ISIS

ISIS is a routing protocol which is described in ISO10589, RFC 1195, RFC 5308. ISIS is an IGP. Compared with RIP, ISIS can provide scalable network support and faster convergence times like OSPF. ISIS is widely used in large networks such as ISP and carrier backbone networks.

ISIS router

To start the ISIS process you have to specify the ISIS router. As of this writing, isisd does not support multiple ISIS processes.

router isis WORD [vrf NAME]: Enable or disable the ISIS process by specifying the ISIS domain with ‘WORD’. isisd does not yet support multiple ISIS processes but you must specify the name of ISIS process. The ISIS process name ‘WORD’ is then used for interface (see command ip router isis WORD).

net XX.XXXX. ... .XXX.XX: Set/Unset network entity title (NET) provided in ISO format.

hostname dynamic: Enable support for dynamic hostname.

area-password [clear | md5] <password>

domain-password [clear | md5] <password>: Configure the authentication password for an area, respectively a domain, as clear text or md5 one.

attached-bit [receive ignore | send]

Set attached bit for inter-area traffic:

receive If LSP received with attached bit set, create default route to neighbor
send If L1|L2 router, set attached bit in LSP sent to L1 router

log-adjacency-changes: Log changes in adjacency state.

log-pdu-drops: Log any dropped PDUs.

metric-style [narrow | transition | wide]

Set old-style (ISO 10589) or new-style packet formats:

narrow Use old style of TLVs with narrow metric
transition Send and accept both styles of TLVs during transition
wide Use new style of TLVs to carry wider metric. SoodarOS uses this as a default value

advertise-high-metrics

Advertise high metric value on all interfaces to gracefully shift traffic off the router. Reference: RFC 3277

For narrow metrics, the high metric value is 63; for wide metrics, 16777215; for transition metrics, 62.

set-overload-bit: Set overload bit to avoid any transit traffic.

set-overload-bit on-startup (0-86400): Set overload bit on startup for the specified duration, in seconds. Reference: RFC 3277

purge-originator: Enable or disable RFC 6232 purge originator identification.

lsp-mtu (128-4352): Configure the maximum size of generated LSPs, in bytes.

advertise-passive-only: Advertise prefixes of passive interfaces only.

ISIS Timer

lsp-gen-interval [level-1 | level-2] (1-120): Set minimum interval in seconds between regenerating same LSP, globally, for an area (level-1) or a domain (level-2).

lsp-refresh-interval [level-1 | level-2] (1-65235): Set LSP refresh interval in seconds, globally, for an area (level-1) or a domain (level-2).

max-lsp-lifetime [level-1 | level-2] (360-65535): Set LSP maximum LSP lifetime in seconds, globally, for an area (level-1) or a domain (level-2).

spf-interval [level-1 | level-2] (1-120): Set minimum interval between consecutive SPF calculations in seconds.

ISIS region

is-type [level-1 | level-1-2 | level-2-only]

Define the ISIS router behavior:

level-1 Act as a station router only
level-1-2 Act as both a station router and an area router
level-2-only Act as an area router only

ISIS interface

<ip|ipv6> router isis WORD: Activate ISIS adjacency on this interface. Note that the name of ISIS instance must be the same as the one used to configure the ISIS process (see command router isis WORD). To enable IPv4, issue ip router isis WORD; to enable IPv6, issue ipv6 router isis WORD.

isis circuit-type [level-1 | level-1-2 | level-2]

Configure circuit type for interface:

level-1 Level-1 only adjacencies are formed
level-1-2 Level-1-2 adjacencies are formed
level-2-only Level-2 only adjacencies are formed

isis csnp-interval (1-600) [level-1 | level-2]: Set CSNP interval in seconds globally, for an area (level-1) or a domain (level-2).

isis hello padding: Add padding to IS-IS hello packets.

isis hello padding during-adjacency-formation: Add padding to IS-IS hello packets during adjacency formation only.

isis hello-interval (1-600) [level-1 | level-2]: Set Hello interval in seconds globally, for an area (level-1) or a domain (level-2).

isis hello-multiplier (2-100) [level-1 | level-2]: Set multiplier for Hello holding time globally, for an area (level-1) or a domain (level-2).

isis metric [(0-255) | (0-16777215)] [level-1 | level-2]: Set default metric value globally, for an area (level-1) or a domain (level-2). Max value depend if metric support narrow or wide value (see command metric-style [narrow | transition | wide]).

isis network point-to-point: Set network type to ‘Point-to-Point’ (broadcast by default).

isis passive: Configure the passive mode for this interface.

isis password [clear | md5] <password>: Configure the authentication password (clear or encoded text) for the interface.

isis priority (0-127) [level-1 | level-2]: Set priority for Designated Router election, globally, for the area (level-1) or the domain (level-2).

isis psnp-interval (1-120) [level-1 | level-2]: Set PSNP interval in seconds globally, for an area (level-1) or a domain (level-2).

isis three-way-handshake: Enable or disable RFC 5303 Three-Way Handshake for P2P adjacencies. Three-Way Handshake is enabled by default.

Showing ISIS information

show isis [vrf <NAME|all>] summary [json]: Show summary information about ISIS.

show isis hostname: Show information about ISIS node.

show isis [vrf <NAME|all>] interface [detail] [IFNAME] [json]: Show state and configuration of ISIS specified interface, or all interfaces if no interface is given with or without details.

show isis [vrf <NAME|all>] neighbor [detail] [SYSTEMID] [json]: Show state and information of ISIS specified neighbor, or all neighbors if no system id is given with or without details.

show isis [vrf <NAME|all>] database [detail] [LSPID] [json]: Show the ISIS database globally, for a specific LSP id without or with details.

show isis topology [level-1|level-2] [algorithm (128-255)]: Show topology IS-IS paths to Intermediate Systems, globally, in area (level-1) or domain (level-2).

show isis route [level-1|level-2] [prefix-sid|backup] [algorithm (128-255)]: Show the ISIS routing table, as determined by the most recent SPF calculation.

Debugging ISIS

debug isis adj-packets: IS-IS Adjacency related packets.

debug isis checksum-errors: IS-IS LSP checksum errors.

debug isis events: IS-IS Events.

debug isis local-updates: IS-IS local update packets.

debug isis packet-dump: IS-IS packet dump.

debug isis protocol-errors: IS-IS LSP protocol errors.

debug isis route-events: IS-IS Route related events.

debug isis snp-packets: IS-IS CSNP/PSNP packets.

debug isis spf-events

debug isis spf-statistics

debug isis spf-triggers: IS-IS Shortest Path First Events, Timing and Statistic Data and triggering events.

debug isis update-packets: Update related packets.

show debugging isis: Print which ISIS debug level is activate.

ISIS Configuration Examples

A simple example, with MD5 authentication enabled:

!
interface eth0
 ip router isis FOO
 isis network point-to-point
 isis circuit-type level-2-only
!
router isis FOO
net 47.0023.0000.0000.0000.0000.0000.0000.1900.0004.00
 metric-style wide
 is-type level-2-only

ISIS Vrf Configuration Examples

A simple vrf example:

!
interface ge0 vrf RED
 ip vrf forwarding RED
 ip router isis FOO vrf RED
 isis network point-to-point
 isis circuit-type level-2-only
!
router isis FOO vrf RED
 net 47.0023.0000.0000.0000.0000.0000.0000.1900.0004.00
 metric-style wide
 is-type level-2-only