底辺エンジニアの備忘録

30過ぎて、記憶力低下が著しい為、メモ代わりにしていく予定。 自身のスキルが低いので、内容の正確さは保障できません・・・OTL

JUNOS_BGP_その1(timer)

JUNOSのBGP
まずか簡単なところから構成は↓

f:id:klock_3rd:20180520210748p:plain

R4はR6のConfigはR3とR5と似た内容なので、省略

R3

 R3#show run | sec router bgp 100
router bgp 100
 bgp router-id 1.1.1.3
 bgp log-neighbor-changes
 neighbor 172.16.4.254 remote-as 100
 neighbor 172.16.5.254 remote-as 200
 !
 address-family ipv4
  network 1.1.1.3 mask 255.255.255.255
  neighbor 172.16.4.254 activate
  neighbor 172.16.4.254 next-hop-self
  neighbor 172.16.4.254 soft-reconfiguration inbound
  neighbor 172.16.5.254 activate
  neighbor 172.16.5.254 soft-reconfiguration inbound
 exit-address-family

 

R5

router-id 2.1.1.5;
autonomous-system 200;
set policy-options prefix-list LOCAL 2.1.1.5/32
set policy-options policy-statement EXT term 1 from protocol bgp
set policy-options policy-statement EXT term 1 then next-hop self
set policy-options policy-statement EXT term 2 from prefix-list LOCAL
set policy-options policy-statement EXT term 2 then accept
set policy-options policy-statement INT term 1 from protocol bgp
set policy-options policy-statement INT term 1 then next-hop self
set policy-options policy-statement INT term 1 then accept
set policy-options policy-statement INT term 2 from prefix-list LOCAL
set policy-options policy-statement INT term 2 then next-hop self
set protocols bgp group external type external
set protocols bgp group external local-address 172.16.5.254
set protocols bgp group external neighbor 172.16.5.1 export EXT
set protocols bgp group external neighbor 172.16.5.1 peer-as 100
set protocols bgp group internal type internal
set protocols bgp group internal local-address 172.16.7.1
set protocols bgp group internal neighbor 172.16.7.254 export INT

 

R5でR6とのpeer確認

admin@R5# run show bgp neighbor 172.16.7.254
Peer: 172.16.7.254+54497 AS 200 Local: 172.16.7.1+179 AS 200
  Group: internal Routing-Instance: master
  Forwarding routing-instance: master
  Type: Internal State: Established Flags: <Sync>
  Last State: OpenConfirm Last Event: RecvKeepAlive
  Last Error: Cease
  Export: [ INT ]
  Options: <Preference LocalAddress GracefulRestart Refresh>
  Local Address: 172.16.7.1 Holdtime: 90 Preference: 170
  Number of flaps: 9
  Last flap event: Stop
  Error: 'Cease' Sent: 7 Recv: 2
  Peer ID: 2.1.1.6 Local ID: 2.1.1.5 Active Holdtime: 90
  Keepalive Interval: 30 Group index: 1 Peer index: 0 SNMP index: 3

 R5でR3とのpeer確認

admin@R5# run show bgp neighbor 172.16.5.1
Peer: 172.16.5.1+36571 AS 100 Local: 172.16.5.254+179 AS 200
  Group: external Routing-Instance: master
  Forwarding routing-instance: master
  Type: External State: Established Flags: <Sync>
  Last State: OpenConfirm Last Event: RecvKeepAlive
  Last Error: Cease
  Export: [ EXT ]
  Options: <Preference LocalAddress GracefulRestart PeerAS Refresh>
  Local Address: 172.16.5.254 Holdtime: 90 Preference: 170
  Number of flaps: 6
  Last flap event: Stop
  Error: 'Cease' Sent: 6 Recv: 0
  Peer ID: 1.1.1.3 Local ID: 2.1.1.5 Active Holdtime: 90
  Keepalive Interval: 30 Group index: 0 Peer index: 0 SNMP index: 2

 

JUNOSのinterval / holdtime は30/90
Ciscoのinterval / holdtime は60/180


BGPのtimer不一致時は小さいほうに従うので、このR3-R5はJUNOSに従っている。
R3側でも確認

 R3#show bgp ipv4 unicast neighbors 172.16.5.254
BGP neighbor is 172.16.5.254, remote AS 200, external link
  BGP version 4, remote router ID 2.1.1.5
  BGP state = Established, up for 00:57:07
  Last read 00:00:13, last write 00:00:16, hold time is 90, keepalive interval is 30 seconds
  Neighbor sessions:
  1 active, is not multisession capable (disabled)

 念のため、R5との接続はデフォルト60/180になっている事を確認

 R3#show bgp ipv4 unicast neighbors 172.16.4.254
BGP neighbor is 172.16.4.254, remote AS 100, internal link
  BGP version 4, remote router ID 1.1.1.4
  BGP state = Established, up for 00:29:41
  Last read 00:00:14, last write 00:00:18, hold time is 180, keepalive interval is 60 seconds
  Neighbor sessions:
  1 active, is not multisession capable (disabled)
  Neighbor capabilities:

 

こっから本題

この状態でR3をtimer 10/30、R5を15/45に変更してみる。
この場合、R3-R5は10/30 R5-R6は15/45になると思われる。

変更後、R5でR3とのpeer確認

 admin@R5# run show bgp neighbor 172.16.5.1
Peer: 172.16.5.1+56976 AS 100 Local: 172.16.5.254+179 AS 200
  Group: external Routing-Instance: master
  Forwarding routing-instance: master
  Type: External State: Established Flags: <Sync>
  Last State: OpenConfirm Last Event: RecvKeepAlive
  Last Error: None
  Export: [ EXT ]
  Options: <Preference LocalAddress HoldTime GracefulRestart PeerAS Refresh>
  Local Address: 172.16.5.254 Holdtime: 45 Preference: 170
  Number of flaps: 1
  Last flap event: TransportError
  Peer ID: 1.1.1.3 Local ID: 2.1.1.5 Active Holdtime: 30
  Keepalive Interval: 10 Group index: 0 Peer index: 0 SNMP index: 2
  I/O Session Thread: bgpio-0 State: Enabled

 変更後、R6でR5とのpeer確認

 admin@R6# run show bgp neighbor 172.16.7.1
Peer: 172.16.7.1+179 AS 200 Local: 172.16.7.254+64962 AS 200
  Group: internal Routing-Instance: master
  Forwarding routing-instance: master
  Type: Internal State: Established Flags: <Sync>
  Last State: OpenConfirm Last Event: RecvKeepAlive
  Last Error: Cease
  Export: [ INT ]
  Options: <Preference LocalAddress GracefulRestart Refresh>
  Local Address: 172.16.7.254 Holdtime: 90 Preference: 170
  Number of flaps: 9
  Last flap event: RecvNotify
  Error: 'Cease' Sent: 1 Recv: 8
  Peer ID: 2.1.1.5 Local ID: 2.1.1.6 Active Holdtime: 45
  Keepalive Interval: 15 Group index: 1 Peer index: 0 SNMP index: 3