3Com Switch 4800G 24-Port - Page 337

IS-IS Overview 337
Figure 110 shows the PSNP packet format.
Figure 110 L1/L2 PSNP format
CLV
The variable fields of PDU are composed of multiple Code-Length-Value (CLV)
triplets. Figure 111 shows the CLV format.
Figure 111 CLV format
Table 45 shows different PDUs contain different CLVs.
Table 45 CLV name and the corresponding PDU type
CLV Code Name PDU Type
1 Area Addresses IIH, LSP
2 IS Neighbors (LSP) LSP
4 Partition Designated Level2 IS L2 LSP
6 IS Neighbors (MAC Address) LAN IIH
7 IS Neighbors (SNPA Address) LAN IIH
8 Padding IIH
9 LSP Entries SNP
10 Authentication Information IIH, LSP, SNP
128 IP Internal Reachability Information LSP
129 Protocols Supported IIH, LSP
130 IP External Reachability Information L2 LSP
131 Inter-Domain Routing Protocol Information L2 LSP
132 IP Interface Address IIH, LSP
Intradomain routing protocol discriminator
Reserved
Version
R
ID length
Version/Protocol ID extension
Length indicator
Maximum area address
R R PDU type
No. of Octets
1
1
1
1
1
1
1
1
PDU length
Source ID
Variable length fields
2
ID length+1
No. of Octets
1
1
Length
Code
Length
Value