BGP TTL check in 12.3(7)T

Thu Apr 8 17:36:38 UTC 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?