Cisco Support Community
cancel
Showing results for 
Search instead for 
Did you mean: 
Announcements
Webcast-Catalyst9k
New Member

Define: non-blocking ports

Does this refer to the STP blocking state or something else? I notice switches listed with Layer 2-4 non-blocking and in pktspersec/pps non-blocking speed.

1 ACCEPTED SOLUTION

Accepted Solutions

Re: Define: non-blocking ports

non-blocking refers to the the port's access to the backplane or the line card's ASIC interface to the ports. When a line card is sadi to be non-blocking it usually means that for all it's ports it has full b/w to the backplane. In some line card, due to h/w designed are said to be blocking line card or over-subscribed. This usually means that for x number of ports it shares an interface to the ASIC hence does not have full b/w access to the backplane. some example of a blocking or (oversubscribed) line card are WS-X4418-GB, WS-X4448-GB and there are some 6500 line cards that escapes my mind right now.

non-blocking ports in terms of pps have nothing to do with STP.

Please rate helpful posts.

2 REPLIES

Re: Define: non-blocking ports

non-blocking refers to the the port's access to the backplane or the line card's ASIC interface to the ports. When a line card is sadi to be non-blocking it usually means that for all it's ports it has full b/w to the backplane. In some line card, due to h/w designed are said to be blocking line card or over-subscribed. This usually means that for x number of ports it shares an interface to the ASIC hence does not have full b/w access to the backplane. some example of a blocking or (oversubscribed) line card are WS-X4418-GB, WS-X4448-GB and there are some 6500 line cards that escapes my mind right now.

non-blocking ports in terms of pps have nothing to do with STP.

Please rate helpful posts.

Green

Re: Define: non-blocking ports

These are two completely different contexts ("Damn the technological revolution, we've run out of non-overlapping terms, fire up the Marketing People!!")

In the spanning tree context these would be the ports to the open path towards the root bridge.

In the throughput context, it indicates that the logic and electronics are fast enough, and have enough bandwidth available that no queuing of the frame occurs beyond the normal store & forward buffering (i.e., frames coming from a 100BASE port, going to a 100BASE port get clocked in, then out ... no waiting)

Blocking/Non-Blocking usually is in reference to the backplane / switching fabric of the switch. Same meaning: Thee is enough bandwidth available such that even if the first half of the ports are talking to the second half of the switch ports, the fabric can switch them all concurrently without additional buffering/latency.

Good Luck

Scott

6773
Views
26
Helpful
2
Replies
CreatePlease to create content