JUNOS software Routing Tables
The JUNOS software provides multiple routing tables that are used to store routes for your network. Each table is represented within the output of the show route command. The software provides default tables that the operating system builds on an as-needed basis. Each of the default tables contains separate route information.
inet.0
inet.1
inet.2
inet.3
inet.4
inet6.0
mpls.0
bgp.l3vpn.0
bgp.l2vpn.0
Table inet.0
The inet.0 routing table is the table used to store IPv4 unicast routes. This is the table we’ve been using throughout this chapter. The router interfaces and all routing protocols place information into this table by default. This output is an example of routes that populate the inet.0 routing table:
user@Riesling> show route table inet.0
inet.0: 49 destinations, 49 routes (49 active, 0 holddown, 0 hidden)
+ = Active Route, - = Last Active, * = Both
10.0.8.0/24 *[Direct/0] 00:11:43
> via so-0/0/2.900
10.0.8.3/32 *[Local/0] 00:11:43
Local
172.16.16.0/21 *[Aggregate/130] 00:36:17
Reject
172.16.16.0/24 *[Static/5] 00:06:12
Reject
192.168.5.1/32 *[OSPF/10] 00:00:15, metric 1
> via so-0/0/2.900
192.168.6.0/24 *[IS-IS/18] 00:24:49, metric 10, tag 2
> to 10.0.0.1 via fe-0/0/0.0
192.168.10.0/24 *[BGP/170] 00:06:08, localpref 100
AS path: 1 I
> to 121.10.0.2 via at-0/1/0.100
Route status Routes are marked with a status icon. Options include the active route (+), the last active route (–), both the current and last active routes (*), or inactive routes (no icon is used). In a steady state, routes are marked active with an asterisk or they are not active. Only the active routes are copied to the Packet Forwarding Engine.
Protocol name Routes placed into the routing table are assigned a protocol name. This name tells you how the routing table learned the route. This name is also used by routing policies to advertise and filter routes.
Protocol preference Each protocol is assigned a numerical value called a protocol preference. This preference value assists the routing table in selecting the active route when more than one version of a route exists.
Next hop information Routes may be assigned more than one next-hop value. Each next hop instructs the router where to forward packets for each route. When multiple next hops exist, the routing table selects a single next hop to be placed in the forwarding table. This selected next hop is marked with a caret (>) in the output. Multiple next-hop values can be placed in the forwarding table. You’ll learn more in the “Load Balancing” section later in this chapter.
Table inet.1
The inet.1 routing table is the table used to store IPv4 multicast routes. This is often referred to as the multicast forwarding cache. Each (Source, Group) pair in the network is placed into this table. In this example of the inet.1 routing table, the multicast group 224.2.2.2 /32 is being advertised by a source located at 10.10.200.200 /32.
user@Riesling> show route table inet.1
inet.1: 1 destinations, 1 routes (1 active, 0 holddown, 0 hidden)
+ = Active Route, - = Last Active, * = Both
224.2.2.2,10.10.200.200/32*[PIM/105] 00:01:58
Multicast
Table inet.2
The inet.2 routing table is also used to store IPv4 unicast routes. The use of those routes, however, is quite different from the inet.0 table. Routes in the inet.2 table are used by multicast routing protocols to prevent routing loops. This process is called the Reverse Path Forwarding (RPF) check
user@Riesling> show route table inet.2
inet.2: 49 destinations, 49 routes (49 active, 0 holddown, 0 hidden)
+ = Active Route, - = Last Active, * = Both
10.0.8.0/24 *[Direct/0] 00:15:43
> via so-0/0/2.900
10.0.8.3/32 *[Local/0] 00:15:43
Local
10.0.9.0/24 *[Direct/0] 00:15:43
> via so-0/0/1.0
10.0.9.2/32 *[Local/0] 00:15:43
Local
10.0.10.0/24 *[Direct/0] 00:15:43
> via so-0/0/0.212
10.0.10.1/32 *[Local/0] 00:15:43
Local
Table inet.3
The inet.3 routing table contains the egress IP address of a MPLS label switched path (LSP). The inet.3 routing table looks like this:
user@Riesling> show route table inet.3
inet.3: 1 destinations, 1 routes (1 active, 0 holddown, 0 hidden)
+ = Active Route, - = Last Active, * = Both
192.168.96.1/32 *[RSVP/7] 00:05:12, metric 20, metric2 0
> via so-0/0/3.0, label-switched-path to-the-egress
Table inet.4
The inet.4 routing table stores information learned using the Multicast Source Discovery Protocol (MSDP). The inet.4 routing table looks like this:
user@Riesling> show route table inet.4
inet.4: 1 destinations, 1 routes (1 active, 0 holddown, 0 hidden)
+ = Active Route, - = Last Active, * = Both
224.2.2.2,10.10.201.200/32 *[MSDP/175/1] 00:00:45, from 192.168.20.1
> to 192.168.28.1 via fe-0/1/3.0
Table inet6.0
The inet6.0 routing table contains IPv6 unicast routes.
user@Riesling> show route table inet6.0
inet6.0: 2 destinations, 2 routes (2 active, 0 holddown, 0 hidden)
+ = Active Route, - = Last Active, * = Both
fec0:0:0:2003::/64 *[Direct/0] 00:06:14
> via fe-0/0/1.0
fec0:0:0:2003::1/128 *[Local/0] 00:06:14
Local via fe-0/0/1.0
Table mpls.0
The mpls.0 table is not actually a routing table but is instead a switching table. MPLS label values are stored in this table. You view the switching table using the show route command, so we’ve included it here. The mpls.0 routing table looks like this:
user@Riesling> show route table mpls.0
mpls.0: 3 destinations, 3 routes (3 active, 0 holddown, 0 hidden)
+ = Active Route, - = Last Active, * = Both
0 *[MPLS/0] 00:06:40, metric 1
Receive
1 *[MPLS/0] 00:06:40, metric 1
Receive
100000 *[RSVP/7] 00:06:18, metric 1
> via so-0/0/1.0, label-switched-path to-the-egress
Table bgp.l3vpn.0
The bgp.l3vpn.0 routing table stores routing information in a Layer 3 virtual private network (VPN) environment. Here are sample routes from the bgp.l3vpn.0 routing table:
user@Riesling> show route table bgp.l3vpn.0
bgp.l3vpn.0: 13 destinations, 13 routes (13 active, 0 holddown, 0 hidden)
+ = Active Route, - = Last Active, * = Both
192.168.16.1:1:172.20.0.0/24
*[BGP/170] 14:28:30, localpref 100, from 192.168.5.1
AS path: 65000 I
> to 10.0.0.2 via fe-0/0/0.0, label-switched-path LSP
192.168.16.1:1:172.20.1.0/24
*[BGP/170] 14:28:30, localpref 100, from 192.168.5.1
AS path: 65000 I
> to 10.0.0.2 via fe-0/0/0.0, label-switched-path LSP
192.168.16.1:1:172.20.2.0/24
*[BGP/170] 14:28:30, localpref 100, from 192.168.5.1
AS path: 65000 I
> to 10.0.0.2 via fe-0/0/0.0, label-switched-path LSP
Table bgp.l2vpn.0
The bgp.l2vpn.0 routing table stores routing information in a Layer 2 VPN environment. Here are sample routes from the bgp.l2vpn.0 routing table:
user@Riesling> show route table bgp.l2vpn.0
bgp.l2vpn.0: 1 destinations, 1 routes (1 active, 0 holddown, 0 hidden)
+ = Active Route, - = Last Active, * = Both
192.168.24.1:1:4:1/96
*[BGP/170] 01:08:58, localpref 100, from 192.168.24.1
AS path: I
> to 10.0.16.2 via fe-0/0/1.0, label-switched-path LSP
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