Avaya Troubleshooting Routers Průvodce řešením problémů stáhnout pdf (Strana 250)

Troubleshooting Routers

B-56

308656-14.00 Rev 00

Token Ring

The token ring physical medium has a data link filter offset of 14 bytes plus the

routing information field (RIF), if one is present. This places the data link filter

point at the DSAP (destination service access point) byte. Packet Capture receives

only LLC frames from the token ring. It does not receive the access control and

frame control bytes at the beginning of each packet. Packet Capture inserts the

hexadecimal value 1040 at the beginning of each packet for compatibility and

possible future use.

An example of a hexadecimal display of a token ring frame follows:

Pkt# 10 04/18/98 12:58:58.885 TOKEN 52 Rx

00000000: 10 40 c0 00 00 00 01 00 00 00 c5 00 00 30 42 42

00000010: 03 00 00 00 00 00 80 00 00 00 a3 00 00 0c 00 00

00000020: 00 00 80 00 00 00 a3 00 00 0c 80 06 00 00 14 00

00000030: 02 00 0f 00 00 00 00 00 00 00 00 00 00 00 00 00

FDDI

The Fiber Distributed Data Interface (FDDI) physical medium has a data link

filter offset of 13 bytes. This places the data link filter point at the DSAP byte.

Packet Capture does not receive all frames from the FDDI because the hardware

handles certain frames.

An example of a hexadecimal display of a FDDI frame follows:

Pkt# 10 04/18/98 12:59:04.017 FDDI 51 Rx

00000000: 50 80 01 43 00 00 00 00 00 c5 00 00 30 42 42 03

00000010: 00 00 00 00 00 80 00 00 00 a3 00 00 0c 00 00 00

00000020: 00 80 00 00 00 a3 00 00 0c 80 08 00 00 14 00 02

00000030: 00 0f 00 b7 00 00 00 00 00 00 00 00 00 00 00 00

HSSI

The high-speed serial interface (HSSI) physical medium works exactly the same

way as the previously described serial media (see “Protocols Supported by

Synchronous, T1, E1, and MCT1 Media” on page B-52), except for the HPTP

(Standard) protocol.

HPTP has a data link filter offset of 14 bytes from the beginning of the packet.

This places the data link filter point at the first byte after the TYPE/LENGTH

field. The HPTP packets do not have an address or control field.

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