Juniper M/T Router Notes

1."commit synchronize" to ensures that a configuration file on a backup Routing Engine isidentical to the file on the primary Routing Engine.

 

2. The inet.0 routing table is used to store IPv4 routes. All routing protocols place information into this table by default.

    The inet.3 routing table contains the egress IP address of a MPLS lable switched path (LSP). Routes are inserted into inet.3 by the RSVP protocol.

    

3. When router receives a label of zero it will perform a label swap.

   Our definition of each router’s role along the path of an LSP assumes the default JUNOS software behavior of penultimate hop popping (PHP).  

    

4.configure a static LSP for switched path requires that each router along the LSP be configured explicitly.

 

5. Label Request Object

    The label request object is encoded in the Path messages sent to the egress router. This object allows each router to assign a label value to the requested LSP. When the Path message is received, the local router allocates a label and stores it with the Path soft state for that LSP. When the Resv message arrives from the downstream neighbor, the label is advertised upstream in an RSVP label object.

 

6. The OSPF stub area provides for a smaller link-state database by restricting the presence of AS external LSAs (type 5) within the area. A not-so-stubby area restricts type 5 external LSAs, but still allows for some external routes to be present in the database with a new NSSA external LSA type 7.

 

7. OSPF Process in the ExStart state, the local router and its neighbor establish which router is in charge of the database synchronization process.
The higher router ID of the two neighbors controls which router becomes the master.
OPENSENT state is reached once TCP session is established. Established designates a fully operational OSPF connection

8. BGP Process States
IDLE: After the BGP process starts, a TCP session is initiated with the remote peer. The local router transitions to the Connect state and begins listening for a connection initiated by the remote peer.
CONNECT: In this state, the local router is has seen a TCP connection attempt from a peer and is waiting for the TCP session to be completed. If it is successful, the local router sends an Open message to the peer and transitions to the OPENSENT state.
ACTIVE: In the active state, the local router is trying to establish a TCP session with its peer. If the session establishes successfully, an Open message is sent and the local router transitions to the OPENSENT state.

9. The order of BGP route selection:
1. The next hop must be reachable
2. Highest local preference
3. Shortest AS Path
4. Smallest Origin attribute
5. Smallest Multiple Exit Discriminator (MED)
6. EGP routes preferred over IBGP routes
7. Smallest IGP metric to advertised BGP next-hop
8. Shortest cluster-list length if route reflection is used for IBGP
9. Smallest numerical ID
10. Smallest numerical IP address

 

10. The current BGP specification dictates three possible origin values:
IGP: The route was originally learned from an IGP on the source router. IGP is
displayed with the character "I" and is encoded as a value of 0.
EGP: The route was originally learned by the EGP protocol on the source router. EGP is
displayed with the character "E" and is encoded as a value of 1.
Incomplete: The route’s source was unkown to the initial BGP router. Incomplete is
displayed with the character "?" and is encoded as a value of 2.

 

11.