Consider the above scenario. I configured ebgp neighborship to form between R1 and R4.
Below mentioned are the device configs:
R1(config-router)#do sh ip int br
Interface IP-Address OK? Method Status Protocol
FastEthernet0/0 unassigned YES NVRAM administratively down down
Serial0/0 40.1.1.1 YES NVRAM up up
FastEthernet0/1 unassigned YES NVRAM administratively down down
Serial0/1 20.1.1.2 YES NVRAM up down
Serial0/2 unassigned YES NVRAM administratively down down
Serial0/3 unassigned YES NVRAM administratively down down
R1#
router bgp 200
no synchronization
bgp log-neighbor-changes
network 20.1.1.0 mask 255.255.255.0
network 40.1.1.0 mask 255.255.255.0
neighbor 20.1.1.1 remote-as 100
neighbor 40.1.1.2 remote-as 200
neighbor 60.1.1.1 remote-as 400
neighbor 60.1.1.1 ebgp-multihop 255 <<<<
no auto-summary
R4#
router bgp 400
no synchronization
bgp log-neighbor-changes
network 60.1.1.0 mask 255.255.255.0
neighbor 40.1.1.1 remote-as 200
neighbor 40.1.1.1 ebgp-multihop 255<<<<<<<<<<<<<<<<<
neighbor 50.1.0.1 remote-as 200
neighbor 60.1.1.2 remote-as 400
R4(config-router)#DO SH IP INT BR
Interface IP-Address OK? Method Status Protocol
FastEthernet0/0 unassigned YES NVRAM administratively down down
Serial0/0 60.1.1.1 YES NVRAM up up
FastEthernet0/1 unassigned YES NVRAM administratively down down
Serial0/1 50.1.0.2 YES NVRAM up up
Serial0/2 unassigned YES NVRAM administratively down down
>>While configuring ebgp multihop on both routers, I simply configured ebgp multihop, instead of ebgp multihop 2. I expected the neighborship to not come up
But it did come up and also, in the configuration, I saw a value assigned to 255 automatically, as I have pasted above.
Is this some implicit rule of ebgp multihop, that an automatic value is assigned if we dont configure it?
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