Static Route Preference and 'qualified-next-hop' Configuration(Juniper vMX)

1. Static Route Preference and 'qualified-next-hop' Configuration 구성도

1) Static Route Preference and 'qualified-next-hop' Configuration 구성도

 

2) 테스트 장비

• Emulator : EVE-NG
• OS : Juniper vMX 18.2R1.9

 

 

2. Static Route Preference and 'qualified-next-hop' Configuration

1) Interface IP Address Configuration

< R1 : Interface IP 설정 >
set interfaces ge-0/0/0 unit 0 family inet address 1.1.3.1/24
set interfaces ge-0/0/1 unit 0 family inet address 1.1.2.1/24
set interfaces lo0 unit 0 family inet address 1.1.1.1/32

< R2 : Interface IP 설정 >
set interfaces ge-0/0/0 unit 0 family inet address 1.1.2.2/24
set interfaces ge-0/0/1 unit 0 family inet address 1.2.3.2/24
set interfaces lo0 unit 0 family inet address 2.2.2.2/32

< R3 : Interface IP 설정 >
set interfaces ge-0/0/0 unit 0 family inet address 1.2.3.3/24
set interfaces ge-0/0/1 unit 0 family inet address 1.1.3.3/24
set interfaces lo0 unit 0 family inet address 3.3.3.3/32

 

2) Static Route Preference and 'qualified-next-hop' Configuration

< R1 : Static Route 설정 >
set routing-options static route 3.3.3.3/32 qualified-next-hop 1.1.2.2 preference 20
set routing-options static route 3.3.3.3/32 qualified-next-hop 1.1.3.3 preference 10

 

3) Routing Table and Forwarding Table

root@R1> show route table inet.0        

inet.0: 6 destinations, 7 routes (6 active, 0 holddown, 0 hidden)
+ = Active Route, - = Last Active, * = Both

1.1.1.1/32         *[Direct/0] 02:33:28
                    > via lo0.0
1.1.2.0/24         *[Direct/0] 02:34:58
                    > via ge-0/0/1.0
1.1.2.1/32         *[Local/0] 02:34:58
                      Local via ge-0/0/1.0
1.1.3.0/24         *[Direct/0] 02:34:58
                    > via ge-0/0/0.0
1.1.3.1/32         *[Local/0] 02:34:58
                      Local via ge-0/0/0.0
3.3.3.3/32         *[Static/10] 00:01:39
                    > to 1.1.3.3 via ge-0/0/0.0
                    [Static/20] 00:01:39
                    > to 1.1.2.2 via ge-0/0/1.0

root@R1> show route protocol static table inet.0 

inet.0: 6 destinations, 7 routes (6 active, 0 holddown, 0 hidden)
+ = Active Route, - = Last Active, * = Both

3.3.3.3/32         *[Static/10] 00:01:48
                    > to 1.1.3.3 via ge-0/0/0.0
                    [Static/20] 00:01:48
                    > to 1.1.2.2 via ge-0/0/1.0

• Prefernec 값이 서로 다른 Entry가 라우팅 테이블에 존재
• 여러 Entry 중에 Preference 값이 제일 작은 Entry에 ' * '가 표시되며 Forwarding Table에 설치

 

root@R1> show route forwarding-table family inet table default 
Routing table: default.inet
Internet:
Enabled protocols: Bridging, 
Destination        Type RtRef Next hop           Type Index    NhRef Netif
default            perm     0                    rjct       36     1
0.0.0.0/32         perm     0                    dscd       34     1
1.1.1.1/32         intf     0 1.1.1.1            locl      584     1
1.1.2.0/24         intf     0                    rslv      583     1 ge-0/0/1.0
1.1.2.0/32         dest     0 1.1.2.0            recv      581     1 ge-0/0/1.0
1.1.2.1/32         intf     0 1.1.2.1            locl      582     2
1.1.2.1/32         dest     0 1.1.2.1            locl      582     2
1.1.2.2/32         dest     0 50:0:0:b:0:2       ucst      585     1 ge-0/0/1.0
1.1.2.255/32       dest     0 1.1.2.255          bcst      580     1 ge-0/0/1.0
1.1.3.0/24         intf     0                    rslv      579     1 ge-0/0/0.0
1.1.3.0/32         dest     0 1.1.3.0            recv      577     1 ge-0/0/0.0
1.1.3.1/32         intf     0 1.1.3.1            locl      578     2
1.1.3.1/32         dest     0 1.1.3.1            locl      578     2
1.1.3.3/32         dest     0 50:0:0:d:0:3       ucst      586     3 ge-0/0/0.0
1.1.3.255/32       dest     0 1.1.3.255          bcst      512     1 ge-0/0/0.0
3.3.3.3/32         user     0 1.1.3.3            ucst      586     3 ge-0/0/0.0
224.0.0.0/4        perm     0                    mdsc       35     1
224.0.0.1/32       perm     0 224.0.0.1          mcst       31     1
255.255.255.255/32 perm     0                    bcst       32     1

root@R1> show route forwarding-table matching 3.3.3.3 family inet table default 
Routing table: default.inet
Internet:
Enabled protocols: Bridging, 
Destination        Type RtRef Next hop           Type Index    NhRef Netif
3.3.3.3/32         user     0 1.1.3.3            ucst      586     3 ge-0/0/0.0

• 라우팅 테이블에서 Preference 값이 다른 Entry 중, ' * ' 표시가 있는 Entry만 설치되었음을 확인

 

4) R1 → R3 Lo0 Ping Test

root@R1> ping 3.3.3.3 count 2 
PING 3.3.3.3 (3.3.3.3): 56 data bytes
64 bytes from 3.3.3.3: icmp_seq=0 ttl=64 time=5.233 ms
64 bytes from 3.3.3.3: icmp_seq=1 ttl=64 time=4.033 ms

--- 3.3.3.3 ping statistics ---
2 packets transmitted, 2 packets received, 0% packet loss
round-trip min/avg/max/stddev = 4.033/4.633/5.233/0.600 ms

• R1 → R3 Lo으로 ICMP Request 전송 시, R1의 Forwarding Table에 Active되어 있는 Entry를 참고하여 ge-0/0/0.0 인터페이스로 전송

 

• R3는 ICMP Request 수신 시, D-MAC이 본인임을 확인하고 EtherType이 IP 임을 확인하고 D-IP가 ICMP Requset를 수신한 인터페이스가 아님을 확인하고 라우팅 테이블의 Entry 중에 Longest Match Rule에 의해 매칭되는 인터페이스가 Loopback 임을 알고 Protocol이 ICMP임을 확인하고 Type 및 Code를 확인하여 ICMP Request임을 확인하고 ICMP Request의 S-IP를 D-IP로, D-IP를 S-IP로 구성하여 ICMP Reply를 전송