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Re: BGP TTL check in 12.3(7)T

  • From: Iljitsch van Beijnum
  • Date: Thu Apr 08 13:39:09 2004 
On 8-apr-04, at 11:30, Hank Nussbacher wrote:
<http://www.cisco.com/en/US/products/sw/iosswrel/ps5207/ prod_bulletin09186a00801abfda.html#wp55584>


Not bad - Feb 2003 till April 2004 to code, test and implement a
change driven by NANOG :-)



Here is the feature guide, for those who can't wait to implement it:

http://www.cisco.com/en/US/products/sw/iosswrel/ps1829/
products_feature_guide09186a008020e6f5.html



However, this says a TTL of 254 will be accepted. Now the fact that I
can talk to boxes running a slightly older IOS with a TTL of 0 without
any problems suggests to me that emitting packets with a TTL of 255 on
router A and accepting packets with a TTL of 254 on router B allows for
the presence of a router C in the middle. That can't be good.



Also, they say enabling this feature won't change behavior for outgoing
packets. So do these now have a TTL of 255, regardless?