I have this ospf topology, from R1 view it show 5 link connected. If you see the R1 it's directly connected to r3 and r2, and r3-r4, r2-r5. so totally 4 links and if you look R1 database network 18.104.22.168 and 192.168.12.0,192.168.13.0 it showing as STUB network, can any one explain me why it's showing STUB Network and how r1 has 5 links, if you add loop interface as a link, then every router has it's own loop interface, then it should show 10 links am right ?
R1#sh ip ospf data
Router Link States (Area 0)
Link ID ADV Router Age Seq# Checksum Link count
22.214.171.124 126.96.36.199 1576 0x80000004 0x00FEF85
188.8.131.52 184.108.40.206 1577 0x80000003 0x003070 2
220.127.116.11 18.104.22.168 260 0x80000003 0x001481 2
R1#sh ip ospf database router 22.214.171.124
OSPF Router with ID (126.96.36.199) (Process ID 1)
Router Link States (Area 0)
LS age: 123
Options: (No TOS-capability, DC)
LS Type: Router Links
Link State ID: 188.8.131.52
Advertising Router: 184.108.40.206
LS Seq Number: 80000005
Number of Links: 5
Link connected to: a Stub Network
(Link ID) Network/subnet number: 220.127.116.11
(Link Data) Network Mask: 255.255.255.255
Number of TOS metrics: 0
TOS 0 Metrics: 1
Link connected to: another Router (point-to-point)
this is an ongoing question and probably one of the most confusing LSDB details.
The purpose of a router LSA is to describe the states of a router's OSPF interfaces and their attached neighbors.
The developers decided to design the data-structure for such a router LSA as efficient as possible (or what they considered most efficient at this time). Beside a small Type-field, a link is basically described by two 32-bit fields: Link ID and Link Data.
This is perfectly enough to describe an unnumbered link or a loopback interface (which cannot have an OSPF neighbor by nature), but to describe a numbered link (IP address and subnetmask) and the attached neighbor, two 32-bit fields are insufficient.
This is why two link entries are used to describe a numbered link:
Link Type: Point-to-Point
Link ID: The neighbor's Router-ID
Link Data: IP-Address of the local interface
Link Type: Stub Network
Link ID: ID of the network
Link Data: subnetmask
Here you can find some interesting discussions about that topic with much more details:
(...) if you add loop interface as a link, then every router has it's own loop interface, then it should show 10 links am right ?
Remember: The scope of type-1 and type-2 LSAs is the area they belong to. Information about (loopback) interfaces from other areas are propagated by distance-vector mechanisms: Their corresponing RIB-entries are translated to summary LSAs (type-3) by the ABRs.
As per my knowledge why router 1 is showing 5 as link count because point to point serial link is counted as 2 because one count for outgoing and the second count for in comming which is the same link.
point-to-point interface counts as 2 links, all the rest network type links count as 1
This is actually a pretty cool feature, i didn't even know it existed until I was looking for a solution to advertise a subnet (prefix in BGP talk), only if a certain condition existed. This is exactly what conditional advertisements does
j ai une question j ai achete un routeur cisco 887VA-k9 , je le configuré avec la configuration ci- dessous
si je le lier avec mon pc portable sur l un de ses ports directement ça marche toute est bien ( la connexion internet + m...
Attached policy provides CLI access to the Cisco 4G router over text messaging. Two files are in the attached .tar file:
2. PDF with instructions on how to load and use the .tcl file.