I am making an attempt to get some readability round my understanding of FIB use vs. re-use.
To color the image, assume the next configuration:
!
vrf important
address-family ipv4 unicast
import route-target
123:4
!
export route-target
123:4
!
!
address-family ipv6 unicast
import route-target
123:4
!
export route-target
123:4
!
!
!
vrf purple
address-family ipv4 unicast
import route-target
123:4
123:69
!
export route-target
123:4
123:69
!
!
address-family ipv6 unicast
import route-target
123:4
123:69
!
export route-target
123:4
123:69
!
!
vrf blue
address-family ipv4 unicast
import route-target
123:4
123:420
!
export route-target
123:4
123:420
!
!
address-family ipv6 unicast
import route-target
123:4
123:420
!
export route-target
123:4
123:420
!
!
!
router bgp 1
address-family vpnv4 unicast
!
address-family vpnv6 unicast
!
neighbor 10.0.20.1
remote-as 1
update-source Loopback0
address-family vpnv4 unicast
!
address-family vpnv6 unicast
!
!
!
So right here we’ve got an IP-VPN community the place VRF blue and purple are importing routes from VRF important.
# vrf important
B* 0.0.0.0/0 [200/0] by way of 10.0.2.1 (nexthop in vrf default), 19:38:46
B 100.4.20.0/24 is instantly linked, 19:38:34, BVI420 (nexthop in vrf blue)
B 100.4.20.5/32 [200/0] by way of 10.0.9.1 (nexthop in vrf default), 17:02:48
B 100.100.69.0/24 [200/0] by way of 10.0.12.1 (nexthop in vrf default), 19:38:36
B 100.100.69.16/32 [200/0] by way of 10.0.12.1 (nexthop in vrf default), 17:02:48
# vrf blue
B* 0.0.0.0/0 [200/0] by way of 10.0.2.1 (nexthop in vrf default), 17:20:51
C 100.4.20.0/24 is instantly linked, 1d16h, BVI420
L 100.4.20.1/32 is instantly linked, 1d16h, BVI420
B 100.4.20.5/32 [200/0] by way of 10.0.9.1 (nexthop in vrf default), 17:00:30
B 100.100.69.0/24 [200/0] by way of 10.0.12.1 (nexthop in vrf default), 17:20:51
B 100.100.69.16/32 [200/0] by way of 10.0.12.1 (nexthop in vrf default), 17:00:30
# vrf purple
B* 0.0.0.0/0 [200/0] by way of 10.0.2.1 (nexthop in vrf default), 17:21:33
B 100.4.20.0/24 is instantly linked, 17:21:33, BVI420 (nexthop in vrf blue)
B 100.4.20.5/32 [200/0] by way of 10.0.9.1 (nexthop in vrf default), 17:01:12
B 100.100.69.0/24 [200/0] by way of 10.0.12.1 (nexthop in vrf default), 17:21:33
B 100.100.69.16/32 [200/0] by way of 10.0.12.1 (nexthop in vrf default), 17:01:12
Provided that among the many three VRFs, the next-hop is similar for the respective vacation spot, when it comes to FIB, what’s occurring? Within the instance beneath, the three FIB entries are for the main half equivalent, save for ptr (which so far as I perceive is the {hardware} pointer for that specific entry).
By advantage of every entry’s distinctive ptr worth, do every of those three entries eat (use) an IPv4 FIB useful resource, as a substitute of a single entry being created and all three routes reference that singular entry (re-use)?
RP/0/RP0/CPU0:ncs55a1-13.lab#present cef vrf important 100.4.20.5/32 transient
Wed Aug 28 15:33:08.761 EDT
100.4.20.5/32, model 11141873, inside 0x5000001 0x30 (ptr 0xd25eb1b0) [1], 0x0 (0x0), 0x208 (0xd201b938)
Up to date Aug 28 11:45:30.612
Prefix Len 32, site visitors index 0, priority n/a, precedence 3
by way of 10.0.9.1/32, 9 dependencies, recursive [flags 0x6000]
path-idx 0 NHID 0x0 [0x8a40ccb8 0x0]
recursion-via-/32
subsequent hop VRF - 'default', desk - 0xe0000000
subsequent hop 10.0.9.1/32 by way of 130018/0/21
subsequent hop 10.8.13.8/32 BE8 labels imposed {100003 92066}
subsequent hop 10.13.14.14/32 BE14 labels imposed {100003 92066}
RP/0/RP0/CPU0:ncs55a1-13.lab#present cef vrf purple 100.4.20.5/32 transient
Wed Aug 28 15:33:17.514 EDT
100.4.20.5/32, model 190, inside 0x5000001 0x30 (ptr 0xd25ed390) [1], 0x0 (0x0), 0x208 (0xd201daa8)
Up to date Aug 28 11:45:30.612
Prefix Len 32, site visitors index 0, priority n/a, precedence 3
by way of 10.0.9.1/32, 9 dependencies, recursive [flags 0x6000]
path-idx 0 NHID 0x0 [0x8a40ccb8 0x0]
recursion-via-/32
subsequent hop VRF - 'default', desk - 0xe0000000
subsequent hop 10.0.9.1/32 by way of 130018/0/21
subsequent hop 10.8.13.8/32 BE8 labels imposed {100003 92066}
subsequent hop 10.13.14.14/32 BE14 labels imposed {100003 92066}
RP/0/RP0/CPU0:ncs55a1-13.lab#present cef vrf blue 100.4.20.5/32 transient
Wed Aug 28 15:33:23.096 EDT
100.4.20.5/32, model 161, inside 0x5000001 0x30 (ptr 0xd25eac18) [1], 0x0 (0x0), 0x208 (0xd201c1a8)
Up to date Aug 28 11:45:30.612
Prefix Len 32, site visitors index 0, priority n/a, precedence 3
by way of 10.0.9.1/32, 9 dependencies, recursive [flags 0x6000]
path-idx 0 NHID 0x0 [0x8a40ccb8 0x0]
recursion-via-/32
subsequent hop VRF - 'default', desk - 0xe0000000
subsequent hop 10.0.9.1/32 by way of 130018/0/21
subsequent hop 10.8.13.8/32 BE8 labels imposed {100003 92066}
subsequent hop 10.13.14.14/32 BE14 labels imposed {100003 92066}
RP/0/RP0/CPU0:ncs55a1-13.lab#