcome you to my site. My name is Chris and I'm from the UK and work as a Systems Engineer for Cisco. This blog was initially created to post up my subnetting technique but has now got more stuff to do with attaining Cisco certifications. Either way I really hope that the content is sufficent for your needs and I look forward to hearing your feedback. If you find that the content really helps you please feel free to donate using the PayPal link on the right.
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Frame Relay - BECN/FECN
Saturday, 19 February 2011
BECN - Backward Explicit Congestion Notification is a bit in the Frame Relay header that is set by the destination and sent BACK to the originator indicating congestion in the path and to slow down transmission of data.
FECN - Forward Explicit Congestion Notification is a bit in the Frame Relay header that is set by the sender and is FORWARDED to the destination to indicate congestion in the path and to slow down requests for data.
Note that these are set by a Frame Relay switch in general so are received by a router rather than sent by a router.
Posted byChris Bloomfield at 14:27 0 comments
Labels: becn, fecn, frame relay
Frame Relay - CIR, Bc, Tc
Tuesday, 18 August 2009
Very quick post. For whatever reason this formula does not stick in my head although it should be fairly straightforward to second guess.
CIR = Bc/Tc
Tc can never be smaller than 10ms!
Posted byChris Bloomfield at 15:33 0 comments
Labels: Bc, CIR, FR, frame relay, FRTS, Tc
OSPF and NBMA Networks
Tuesday, 27 November 2007
Confused about which NBMA network type requires a DR/BDR or neighbours to be statically defined? Worry no longer..............................
If the keyword nonbroadcast is within the network type (i.e. ip ospf network non-broadcast, or ip ospf network point-to-multipoint non-broadcast) then neighbours must be defined.
If the keyword point is within the network type (i.e. ip ospf network point-to-point, ip ospf network point-to-multipoint, ip ospf network point-to-multipoint non-broadcast) then a DR/BDR is NOT elected.
You may see a question which has an output showing the network type as point-to-multipoint. It will then ask you to choose a couple of correct answers. From above we know the answer to be that DR/BDR are not elected and neighbours do not need to be statically defined.
HTH!
Posted byChris Bloomfield at 15:47 2 comments
Labels: bdr, broadcast, dr, frame relay, multipoint, nbma, non-broadcast, ospf, point
