Your reasoning is sound.
-- Marko Milivojevic - CCIE #18427 Senior Technical Instructor - IPexpert FREE CCIE training: http://bit.ly/vLecture Mailto: markom_at_ipexpert.com Telephone: +1.810.326.1444 Web: http://www.ipexpert.com/ On Wed, Jun 29, 2011 at 13:16, Nathan Falcon <nathan.falcon_at_gmail.com> wrote: > Thanks Marko, I understand that it will function if configured correctly, > but I'm looking at this from an "interpretation or the question" > perspective. > Based off your topology: > If the lab states that Area 254 should be authenticated and it so happens > that you need to configure a virtual-link through area 254, would you need > to configure authentication on that link to satisfy the question? B I'm > pretty sure the virtual-link will work with or without authentication, but I > understand virtual-links to be considered area 0, not 254 (in this case). > My deduction would be that if: > Area 254 requiresB authenticationB - NO authentication required by > theB scenarioB on a virtual-link through Area254 > Area 0 requiresB authenticationB - B authentication requiredB on the > virtual-linkB through Area254 > Is my logic sound in this case, or am I missing something? > Much appreciated, > Nate > > On Wed, Jun 29, 2011 at 3:42 PM, Marko Milivojevic <markom_at_ipexpert.com> > wrote: >> >> On Wed, Jun 29, 2011 at 12:27, -Hammer- <bhmccie_at_gmail.com> wrote: >> > Thanks for clarifying Marko. >> >> Don't take my word for it though. Here's the quick verification: >> >> R2---R5---R4 >> >> R2: >> Lo0: Area 0 >> Se0/2/0: Area 254 to R5 >> >> R5: >> Lo0: Area 254 >> Se0/2/0: Area 254 to R2 >> Se0/0/0: Area 254 to R4 >> >> R4: >> Lo0: Area 0 >> Se0/1/0: Area 254 to R5 >> >> Configurations: >> >> R2: >> >> interface Loopback0 >> B ip address 192.168.0.2 255.255.255.255 >> ! >> interface Serial0/2/0 >> B ip address 192.168.25.2 255.255.255.0 >> B ip ospf message-digest-key 1 md5 ipexpert >> ! >> router ospf 1 >> B router-id 2.2.2.2 >> B area 254 authentication message-digest >> B area 254 virtual-link 4.4.4.4 >> B network 192.168.0.2 0.0.0.0 area 0 >> B network 192.168.25.0 0.0.0.255 area 254 >> ! >> >> R5: >> >> interface Loopback0 >> B ip address 192.168.0.5 255.255.255.255 >> ! >> interface Serial0/0/0 >> B ip address 192.168.45.5 255.255.255.0 >> B ip ospf message-digest-key 1 md5 ipexpert >> ! >> interface Serial0/2/0 >> B ip address 192.168.25.5 255.255.255.0 >> B ip ospf message-digest-key 1 md5 ipexpert >> ! >> router ospf 1 >> B router-id 5.5.5.5 >> B area 254 authentication message-digest >> B network 192.168.0.5 0.0.0.0 area 254 >> B network 192.168.25.0 0.0.0.255 area 254 >> B network 192.168.45.0 0.0.0.255 area 254 >> ! >> >> R4: >> >> interface Loopback0 >> B ip address 192.168.0.4 255.255.255.255 >> ! >> interface Serial0/1/0 >> B ip address 192.168.45.4 255.255.255.0 >> B ip ospf message-digest-key 1 md5 ipexpert >> ! >> router ospf 1 >> B router-id 4.4.4.4 >> B area 254 authentication message-digest >> B area 254 virtual-link 2.2.2.2 >> B network 192.168.0.4 0.0.0.0 area 0 >> B network 192.168.45.0 0.0.0.255 area 254 >> ! >> >> Verification: >> >> R2#sh ip ospf int s0/2/0 >> Serial0/2/0 is up, line protocol is up >> B Internet Address 192.168.25.2/24, Area 254 >> B Process ID 1, Router ID 2.2.2.2, Network Type POINT_TO_POINT, Cost: 64 >> B Transmit Delay is 1 sec, State POINT_TO_POINT >> B Timer intervals configured, Hello 10, Dead 40, Wait 40, Retransmit 5 >> B B oob-resync timeout 40 >> B B Hello due in 00:00:00 >> B Supports Link-local Signaling (LLS) >> B Cisco NSF helper support enabled >> B IETF NSF helper support enabled >> B Index 1/2, flood queue length 0 >> B Next 0x0(0)/0x0(0) >> B Last flood scan length is 1, maximum is 1 >> B Last flood scan time is 0 msec, maximum is 0 msec >> B Neighbor Count is 1, Adjacent neighbor count is 1 >> B B Adjacent with neighbor 5.5.5.5 >> B Suppress hello for 0 neighbor(s) >> B Message digest authentication enabled >> B B Youngest key id is 1 >> >> We can see authentication enabled on Serial 0/2/0 >> >> R2#show ip ospf int br >> Interface B B PID B Area B B B B B B IP Address/Mask B B Cost B State Nbrs F/C >> VL0 B B B B B 1 B B 0 B B B B B B B 192.168.25.2/24 B B 128 B P2P B 1/1 >> Lo0 B B B B B 1 B B 0 B B B B B B B 192.168.0.2/32 B B 1 B B LOOP B 0/0 >> Se0/2/0 B B B 1 B B 254 B B B B B B 192.168.25.2/24 B B 64 B B P2P B 1/1 >> >> We see a neighbor on Virutal-link0. Let's check the neioghbors: >> >> R2#show ip ospf nei >> >> Neighbor ID B B Pri B State B B B B B Dead Time B Address >> Interface >> 4.4.4.4 B B B B B 0 B FULL/ B - B B B B B - B B B B 192.168.45.4 B B OSPF_VL0 >> 5.5.5.5 B B B B B 0 B FULL/ B - B B B B 00:00:39 B B 192.168.25.5 >> B Serial0/2/0 >> >> Looks like R4 is our neighbor. How about the routes in the table? >> >> R2#show ip route ospf >> O B B 192.168.45.0/24 [110/128] via 192.168.25.5, 00:06:31, Serial0/2/0 >> B B 192.168.0.0/32 is subnetted, 3 subnets >> O B B B 192.168.0.4 [110/129] via 192.168.25.5, 00:04:41, Serial0/2/0 >> O B B B 192.168.0.5 [110/65] via 192.168.25.5, 00:06:31, Serial0/2/0 >> >> Finally, reachability: >> >> R2#ping 192.168.0.4 so lo0 >> >> Type escape sequence to abort. >> Sending 5, 100-byte ICMP Echos to 192.168.0.4, timeout is 2 seconds: >> Packet sent with a source address of 192.168.0.2 >> !!!!! >> Success rate is 100 percent (5/5), round-trip min/avg/max = 1/3/4 ms >> >> -- >> Marko Milivojevic - CCIE #18427 >> Senior Technical Instructor - IPexpert >> >> FREE CCIE training: http://bit.ly/vLecture >> >> Mailto: markom_at_ipexpert.com >> Telephone: +1.810.326.1444 >> Web: http://www.ipexpert.com/ >> >> >> Blogs and organic groups at http://www.ccie.net >> >> _______________________________________________________________________ >> Subscription information may be found at: >> http://www.groupstudy.com/list/CCIELab.html Blogs and organic groups at http://www.ccie.netReceived on Wed Jun 29 2011 - 13:53:49 ART
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