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Workaround for "check-fir...

Workaround for "check-first-as disable" on a peer level

Created: Mar 31, 2020 09:28:26Latest reply: Apr 1, 2020 02:56:02 658 4 0 0 0
  Rewarded HiCoins： 0 (problem resolved)
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The question relates to HUAWEI NE20E-S8 with VRP NE20E V800R008C10SPC500.


We're in a need to define the command "check-first-as disable" on a peer level, ex:


bgp XXX
  peer X.X.X.X check-first-as disable


The command is only available on bgp level, which is not acceptable for us.


The newer VRP versions, namely V800R010 support the command "check-first-as disable" on a peer level, but the downtime for VRP upgrade will be very costly.


Is there a workaround to this command in order to have the same effect on a per peer level?


Thank you.

NE20Echeck-first-asbgp

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(1) (0)
chenhui
Admin Created Apr 1, 2020 02:56:02

Hi @ispace,
I didn't find such command which only check the first AS for only one BGP peer.
But I thought out a indirect way to do that.
We can use the route-policy to filter the BGP update those first AS is same with the BGP peer's AS.
Kindly check the example below:
Topology: R1(AS 100)-----------R2(AS 200)----------R3(AS 200)

On R3, configure the route-policy as below to filter the BGP updates learned on R2 from R1.

R3:
#
route-policy chcek_as permit node 5
 if-match as-path-filter 10
#
ip as-path-filter 10 permit ^100
#


This route-policy allows only the BGP updates those AS start with 100.

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  • x
  • convention：

Recommended answer

(1) (0)
Popeye_Wang
Admin Created Mar 31, 2020 09:48:48

Hi,
According to the product documentation, the NE20E of V800R008 supports the check-first-as command but doesn't support the peer check-first-as command.

You can use the undo check-first-as command to disable the function for all peers.

https://support.huawei.com/hedex/hdx.do?docid=EDOC1000142113&id=check-first-as&lang=en


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ispace
ispace Created Mar 31, 2020 14:30:42 (0) (0)
Disabling it for all peers with "undo check-first-as" is not accetable, we only need per peer. Any other command that mimics the same function, available in NE20E of V800R008?  
All Answers
(0) (0)
2#
Steelblue
Steelblue Created Mar 31, 2020 09:34:47

Good question, waiting for replies. Workaround for
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  • convention：
(1) (0)
3#
Popeye_Wang
Popeye_Wang Admin Created Mar 31, 2020 09:48:48

Hi,
According to the product documentation, the NE20E of V800R008 supports the check-first-as command but doesn't support the peer check-first-as command.

You can use the undo check-first-as command to disable the function for all peers.

https://support.huawei.com/hedex/hdx.do?docid=EDOC1000142113&id=check-first-as&lang=en


View more
  • x
  • convention：

ispace
ispace Created Mar 31, 2020 14:30:42 (0) (0)
Disabling it for all peers with "undo check-first-as" is not accetable, we only need per peer. Any other command that mimics the same function, available in NE20E of V800R008?  
(1) (0)
4#
chenhui
chenhui Admin Created Apr 1, 2020 02:56:02

Hi @ispace,
I didn't find such command which only check the first AS for only one BGP peer.
But I thought out a indirect way to do that.
We can use the route-policy to filter the BGP update those first AS is same with the BGP peer's AS.
Kindly check the example below:
Topology: R1(AS 100)-----------R2(AS 200)----------R3(AS 200)

On R3, configure the route-policy as below to filter the BGP updates learned on R2 from R1.

R3:
#
route-policy chcek_as permit node 5
 if-match as-path-filter 10
#
ip as-path-filter 10 permit ^100
#


This route-policy allows only the BGP updates those AS start with 100.

View more
  • x
  • convention：
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