IP-ROUTE(8)

Inspect and manage IP routing tables. Static snapshot from Ubuntu 24.04.

IP-ROUTE(8) Linux IP-ROUTE(8)

NAME
ip-route - routing table management

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

ip route { show | flush } SELECTOR

ip route save SELECTOR

ip route restore

ip route get ROUTE_GET_FLAGS ADDRESS [ from ADDRESS iif STRING ] [ oif STRING ]
[ mark MARK ] [ tos TOS ] [ vrf NAME ] [ ipproto PROTOCOL ] [ sport NUM‐
BER ] [ dport NUMBER ]

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

SELECTOR := [ root PREFIX ] [ match PREFIX ] [ exact PREFIX ] [ table TABLE_ID ]
[ vrf NAME ] [ proto RTPROTO ] [ type TYPE ] [ scope SCOPE ]

ROUTE := NODE_SPEC [ INFO_SPEC ]

NODE_SPEC := [ TYPE ] PREFIX [ tos TOS ] [ table TABLE_ID ] [ proto RTPROTO ] [
scope SCOPE ] [ metric METRIC ] [ ttl-propagate { enabled | disabled } ]

INFO_SPEC := { NH | nhid ID } OPTIONS FLAGS [ nexthop NH ] ...

NH := [ encap ENCAP ] [ via [ FAMILY ] ADDRESS ] [ dev STRING ] [ weight NUMBER ]
NHFLAGS

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

OPTIONS := FLAGS [ mtu NUMBER ] [ advmss NUMBER ] [ as [ to ] ADDRESS ] rtt TIME
] [ rttvar TIME ] [ reordering NUMBER ] [ window NUMBER ] [ cwnd NUMBER ]
[ ssthresh NUMBER ] [ realms REALM ] [ rto_min TIME ] [ initcwnd NUMBER ]
[ initrwnd NUMBER ] [ features FEATURES ] [ quickack BOOL ] [ congctl
NAME ] [ pref PREF ] [ expires TIME ] [ fastopen_no_cookie BOOL ]

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_MPLS := mpls [ LABEL ] [ ttl TTL ]

ENCAP_IP := ip id TUNNEL_ID dst REMOTE_IP [ src SRC ] [ tos TOS ] [ ttl TTL ]

ENCAP_BPF := bpf [ in PROG ] [ out PROG ] [ xmit PROG ] [ headroom SIZE ]

ENCAP_SEG6 := seg6 mode [ encap | encap.red | inline | l2encap | l2encap.red ]
segs SEGMENTS [ hmac KEYID ]

ENCAP_SEG6LOCAL := seg6local action SEG6_ACTION [ SEG6_ACTION_PARAM ] [ count ]

ENCAP_IOAM6 := ioam6 [ freq K/N ] mode [ inline | encap | auto ] [ tundst ADDRESS
] trace prealloc type IOAM6_TRACE_TYPE ns IOAM6_NAMESPACE size
IOAM6_TRACE_SIZE

ROUTE_GET_FLAGS := [ fibmatch ]

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 cov‐
ered 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 ab‐
sence of the route in the routing table. The packets are dropped and the
ICMP message net unreachable is generated. The local senders get an ENE‐
TUNREACH error.

nat - a special NAT route. Destinations covered by the prefix are consid‐
ered 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 the file
/etc/iproute2/rt_tables By default all normal routes are inserted into the main
table (ID 254) and the kernel only uses this table when calculating routes. Val‐
ues (0, 253, 254, and 255) are reserved for built-in use.

Actually, one other table always exists, which is invisible but even more impor‐
tant. 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 admin‐
istrator 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

to TYPE 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 PREFIX default - which
is equivalent to IP 0/0 or to IPv6 ::/0.

tos TOS

dsfield TOS
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 hexa‐
decimal number or an identifier from /etc/iproute2/rt_dsfield.

metric NUMBER

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

table TABLEID
the table to add this route to. TABLEID may be a number or a
string from the file /etc/iproute2/rt_tables. 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 de‐
fault.

vrf NAME
the vrf name to add this route to. Implicitly means the table asso‐
ciated with the VRF.

dev NAME
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.

src ADDRESS
the source address to prefer when sending to the destinations cov‐
ered by the route prefix.

realm REALMID
the realm to which this route is assigned. REALMID may be a number
or a string from the file /etc/iproute2/rt_realms.

mtu MTU

mtu lock MTU
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 Dis‐
covery. 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.

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

rtt TIME
the initial RTT ('Round Trip Time') estimate. If no suffix is spec‐
ified 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.

rttvar TIME (Linux 2.3.15+ only)
the initial RTT variance estimate. Values are specified as with rtt
above.

rto_min TIME (Linux 2.6.23+ only)
the minimum TCP Retransmission TimeOut to use when communicating
with this destination. Values are specified as with rtt above.

ssthresh NUMBER (Linux 2.3.15+ only)
an estimate for the initial slow start threshold.

cwnd NUMBER (Linux 2.3.15+ only)
the clamp for congestion window. It is ignored if the lock flag is
not used.

initcwnd NUMBER (Linux 2.5.70+ only)
the initial congestion window size for connections to this destina‐
tion. 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.

initrwnd NUMBER (Linux 2.6.33+ only)
the initial receive window size for connections to this destina‐
tion. Actual window size is this value multiplied by the MSS of
the connection. The default value is zero, meaning to use Slow
Start value.

features FEATURES (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 re‐
sponding 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.

quickack BOOL (Linux 3.11+ only)
Enable or disable quick ack for connections to this destination.

fastopen_no_cookie BOOL (Linux 4.15+ only)
Enable TCP Fastopen without a cookie for connections to this desti‐
nation.

congctl NAME (Linux 3.20+ only)

congctl lock NAME (Linux 3.20+ only)
Sets a specific TCP congestion control algorithm only for a given
destination. If not specified, Linux keeps the current global de‐
fault TCP congestion control algorithm, or the one set from the ap‐
plication. 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 appli‐
cation is not allowed to overwrite the specified congestion control
algorithm for that destination, thus it will be enforced/guaranteed
to use the proposed algorithm.

advmss NUMBER (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.)

reordering NUMBER (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.

nexthop NEXTHOP
the nexthop of a multipath route. NEXTHOP is a complex value with
its own syntax similar to the top level argument lists:

via [ FAMILY ] ADDRESS - is the nexthop router.

dev NAME - is the output device.

weight NUMBER - 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 pos‐
sible per route. With IPv6, further nexthops may be appended to the
same route via ip route append command.

scope SCOPE_VAL
the scope of the destinations covered by the route prefix.
SCOPE_VAL may be a number or a string from the file
/etc/iproute2/rt_scopes. If this parameter is omitted, ip assumes
scope global for all gatewayed unicast routes, scope link for di‐
rect unicast and broadcast routes and scope host for local routes.

protocol RTPROTO
the routing protocol identifier of this route. RTPROTO may be a
number or a string from the file /etc/iproute2/rt_protos. If the
routing protocol ID is not given, ip assumes protocol boot (i.e. it
assumes the route was added by someone who doesn't understand what
they are doing). Several protocol values have a fixed interpreta‐
tion. Namely:

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

kernel - the route was installed by the kernel during auto‐
configuration.

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.

pref PREF
the IPv6 route preference. PREF is a string specifying the route
preference as defined in RFC4191 for Router Discovery messages.
Namely:

low - the route has a lowest priority

medium - the route has a default priority

high - the route has a highest priority

nhid ID
use nexthop object with given id as nexthop specification.

encap ENCAPTYPE ENCAPHDR
attach tunnel encapsulation attributes to this route.

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 EN‐
CAPTYPE.

mpls
MPLSLABEL - mpls label stack with labels separated by /

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

ip
id TUNNEL_ID dst REMOTE_IP [ src SRC ] [ tos TOS ] [ ttl
TTL ] [ key ] [ csum ] [ seq ]

bpf
in PROG - BPF program to execute for incoming packets

out PROG - BPF program to execute for outgoing packets

xmit PROG - BPF program to execute for transmitted pack‐
ets

headroom SIZE - Size of header BPF program will attach
(xmit)

seg6
mode inline - Directly insert Segment Routing Header af‐
ter 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 at‐
tribute 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 re‐
lated to an action use the -s flag in the show command.
The following actions are currently supported (Linux
4.14+ only).

End [ flavors FLAVORS ] - Regular SRv6 processing as
intermediate segment endpoint. This action only ac‐
cepts 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 be‐
havior according to the user-provided Flavor operations
and information carried in the packet. See Flavors pa‐
rameters section.

End.X nh6 NEXTHOP - Regular SRv6 processing as interme‐
diate 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.

End.DX6 nh6 NEXTHOP - 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 spec‐
ified lookup table. TABLEID is either a number or a
string from the file /etc/iproute2/rt_tables. If
vrftable is used, the argument must be a VRF device as‐
sociated with the table id. Moreover, the VRF table as‐
sociated 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 vrftable TABLEID - Decapsulate the inner IPv4
packet and forward it according to the specified lookup
table. TABLEID is either a number or a string from the
file /etc/iproute2/rt_tables. The argument must be a
VRF device associated with the table id. Moreover, the
VRF table associated with the table id must be config‐
ured with the VRF strict mode turned on
(net.vrf.strict_mode=1). This action only accepts pack‐
ets with either a zero Segments Left value or no SRH at
all, and an inner IPv4 packet. Other matching packets
are dropped.

End.DT46 vrftable TABLEID - Decapsulate the inner IPv4
or IPv6 packet and forward it according to the speci‐
fied lookup table. TABLEID is either a number or a
string from the file /etc/iproute2/rt_tables. The ar‐
gument 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 segs SEGMENTS [ hmac KEYID ] - 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 segs SEGMENTS [ hmac KEYID ] - Regu‐
lar 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.

flavors OPERATION[,OPERATION] [ATTRIBUTES]

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

ATTRIBUTES := { KEY VALUE } [ ATTRIBUTES ]

KEY := { lblen | nflen }

psp - Penultimate Segment Pop of the SRH (not yet
supported in kernel)

usp - Ultimate Segment Pop of the SRH (not yet sup‐
ported in kernel)

usd - Ultimate Segment Decapsulation (not yet sup‐
ported in kernel)

next-csid - The NEXT-C-SID mechanism offers the pos‐
sibility 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 be‐
havior instance with NEXT-C-SID flavor, the default
value is 32-bit for Locator-Block and 16-bit for Lo‐
cator-Node Function.

lblen VALUE - 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 at‐
tribute can be used only with NEXT-C-SID flavor.

nflen VALUE - defines the Locator-Node Function
length for NEXT-C-SID flavors. The Locator-Node Func‐
tion length must be greater than 0 and evenly divisi‐
ble 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.

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

type IOAM6_TRACE_TYPE - List of IOAM data required in
the trace, represented by a bitfield (24 bits).

ns IOAM6_NAMESPACE - Numerical value to represent an
IOAM namespace. See ip-ioam(8).

size IOAM6_TRACE_SIZE - Size, in octets, of the pre-al‐
located trace data block.

xfrm
if_id IF_ID [ link_dev LINK_DEV ]

expires TIME (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
ip route del has the same arguments as ip route add, but their semantics
are a bit different.

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 at‐
tributes was found, ip route del fails.

ip route show
list routes
the command displays the contents of the routing tables or the route(s)
selected by some criteria.

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

tos TOS

dsfield TOS
only select routes with the given TOS.

table TABLEID
show the routes from this table(s). The default setting is to show
table main. TABLEID may either be the ID of a real table or one of
the special values:

all - list all of the tables.

cache - dump the routing cache.

vrf NAME
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.

from SELECTOR
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.

protocol RTPROTO
only list routes of this protocol.

scope SCOPE_VAL
only list routes with this scope.

type TYPE
only list routes of this type.

dev NAME
only list routes going via this device.

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

src PREFIX
only list routes with preferred source addresses selected by PRE‐
FIX.

realm REALMID

realms FROMREALM/TOREALM
only list routes with these realms.

ip route flush
flush routing tables
this command flushes routes selected by some criteria.

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 differ‐
ence 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
this command gets a single route to a destination and prints its contents
exactly as the kernel sees it.

fibmatch
Return full fib lookup matched route. Default is to return the re‐
solved dst entry

to ADDRESS (default)
the destination address.

from ADDRESS
the source address.

tos TOS

dsfield TOS
the Type Of Service.

iif NAME
the device from which this packet is expected to arrive.

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

mark MARK
the firewall mark (fwmark)

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

ipproto PROTOCOL
ip protocol as seen by the route lookup

sport NUMBER
source port as seen by the route lookup

dport NUMBER
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.

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 pack‐
ets 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
This command behaves like ip route show except that the output is raw data
suitable for passing to ip route restore.

ip route restore
restore routing table information from stdin
This command expects to read a data stream as returned from ip route save.
It will attempt to restore the routing table information exactly as it was
at the time of the save, so any translation of information in the stream
(such as device indexes) must be done first. Any existing routes are left
unchanged. Any routes specified in the data stream that already exist in
the table will be ignored.

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

EXAMPLES
ip ro
Show all route entries in the kernel.

ip route add default via 192.168.1.1 dev eth0
Adds a default route (for all addresses) via the local gateway 192.168.1.1
that can be reached on device eth0.

ip route add 10.1.1.0/30 encap mpls 200/300 via 10.1.1.1 dev eth0
Adds an ipv4 route with mpls encapsulation attributes attached to it.

ip -6 route add 2001:db8:1::/64 encap seg6 mode encap segs
2001:db8:42::1,2001:db8:ffff::2 dev eth0
Adds an IPv6 route with SRv6 encapsulation and two segments attached.

ip -6 route add 2001:db8:1::/64 encap seg6local action End.DT46 vrftable 100 dev
vrf100
Adds an IPv6 route with SRv6 decapsulation and forward with lookup in VRF ta‐
ble.

ip -6 route add 2001:db8:1::/64 encap seg6local action End flavors next-csid dev
eth0
Adds an IPv6 route with SRv6 End behavior with next-csid flavor enabled.

ip -6 route add 2001:db8:1::/64 encap seg6local action End flavors next-csid
lblen 48 nflen 16 dev eth0
Adds an IPv6 route with SRv6 End behavior with next-csid flavor enabled and
user-provided Locator-Block and Locator-Node Function lengths.

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
Adds an IPv6 route with an IOAM Pre-allocated Trace encapsulation (ip6ip6)
that only includes the hop limit and the node id, configured for the IOAM
namespace 1 and a pre-allocated data block of 12 octets (will be injected in
2 packets every 5 packets).

ip route add 10.1.1.0/30 nhid 10
Adds an ipv4 route using nexthop object with id 10.