mikey250
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bgp ibgp/ebgp & as_path attribute - query
hi ive configured a small test network representing both 'ibgp & ebgp with router 1 connected to both router 2 & 3.
1st task:
note: router 1 & 2 have configured both 'bgp & ospf representing igp'
- router 1 is connected via a serial cable to router 3
- router 1 is also connected via a fastethernet cable to router 2
- router 1 also has a single loopback
- router 2 is connected to router 1
- router 2 also has a single loopback
- router 3 is also configured with just 'bgp & not ospf' as it is external
- router 3 has also a fastethernet connection to a lan
ive configured on router 1 & router 3 for example:
router 1
router bgp 200
network 172.16.1.0 mask 255.255.255.0
router 3
router bgp 100
network 192.168.1.32 mask 255.255.255.224
2nd task:
ive configured a small network for using the 'as_path attribute' - but instead of configuring something simular to above 'mask' command ive done the following:
router 1
router bgp 300
no synchronization
neighbor 192.168.1.5 remote-as 100
neighbor 172.16.1.18 remote-as 65000
network 202.2.2.0
router 2
router bgp 100
no synchronization
neighbor 192.168.1.6 remote-as 300
network 201.1.1.0
router 3
router bgp 65000
no synchronization
neighbor 172.24.1.17 remote-as 300
network 203.3.3.0
question. i assume it is something to do with how ibgp & ebgp distinguish itself with 'bgp' as why step 2 does not use the 'mask' command ?
1st task:
note: router 1 & 2 have configured both 'bgp & ospf representing igp'
- router 1 is connected via a serial cable to router 3
- router 1 is also connected via a fastethernet cable to router 2
- router 1 also has a single loopback
- router 2 is connected to router 1
- router 2 also has a single loopback
- router 3 is also configured with just 'bgp & not ospf' as it is external
- router 3 has also a fastethernet connection to a lan
ive configured on router 1 & router 3 for example:
router 1
router bgp 200
network 172.16.1.0 mask 255.255.255.0
router 3
router bgp 100
network 192.168.1.32 mask 255.255.255.224
2nd task:
ive configured a small network for using the 'as_path attribute' - but instead of configuring something simular to above 'mask' command ive done the following:
router 1
router bgp 300
no synchronization
neighbor 192.168.1.5 remote-as 100
neighbor 172.16.1.18 remote-as 65000
network 202.2.2.0
router 2
router bgp 100
no synchronization
neighbor 192.168.1.6 remote-as 300
network 201.1.1.0
router 3
router bgp 65000
no synchronization
neighbor 172.24.1.17 remote-as 300
network 203.3.3.0
question. i assume it is something to do with how ibgp & ebgp distinguish itself with 'bgp' as why step 2 does not use the 'mask' command ?
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ASKER
hi pergr, i have used a 'classful' address.!!!
question 1.
i responded on my last 'thread' about 'mask', but my query is ive used a 'classful mask', although you say 'mask' is supposed to be used as per below:
The "mask" part of the network statement is need only when you want to use a none "classful" mask. For example:
network 192.168.1.32 mask 255.255.255.224 - ?
question 1.
i responded on my last 'thread' about 'mask', but my query is ive used a 'classful mask', although you say 'mask' is supposed to be used as per below:
The "mask" part of the network statement is need only when you want to use a none "classful" mask. For example:
network 192.168.1.32 mask 255.255.255.224 - ?
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ASKER
hi,
oh ok so if 'no mask' command was added it would by default be taken as a classful mask .!!
so by myself using a 'classful address - 255.255.255.0 - ie adding this command statement are you saying it still reacts in the same manner & so it does need to be a 'classless address' to get the correct routing response ?
oh ok so if 'no mask' command was added it would by default be taken as a classful mask .!!
so by myself using a 'classful address - 255.255.255.0 - ie adding this command statement are you saying it still reacts in the same manner & so it does need to be a 'classless address' to get the correct routing response ?
Yes, for 192...., if you do not include a mask, it takes it as if you had entered a mask 255.255.255.0.
ASKER
ok i will need to make a note of this!!
ASKER
sound advice!!
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ASKER
i had previously configured the following for 'bgp'
- sanjose3 serial0 & 1 connected to isp1a & isp12
note: all 3 routers have separate 'as' numbers
- sanjose3 - loopbacks were set as 'network' statements:
network 192.168.0.0
network 192.168.1.0
- isp1a - loopback was set as 'network 12.0.1.0 mask 255.255.255.0
- isp2 - loopback was set as 'network 172.16.1.0 mask 255.255.255.0
"so when you say the below im not getting my head around it although i understand what you have said, unless it refers to not using loopbacks or something: uuuuum
The "mask" part of the network statement is need only when you want to use a none "classful" mask. For example:
network 192.168.1.32 mask 255.255.255.224
If you had not included the mask, the router would have assumed the mask was 255.255.255.0."