Ccna routing and Switching Complete Study Guide

sh ip bgp summary

BGP router identifier 10.0.0.1, local AS number 1

BGP table version is 4, main routing table version 6

3 network entries using 396 bytes of memory

3 path entries using 156 bytes of memory

2/2 BGP path/bestpath attribute entries using 368 bytes of memory

3 BGP AS-PATH entries using 72 bytes of memory

0 BGP route-map cache entries using 0 bytes of memory

0 BGP filter-list cache entries using 0 bytes of memory

Bitfield cache entries: current 1 (at peak 1) using 32 bytes of memory

BGP using 1024 total bytes of memory

BGP activity 3/0 prefixes, 3/0 paths, scan interval 60 secs

 

Neighbor        V    AS MsgRcvd MsgSent   TblVer  InQ OutQ Up/Down State/PfxRcd

192.168.1.2     4   100      56      55        4    0    0 00:53:33        4

192.168.2.2     4   200      47      46        4    0    0 00:44:53        4

---

932

 

Chapter 21 

■

  Wide Area Networks

The first section of the 

show ip bgp summary

 command output describes the BGP table 

and its content:

 

■

The router ID of the router and local AS number.

 

■

The BGP table version is the version number of the local BGP table. This number is 

increased every time the table is changed.

The second section of the 

show ip bgp summary

 command output is a table in which the 

current neighbor statuses are shown. Here’s information about what you see displayed in 

the output of this command:

 

■

IP address of the neighbor.

 

■

BGP version number that is used by the router when communicating with the  

neighbor (v4).

 

■

AS number of the remote neighbor.

 

■

Number of messages and updates that have been received from the neighbor since the 

session was established.

 

■

Number of messages and updates that have been sent to the neighbor since the session 

was established.

 

■

Version number of the local BGP table that has been included in the most recent update 

to the neighbor.

 

■

Number of messages that are waiting to be processed in the incoming queue from this 

neighbor.

 

■

Number of messages that are waiting in the outgoing queue for transmission to the 

neighbor.

 

■

How long the neighbor has been in the current state and the name of the current state. 

Interestingly, notice there is no state listed, which is actually what you want because 

that means the peers are established.

 

■

Number of received prefixes from the neighbor.

 

■

ISP1 has two established sessions with the following neighbors:

 

■

192.168.1.2, which is the IP address of R1 router and is in AS 100

 

■

192.168.2.2, which is the IP address of R2 router and is in AS 200

 

■

From each of the neighbors, ISP1 has received one prefix (one network).

Now, for the CCNA objectives, remember that if you see this type of output at the end of 

the 

show ip bgp summary

 command, that the BGP session is not established between peers:

Neighbor       V    AS MsgRcvd MsgSent   TblVer  InQ OutQ Up/Down State/PfxRcd

192.168.1.2    4   64       0       0        0    0    0  never    Active

Notice the state of Active. Remember, seeing no state output is good! Active means we’re 

actively trying to establish with the peer.

---

Single-Homed EBGP