Is-Is Pdu Format - HP MSR2000 series Configuration Manual

NOTE:
On IS-IS broadcast networks, all routers are adjacent with each other. However, the DIS is responsible for
the synchronization of their LSDBs.

IS-IS PDU format

PDU header format
IS-IS packets are encapsulated into link layer frames. The Protocol Data Unit (PDU) consists of two parts,
the headers and the variable length fields. The headers comprise the PDU common header and the PDU
specific header. All PDUs have the same PDU common header. The specific headers vary by PDU type.
Figure 53 PDU format
Common header format
Figure 54 PDU common header format
Intradomain routing protocol discriminator
Version/Protocol ID extension
R R
Major fields of the PDU common header are as follows:
• Intradomain routing protocol discriminator—Set to 0x83.
Length indicator—Length of the PDU header in bytes, including both common and specific headers.
•
Version/Protocol ID extension—Set to 1(0x01).
•
ID length—Length of the NSAP address and NET ID.
•
R (Reserved)—Set to 0.
•
• PDU type—See
Version—Set to 1(0x01).
•
Maximum area address—Maximum number of area addresses supported.
•
Table 4 PDU type
Type
15
16
17
Length indicator
ID length
R PDU type
Version
Reserved
Maximum area address
Table 4.
PDU Type
Level-1 LAN IS-IS hello PDU
Level-2 LAN IS-IS hello PDU
Point-to-Point IS-IS hello PDU
No. of Octets
1
1
1
1
1
1
1
1
132
Acronym
L1 LAN IIH
L2 LAN IIH
P2P IIH