[69364] in North American Network Operators' Group
Re: BGP TTL check in 12.3(7)T
daemon@ATHENA.MIT.EDU (Iljitsch van Beijnum)
Thu Apr 8 13:37:34 2004
In-Reply-To: <5.1.0.14.2.20040408112953.00b0b618@max.att.net.il>
Cc: nanog@merit.edu
From: Iljitsch van Beijnum <iljitsch@muada.com>
Date: Thu, 8 Apr 2004 19:36:38 +0200
To: Hank Nussbacher <hank@att.net.il>
Errors-To: owner-nanog-outgoing@merit.edu
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?
