تكوين مقياس الكثافة في BGP على محولات Cisco Nexus

Nexus# configure terminal
Enter configuration commands, one per line. End with CNTL/Z.
Nexus(config)# router bgp 65535
Nexus(config-router)# address-family ipv4 unicast        
Nexus(config-router-af)# dampen-igp-metric ?
  <20-3600>  Time interval in seconds
             *Default value is 600

Nexus(config-router-af)# no dampen-igp-metric

configure terminal
!
hostname R1
!
router ospf 1
 router-id 10.255.255.1
!
interface Loopback0
 ip address 10.255.255.1 255.255.255.255
 ip ospf 1 area 0
!
interface GigabitEthernet0/0
 ip address 10.1.2.1 255.255.255.0
 ip ospf network point-to-point
 ip ospf 1 area 0
 no shutdown
!
end

configure terminal
!
hostname Nexus
!
feature ospf
feature bgp
!
route-map ALL
!
router ospf 1
  router-id 10.255.255.2
!
router bgp 65535
  router-id 10.255.255.2
  address-family ipv4 unicast
    redistribute ospf 1 route-map ALL
  neighbor 10.2.3.3
    remote-as 65535
    address-family ipv4 unicast
!
interface Ethernet1/1
  ip address 10.1.2.2/24
  ip ospf network point-to-point
  ip router ospf 1 area 0.0.0.0
  no shutdown
!
interface Ethernet1/2
  ip address 10.2.3.2/24
  no shutdown

configure terminal
!
hostname R3
!
router bgp 65535
 bgp log-neighbor-changes
 neighbor 10.2.3.2 remote-as 65535
!
interface GigabitEthernet0/0
 ip address 10.2.3.3 255.255.255.0
 no shutdown
!
end

Nexus# show bgp internal af 
. . .

BGP Address Family Information for VRF: default
  Import Pending               : No
  Import Pending               : never
  Import Pending Reset         : never

Table Context Address : 0xcfa08bf4

Address family: IPv4 Unicast
. . .
IGP Metric Dampening Interval  : 600

Nexus# show ip route 10.255.255.1
IP Route Table for VRF "default"
'*' denotes best ucast next-hop
'**' denotes best mcast next-hop
'[x/y]' denotes [preference/metric]
'%<string>' in via output denotes VRF <string>

10.255.255.1/32, ubest/mbest: 1/0
    *via 10.1.2.1, Eth1/1, [110/41], 01:58:41, ospf-1, intra
Nexus# 


* There is an update in the Cost of the OSPF route 10.255.255.1/32


Nexus# show ip route 10.255.255.1
IP Route Table for VRF "default"
'*' denotes best ucast next-hop
'**' denotes best mcast next-hop
'[x/y]' denotes [preference/metric]
'%<string>' in via output denotes VRF <string>

10.255.255.1/32, ubest/mbest: 1/0
    *via 10.1.2.1, Eth1/1, [110/190], 00:00:02, ospf-1, intra
Nexus# 
Nexus# show bgp ipv4 unicast
BGP routing table information for VRF default, address family IPv4 Unicast
BGP table version is 4, Local Router ID is 10.255.255.2
Status: s-suppressed, x-deleted, S-stale, d-dampened, h-history, *-valid, >-best
Path type: i-internal, e-external, c-confed, l-local, a-aggregate, r-redist, I-i
njected
Origin codes: i - IGP, e - EGP, ? - incomplete, | - multipath, & - backup

   Network            Next Hop            Metric     LocPrf     Weight Path
*>r10.255.255.1/32    0.0.0.0                 41        100      32768 ?

Nexus#


* After 600 seconds.


Nexus# show bgp ipv4 unicast
BGP routing table information for VRF default, address family IPv4 Unicast
BGP table version is 5, Local Router ID is 10.255.255.2
Status: s-suppressed, x-deleted, S-stale, d-dampened, h-history, *-valid, >-best
Path type: i-internal, e-external, c-confed, l-local, a-aggregate, r-redist, I-i
njected
Origin codes: i - IGP, e - EGP, ? - incomplete, | - multipath, & - backup

   Network            Next Hop            Metric     LocPrf     Weight Path
*>r10.255.255.1/32    0.0.0.0                190        100      32768 ?

Nexus# configure terminal
Enter configuration commands, one per line. End with CNTL/Z.
Nexus(config)# router bgp 65535
Nexus(config-router)#   address-family ipv4 unicast       
Nexus(config-router-af)# no dampen-igp-metric


* There is an update in the Cost of the OSPF route 10.255.255.1/32


Nexus# show ip route 10.255.255.1
IP Route Table for VRF "default"
'*' denotes best ucast next-hop
'**' denotes best mcast next-hop
'[x/y]' denotes [preference/metric]
'%<string>' in via output denotes VRF <string>

10.255.255.1/32, ubest/mbest: 1/0
    *via 10.1.2.1, Eth1/1, [110/190], 00:00:02, ospf-1, intra


Nexus# show ip bgp 
BGP routing table information for VRF default, address family IPv4 Unicast
BGP table version is 7, Local Router ID is 10.255.255.2
Status: s-suppressed, x-deleted, S-stale, d-dampened, h-history, *-valid, >-best
Path type: i-internal, e-external, c-confed, l-local, a-aggregate, r-redist, I-i
njected
Origin codes: i - IGP, e - EGP, ? - incomplete, | - multipath, & - backup

   Network            Next Hop            Metric     LocPrf     Weight Path
*>r10.255.255.1/32    0.0.0.0                190        100      32768 ?

Nexus# debug-filter bgp prefix 10.255.255.1/32
Nexus# debug logfile bgpdebug.log
Nexus# debug bgp dampening brib 
Nexus# 

Nexus# show debug logfile bgpdebug.log
2019 Jul 23 21:13:27.676328 bgp: [25368] (default) BRIB: [IPv4 Unicast] Setting the update pending flag for 10.255.255.1/32
Nexus# show debug logfile bgpdebug.log
2019 Jul 23 21:13:27.676328 bgp: [25368] (default) BRIB: [IPv4 Unicast] Setting the update pending flag for 10.255.255.1/32
2019 Jul 23 21:20:47.641987 bgp: [25368] (default) BRIB: [IPv4 Unicast] Clearing the update pending flag for 10.255.255.1/32
2019 Jul 23 21:20:47.642013 bgp: [25368] (default) BRIB: [IPv4 Unicast] Originating prefix 10.255.255.1/32, route type redist 
2019 Jul 23 21:20:47.642075 bgp: [25368] (default) BRIB: [IPv4 Unicast] Installing prefix 10.255.255.1/32 (redist) via 0.0.0.0 (0x0/0x0) into BRIB with extcomm Extcommunity: OSPF RT:0.0.0.0:0:0 
2019 Jul 23 21:20:47.642395 bgp: [25368] (default) BRIB: [IPv4 Unicast] Path to 10.255.255.1/32 via 0.0.0.0 already exists, dflags=0x80002 
2019 Jul 23 21:20:47.642415 bgp: [25368] (default) BRIB: [IPv4 Unicast] (10.255.255.1/32 (local)): bgp_brib_add: handling nexthop, path->flags2: 0x1 
2019 Jul 23 21:20:47.642447 bgp: [25368] (default) BRIB: [IPv4 Unicast] (10.255.255.1/32 (local)): returning from bgp_brib_add, reeval=0new_path: 0, change: 1, undelete: 0, history: 0, force: 0, (pflags=0x2408) rnh_flag_change 0 
2019 Jul 23 21:20:47.642475 bgp: [25368] (default) BRIB: [IPv4 Unicast] Cleanup for dest 10.255.255.1/32 exits since it's on newlist
Nexus#