ip-route(8)

NAME#

ip-route - routing table management

SYNOPSIS#

ip [ ip-OPTIONS ] route { COMMAND | help }

ip route { show | flush } SELECTOR

ip route saveSELECTOR

ip route restore

ip route getROUTE_GET_FLAGS[ to ]ADDRESS [ fromADDRESSiifSTRING ] [ oifSTRING ] [ markMARK ] [ tosTOS ] [ vrfNAME ] [ ipprotoPROTOCOL ] [ sportNUMBER ] [ dportNUMBER ] [ asADDRESS ] [ flowlabelFLOWLABEL ]

ip route { add | del | change | append | replace } ROUTE

SELECTOR := [ rootPREFIX ] [ matchPREFIX ] [ exactPREFIX ] [ tableTABLE_ID ] [ vrfNAME ] [ protoRTPROTO ] [ typeTYPE ] [ scopeSCOPE ]

ROUTE := NODE_SPEC [ INFO_SPEC ]

NODE_SPEC := [ TYPE ] PREFIX [ tosTOS ] [ tableTABLE_ID ] [ protoRTPROTO ] [ scopeSCOPE ] [ metricMETRIC ] [ ttl-propagate { enabled | disabled } ]

INFO_SPEC := { NH | nhidID } OPTIONS FLAGS [ nexthopNH ] ...

NH := [ encapENCAP ] [ via [ FAMILY ] ADDRESS ] [ devSTRING ] [ weightNUMBER ] NHFLAGS

FAMILY := [ inet | inet6 | mpls | bridge | link ]

OPTIONS := FLAGS [ mtuNUMBER ] [ advmssNUMBER ] [ as [ to ] ADDRESS ] rttTIME ] [ rttvarTIME ] [ reorderingNUMBER ] [ windowNUMBER ] [ cwndNUMBER ] [ ssthreshNUMBER ] [ realmsREALM ] [ rto_minTIME ] [ initcwndNUMBER ] [ initrwndNUMBER ] [ featuresFEATURES ] [ quickackBOOL ] [ congctlNAME ] [ prefPREF ] [ expiresTIME ] [ fastopen_no_cookieBOOL ]

TYPE := [ unicast | local | broadcast | multicast | throw | unreachable | prohibit | blackhole | nat ]

TABLE_ID := [ local| main | default | all | NUMBER ]

SCOPE := [ host | link | global | NUMBER ]

NHFLAGS := [ onlink | pervasive ]

RTPROTO := [ kernel | boot | static | NUMBER ]

FEATURES := [ ecn | ]

PREF := [ low | medium | high ]

ENCAP := [ ENCAP_MPLS | ENCAP_IP | ENCAP_BPF | ENCAP_SEG6 | ENCAP_SEG6LOCAL | ENCAP_IOAM6 ]

ENCAP_MPLS := mpls [ LABEL ] [ ttlTTL ]

ENCAP_IP := ipidTUNNEL_IDdstREMOTE_IP [ srcSRC ] [ tosTOS ] [ ttlTTL ] [ key ] [ csum ] [ seq ] [ GENEVE_OPTS | VXLAN_OPTS | ERSPAN_OPTS ]

ENCAP_BPF := bpf [ inPROG ] [ outPROG ] [ xmitPROG ] [ headroomSIZE ]

ENCAP_SEG6 := seg6mode [ encap | encap.red | inline | l2encap | l2encap.red ] segsSEGMENTS [ hmacKEYID ]

ENCAP_SEG6LOCAL := seg6localactionSEG6_ACTION [ SEG6_ACTION_PARAM ] [ count ]

ENCAP_IOAM6 := ioam6 [ freqK/N ] mode [ inline | encap | auto ] [ tunsrcADDRESS ] [ tundstADDRESS ] traceprealloctypeIOAM6_TRACE_TYPEnsIOAM6_NAMESPACEsizeIOAM6_TRACE_SIZE

ROUTE_GET_FLAGS := ROUTE_GET_FLAG [ ROUTE_GET_FLAGS ]

ROUTE_GET_FLAG := [connected | fibmatch | notify]

DESCRIPTION#

ip route is used to manipulate entries in the kernel routing tables.

Route types:

unicast - the route entry describes real paths to the destinations covered by the route prefix.

unreachable - these destinations are unreachable. Packets are discarded and the ICMP message host unreachable is generated. The local senders get an EHOSTUNREACH error.

blackhole - these destinations are unreachable. Packets are discarded silently. The local senders get an EINVAL error.

prohibit - these destinations are unreachable. Packets are discarded and the ICMP message communication administratively prohibited is generated. The local senders get an EACCES error.

local - the destinations are assigned to this host. The packets are looped back and delivered locally.

broadcast - the destinations are broadcast addresses. The packets are sent as link broadcasts.

throw - a special control route used together with policy rules. If such a route is selected, lookup in this table is terminated pretending that no route was found. Without policy routing it is equivalent to the absence of the route in the routing table. The packets are dropped and the ICMP message net unreachable is generated. The local senders get an ENETUNREACH error.

nat - a special NAT route. Destinations covered by the prefix are considered to be dummy (or external) addresses which require translation to real (or internal) ones before forwarding. The addresses to translate to are selected with the attribute via. Warning: Route NAT is no longer supported in Linux 2.6.

anycast - not implemented the destinations are anycast addresses assigned to this host. They are mainly equivalent to local with one difference: such addresses are invalid when used as the source address of any packet.

multicast - a special type used for multicast routing. It is not present in normal routing tables.

Route tables: Linux-2.x can pack routes into several routing tables identified by a number in the range from 1 to 2^32-1 or by name from /usr/share/iproute2/rt_tables or /etc/iproute2/rt_tables (has precedence if exists). By default all normal routes are inserted into the main table (ID 254) and the kernel only uses this table when calculating routes. Values (0, 253, 254, and 255) are reserved for built-in use.

Actually, one other table always exists, which is invisible but even more important. It is the local table (ID 255). This table consists of routes for local and broadcast addresses. The kernel maintains this table automatically and the administrator usually need not modify it or even look at it.

The multiple routing tables enter the game when policy routing is used.

ip route add

add new route

ip route change

change route

ip route replace

change or add new one

toTYPE PREFIX(default)

the destination prefix of the route. If TYPE is omitted, ip assumes type unicast. Other values of TYPE are listed above. PREFIX is an IP or IPv6 address optionally followed by a slash and the prefix length. If the length of the prefix is missing, ip assumes a full-length host route. There is also a special PREFIXdefault - which is equivalent to IP 0/0 or to IPv6 ::/0.

tosTOS

dsfieldTOS

the Type Of Service (TOS) key. This key has no associated mask and the longest match is understood as: First, compare the TOS of the route and of the packet. If they are not equal, then the packet may still match a route with a zero TOS. TOS is either an 8 bit hexadecimal number or an identifier from /usr/share/iproute2/rt_dsfield or /etc/iproute2/rt_dsfield (has precedence if exists).

metricNUMBER

preferenceNUMBER

the preference value of the route. NUMBER is an arbitrary 32bit number, where routes with lower values are preferred.

tableTABLEID

the table to add this route to. TABLEID may be a number or a string from /usr/share/iproute2/rt_tables or /etc/iproute2/rt_tables (has precedence if exists). If this parameter is omitted, ip assumes the main table, with the exception of local, broadcast and nat routes, which are put into the local table by default.

vrfNAME

the vrf name to add this route to. Implicitly means the table associated with the VRF.

devNAME

the output device name.

via[ FAMILY ] ADDRESS

the address of the nexthop router, in the address family FAMILY. Actually, the sense of this field depends on the route type. For normal unicast routes it is either the true next hop router or, if it is a direct route installed in BSD compatibility mode, it can be a local address of the interface. For NAT routes it is the first address of the block of translated IP destinations.

srcADDRESS

the source address to prefer when sending to the destinations covered by the route prefix.

realmREALMID

the realm to which this route is assigned. REALMID may be a number or a string from /usr/share/iproute2/rt_realms or /etc/iproute2/rt_realms (has precedence if exists).

mtuMTU

mtu lockMTU

the MTU along the path to the destination. If the modifier lock is not used, the MTU may be updated by the kernel due to Path MTU Discovery. If the modifier lock is used, no path MTU discovery will be tried, all packets will be sent without the DF bit in IPv4 case or fragmented to MTU for IPv6.

windowNUMBER

the maximal window for TCP to advertise to these destinations, measured in bytes. It limits maximal data bursts that our TCP peers are allowed to send to us.

rttTIME

the initial RTT ('Round Trip Time') estimate. If no suffix is specified the units are raw values passed directly to the routing code to maintain compatibility with previous releases. Otherwise if a suffix of s, sec or secs is used to specify seconds and ms, msec or msecs to specify milliseconds.

rttvarTIME(Linux 2.3.15+ only)

the initial RTT variance estimate. Values are specified as with rtt above.

rto_minTIME(Linux 2.6.23+ only)

the minimum TCP Retransmission TimeOut to use when communicating with this destination. Values are specified as with rtt above.

ssthreshNUMBER(Linux 2.3.15+ only)

an estimate for the initial slow start threshold.

cwndNUMBER(Linux 2.3.15+ only)

the clamp for congestion window. It is ignored if the lock flag is not used.

initcwndNUMBER(Linux 2.5.70+ only)

the initial congestion window size for connections to this destination. Actual window size is this value multiplied by the MSS (``Maximal Segment Size'') for same connection. The default is zero, meaning to use the values specified in RFC2414.

initrwndNUMBER(Linux 2.6.33+ only)

the initial receive window size for connections to this destination. Actual window size is this value multiplied by the MSS of the connection. The default value is zero, meaning to use Slow Start value.

featuresFEATURES(Linux3.18+only)

Enable or disable per-route features. Only available feature at this time is ecn to enable explicit congestion notification when initiating connections to the given destination network. When responding to a connection request from the given network, ecn will also be used even if the net.ipv4.tcp_ecn sysctl is set to 0.

quickackBOOL(Linux 3.11+ only)

Enable or disable quick ack for connections to this destination.

fastopen_no_cookieBOOL(Linux 4.15+ only)

Enable TCP Fastopen without a cookie for connections to this destination.

congctlNAME(Linux 3.20+ only)

congctl lockNAME(Linux 3.20+ only)

Sets a specific TCP congestion control algorithm only for a given destination. If not specified, Linux keeps the current global default TCP congestion control algorithm, or the one set from the application. If the modifier lock is not used, an application may nevertheless overwrite the suggested congestion control algorithm for that destination. If the modifier lock is used, then an application is not allowed to overwrite the specified congestion control algorithm for that destination, thus it will be enforced/guaranteed to use the proposed algorithm.

advmssNUMBER(Linux 2.3.15+ only)

the MSS ('Maximal Segment Size') to advertise to these destinations when establishing TCP connections. If it is not given, Linux uses a default value calculated from the first hop device MTU. (If the path to these destination is asymmetric, this guess may be wrong.)

reorderingNUMBER(Linux 2.3.15+ only)

Maximal reordering on the path to this destination. If it is not given, Linux uses the value selected with sysctl variable net/ipv4/tcp_reordering.

nexthopNEXTHOP

via[ FAMILY ] ADDRESS - is the nexthop router.

devNAME - is the output device.

weightNUMBER - is a weight for this element of a multipath route reflecting its relative bandwidth or quality.

The internal buffer used in iproute2 limits the maximum number of nexthops that may be specified in one go. If only ADDRESS is given, the current buffer size allows for 144 IPv6 nexthops and 253 IPv4 ones. For IPv4, this effectively limits the number of nexthops possible per route. With IPv6, further nexthops may be appended to the same route via ip route append command.

scopeSCOPE_VAL

the scope of the destinations covered by the route prefix. SCOPE_VAL may be a number or a string from /usr/share/iproute2/rt_scopes or /etc/iproute2/rt_scopes (has precedence if exists). If this parameter is omitted, ip assumes scope global for all gatewayed unicast routes, scope link for direct unicast and broadcast routes and scope host for local routes.

protocolRTPROTO

redirect - the route was installed due to an ICMP redirect.

kernel - the route was installed by the kernel during autoconfiguration.

boot - the route was installed during the bootup sequence. If a routing daemon starts, it will purge all of them.

static - the route was installed by the administrator to override dynamic routing. Routing daemon will respect them and, probably, even advertise them to its peers.

ra - the route was installed by Router Discovery protocol.

The rest of the values are not reserved and the administrator is free to assign (or not to assign) protocol tags.

onlink

pretend that the nexthop is directly attached to this link, even if it does not match any interface prefix.

prefPREF

low - the route has a lowest priority

medium - the route has a default priority

high - the route has a highest priority

nhidID

use nexthop object with given id as nexthop specification.

encapENCAPTYPE ENCAPHDR

ENCAPTYPE is a string specifying the supported encapsulation type. Namely:

mpls - encapsulation type MPLS

ip - IP encapsulation (Geneve, GRE, VXLAN, ...)

bpf - Execution of BPF program

seg6 - encapsulation type IPv6 Segment Routing

seg6local - local SRv6 segment processing

ioam6 - encapsulation type IPv6 IOAM

xfrm - encapsulation type XFRM

ENCAPHDR is a set of encapsulation attributes specific to the ENCAPTYPE.

mpls MPLSLABEL - mpls label stack with labels separated by /

ttlTTL - TTL to use for MPLS header or 0 to inherit from IP header

ip idTUNNEL_ID - Tunnel ID (for example VNI in VXLAN tunnel)

dstREMOTE_IP - Outer header destination IP address (IPv4 or IPv6)

srcSRC - Outer header source IP address (IPv4 or IPv6)

tosTOS - Outer header TOS

ttlTTL - Outer header TTL

key - Outer header flags with key in GRE tunnel

csum - Outer header flags with csum in GRE tunnel

seq - Outer header flags with seq in GRE tunnel

GENEVE_OPTS - Specified in the form CLASS:TYPE:DATA, where CLASS is represented as a 16bit hexadecimal value, TYPE as an 8bit hexadecimal value and DATA as a variable length hexadecimal value. Additionally multiple options may be listed using a comma delimiter.

VXLAN_OPTS - Specified in the form GBP, as a 32bit number. Multiple options is not supported.

ERSPAN_OPTS - Specified in the form VERSION:INDEX:DIR:HWID, where VERSION is represented as a 8bit number, INDEX as an 32bit number, DIR and HWID as a 8bit number. Multiple options is not supported. Note INDEX is used when VERSION is 1, and DIR and HWID are used when VERSION is 2.

bpf inPROG - BPF program to execute for incoming packets

outPROG - BPF program to execute for outgoing packets

xmitPROG - BPF program to execute for transmitted packets

headroomSIZE - Size of header BPF program will attach (xmit)

seg6 mode inline - Directly insert Segment Routing Header after IPv6 header

mode encap - Encapsulate packet in an outer IPv6 header with SRH

mode encap.red - Encapsulate packet in an outer IPv6 header with SRH applying the reduced segment list. When there is only one segment and the HMAC is not present, the SRH is omitted.

mode l2encap - Encapsulate ingress L2 frame within an outer IPv6 header and SRH

mode l2encap.red - Encapsulate ingress L2 frame within an outer IPv6 header and SRH applying the reduced segment list. When there is only one segment and the HMAC is not present, the SRH is omitted.

SEGMENTS - List of comma-separated IPv6 addresses

KEYID - Numerical value in decimal representation. See ip-sr(8).

seg6local SEG6_ACTION [ SEG6_ACTION_PARAM ] [ count ] - Operation to perform on matching packets. The optional count attribute is used to collect statistics on the processing of actions. Three counters are implemented: 1) packets correctly processed; 2) bytes correctly processed; 3) packets that cause a processing error (i.e., missing SID List, wrong SID List, etc). To retrieve the counters related to an action use the -s flag in the show command. The following actions are currently supported (Linux 4.14+ only).

End [ flavorsFLAVORS ] - Regular SRv6 processing as intermediate segment endpoint. This action only accepts packets with a non-zero Segments Left value. Other matching packets are dropped. The presence of flavors can change the regular processing of an End behavior according to the user-provided Flavor operations and information carried in the packet. See Flavors parameters section.

End.X nh6NEXTHOP [flavorsFLAVORS ] - Regular SRv6 processing as intermediate segment endpoint. Additionally, forward processed packets to given next-hop. This action only accepts packets with a non-zero Segments Left value. Other matching packets are dropped. The presence of flavors can change the regular processing of an End.X behavior according to the user-provided Flavor operations and information carried in the packet. See Flavors parameters section.

End.DX6 nh6NEXTHOP - Decapsulate inner IPv6 packet and forward it to the specified next-hop. If the argument is set to ::, then the next-hop is selected according to the local selection rules. This action only accepts packets with either a zero Segments Left value or no SRH at all, and an inner IPv6 packet. Other matching packets are dropped.

End.DT6 { table | vrftable } TABLEID - Decapsulate the inner IPv6 packet and forward it according to the specified lookup table. TABLEID is either a number or a string from /usr/share/iproute2/rt_tables or /etc/iproute2/rt_tables (has precedence if exists). If vrftable is used, the argument must be a VRF device associated with the table id. Moreover, the VRF table associated with the table id must be configured with the VRF strict mode turned on (net.vrf.strict_mode=1). This action only accepts packets with either a zero Segments Left value or no SRH at all, and an inner IPv6 packet. Other matching packets are dropped.

End.DT4 vrftableTABLEID - Decapsulate the inner IPv4 packet and forward it according to the specified lookup table. TABLEID is either a number or a string from /usr/share/iproute2/rt_tables or /etc/iproute2/rt_tables (has precedence if exists). The argument must be a VRF device associated with the table id. Moreover, the VRF table associated with the table id must be configured with the VRF strict mode turned on (net.vrf.strict_mode=1). This action only accepts packets with either a zero Segments Left value or no SRH at all, and an inner IPv4 packet. Other matching packets are dropped.

End.DT46 vrftableTABLEID - Decapsulate the inner IPv4 or IPv6 packet and forward it according to the specified lookup table. TABLEID is either a number or a string from /usr/share/iproute2/rt_tables or /etc/iproute2/rt_tables (has precedence if exists). The argument must be a VRF device associated with the table id. Moreover, the VRF table associated with the table id must be configured with the VRF strict mode turned on (net.vrf.strict_mode=1). This action only accepts packets with either a zero Segments Left value or no SRH at all, and an inner IPv4 or IPv6 packet. Other matching packets are dropped.

End.B6 srh segsSEGMENTS [ hmacKEYID ] - Insert the specified SRH immediately after the IPv6 header, update the DA with the first segment of the newly inserted SRH, then forward the resulting packet. The original SRH is not modified. This action only accepts packets with a non-zero Segments Left value. Other matching packets are dropped.

End.B6.Encaps srh segsSEGMENTS [ hmacKEYID ] - Regular SRv6 processing as intermediate segment endpoint. Additionally, encapsulate the matching packet within an outer IPv6 header followed by the specified SRH. The destination address of the outer IPv6 header is set to the first segment of the new SRH. The source address is set as described in ip-sr(8).

Flavors parameters

The flavors represent additional operations that can modify or extend a subset of the existing behaviors.

flavorsOPERATION[,OPERATION] [ATTRIBUTES]

OPERATION := { psp | usp | usd | next-csid }

ATTRIBUTES := { KEY VALUE } [ ATTRIBUTES ]

KEY := { lblen | nflen }

psp - The Penultimate Segment Pop (PSP) copies the last SID from the SID List (carried by the outermost SRH) into the IPv6 Destination Address (DA) and removes (i.e. pops) the SRH from the IPv6 header. The PSP operation takes place only at a penultimate SR Segment Endpoint node (e.g., the Segment Left must be one) and does not happen at non-penultimate endpoint nodes. This flavor is currently only supported by End behavior.

usp - Ultimate Segment Pop of the SRH (not yet supported in kernel)

usd - Ultimate Segment Decapsulation (not yet supported in kernel)

next-csid - The NEXT-C-SID mechanism offers the possibility of encoding several SRv6 segments within a single 128 bit SID address. The NEXT-C-SID flavor can be configured to support user-provided Locator-Block and Locator-Node Function lengths. If Locator-Block and/or Locator-Node Function lengths are not provided by the user during configuration of an SRv6 End behavior instance with NEXT-C-SID flavor, the default value is 32-bit for Locator-Block and 16-bit for Locator-Node Function.

lblenVALUE - defines the Locator-Block length for NEXT-C-SID flavor. The Locator-Block length must be greater than 0 and evenly divisible by 8. This attribute can be used only with NEXT-C-SID flavor.

nflenVALUE - defines the Locator-Node Function length for NEXT-C-SID flavors. The Locator-Node Function length must be greater than 0 and evenly divisible by 8. This attribute can be used only with NEXT-C-SID flavor.

ioam6 freq K/N - Inject IOAM in K packets every N packets (default is 1/1).

mode inline - Directly insert IOAM after IPv6 header (default mode).

mode encap - Encapsulate packet in an outer IPv6 header with IOAM.

mode auto - Automatically use inline mode for local packets and encap mode for in-transit packets.

tunsrcADDRESS - IPv6 address of the tunnel source (outer header), not used with inline mode. It is optional: if not provided, the tunnel source address is chosen automatically.

tundstADDRESS - IPv6 address of the tunnel destination (outer header), not used with inline mode.

typeIOAM6_TRACE_TYPE - List of IOAM data required in the trace, represented by a bitfield (24 bits).

nsIOAM6_NAMESPACE - Numerical value to represent an IOAM namespace. See ip-ioam(8).

sizeIOAM6_TRACE_SIZE - Size, in octets, of the pre-allocated trace data block.

xfrm if_idIF_ID[ link_devLINK_DEV ]

expiresTIME(Linux 4.4+ only)

the route will be deleted after the expires time. Only support IPv6 at present.

ttl-propagate { enabled | disabled }

Control whether TTL should be propagated from any encap into the un-encapsulated packet, overriding any global configuration. Only supported for MPLS at present.

ip route delete

delete route

Key values (to, tos, preference and table) select the route to delete. If optional attributes are present, ip verifies that they coincide with the attributes of the route to delete. If no route with the given key and attributes was found, ip route del fails.

ip route show

list routes

toSELECTOR(default)

only select routes from the given range of destinations. SELECTOR consists of an optional modifier (root, match or exact) and a prefix. rootPREFIX selects routes with prefixes not shorter than PREFIX. F.e. root0/0 selects the entire routing table. matchPREFIX selects routes with prefixes not longer than PREFIX. F.e. match10.0/16 selects 10.0/16, 10/8 and 0/0, but it does not select 10.1/16 and 10.0.0/24. And exactPREFIX (or just PREFIX) selects routes with this exact prefix. If neither of these options are present, ip assumes root0/0 i.e. it lists the entire table.

tosTOS

dsfieldTOS

only select routes with the given TOS.

tableTABLEID

all - list all of the tables.

cache - dump the routing cache.

vrfNAME

show the routes for the table associated with the vrf name

cloned

cached

list cloned routes i.e. routes which were dynamically forked from other routes because some route attribute (f.e. MTU) was updated. Actually, it is equivalent to table cache.

fromSELECTOR

the same syntax as for to, but it binds the source address range rather than destinations. Note that the from option only works with cloned routes.

protocolRTPROTO

only list routes of this protocol.

scopeSCOPE_VAL

only list routes with this scope.

typeTYPE

only list routes of this type.

devNAME

only list routes going via this device.

via[ FAMILY ] PREFIX

only list routes going via the nexthop routers selected by PREFIX.

srcPREFIX

only list routes with preferred source addresses selected by PREFIX.

realmREALMID

realmsFROMREALM/TOREALM

only list routes with these realms.

ip route flush

flush routing tables

The arguments have the same syntax and semantics as the arguments of ip route show, but routing tables are not listed but purged. The only difference is the default action: show dumps all the IP main routing table but flush prints the helper page.

With the -statistics option, the command becomes verbose. It prints out the number of deleted routes and the number of rounds made to flush the routing table. If the option is given twice, ip route flush also dumps all the deleted routes in the format described in the previous subsection.

ip route get

get a single route

fibmatch

Return full fib lookup matched route. Default is to return the resolved dst entry

toADDRESS(default)

the destination address.

fromADDRESS

the source address.

tosTOS

dsfieldTOS

the Type Of Service.

iifNAME

the device from which this packet is expected to arrive.

oifNAME

force the output device on which this packet will be routed.

markMARK

the firewall mark (fwmark)

vrfNAME

force the vrf device on which this packet will be routed.

ipprotoPROTOCOL

ip protocol as seen by the route lookup

sportNUMBER

source port as seen by the route lookup

dportNUMBER

destination port as seen by the route lookup

connected

if no source address (option from) was given, relookup the route with the source set to the preferred address received from the first lookup. If policy routing is used, it may be a different route.

flowlabelFLOWLABEL

ipv6 flow label as seen by the route lookup

Note that this operation is not equivalent to ip route show. show shows existing routes. get resolves them and creates new clones if necessary. Essentially, get is equivalent to sending a packet along this path. If the iif argument is not given, the kernel creates a route to output packets towards the requested destination. This is equivalent to pinging the destination with a subsequent ip route ls cache, however, no packets are actually sent. With the iif argument, the kernel pretends that a packet arrived from this interface and searches for a path to forward the packet.

ip route save

save routing table information to stdout

ip route restore

restore routing table information from stdin

NOTES#

Starting with Linux kernel version 3.6, there is no routing cache for IPv4 anymore. Hence ip route show cached will never print any entries on systems with this or newer kernel versions.

EXAMPLES#

ip ro

ip route add default via 192.168.1.1 dev eth0

ip route add 10.1.1.0/30 encap mpls 200/300 via 10.1.1.1 dev eth0

ip -6 route add 2001:db8:1::/64 encap seg6 mode encap segs 2001:db8:42::1,2001:db8:ffff::2 dev eth0

ip -6 route add 2001:db8:1::/64 encap seg6local action End.DT46 vrftable 100 dev vrf100

ip -6 route add 2001:db8:1::/64 encap seg6local action End flavors psp dev eth0

ip -6 route add 2001:db8:1::/64 encap seg6local action End flavors next-csid dev eth0

ip -6 route add 2001:db8:1::/64 encap seg6local action End flavors next-csid lblen 48 nflen 16 dev eth0

ip -6 route add 2001:db8:1::/64 encap ioam6 freq 2/5 mode encap tundst 2001:db8:42::1 trace prealloc type 0x800000 ns 1 size 12 dev eth0

ip route add 10.1.1.0/30 nhid 10

SEE ALSO#

ip(8)

AUTHOR#

Original Manpage by Michail Litvak <[email protected]>