Cisco 11503 Administration Guide - Page 256

Viewing RMON Information Chapter 6 Configuring Remote Monitoring (RMON) 6-30 Table 6-4 Field Descriptions for the show rmon Command (continued) Field Description Collisions The best estimate of the total number of collisions on this Ethernet segment. The returned value depends on the location of the RMON probe. Section 8.2.1.3, 10BASE-5, and section 10.3.1.3, 10BASE-2, of IEEE standard 802.3 states that a station must detect a collision, in the receive mode, if three or more stations are transmitting simultaneously. A repeater port must detect a collision when two or more stations are transmitting simultaneously. Thus, a probe placed on a repeater port might record more collisions than would a probe connected to a station on the same segment. Probe location plays a much smaller role when considering 10BASE-T. IEEE standard 802.3 14.2.1.4, 10BASE-T, defines a collision as the simultaneous presence of signals on the DO and RD circuits (transmitting and receiving at the same time). A 10BASE-T station can detect collisions only when it is transmitting. Probes placed on a station and a repeater should report the same number of collisions. Ideally, an RMON probe inside a repeater should report collisions between the repeater and one or more other hosts (transmit collisions as defined by IEEE 802.3k), plus receiver collisions observed on any coaxial segments to which the repeater is connected. Packets (0-64) Packets (65-127) Packets (128-255) Packets (256-511) The total number of received packets (including bad packets) that were between the following octets in length inclusive (excluding framing bits but including FCS octets): • 0 to 64 Packets (512-1023) Packets (1024-1518) • 65 to 127 • 128 to 255 • 256 to 511 • 512 to 1023 • 1024 to 1518 Cisco Content Services Switch Administration Guide OL-5647-02