Solved by changing the value of "/ proc / sys / net / core / optmem_max" to "101120".
Thank you for giving me a hand.

Hello!
Have you tried to use the workaround mentioned here?

https://bird.network.cz/pipermail/bird-users/2015-August/009882.html

Maria

On December 25, 2019 9:59:30 AM GMT+01:00, "穴澤 正恒" <ma-anazawa@hoster.jp> wrote:

Dear all,

My name is Masatsune Anazawa, an affiliate of JPIX.
We are verifying the root server that is being considered for 
installation on JPIX.
When MD5 authentication is performed on bird and 1000 peers are set, the 
following error occurs and only 150 to 300 peers can be established.
Please let me know if there is a solution.

I’m looking forward to your reply.

/var/log/messages
Dec 18 16:23:28 rs-bird bird: AS2855_IPv6: Socket error: TCP_MD5SIG: 
Cannot allocate memory
Dec 18 16:23:28 rs-bird bird: AS2854_IPv6: Socket error: TCP_MD5SIG: 
Cannot allocate memory
Dec 18 16:23:28 rs-bird bird: AS2853_IPv6: Socket error: TCP_MD5SIG: 
Cannot allocate memory
Dec 18 16:23:28 rs-bird bird: AS2852_IPv6: Socket error: TCP_MD5SIG: 
Cannot allocate memory
Dec 18 16:23:28 rs-bird bird: AS2851_IPv6: Socket error: TCP_MD5SIG: 
Cannot allocate memory
Dec 18 16:23:28 rs-bird bird: AS2850_IPv6: Socket error: TCP_MD5SIG: 
Cannot allocate memory
Dec 18 16:23:28 rs-bird bird: AS2849_IPv6: Socket error: TCP_MD5SIG: 
Cannot allocate memory
Dec 18 16:23:28 rs-bird bird: AS2848_IPv6: Socket error: TCP_MD5SIG: 
Cannot allocate memory
Dec 18 16:23:28 rs-bird bird: AS2847_IPv6: Socket error: TCP_MD5SIG: 
Cannot allocate memory
Dec 18 16:23:28 rs-bird bird: AS2846_IPv6: Socket error: TCP_MD5SIG: 
Cannot allocate memory
Dec 18 16:23:28 rs-bird bird: AS2845_IPv6: Socket error: TCP_MD5SIG: 
Cannot allocate memory
Dec 18 16:23:28 rs-bird bird: AS2844_IPv6: Socket error: TCP_MD5SIG: 
Cannot allocate memory
Dec 18 16:23:28 rs-bird bird: AS2843_IPv6: Socket error: TCP_MD5SIG: 
Cannot allocate memory
Dec 18 16:23:28 rs-bird bird: AS2842_IPv6: Socket error: TCP_MD5SIG: 
Cannot allocate memory
Dec 18 16:23:28 rs-bird bird: AS2841_IPv6: Socket error: TCP_MD5SIG: 
Cannot allocate memory
Dec 18 16:23:28 rs-bird bird: AS2840_IPv6: Socket error: TCP_MD5SIG: 
Cannot allocate memory
Dec 18 16:23:28 rs-bird bird: AS2839_IPv6: Socket error: TCP_MD5SIG: 
Cannot allocate memory
Dec 18 16:23:28 rs-bird bird: AS2838_IPv6: Socket error: TCP_MD5SIG: 
Cannot allocate memory
-- 
株式会社 Hoster-JP (HJP)

Masatsune Anazawa (穴澤　正恒)
http://www.hoster.jp
Mail: ma-anazawa@hoster.jp
TEL: 03-5977-0888
FAX：03-5977-0887

113-0021
東京都文京区本駒込6-5-3 ビューネ本駒込3F

--
Sent from my Android device with K-9 Mail. Please excuse my brevity.

-- 
-----------------------------------------
株式会社 Hoster-JP (HJP)

Masatsune Anazawa (穴澤　正恒)
http://www.hoster.jp
Mail: ma-anazawa@hoster.jp   
TEL: 03-5977-0888
FAX：03-5977-0887

113-0021
東京都文京区本駒込6-5-3 ビューネ本駒込3F
-----------------------------------------