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pespin has posted comments on this change by pespin. ( https://gerrit.osmocom.org/c/osmo-ggsn/+/38457?usp=email )

Change subject: ggsn: Support announcing APN MTU over PCO ......................................................................

Patch Set 4:

(4 comments)

File ggsn/ggsn.h:

https://gerrit.osmocom.org/c/osmo-ggsn/+/38457/comment/e4591f7e_4f4da016?usp... : PS4, Line 36: #define IPV6_HDR_MAX_SIZE 40 /* Assume no extension headers in general... */

IPV6_HDR_MAX_SIZE < IPV4_HDR_MAX_SIZE, is this correct?

Yes because we assume no extension headers used by ipv6, while we account for maximum number of extension headers for ipv4.

File ggsn/ggsn_vty.c:

https://gerrit.osmocom.org/c/osmo-ggsn/+/38457/comment/bdfe5efe_40d5d22f?usp... : PS4, Line 425: "mtu (<0-1464>|default)",

maybe use MAX_POSSIBLE_APN_MTU instead of 1464 here?

It cannot be done, I already tried once. The preprocessor puts there the expression, not the result, hence not a number.

https://gerrit.osmocom.org/c/osmo-ggsn/+/38457/comment/bf4f1435_19dbf5d1?usp... : PS4, Line 428: "Default value of the MTU of the APN (1420)")

maybe use MAX_DESIRED_APN_MTU instead of 1420 here?

It cannot be done, I already tried once. The preprocessor puts there the expression, not the result, hence not a number.

https://gerrit.osmocom.org/c/osmo-ggsn/+/38457/comment/6f1ad165_7addd094?usp... : PS4, Line 708: vty_out(vty, " mtu %" PRIu16 "%s", apn->cfg.mtu, VTY_NEWLINE);

skip if == default?

I'd rather keep it like this, I think it's actually a good idea to always print it, the default is not obvious at all and may need some tweaking sometimes...