Default TTL

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Mar 29th, 2010
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I've read in other posts here that Cisco devices start with TTL=255 in echo reply packets. Is this still true?

I'm troubleshooting a routing issue with several other autonomous systems/engineers. One engineer showed how a ping to one IP address has a TTL of 253 and a ping to the next hop down stream has a drastically different TTL of 126. The latter device is a Cisco 6500. The former is non-cisco, possibly Juniper.

1) Is there any way to get the Cat6k to show me TTL values?

2) Is it possible that the Cat6k is actually sending echo reply packets starting with TTL=128, instead of the 255 that my other research has indicated?


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milan.kulik Tue, 03/30/2010 - 00:40
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I just Pinged to a 6509.

It replied with a standard TTL=255.

Are you able to Ping from that Juniper to your 6500 directly?



b.gamble Fri, 04/02/2010 - 08:14
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I don't have access to the Juniper router. As well, troubleshooting has moved in a different direction so I'm not able to request that the other parties try that at this point.


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