IS-IS L1 CSNP (`isis_l1_csnp`)

Layer: L3 (network)
Header: variable length
Notes: IS-IS (P2)

Reached from

Lower layer	Selector	Value
`llc`	First 8 bits of the payload when `dsap` = 254 (0xfe)	131 (0x83)
`ppp`	First 8 bits of the payload when `protocol` = 35 (0x0023)	131 (0x83)
`isis`	`pdu_type`	24 (re-decodes this layer)

Fields

Field	Type	Default	Auto	Description
`irpd`	`enum(8)`	`131` (isis)		Intradomain routing protocol discriminator (0x83 = IS-IS).
`header_length`	`uint(8)`	`33`		Length of the fixed header in octets (constant for each PDU type: LAN Hello / LSP 27, P2P Hello 20, CSNP 33, PSNP 17).
`version_ext`	`uint(8)`	`1`		Version / protocol ID extension (1).
`id_length`	`uint(8)`	`0`		System ID length (0 = 6 octets).
`reserved`	`uint(3)`	`0`
`pdu_type`	`enum(5)`	`24` (l1_csnp)		PDU type (15/16 LAN Hello L1/L2, 17 P2P Hello, 18/20 LSP L1/L2, 24/25 CSNP, 26/27 PSNP).
`version`	`uint(8)`	`1`		Version (1).
`reserved2`	`uint(8)`	`0`
`max_area_addresses`	`uint(8)`	`0`		Maximum number of area addresses (0 = 3).
`pdu_length`	`uint(16)`		Length of the header and payload in octets	Length of the whole PDU (Auto). On a Hello, a Manual value pads the PDU to that length with Padding TLVs (e.g. 1497 for an MTU of 1500).
`source_id`	`bytes(7)`	`00 00 00 00 00 01 00`		System ID of the sender and circuit ID (0).
`start_lsp_id`	`bytes(8)`	`00 00 00 00 00 00 00 00`		First LSP ID covered by the CSNP.
`end_lsp_id`	`bytes(8)`	`ff ff ff ff ff ff ff ff`		Last LSP ID covered by the CSNP.
`tlvs`	`tlv` — rest of the PDU	1 items		TLVs (8-bit code / 8-bit length) and their sub-TLVs.

`irpd`

Value	Name
131 (0x83)	`isis`

`pdu_type`

Value	Name
15	`l1_lan_hello`
16	`l2_lan_hello`
17	`p2p_hello`
18	`l1_lsp`
20	`l2_lsp`
24	`l1_csnp`
25	`l2_csnp`
26	`l1_psnp`
27	`l2_psnp`

`tlvs`

Type 8 bits, length 8 bits.
The length counts the value only.
Unknown types are kept as raw value octets.

Type	Name	Value fields
1 (0x01)	`area_addresses`	`addresses`
2 (0x02)	`is_reachability`	`virtual_flag`, `neighbors`
6 (0x06)	`is_neighbors`	`neighbors`
8 (0x08)	`padding`	`data`
9 (0x09)	`lsp_entries`	`entries`
10 (0x0a)	`authentication`	`auth_type`, `value`
22 (0x16)	`extended_is_reachability`	`neighbors`
128 (0x80)	`ip_internal_reachability`	`prefixes`
129 (0x81)	`protocols_supported`	`nlpids`
130 (0x82)	`ip_external_reachability`	`prefixes`
132 (0x84)	`ip_interface_addresses`	`addresses`
134 (0x86)	`te_router_id`	`router_id`
135 (0x87)	`extended_ip_reachability`	`prefixes`
137 (0x89)	`dynamic_hostname`	`hostname`
232 (0xe8)	`ipv6_interface_addresses`	`addresses`
236 (0xec)	`ipv6_reachability`	`prefixes`
240 (0xf0)	`p2p_adjacency_state`	`adjacency_state`, `extended_local_circuit_id`, `neighbor_system_id`, `neighbor_extended_local_circuit_id`
242 (0xf2)	`router_capability`	`router_id`, `flags`, `sub_tlvs`

`tlvs` › `area_addresses`

Field	Type	Default	Auto	Description
`addresses`	`list<struct>` — rest of the PDU

`tlvs` › `area_addresses` › `addresses`

Each item is a group of the fields below.

Field	Type	Default	Auto	Description
`address`	`nsap`

`tlvs` › `is_reachability`

Field	Type	Default	Auto	Description
`virtual_flag`	`uint(8)`
`neighbors`	`list<struct>` — rest of the PDU

`tlvs` › `is_reachability` › `neighbors`

Each item is a group of the fields below.

Field	Type	Default
`default_metric`	`uint(8)`	`10`
`delay_metric`	`uint(8)`	`128`
`expense_metric`	`uint(8)`	`128`
`error_metric`	`uint(8)`	`128`
`neighbor_id`	`bytes(7)`

`tlvs` › `is_neighbors`

Field	Type	Default	Auto	Description
`neighbors`	`list<mac>` — rest of the PDU

`tlvs` › `padding`

Field	Type	Default	Auto	Description
`data`	`bytes` — rest of the PDU

`tlvs` › `lsp_entries`

Field	Type	Default	Auto	Description
`entries`	`list<struct>` — rest of the PDU

`tlvs` › `lsp_entries` › `entries`

Each item is a group of the fields below.

Field	Type	Default	Auto	Description
`remaining_lifetime`	`uint(16)`
`lsp_id`	`bytes(8)`
`sequence_number`	`uint(32)`
`checksum`	`uint(16)`

`tlvs` › `authentication`

Field	Type	Default	Auto	Description
`auth_type`	`enum(8)`
`value`	`bytes` — rest of the PDU

`tlvs` › `authentication` › `auth_type`

Value	Name
1 (0x01)	`cleartext`
54 (0x36)	`hmac_md5`

`tlvs` › `extended_is_reachability`

Field	Type	Default	Auto	Description
`neighbors`	`list<struct>` — rest of the PDU

`tlvs` › `extended_is_reachability` › `neighbors`

Each item is a group of the fields below.

Field	Type	Auto
`neighbor_id`	`bytes(7)`
`metric`	`uint(24)`
`sub_tlvs_length`	`uint(8)`	Size of `sub_tlvs` in octets
`sub_tlvs`	`tlv` — `sub_tlvs_length` octets

`tlvs` › `extended_is_reachability` › `neighbors` › `sub_tlvs`

Type 8 bits, length 8 bits.
The length counts the value only.
Unknown types are kept as raw value octets.

Type	Name	Value fields
3 (0x03)	`admin_group`	`value`
4 (0x04)	`link_ids`	`local_id`, `remote_id`
6 (0x06)	`ipv4_interface_address`	`address`
8 (0x08)	`ipv4_neighbor_address`	`address`
9 (0x09)	`max_link_bandwidth`	`value`
10 (0x0a)	`max_reservable_bandwidth`	`value`
11 (0x0b)	`unreserved_bandwidth`	`values`
18 (0x12)	`te_default_metric`	`value`
31 (0x1f)	`adj_sid`	`flags`, `weight`, `sid`
32 (0x20)	`lan_adj_sid`	`flags`, `weight`, `neighbor_id`, `sid`

tlvs › extended_is_reachability › neighbors › sub_tlvs › admin_group

Field	Type	Default	Auto	Description
`value`	`uint(32)`

tlvs › extended_is_reachability › neighbors › sub_tlvs › link_ids

Field	Type	Default	Auto	Description
`local_id`	`uint(32)`
`remote_id`	`uint(32)`

tlvs › extended_is_reachability › neighbors › sub_tlvs › ipv4_interface_address

Field	Type	Default	Auto	Description
`address`	`ipv4`

tlvs › extended_is_reachability › neighbors › sub_tlvs › ipv4_neighbor_address

Field	Type	Default	Auto	Description
`address`	`ipv4`

tlvs › extended_is_reachability › neighbors › sub_tlvs › max_link_bandwidth

Field	Type	Default	Auto	Description
`value`	`uint(32)`

tlvs › extended_is_reachability › neighbors › sub_tlvs › max_reservable_bandwidth

Field	Type	Default	Auto	Description
`value`	`uint(32)`

tlvs › extended_is_reachability › neighbors › sub_tlvs › unreserved_bandwidth

Field	Type	Default	Auto	Description
`values`	`bytes(32)`

tlvs › extended_is_reachability › neighbors › sub_tlvs › te_default_metric

Field	Type	Default	Auto	Description
`value`	`uint(24)`

tlvs › extended_is_reachability › neighbors › sub_tlvs › adj_sid

Field	Type	Default	Auto	Description
`flags`	`flags(8)`
`weight`	`uint(8)`
`sid`	`bytes` — rest of the PDU

tlvs › extended_is_reachability › neighbors › sub_tlvs › adj_sid › flags

Bit	Mask	Name
7	128 (0x80)	`f`
6	64 (0x40)	`b`
5	32 (0x20)	`v`
4	16 (0x10)	`l`
3	8 (0x08)	`s`
2	4 (0x04)	`p`

tlvs › extended_is_reachability › neighbors › sub_tlvs › lan_adj_sid

Field	Type	Default	Auto	Description
`flags`	`flags(8)`
`weight`	`uint(8)`
`neighbor_id`	`bytes(6)`
`sid`	`bytes` — rest of the PDU

tlvs › extended_is_reachability › neighbors › sub_tlvs › lan_adj_sid › flags

Bit	Mask	Name
7	128 (0x80)	`f`
6	64 (0x40)	`b`
5	32 (0x20)	`v`
4	16 (0x10)	`l`
3	8 (0x08)	`s`
2	4 (0x04)	`p`

`tlvs` › `ip_internal_reachability`

Field	Type	Default	Auto	Description
`prefixes`	`list<struct>` — rest of the PDU

`tlvs` › `ip_internal_reachability` › `prefixes`

Each item is a group of the fields below.

Field	Type	Default
`default_metric`	`uint(8)`	`10`
`delay_metric`	`uint(8)`	`128`
`expense_metric`	`uint(8)`	`128`
`error_metric`	`uint(8)`	`128`
`ip_address`	`ipv4`
`subnet_mask`	`ipv4`

`tlvs` › `protocols_supported`

Field	Type	Default	Auto	Description
`nlpids`	`list<enum(8)>` — rest of the PDU

`tlvs` › `protocols_supported` › `nlpids`

Value	Name
129 (0x81)	`clnp`
142 (0x8e)	`ipv6`
204 (0xcc)	`ipv4`

`tlvs` › `ip_external_reachability`

Field	Type	Default	Auto	Description
`prefixes`	`list<struct>` — rest of the PDU

`tlvs` › `ip_external_reachability` › `prefixes`

Each item is a group of the fields below.

Field	Type	Default
`default_metric`	`uint(8)`	`10`
`delay_metric`	`uint(8)`	`128`
`expense_metric`	`uint(8)`	`128`
`error_metric`	`uint(8)`	`128`
`ip_address`	`ipv4`
`subnet_mask`	`ipv4`

`tlvs` › `ip_interface_addresses`

Field	Type	Default	Auto	Description
`addresses`	`list<ipv4>` — rest of the PDU

`tlvs` › `te_router_id`

Field	Type	Default	Auto	Description
`router_id`	`ipv4`

`tlvs` › `extended_ip_reachability`

Field	Type	Default	Auto	Description
`prefixes`	`list<struct>` — rest of the PDU

`tlvs` › `extended_ip_reachability` › `prefixes`

Each item is a group of the fields below.

Field	Type	Auto
`metric`	`uint(32)`
`up_down`	`uint(1)`
`sub_tlvs_present`	`uint(1)`	Number of items of `sub_tlv_block`
`prefix_length`	`uint(6)`
`prefix`	`bytes` — `(prefix_length + 7) / 8` octets
`sub_tlv_block`	`list<struct>` — `sub_tlvs_present` items

`tlvs` › `extended_ip_reachability` › `prefixes` › `sub_tlv_block`

Each item is a group of the fields below.

Field	Type	Default	Auto	Description
`sub_tlvs_length`	`uint(8)`		Size of `sub_tlvs` in octets
`sub_tlvs`	`tlv` — `sub_tlvs_length` octets

tlvs › extended_ip_reachability › prefixes › sub_tlv_block › sub_tlvs

Type 8 bits, length 8 bits.
The length counts the value only.
Unknown types are kept as raw value octets.

Type	Name	Value fields
1 (0x01)	`admin_tag`	`tags`
2 (0x02)	`admin_tag64`	`tags`
3 (0x03)	`prefix_sid`	`flags`, `algorithm`, `sid`
4 (0x04)	`prefix_attribute_flags`	`flags`

tlvs › extended_ip_reachability › prefixes › sub_tlv_block › sub_tlvs › admin_tag

Field	Type	Default	Auto	Description
`tags`	`list<uint(32)>` — rest of the PDU

tlvs › extended_ip_reachability › prefixes › sub_tlv_block › sub_tlvs › admin_tag64

Field	Type	Default	Auto	Description
`tags`	`list<uint(64)>` — rest of the PDU

tlvs › extended_ip_reachability › prefixes › sub_tlv_block › sub_tlvs › prefix_sid

Field	Type	Default	Auto	Description
`flags`	`flags(8)`
`algorithm`	`uint(8)`
`sid`	`bytes` — rest of the PDU

tlvs › extended_ip_reachability › prefixes › sub_tlv_block › sub_tlvs › prefix_sid › flags

Bit	Mask	Name
7	128 (0x80)	`r`
6	64 (0x40)	`n`
5	32 (0x20)	`p`
4	16 (0x10)	`e`
3	8 (0x08)	`v`
2	4 (0x04)	`l`

tlvs › extended_ip_reachability › prefixes › sub_tlv_block › sub_tlvs › prefix_attribute_flags

Field	Type	Default	Auto	Description
`flags`	`bytes` — rest of the PDU

`tlvs` › `dynamic_hostname`

Field	Type	Default	Auto	Description
`hostname`	`bytes` — rest of the PDU

`tlvs` › `ipv6_interface_addresses`

Field	Type	Default	Auto	Description
`addresses`	`list<ipv6>` — rest of the PDU

`tlvs` › `ipv6_reachability`

Field	Type	Default	Auto	Description
`prefixes`	`list<struct>` — rest of the PDU

`tlvs` › `ipv6_reachability` › `prefixes`

Each item is a group of the fields below.

Field	Type	Auto
`metric`	`uint(32)`
`up_down`	`uint(1)`
`external`	`uint(1)`
`sub_tlvs_present`	`uint(1)`	Number of items of `sub_tlv_block`
`reserved`	`uint(5)`
`prefix_length`	`uint(8)`
`prefix`	`bytes` — `(prefix_length + 7) / 8` octets
`sub_tlv_block`	`list<struct>` — `sub_tlvs_present` items

`tlvs` › `ipv6_reachability` › `prefixes` › `sub_tlv_block`

Each item is a group of the fields below.

Field	Type	Default	Auto	Description
`sub_tlvs_length`	`uint(8)`		Size of `sub_tlvs` in octets
`sub_tlvs`	`tlv` — `sub_tlvs_length` octets

tlvs › ipv6_reachability › prefixes › sub_tlv_block › sub_tlvs

Type 8 bits, length 8 bits.
The length counts the value only.
Unknown types are kept as raw value octets.

Type	Name	Value fields
1 (0x01)	`admin_tag`	`tags`
2 (0x02)	`admin_tag64`	`tags`
3 (0x03)	`prefix_sid`	`flags`, `algorithm`, `sid`
4 (0x04)	`prefix_attribute_flags`	`flags`

tlvs › ipv6_reachability › prefixes › sub_tlv_block › sub_tlvs › admin_tag

Field	Type	Default	Auto	Description
`tags`	`list<uint(32)>` — rest of the PDU

tlvs › ipv6_reachability › prefixes › sub_tlv_block › sub_tlvs › admin_tag64

Field	Type	Default	Auto	Description
`tags`	`list<uint(64)>` — rest of the PDU

tlvs › ipv6_reachability › prefixes › sub_tlv_block › sub_tlvs › prefix_sid

Field	Type	Default	Auto	Description
`flags`	`flags(8)`
`algorithm`	`uint(8)`
`sid`	`bytes` — rest of the PDU

tlvs › ipv6_reachability › prefixes › sub_tlv_block › sub_tlvs › prefix_sid › flags

Bit	Mask	Name
7	128 (0x80)	`r`
6	64 (0x40)	`n`
5	32 (0x20)	`p`
4	16 (0x10)	`e`
3	8 (0x08)	`v`
2	4 (0x04)	`l`

tlvs › ipv6_reachability › prefixes › sub_tlv_block › sub_tlvs › prefix_attribute_flags

Field	Type	Default	Auto	Description
`flags`	`bytes` — rest of the PDU

`tlvs` › `p2p_adjacency_state`

Field	Type	Default	Auto	Description
`adjacency_state`	`enum(8)`
`extended_local_circuit_id`	`uint(32)`
`neighbor_system_id`	`bytes(6)`
`neighbor_extended_local_circuit_id`	`uint(32)`

`tlvs` › `p2p_adjacency_state` › `adjacency_state`

Value	Name
0 (0x00)	`up`
1 (0x01)	`initializing`
2 (0x02)	`down`

`tlvs` › `router_capability`

Field	Type	Default	Auto	Description
`router_id`	`ipv4`
`flags`	`flags(8)`
`sub_tlvs`	`tlv` — rest of the PDU

`tlvs` › `router_capability` › `flags`

Bit	Mask	Name
0	1 (0x01)	`s`
1	2 (0x02)	`d`

`tlvs` › `router_capability` › `sub_tlvs`

Type 8 bits, length 8 bits.
The length counts the value only.
Unknown types are kept as raw value octets.

Type	Name	Value fields	Description
2 (0x02)	`sr_capabilities`	`flags`, `ranges`
19 (0x13)	`sr_algorithms`	`algorithms`

`tlvs` › `router_capability` › `sub_tlvs` › `sr_capabilities`

Field	Type	Default	Auto	Description
`flags`	`flags(8)`
`ranges`	`bytes` — rest of the PDU

tlvs › router_capability › sub_tlvs › sr_capabilities › flags

Bit	Mask	Name
7	128 (0x80)	`i`
6	64 (0x40)	`v`

`tlvs` › `router_capability` › `sub_tlvs` › `sr_algorithms`

Field	Type	Default	Auto	Description
`algorithms`	`list<uint(8)>` — rest of the PDU

Constraints

Level	Rule
warning	`header_length` = 33

Sample templates

isis-l1-csnp — templates/protocols/routing/isis-l1-csnp.wpg.yaml

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