Packet/octet loss measurement for bridging domains
View Patent ↗An apparatus for and method of packet loss measurement for TLS connections in an MEN that overcomes the problems of the prior art. The mechanism is operative to ensure that only one copy of each received packet is counted when exiting the TLS connection (unless dropped along the path due to congestion, etc.), so that the number of egress packets counted can be accurately compared with the number of ingress packets counted. Only a single copy of each packet is marked, i.e. flagged, at ingress. Any bridging along the path that needs to duplicate the packet forwards only a single marked copy of the packet. All other copies are forwarded unmarked. At the egress from the TLS, only marked packets are counted by the egress counter. In a second embodiment, a duplication field is inserted into each packet to better track all the duplicate copies of a packet.
1. A method of measuring packet and/or octet loss for use in a bridging domain, said method comprising the steps of:
receiving a plurality of packets from a source;
marking, at a switch, a received packet if only one copy of the packet is received;
marking, at said switch, only a single copy of a received packet if more than one copy of a packet is received, wherein remaining copies of the received packet are unmarked;
counting, at said switch, only marked packets at ingress;
receiving unmarked packets at a bridge and forwarding any copies of unmarked packets as unmarked;
receiving marked packets at said bridge and forwarding only a single copy of a marked packet as marked wherein all remaining copies of the marked packet are forwarded as unmarked; and
counting only marked packets at egress.
2. The method according to claim 1 , wherein said bridging domain comprises a Transparent LAN Services (TLS) connection in a metro Ethernet network (MEN).
3. The method according to claim 1 , wherein said bridging domain comprises a plurality of Virtual LAN domains.
4. The method according to claim 1 , further comprising the step of forwarding one marked copy of a packet if the packet is to be dropped and is at a point that is not an exit point from said bridging domain.
5. The method according to claim 1 , further comprising the step of counting a packet with an egress counter and then dropping said packet if said packet is to be dropped and is at a point that is an exit point from said bridging domain.
6. The method according to claim 1 , wherein an ingress counter comprises a packet counter and an octet counter.
7. The method according to claim 1 , wherein an egress counter comprises a packet counter and an octet counter.
8. The method according to claim 1 , wherein an egress counter comprises a packet counter and octet counter pair per quality-of-service class.
9. The method according to claim 1 , wherein said step of marking comprises the step of setting a multicast bit in a source Media Access Control (MAC) address field of a packet.
10. The method according to claim 1 , wherein said step of marking comprises the step of setting a Cononical Format Indicator (CFI) bit in a 802.1Q Virtual LAN (VLAN) tag field of a packet.
11. The method according to claim 1 , wherein said step of marking comprises the step of setting a bit in a control word portion of a packet sent over a Virtual Private LAN Service (VPLS) connection.
12. The method according to claim 1 , further comprising the steps of:
synchronizing the collection of counter data from edge devices that are part of a bridging domain;
collecting counter data from said edge devices; and
calculating losses per bridging domain connection utilizing said counter data.
13. The method according to claim 12 , wherein said step of calculating losses comprises the step of calculating packet losses, said step of calculating packet losses comprising the steps of:
summing all ingress packet counter readings of a first phase to generate a first phase ingress packet sum;
summing all egress packet counter readings of said first phase to generate a first phase egress packet sum;
summing all ingress packet counter readings of a second phase to generate a second phase ingress packet sum;
summing all egress packet counter readings of said second phase to generate a second phase egress packet sum;
subtracting said first phase ingress packet sum from said second phase ingress packet sum to yield an ingress packet delta;
subtracting said first phase egress packet sum from said second phase egress packet sum to yield an egress packet delta; and
subtracting said egress packet delta from said ingress packet delta to yield said packet loss measurement.
14. The method according to claim 12 , wherein said step of calculating losses comprises the step of calculating octet losses, said step of calculating octet losses comprising the steps of:
summing all ingress octet counter readings of a first phase to generate a first phase ingress octet sum;
summing all egress octet counter readings of said first phase to generate a first phase egress octet sum;
summing all ingress octet counter readings of a second phase to generate a second phase ingress octet sum;
summing all egress octet counter readings of said second phase to generate a second phase egress octet sum;
subtracting said first phase ingress octet sum from said second phase ingress octet sum to yield an ingress octet delta;
subtracting said first phase egress octet sum from said second phase egress octet sum to yield an egress octet delta; and
subtracting said egress octet delta from said ingress octet delta to yield said octet loss measurement.
15. An apparatus for measuring packet loss for Transparent LAN Services (TLS) connections in a metro Ethernet network (MEN), comprising:
packet receiving means for receiving packets from a client;
marking means for marking a received packet if only one copy of the packet is received and for marking only a single copy of a received packet if more than one copy of a packet is received, wherein remaining copies of the received packet are unmarked;
an ingress counter operative to be incremented once for each marked packet received at ingress;
a bridge operative to forward all unmarked packets and copies of unmarked packets as unmarked, and to forward only a single copy of a marked packet as marked, wherein remaining copies of the marked packet are forwarded as unmarked; and
an egress counter operative to be incremented only for marked packets exiting a TLS connection.
16. The apparatus according to claim 15 , wherein said bridge further comprises means for forwarding one marked copy of a packet if the packet is to be dropped and is at a point that is not an exit point from said TLS connection.
17. The apparatus according to claim 15 , wherein said bridge further comprises means for counting a packet via said egress counter and then dropping said packet if said packet is to be dropped and is at a point that is an exit point from said TLS connection.
18. The apparatus according to claim 15 , wherein said ingress counter comprises a packet counter and an octet counter.
19. The apparatus according to claim 15 , wherein said egress counter comprises a packet counter and an octet counter.
20. The apparatus according to claim 15 , wherein said marking means comprises means for setting a multicast bit in a source Media Access Control (MAC) address field of a packet.
21. The apparatus according to claim 15 , wherein said marking means comprises means for setting a bit in a control word portion of a packet sent over a Virtual Private LAN Service (VPLS) connection.
22. The apparatus according to claim 15 , further comprising:
means for synchronizing the collection of counter data from provider edge devices that are part of a TLS connection;
means for collecting counter data from said provider edge devices; and
means for calculating losses per TLS connection utilizing said counter data.
23. The apparatus according to claim 22 , wherein said means for calculating losses comprises means for calculating packet loss, said means for calculating packet loss comprises:
means for summing all ingress packet counter readings of a first phase to generate a first phase ingress packet sum;
means for summing all egress packet counter readings of said first phase to generate a first phase egress packet sum;
means for summing all ingress packet counter readings of a second phase to generate a second phase ingress packet sum;
means for summing all egress packet counter readings of said second phase to generate a second phase egress packet sum;
means for subtracting said first phase ingress packet sum from said second phase ingress packet sum to yield an ingress packet delta;
means for subtracting said first phase egress packet sum from said second phase egress packet sum to yield an egress packet delta; and
means for subtracting said egress packet delta from said ingress packet delta to yield said packet loss measurement.
24. The apparatus according to claim 22 , wherein said means for calculating losses comprises means for calculating octet loss, said means for calculating octet loss comprises:
means for summing all ingress octet counter readings of a first phase to generate a first phase ingress octet sum;
means for summing all egress octet counter readings of said first phase to generate a first phase egress octet sum;
means for summing all ingress octet counter readings of a second phase to generate a second phase ingress octet sum;
means for summing all egress octet counter readings of said second phase to generate a second phase egress octet sum;
means for subtracting said first phase ingress octet sum from said second phase ingress octet sum to yield an ingress octet delta;
means for subtracting said first phase egress octet sum from said second phase egress octet sum to yield an egress octet delta; and
means for subtracting said egress octet delta from said ingress octet delta to yield said octet loss measurement.
25. A bridge for forwarding marked packets over Transparent LAN Services (TLS) connections in a metro Ethernet network (MEN), comprising:
packet receiving means for receiving a plurality of packets from a source;
first means for marking a received packet if only one copy of the packet is received and for marking only a single copy of a received packet if more than one copy of a packet is received, wherein remaining copies of the received packet are unmarked;
second means for counting only marked packets at ingress;
third means for receiving unmarked packets at a bridge and forwarding any copies of unmarked packets as unmarked;
fourth means for receiving marked packets at said bridge and forwarding only a single copy of a marked packet as marked wherein all remaining copies of the marked packet are forwarded as unmarked; and
fifth for counting only marked packets at egress.
26. An edge switch for use in an Ethernet based network, comprising:
a plurality of user ports for interfacing said edge switch to one or more users;
a plurality of network ports for interfacing said edge switch to one or more communication links;
a packet processor comprising ingress packet processing means and egress packet processing means;
a loss measurement module for measuring packet and/or octet loss for Transparent LAN Services (TLS) connections in a metro Ethernet network (MEN), said loss measurement module comprising:
marking means for marking a received packet if only one copy of the packet is received and for marking only a single copy of a received packet if more than one copy of a packet is received, wherein remaining copies of the received packet are unmarked;
an ingress counter operative to be incremented once for each marked packet received at ingress;
a bridge operative to forward all unmarked packets and copies of unmarked packets as unmarked, and to forward only a single copy of a marked packet as marked, wherein remaining copies of the marked packet are forwarded as unmarked; and
an egress counter operative to be incremented only for marked packets exiting a TLS connection.
27. The switch according to claim 26 , further comprising:
means for synchronizing the collection of counter data from edge switches that are part of a TLS connection; and
means for providing counter data to an external collection entity for calculation of packet and/or octet loss measurements utilizing said counter data.
28. The switch according to claim 26 , further comprising means for calculating packet loss, comprising:
means for summing all ingress packet counter readings of a first phase to generate a first phase ingress packet sum;
means for summing all egress packet counter readings of said first phase to generate a first phase egress packet sum;
means for summing all ingress packet counter readings of a second phase to generate a second phase ingress packet sum;
means for summing all egress packet counter readings of said second phase to generate a second phase egress packet sum;
means for subtracting said first phase ingress packet sum from said second phase ingress packet sum to yield an ingress packet delta;
means for subtracting said first phase egress packet sum from said second phase egress packet sum to yield an egress packet delta; and
means for subtracting said egress packet delta from said ingress packet delta to yield said packet loss measurement.
29. The switch according to claim 26 , further comprising means for calculating octet loss comprising:
means for summing all ingress octet counter readings of a first phase to generate a first phase ingress octet sum;
means for summing all egress octet counter readings of said first phase to generate a first phase egress octet sum;
means for summing all ingress octet counter readings of a second phase to generate a second phase ingress octet sum;
means for summing all egress octet counter readings of said second phase to generate a second phase egress octet sum;
means for subtracting said first phase ingress octet sum from said second phase ingress octet sum to yield an ingress octet delta;
means for subtracting said first phase egress octet sum from said second phase egress octet sum to yield an egress octet delta; and
means for subtracting said egress octet delta from said ingress octet delta to yield said octet loss measurement.
30. An edge switch for use in an Ethernet based network, comprising:
a plurality of user ports for interfacing said edge switch to one or more users;
a plurality of network ports operative to interface said edge switch to one or more communication links;
a packet processor comprising ingress packet processing means and egress packet processing means;
a loss measurement module operative to measure packet and/or octet loss for Transparent LAN Services (TLS) connections in a metro Ethernet network (MEN), said loss measurement module comprising:
marking means for marking a received packet if only one copy of the packet is received and for marking only a single copy of a received packet if more than one copy of a packet is received, wherein remaining copies of the received packet are unmarked;
an ingress counter operative to be incremented once for each marked packet received at ingress;
an egress counter operative to be incremented only for marked packets exiting a TLS connection.