pinging google

[CCIE Aspirant]

Hi all,

we have our remote office. The router is having IPsec tunnel to our main head office. All the traffic from the remote office is forwarded through the tunnel to head office router. The head office router is getting internet services from ISP 

Our Problem is that we can not ping 8.8.8.8 with size 1500 from the remote office the maximum size is 1000. 

Kindly needs solution for this matter.

[Flavio Miranda]

Hi

 ICMP is not fragmented. Either it is delivered or dropped.  For example, from my machine, right know, I can ping my default gateway with 1500 but I also can not pint google with 1500.

C:\Users\XX>ping 192.168.0.1 -l 1500

Disparando 192.168.0.1 com 1500 bytes de dados:
Resposta de 192.168.0.1: bytes=1500 tempo=1ms TTL=64
Resposta de 192.168.0.1: bytes=1500 tempo=2ms TTL=64
Resposta de 192.168.0.1: bytes=1500 tempo=2ms TTL=64

Estatísticas do Ping para 192.168.0.1:
Pacotes: Enviados = 3, Recebidos = 3, Perdidos = 0 (0% de

C:\Users\XX>ping 8.8.8.8 -l 1500

Disparando 8.8.8.8 com 1500 bytes de dados:
Esgotado o tempo limite do pedido.
Esgotado o tempo limite do pedido.
Esgotado o tempo limite do pedido.
Esgotado o tempo limite do pedido.

Estatísticas do Ping para 8.8.8.8:
Pacotes: Enviados = 4, Recebidos = 0, Perdidos = 4 (100% de
perda),

But I can Ping with 1472:

C:\Users\XX>ping 8.8.8.8 -l 1472

Disparando 8.8.8.8 com 1472 bytes de dados:
Resposta de 8.8.8.8: bytes=68 (enviado 1472) tempo=12ms TTL=58
Resposta de 8.8.8.8: bytes=68 (enviado 1472) tempo=13ms TTL=58

Estatísticas do Ping para 8.8.8.8:
Pacotes: Enviados = 2, Recebidos = 2, Perdidos = 0 (0% de
perda),
Aproximar um número redondo de vezes em milissegundos:
Mínimo = 12ms, Máximo = 13ms, Média = 12ms
Control-C
^C
C:\Users\XX>ping 8.8.8.8 -l 1473

Disparando 8.8.8.8 com 1473 bytes de dados:
Esgotado o tempo limite do pedido.
Esgotado o tempo limite do pedido.
Esgotado o tempo limite do pedido.
Esgotado o tempo limite do pedido.

Estatísticas do Ping para 8.8.8.8:
Pacotes: Enviados = 4, Recebidos = 0, Perdidos = 4 (100% de
perda),

My advise is, try to use another protocol for your tests. ICMP can take you in the wrong direction for this tests.

[CCIE Aspirant]

Thanks for the reply,

what other way to check from our remote office that we can ping google with 1500 size?

[Flavio Miranda]

But you can´t ping google with 1500. I just proved it using my own machine and internet link. 

If you want to test your link, you can use different protocol or destination. Why do you need to ping google with 1500?

[CCIE Aspirant]

This is our requirement from our remote office. we achieved to Ping with size 1336 but can not make more then that.

[Flavio Miranda]

Probably due the reason I mentiined above about fragmentarion.

 As ICMP is not fragmented and the link between you and Google has different mtu sizes, you got dropped. 

[Flavio Miranda]

Probably due the reason I mentiined above about fragmentarion.

 As ICMP is not fragmented and the link between you and Google has different mtu sizes, you got dropped

[CCIE Aspirant]

so how I can resolve this issue? we need a solution for this problem.

thanks

[Kasun Bandara]

Its not an issue. the devices between you and google may have custom max MTUs. you dont have a control on that.

[CCIE Aspirant]

Thanks for the reply,

but i have seen ping to google with size of 1500 and getting reply. so my question is that what changes i need to do and where so that we can achieve it?

[MHM Cisco World]

Your packet is U-trun in head office, 
this mean that it appear that head office is ping not remote site, 
so when you ping packet is U-trun in head office and head office config low mtg value "this value may recommend from ISP head office connect" then the MTU of whole path will be the MTU head office not remote side. 

[CCIE Aspirant]

but when i change the mtu at remote side to value more then 1398, then I can not ping head office router with size 1500. so that is why i have to select lower value then 1398.

[Flavio Miranda]

What you are trying to do? Measure latency? Capacity?

 Probaly there are Better way to that. 

[CCIE Aspirant]

we are trying to make connection with one of our servers in UAE and it needs to ping google with 1500 size. this requirement is strange for us but we need to have some solution for it.

[Flavio Miranda]

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Must be some aplication. Weid they test to Google DNS with 1500 bytes.